audioloudnorm.rs 70.7 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448
// Copyright (C) 2019-2020 Sebastian Dröge <sebastian@centricular.com>
//
// Audio processing part of this file ported from ffmpeg/libavfilter/af_loudnorm.c
//
// Copyright (c) 2016 Kyle Swanson <k@ylo.ph>
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// FFmpeg is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with FFmpeg; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

use glib::subclass;
use glib::subclass::prelude::*;
use gst::prelude::*;
use gst::subclass::prelude::*;

use std::mem;
use std::sync::Mutex;
use std::{i32, u64};

use byte_slice_cast::*;

lazy_static! {
    static ref CAT: gst::DebugCategory = gst::DebugCategory::new(
        "rsaudioloudnorm",
        gst::DebugColorFlags::empty(),
        Some("Rust Audio Loudless Normalization Filter"),
    );
}

const DEFAULT_LOUDNESS_TARGET: f64 = -24.0;
const DEFAULT_LOUDNESS_RANGE_TARGET: f64 = 7.0;
const DEFAULT_MAX_TRUE_PEAK: f64 = -2.0;
const DEFAULT_OFFSET: f64 = 0.0;

#[derive(Debug, Clone, Copy)]
struct Settings {
    pub loudness_target: f64,
    pub loudness_range_target: f64,
    pub max_true_peak: f64,
    pub offset: f64,
}

impl Default for Settings {
    fn default() -> Self {
        Settings {
            loudness_target: DEFAULT_LOUDNESS_TARGET,
            loudness_range_target: DEFAULT_LOUDNESS_RANGE_TARGET,
            max_true_peak: DEFAULT_MAX_TRUE_PEAK,
            offset: DEFAULT_OFFSET,
        }
    }
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum FrameType {
    First,
    Inner,
    Final,
    Linear,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum LimiterState {
    Out,
    Attack,
    Sustain,
    Release,
}

struct State {
    info: gst_audio::AudioInfo,
    adapter: gst_base::UniqueAdapter,

    // Current amount of sample we consume per iteration: for the first frame 3s, afterwards 100ms
    current_samples_per_frame: usize,

    // Settings during setup
    offset: f64,
    target_i: f64,
    target_lra: f64,
    target_tp: f64,

    // Input ringbuffer for loudness analysis
    // TODO: Convert to a proper ringbuffer
    buf: Box<[f64]>,
    // read index
    buf_index: usize,
    // write index (always 210ms from buf_index)
    prev_buf_index: usize,

    // Gaussian filter for gains
    // TODO: These are actually constant. Once `for` is allowed
    // in `const fn` we can make them proper constants.
    weights: [f64; 21],
    // TODO: Convert to a proper ringbuffer
    delta: [f64; 30],
    index: usize,
    prev_delta: f64,

    // Limiter
    gain_reduction: [f64; 2],
    // TODO: Convert to a proper ringbuffer
    limiter_buf: Box<[f64]>,
    // Read/write index, depending on context
    limiter_buf_index: usize,
    // Previous sample (potentially of the previous frame) used for detecting peaks in the limiter
    prev_smp: Box<[f64]>,
    limiter_state: LimiterState,
    // During attack/release state, the position in the corresponding window
    env_cnt: usize,
    // Number of samples to sustain at the beginning of the sustain state, if any
    sustain_cnt: Option<usize>,

    frame_type: FrameType,
    above_threshold: bool,

    // Input loudness calculation
    r128_in: ebur128::EbuR128,
    // Actual output loudness calculation
    r128_out: ebur128::EbuR128,
}

impl State {
    fn new(settings: &Settings, info: gst_audio::AudioInfo) -> Self {
        let r128_in = ebur128::EbuR128::new(
            info.channels(),
            info.rate(),
            ebur128::Mode::HISTOGRAM
                | ebur128::Mode::I
                | ebur128::Mode::S
                | ebur128::Mode::LRA
                | ebur128::Mode::SAMPLE_PEAK,
        )
        .unwrap();
        let r128_out = ebur128::EbuR128::new(
            info.channels(),
            info.rate(),
            ebur128::Mode::HISTOGRAM
                | ebur128::Mode::I
                | ebur128::Mode::S
                | ebur128::Mode::LRA
                | ebur128::Mode::SAMPLE_PEAK,
        )
        .unwrap();

        let buf_size = GAIN_LOOKAHEAD * info.channels() as usize;
        let buf = vec![0.0; buf_size].into_boxed_slice();

        let limiter_buf_size = (2 * FRAME_SIZE + LIMITER_LOOKAHEAD) * info.channels() as usize;
        let limiter_buf = vec![0.0; limiter_buf_size].into_boxed_slice();

        let prev_smp = vec![0.0; info.channels() as usize].into_boxed_slice();

        let current_samples_per_frame = GAIN_LOOKAHEAD;

        let buf_index = 0;
        let prev_buf_index = 0;
        let limiter_buf_index = 0;
        let index = 1;
        let limiter_state = LimiterState::Out;
        let offset = f64::powf(10., settings.offset / 20.);
        let target_tp = f64::powf(10., settings.max_true_peak / 20.);

        State {
            info,
            adapter: gst_base::UniqueAdapter::new(),
            current_samples_per_frame,
            offset,
            target_i: settings.loudness_target,
            target_lra: settings.loudness_range_target,
            target_tp,
            buf,
            buf_index,
            prev_buf_index,
            delta: [0.0; 30],
            weights: init_gaussian_filter(),
            prev_delta: 0.0,
            index,
            gain_reduction: [0.0; 2],
            limiter_buf,
            prev_smp,
            limiter_buf_index,
            limiter_state,
            env_cnt: 0,
            sustain_cnt: None,
            frame_type: FrameType::First,
            above_threshold: false,
            r128_in,
            r128_out,
        }
    }
}

struct AudioLoudNorm {
    srcpad: gst::Pad,
    sinkpad: gst::Pad,
    settings: Mutex<Settings>,
    state: Mutex<Option<State>>,
}

static PROPERTIES: [subclass::Property; 4] = [
    subclass::Property("loudness-target", |name| {
        glib::ParamSpec::double(
            name,
            "Loudness Target",
            "Loudness target in LUFS",
            -70.0,
            -5.0,
            DEFAULT_LOUDNESS_TARGET,
            glib::ParamFlags::READWRITE,
        )
    }),
    subclass::Property("loudness-range-target", |name| {
        glib::ParamSpec::double(
            name,
            "Loudness Range Target",
            "Loudness range target in LU",
            1.0,
            20.0,
            DEFAULT_LOUDNESS_RANGE_TARGET,
            glib::ParamFlags::READWRITE,
        )
    }),
    subclass::Property("max-true-peak", |name| {
        glib::ParamSpec::double(
            name,
            "Maximum True Peak",
            "Maximum True Peak in dbTP",
            -9.0,
            0.0,
            DEFAULT_MAX_TRUE_PEAK,
            glib::ParamFlags::READWRITE,
        )
    }),
    subclass::Property("offset", |name| {
        glib::ParamSpec::double(
            name,
            "Offset Gain",
            "Offset Gain in LU",
            -99.0,
            99.0,
            DEFAULT_OFFSET,
            glib::ParamFlags::READWRITE,
        )
    }),
];

// Gain analysis parameters
const GAIN_LOOKAHEAD: usize = 3 * 192_000; // 3s
const FRAME_SIZE: usize = 19_200; // 100ms

// Limiter parameters
const LIMITER_ATTACK_WINDOW: usize = 1920; // 10ms
const LIMITER_RELEASE_WINDOW: usize = 19_200; // 100ms
const LIMITER_LOOKAHEAD: usize = 1920; // 10ms

impl State {
    // Drains all full frames that are currently in the adapter
    fn drain_full_frames(
        &mut self,
        element: &gst::Element,
    ) -> Result<Vec<gst::Buffer>, gst::FlowError> {
        let mut outbufs = vec![];
        while self.adapter.available() >= self.info.bpf() as usize * self.current_samples_per_frame
        {
            let (pts, distance) = self.adapter.prev_pts();
            let distance_samples = distance / self.info.bpf() as u64;
            let pts = pts
                + gst::ClockTime::from(
                    distance_samples.mul_div_floor(gst::SECOND_VAL, self.info.rate() as u64),
                );

            let inbuf = self
                .adapter
                .take_buffer(self.info.bpf() as usize * self.current_samples_per_frame)
                .unwrap();
            let src = inbuf.map_readable().map_err(|_| gst::FlowError::Error)?;
            let src = src
                .as_slice_of::<f64>()
                .map_err(|_| gst::FlowError::Error)?;

            let (mut outbuf, pts) = self.process(element, src, pts)?;

            {
                let outbuf = outbuf.get_mut().unwrap();
                outbuf.set_pts(pts);
                outbuf.set_duration(
                    (outbuf.get_size() as u64)
                        .mul_div_floor(gst::SECOND_VAL, (self.info.bpf() * self.info.rate()) as u64)
                        .into(),
                );
            }

            outbufs.push(outbuf);
        }

        Ok(outbufs)
    }

    // Drains everything
    fn drain(&mut self, element: &gst::Element) -> Result<gst::Buffer, gst::FlowError> {
        gst_debug!(CAT, obj: element, "Draining");

        let (pts, distance) = self.adapter.prev_pts();
        let distance_samples = distance / self.info.bpf() as u64;
        let pts = pts
            + gst::ClockTime::from(
                distance_samples.mul_div_floor(gst::SECOND_VAL, self.info.rate() as u64),
            );

        let mut _mapped_inbuf = None;
        let src = if self.adapter.available() > 0 {
            let inbuf = self.adapter.take_buffer(self.adapter.available()).unwrap();

            let inbuf = inbuf
                .into_mapped_buffer_readable()
                .map_err(|_| gst::FlowError::Error)?;

            _mapped_inbuf = Some(inbuf);
            _mapped_inbuf
                .as_ref()
                .unwrap()
                .as_slice_of::<f64>()
                .map_err(|_| gst::FlowError::Error)?
        } else {
            &[]
        };

        // If we already output something before then we go into final frame processing, otherwise
        // we drain any data we still have by doing linear processing.
        if self.current_samples_per_frame == FRAME_SIZE {
            self.frame_type = FrameType::Final;
        } else if src.is_empty() {
            // Nothing to drain at all
            gst_debug!(CAT, obj: element, "No data to drain");
            return Err(gst::FlowError::Eos);
        }

        let (mut outbuf, pts) = self.process(element, src, pts)?;

        {
            let outbuf = outbuf.get_mut().unwrap();
            outbuf.set_pts(pts);
            outbuf.set_duration(
                (outbuf.get_size() as u64)
                    .mul_div_floor(gst::SECOND_VAL, (self.info.bpf() * self.info.rate()) as u64)
                    .into(),
            );
        }

        Ok(outbuf)
    }

    fn process_first_frame_is_last(
        &mut self,
        element: &gst::Element,
    ) -> Result<(), gst::FlowError> {
        // Calculated loudness in LUFS
        let global = self
            .r128_in
            .loudness_global()
            .map_err(|_| gst::FlowError::Error)?;

        // Peak sample value for all changes
        let mut true_peak = 0.0;
        for c in 0..(self.info.channels()) {
            let peak = self
                .r128_in
                .sample_peak(c)
                .map_err(|_| gst::FlowError::Error)?;
            if c == 0 || peak > true_peak {
                true_peak = peak;
            }
        }

        gst_debug!(
            CAT,
            obj: element,
            "Calculated global loudness for first frame {} with peak {}",
            global,
            true_peak
        );

        // Difference between targetted and calculated LUFS loudness as a linear scalefactor.
        let offset = f64::powf(10., (self.target_i - global) / 20.);
        // What the new peak would be after adjusting for the targetted loudness.
        let offset_tp = true_peak * offset;

        // If the new peak would be more quiet than targeted one, take it. Otherwise only go as
        // high as the true peak allows.
        self.offset = if offset_tp < self.target_tp {
            offset
        } else {
            self.target_tp / true_peak
        };

        self.frame_type = FrameType::Linear;

        Ok(())
    }

    fn process_first_frame(
        &mut self,
        element: &gst::Element,
        src: &[f64],
        pts: gst::ClockTime,
    ) -> Result<(gst::Buffer, gst::ClockTime), gst::FlowError> {
        // Fill our whole buffer here with the initial input, i.e. 3000ms of samples.
        self.buf.copy_from_slice(src);

        // Calculate the shortterm loudness in LUFS.
        let shortterm = self
            .r128_in
            .loudness_shortterm()
            .map_err(|_| gst::FlowError::Error)?;

        let env_shortterm = if shortterm < -70.0 {
            self.above_threshold = false;
            0.
        } else {
            self.above_threshold = true;
            self.target_i - shortterm
        };

        // Initialize with linear scale factor for reaching the target loudness.
        for delta in self.delta.iter_mut() {
            *delta = f64::powf(10.0, env_shortterm / 20.);
        }
        self.prev_delta = self.delta[self.index];
        gst_debug!(
            CAT,
            obj: element,
            "Initializing for first frame with gain adjustment of {}",
            self.prev_delta
        );

        // Fill the whole limiter_buf with the gain corrected first part of the buffered
        // input, i.e. 210ms. 100ms for the current frame plus 100ms lookahead for the
449 450 451
        // limiter with the next frame plus 10ms in addition because the limiter would
        // look a few samples further when detecting a peak to make sure no higher values
        // are following.
452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070
        for (limiter_buf, sample) in self.limiter_buf.iter_mut().zip(self.buf.iter()) {
            *limiter_buf = sample * self.prev_delta * self.offset;
        }

        // Read position of the buffer is now advanced.
        self.buf_index = self.limiter_buf.len();

        // Write position of the limiter_buf is at the beginning still. We consume
        // the first 100ms of it below directly so that the next iteration will
        // overwrite these 100ms directly.
        self.limiter_buf_index = 0;

        let mut outbuf = gst::Buffer::with_size(FRAME_SIZE * self.info.bpf() as usize)
            .map_err(|_| gst::FlowError::Error)?;
        {
            let outbuf = outbuf.get_mut().unwrap();
            let mut dst = outbuf.map_writable().map_err(|_| gst::FlowError::Error)?;
            let dst = dst
                .as_mut_slice_of::<f64>()
                .map_err(|_| gst::FlowError::Error)?;
            // This now consumes the first 100ms of limiter_buf for the output.
            self.true_peak_limiter(element, dst);
            self.r128_out
                .add_frames_f64(dst)
                .map_err(|_| gst::FlowError::Error)?;
        }

        // From now on we consume 100ms input frames and output 100ms.
        self.current_samples_per_frame = FRAME_SIZE;
        self.frame_type = FrameType::Inner;

        // PTS is the input PTS for the first frame, we output the first 100ms of the input
        // buffer here
        Ok((outbuf, pts))
    }

    fn process_fill_inner_frame(&mut self, element: &gst::Element, src: &[f64]) {
        // Get gain for this and the next 100ms frame based the delta array
        // and smoothened with a gaussian filter.
        let gain = self.gaussian_filter(if self.index + 10 < 30 {
            self.index + 10
        } else {
            self.index + 10 - 30
        });
        let gain_next = self.gaussian_filter(if self.index + 11 < 30 {
            self.index + 11
        } else {
            self.index + 11 - 30
        });

        gst_debug!(
            CAT,
            obj: element,
            "Applying gain adjustment {}-{}",
            gain,
            gain_next
        );

        // Overwrite the first 100ms of the limiter_buf with the gain corrected 100ms of
        // buf. This is correct because either above (for the first frame) or in the
        // previous iteration here we already have output these 100ms.
        //
        // Also fill 100ms of buf with the 100ms of new input at the same time.
        let channels = self.info.channels() as usize;
        assert!(src.len() / channels <= FRAME_SIZE);
        for (n, samples) in src.chunks_exact(channels).enumerate() {
            // Safety: Index ranges are checked below and both slices from buf are
            // guaranteed to be non-overlapping (210ms limiter_buf difference).
            let (buf_read, buf_write, limiter_buf) = unsafe {
                let buf = &mut &mut *self.buf as *mut &mut [f64];
                let buf_read = (*buf).get_unchecked(self.buf_index..(self.buf_index + channels));
                let buf_write =
                    (*buf).get_unchecked_mut(self.prev_buf_index..(self.prev_buf_index + channels));
                let limiter_buf = self
                    .limiter_buf
                    .get_unchecked_mut(self.limiter_buf_index..(self.limiter_buf_index + channels));

                (buf_read, buf_write, limiter_buf)
            };

            buf_write.copy_from_slice(samples);

            // Linearly interpolate between the current and next gain for each sample.
            let current_gain =
                (gain + ((n as f64 / FRAME_SIZE as f64) * (gain_next - gain))) * self.offset;
            for (o, i) in limiter_buf.iter_mut().zip(buf_read.iter()) {
                *o = *i * current_gain;
            }

            self.limiter_buf_index += channels;
            if self.limiter_buf_index >= self.limiter_buf.len() {
                self.limiter_buf_index -= self.limiter_buf.len();
            }

            self.prev_buf_index += channels;
            if self.prev_buf_index >= self.buf.len() {
                self.prev_buf_index -= self.buf.len();
            }

            self.buf_index += channels;
            if self.buf_index >= self.buf.len() {
                self.buf_index -= self.buf.len();
            }
        }
    }

    fn process_update_gain_inner_frame(
        &mut self,
        element: &gst::Element,
    ) -> Result<(), gst::FlowError> {
        // Calculate global, shortterm loudness and relative threshold in LUFS.
        let global = self
            .r128_in
            .loudness_global()
            .map_err(|_| gst::FlowError::Error)?;
        let shortterm = self
            .r128_in
            .loudness_shortterm()
            .map_err(|_| gst::FlowError::Error)?;
        let relative_threshold = self
            .r128_in
            .relative_threshold()
            .map_err(|_| gst::FlowError::Error)?;

        gst_debug!(
            CAT,
            obj: element,
            "Calculated global loudness {}, short term loudness {} and relative threshold {}",
            global,
            shortterm,
            relative_threshold
        );

        // If we were previously not above the threshold but are now above in the
        // shortterm, slightly increase the scale factor. If the shortterm output was above
        // the target then also consider this frame above threshold.
        if !self.above_threshold {
            if shortterm > -70.0 {
                self.prev_delta *= 1.0058;
            }

            let shortterm_out = self
                .r128_out
                .loudness_shortterm()
                .map_err(|_| gst::FlowError::Error)?;
            if shortterm_out >= self.target_i {
                self.above_threshold = true;
                gst_debug!(
                    CAT,
                    obj: element,
                    "Above threshold now ({} >= {}, {} > -70)",
                    shortterm_out,
                    self.target_i,
                    shortterm
                );
            }
        }

        // If we're still below the threshold, continue using the previous delta. Otherwise
        // calculate a new one.
        if shortterm < relative_threshold || shortterm <= -70. || !self.above_threshold {
            self.delta[self.index] = self.prev_delta;
        } else {
            let env_global = if (shortterm - global).abs() < (self.target_lra / 2.) {
                shortterm - global
            } else if (self.target_lra / 2.) * (shortterm - global) < 0.0 {
                -1.
            } else {
                1.
            };
            let env_shortterm = self.target_i - shortterm;
            self.delta[self.index] = f64::powf(10., (env_global + env_shortterm) / 20.);
        }

        self.prev_delta = self.delta[self.index];
        gst_debug!(
            CAT,
            obj: element,
            "Calculated new gain adjustment {}",
            self.prev_delta
        );

        self.index += 1;
        if self.index >= 30 {
            self.index -= 30;
        }

        Ok(())
    }

    fn process_inner_frame(
        &mut self,
        element: &gst::Element,
        src: &[f64],
        pts: gst::ClockTime,
    ) -> Result<(gst::Buffer, gst::ClockTime), gst::FlowError> {
        // Fill in these 100ms and adjust its gain according to previous measurements, and
        // at the same time copy 100ms over to the limiter_buf.
        self.process_fill_inner_frame(element, src);

        // limiter_buf_index was 100ms advanced above, which brings us to exactly the
        // position where we have to start consuming 100ms for the output now, and exactly
        // the position where we have to start writing the next 100ms in the next
        // iteration.

        let mut outbuf = gst::Buffer::with_size(
            self.current_samples_per_frame as usize * self.info.bpf() as usize,
        )
        .map_err(|_| gst::FlowError::Error)?;
        {
            let outbuf = outbuf.get_mut().unwrap();
            let mut dst = outbuf.map_writable().map_err(|_| gst::FlowError::Error)?;
            let dst = dst
                .as_mut_slice_of::<f64>()
                .map_err(|_| gst::FlowError::Error)?;
            // This now consumes the next 100ms of limiter_buf for the output.
            self.true_peak_limiter(element, dst);
            self.r128_out
                .add_frames_f64(dst)
                .map_err(|_| gst::FlowError::Error)?;
        }

        self.process_update_gain_inner_frame(element)?;

        // PTS is 2.9s seconds before the input PTS as we buffer 3s of samples and just
        // outputted here the first 100ms of that.
        let pts = pts + 100 * gst::MSECOND - 3 * gst::SECOND;
        Ok((outbuf, pts))
    }

    fn process_fill_final_frame(
        &mut self,
        _element: &gst::Element,
        idx: usize,
        num_samples: usize,
    ) {
        let channels = self.info.channels() as usize;

        // Get gain for this and the next 100ms frame based the delta array
        // and smoothened with a gaussian filter.
        let gain = self.gaussian_filter(if self.index + 10 < 30 {
            self.index + 10
        } else {
            self.index + 10 - 30
        });
        let gain_next = self.gaussian_filter(if self.index + 11 < 30 {
            self.index + 11
        } else {
            self.index + 11 - 30
        });

        for n in idx..num_samples {
            // Safety: Index ranges are checked below.
            let (buf_read, limiter_buf) = unsafe {
                let buf_read = self
                    .buf
                    .get_unchecked(self.buf_index..(self.buf_index + channels));
                let limiter_buf = self
                    .limiter_buf
                    .get_unchecked_mut(self.limiter_buf_index..(self.limiter_buf_index + channels));

                (buf_read, limiter_buf)
            };

            // Linearly interpolate between the current and next gain for each sample.
            let current_gain =
                (gain + ((n as f64 / num_samples as f64) * (gain_next - gain))) * self.offset;
            for (o, i) in limiter_buf.iter_mut().zip(buf_read.iter()) {
                *o = *i * current_gain;
            }

            self.limiter_buf_index += channels;
            if self.limiter_buf_index >= self.limiter_buf.len() {
                self.limiter_buf_index -= self.limiter_buf.len();
            }

            self.buf_index += channels;
            if self.buf_index >= self.buf.len() {
                self.buf_index -= self.buf.len();
            }
        }
    }

    fn process_final_frame(
        &mut self,
        element: &gst::Element,
        src: &[f64],
        pts: gst::ClockTime,
    ) -> Result<(gst::Buffer, gst::ClockTime), gst::FlowError> {
        let channels = self.info.channels() as usize;
        let num_samples = src.len() / channels;

        // First process any new/leftover data we get passed. This is the same
        // as for inner frames. After this we will have done all gain adjustments
        // and all samples we ever output are in buf or limiter_buf.
        self.process_fill_inner_frame(element, src);

        // If we got passed less than 100ms in src then limiter_buf_index is now
        // not yet at the correct read position! Adjust accordingly here so that all
        // further reads come from the right position by copying over the next samples
        // from buf.
        if num_samples != FRAME_SIZE {
            self.process_fill_final_frame(element, num_samples, FRAME_SIZE);
        }

        // Now repeatadly run the limiter, output the output gain, update the gains, copy further
        // data from the buf to limiter_buf until we have output everything.
        //
        // At this point we have to output 3s - (FRAME_SIZE - num_samples)
        // buf.
        let out_num_samples = 30 * FRAME_SIZE - (FRAME_SIZE - num_samples);

        let mut outbuf = gst::Buffer::with_size(out_num_samples * self.info.bpf() as usize)
            .map_err(|_| gst::FlowError::Error)?;
        {
            let outbuf = outbuf.get_mut().unwrap();
            let mut dst = outbuf.map_writable().map_err(|_| gst::FlowError::Error)?;
            let dst = dst
                .as_mut_slice_of::<f64>()
                .map_err(|_| gst::FlowError::Error)?;
            let mut smp_cnt = 0;
            while smp_cnt < out_num_samples {
                let frame_size = std::cmp::min(out_num_samples - smp_cnt, FRAME_SIZE);
                let dst = &mut dst[(smp_cnt * channels)..((smp_cnt + frame_size) * channels)];

                // This now consumes the next frame_size samples of limiter_buf for the output.
                // Note that on the very last call this will read up to 10ms of old limiter_buf
                // data but as this was already processed it will not find any peak in there and
                // just pass through.
                //if frame_size < FRAME_SIZE {
                //    self.limiter_buf_index += FRAME_SIZE - num_samples;
                //}

                self.true_peak_limiter(element, dst);

                smp_cnt += frame_size;
                if smp_cnt == out_num_samples {
                    break;
                }

                // Update the gain for the next iteration
                self.r128_out
                    .add_frames_f64(dst)
                    .map_err(|_| gst::FlowError::Error)?;
                self.process_update_gain_inner_frame(element)?;

                // And now copy over the next block of samples from buf to limiter_buf
                let next_frame_size = std::cmp::min(out_num_samples - smp_cnt, FRAME_SIZE);
                self.process_fill_final_frame(element, 0, next_frame_size);

                // Now for the very last frame we need to update the limiter buffer index by the
                // amount of samples the last frame is short to reach the correct read position.
                if next_frame_size < FRAME_SIZE {
                    self.limiter_buf_index += FRAME_SIZE - next_frame_size;
                    if self.limiter_buf_index > self.limiter_buf.len() {
                        self.limiter_buf_index -= self.limiter_buf.len();
                    }
                }
            }
        }

        // PTS is 2.9s seconds before the input PTS as we buffer 3s of samples and just
        // outputted here the first 100ms of that.
        let pts = pts + 100 * gst::MSECOND - 3 * gst::SECOND;
        Ok((outbuf, pts))
    }

    fn process_linear_frame(
        &mut self,
        element: &gst::Element,
        src: &[f64],
        pts: gst::ClockTime,
    ) -> Result<(gst::Buffer, gst::ClockTime), gst::FlowError> {
        // Apply a linear scale factor to the whole buffer

        gst_debug!(
            CAT,
            obj: element,
            "Applying linear gain adjustment of {}",
            self.offset
        );

        let mut outbuf = gst::Buffer::with_size(src.len() * mem::size_of::<f64>())
            .map_err(|_| gst::FlowError::Error)?;
        {
            let outbuf = outbuf.get_mut().unwrap();
            let mut dst = outbuf.map_writable().map_err(|_| gst::FlowError::Error)?;
            let dst = dst
                .as_mut_slice_of::<f64>()
                .map_err(|_| gst::FlowError::Error)?;

            for (o, i) in dst.iter_mut().zip(src.iter()) {
                *o = *i * self.offset;
            }

            self.r128_out
                .add_frames_f64(dst)
                .map_err(|_| gst::FlowError::Error)?;
        }

        // PTS is input PTS as we just pass through the data without latency.
        Ok((outbuf, pts))
    }

    fn process(
        &mut self,
        element: &gst::Element,
        src: &[f64],
        pts: gst::ClockTime,
    ) -> Result<(gst::Buffer, gst::ClockTime), gst::FlowError> {
        self.r128_in
            .add_frames_f64(src)
            .map_err(|_| gst::FlowError::Error)?;

        // If we are at the end and had less than 3s of samples overall, do simple linear volume
        // adjustment. frame_type should only ever be set to Final at the end if we ended up in
        // Inner state before.
        if self.frame_type == FrameType::First
            && (src.len() / self.info.channels() as usize) < self.current_samples_per_frame as usize
        {
            self.process_first_frame_is_last(element)?;
        }

        match self.frame_type {
            FrameType::First => self.process_first_frame(element, src, pts),
            FrameType::Inner => self.process_inner_frame(element, src, pts),
            FrameType::Final => self.process_final_frame(element, src, pts),
            FrameType::Linear => self.process_linear_frame(element, src, pts),
        }
    }

    fn true_peak_limiter_out(
        &mut self,
        element: &gst::Element,
        mut smp_cnt: usize,
        nb_samples: usize,
    ) -> usize {
        // Default out state, check if we have a new peak to act on in the next frame
        // and otherwise simply output all samples with the current gain adjustment.
        let peak = self.detect_peak(smp_cnt, nb_samples - smp_cnt);

        if let Some((peak_delta, peak_value)) = peak {
            self.limiter_state = LimiterState::Attack;
            self.env_cnt = 0;
            self.sustain_cnt = None;
            self.gain_reduction[0] = 1.;
            self.gain_reduction[1] = self.target_tp / peak_value;

            // Skip all samples that don't have to be adjusted because the peak is far
            // enough in the future.
            // Note: peak_delta=0 is LIMITER_LOOKAHEAD in the future and we have to start
            // LIMITER_ATTACK_WINDOW before the peak position.
            smp_cnt += LIMITER_LOOKAHEAD + peak_delta - LIMITER_ATTACK_WINDOW;

            gst_debug!(
                           CAT,
                           obj: element,
                           "Found peak {} at sample {}, going to attack state at sample {} (gain reduction {}-{})",
                           peak_value,
                           smp_cnt + LIMITER_ATTACK_WINDOW,
                           smp_cnt,
                           self.gain_reduction[0],
                           self.gain_reduction[1]
                        );
        } else {
            // Process all samples, no peak found
            smp_cnt = nb_samples;
        }

        smp_cnt
    }

    fn true_peak_limiter_attack(
        &mut self,
        element: &gst::Element,
        mut smp_cnt: usize,
        nb_samples: usize,
    ) -> usize {
        let channels = self.info.channels() as usize;

        // Attack state, we have a peak in the near future and need to apply gain
        // reduction smoothly over the next milliseconds to not go over the threshold.
        // Once env_cnt reaches attack window we're at the peak sample.
        //
        // As there might be another, higher peak right afterwards we still need to
        // check for this and potentially update the gain reduction accordingly.

        let peak = self.detect_peak(smp_cnt, nb_samples - smp_cnt);
        let mut new_peak_smp_cnt = None;
        if let Some((peak_delta, _)) = peak {
            // If smp_cnt == new_peak_smp we're exactly 10ms before the new, higher
            // peak and need to increase the slope.
            new_peak_smp_cnt = Some(smp_cnt + peak_delta);
        }

        let mut index = self.limiter_buf_index + smp_cnt * channels;
        if index >= self.limiter_buf.len() {
            index -= self.limiter_buf.len();
        }

        while self.env_cnt < LIMITER_ATTACK_WINDOW && smp_cnt < nb_samples {
            // Stop once we're exactly 10ms before the new higher peak so we can
            // restart the attack state.
            if let Some(new_peak_smp_cnt) = new_peak_smp_cnt {
                if smp_cnt == new_peak_smp_cnt {
                    break;
                }
            }

            // Linear interpolation between the start and target gain reduction
            let env = self.gain_reduction[0]
                - (self.env_cnt as f64 / (LIMITER_ATTACK_WINDOW as f64 - 1.0)
                    * (self.gain_reduction[0] - self.gain_reduction[1]));

            // Safety: Index checked below
            let samples = unsafe {
                self.limiter_buf
                    .get_unchecked_mut(index..(index + channels))
            };
            for sample in samples {
                *sample *= env;
            }

            index += channels;
            if index >= self.limiter_buf.len() {
                index -= self.limiter_buf.len();
            }

            smp_cnt += 1;
            self.env_cnt += 1;
        }

        if let Some(new_peak_smp) = new_peak_smp_cnt {
            assert!(smp_cnt < nb_samples);

            // Sustain until we are exactly 10ms before the new peak in case
            // we finished the attack window above already.
            if smp_cnt < new_peak_smp {
                for _ in smp_cnt..new_peak_smp {
                    // Safety: Index checked below
                    let samples = unsafe {
                        self.limiter_buf
                            .get_unchecked_mut(index..(index + channels))
                    };
                    for sample in samples {
                        *sample *= self.gain_reduction[1];
                    }

                    index += channels;
                    if index >= self.limiter_buf.len() {
                        index -= self.limiter_buf.len();
                    }
                }

                smp_cnt = new_peak_smp;
            }

            assert!(smp_cnt < nb_samples);

            let (_, peak_value) = peak.unwrap();
            let gain_reduction = self.target_tp / peak_value;

            // If the gain reduction is more than our current target gain reduction we
            // need to change the attack state. If it less or the same we can simply
            // contain the current attack state as we will end up at a low enough again
            // before the new peak. We however have to remember to sustain at least
            // that long.
            if gain_reduction < self.gain_reduction[1] {
                // If we need to change something we need to consider two different
                // cases based on the slope of the gain reduction.

                let current_gain_reduction = self.gain_reduction[0]
                    - (self.env_cnt as f64 / (LIMITER_ATTACK_WINDOW as f64 - 1.0)
                        * (self.gain_reduction[0] - self.gain_reduction[1]));

                // Calculate the slopes. Note the minus!
                let old_slope = -(self.gain_reduction[0] - self.gain_reduction[1]);
                let new_slope = -(current_gain_reduction - gain_reduction);

                if new_slope <= old_slope {
                    // If the slope from our current position to the new gain reduction at
                    // the new peak is higher (we need to reduce gain faster) then we
                    // restart the attack state at this point with the higher slope. We
                    // will then reach the new peak at the end of the attack window.

                    self.limiter_state = LimiterState::Attack;
                    self.gain_reduction[0] = current_gain_reduction;
                    self.gain_reduction[1] = gain_reduction;
                    self.env_cnt = 0;
                    self.sustain_cnt = None;

                    gst_debug!(
                                    CAT,
                                    obj: element,
                                    "Found new peak {} at sample {}, restarting attack state at sample {} (gain reduction {}-{})",
                                    peak_value,
                                    smp_cnt + LIMITER_ATTACK_WINDOW,
                                    smp_cnt,
                                    self.gain_reduction[0],
                                    self.gain_reduction[1],
                                );
                } else {
                    // If the slope is lower we can't simply reduce the slope as we would
                    // then have a lower gain reduction than needed at the previous peak.
                    // Instead of continue with the same slope but continue further than
                    // the old peak until we reach the required gain reduction for the new
                    // peak. Just like above we need to remember to sustain from the end of
                    // the attack window until the new peak.

                    // Calculate at which point we would reach the new gain reduction
                    // relative to 0.0 == attack window start, 1.0 attack window end.
                    let new_end = (gain_reduction - self.gain_reduction[0]) / old_slope;
                    assert!(new_end >= 1.0);

                    // New start of the window, this will be in the past
                    let new_start = new_end - 1.0;

                    // Gain reduction at the new start. Note the plus as the slope is
                    // negative already here.
1071 1072 1073 1074 1075 1076 1077 1078
                    //
                    // Clippy warning ignored here because this is just incidentally the same as
                    // AssignAdd: we calculate a new adjusted gain reduction here, and override the
                    // previous one.
                    #[allow(clippy::assign_op_pattern)]
                    {
                        self.gain_reduction[0] = self.gain_reduction[0] + new_start * old_slope;
                    }
1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720

                    // At env_cnt == ATTACK_WINDOW we need the new gain reduction
                    self.gain_reduction[1] = gain_reduction;

                    // Calculate the current position in the attack window
                    let cur_pos = (current_gain_reduction - self.gain_reduction[0]) / old_slope;
                    assert!(cur_pos >= 0.0 && cur_pos <= 1.0);
                    self.env_cnt = ((LIMITER_ATTACK_WINDOW as f64 - 1.0) * cur_pos) as usize;

                    // Need to sustain in any case for this many samples to actually
                    // reach the new peak
                    self.sustain_cnt = Some(self.env_cnt);

                    gst_debug!(
                                    CAT,
                                    obj: element,
                                    "Found new peak {} at sample {}, adjusting attack state at sample {} (gain reduction {}-{})",
                                    peak_value,
                                    smp_cnt + LIMITER_ATTACK_WINDOW,
                                    smp_cnt,
                                    self.gain_reduction[0],
                                    self.gain_reduction[1],
                                );
                }
                return smp_cnt;
            } else {
                // We're ending the attack state this much before the new peak so need
                // to ensure that we at least sustain it for that long afterwards.
                gst_debug!(
                    CAT,
                    obj: element,
                    "Found new low peak {} at sample {} in attack state at sample {}",
                    peak_value,
                    smp_cnt + LIMITER_ATTACK_WINDOW,
                    smp_cnt,
                );
                if self.env_cnt < LIMITER_ATTACK_WINDOW {
                    self.sustain_cnt = Some(self.env_cnt);
                }
            }
        }

        if self.env_cnt == LIMITER_ATTACK_WINDOW && smp_cnt < nb_samples {
            // If we reached the target gain reduction, go into sustain state.
            gst_debug!(
                CAT,
                obj: element,
                "Going to sustain state at sample {} (gain reduction {})",
                smp_cnt,
                self.gain_reduction[1]
            );
            self.limiter_state = LimiterState::Sustain;
            // Keep sustain_cnt as is from above
        }

        smp_cnt
    }

    fn true_peak_limiter_sustain(
        &mut self,
        element: &gst::Element,
        mut smp_cnt: usize,
        nb_samples: usize,
    ) -> usize {
        let channels = self.info.channels() as usize;

        // Sustain the previous gain reduction as long as a peak is found in the
        // next frame, otherwise go over to smoothly release.
        let peak = self.detect_peak(smp_cnt, nb_samples - smp_cnt);

        // We might have to sustain for a few more samples regardless of any new peak
        // we find in 10ms because of code above (first frame or ending the attack
        // state).
        // If another peak was found afterwards we can start working with that one: if
        // it's higher than we go into attack state, if it's lower we sustain for now.
        if let Some(sustain_cnt) = peak.map(|(d, _v)| d).or(self.sustain_cnt) {
            // Apply the final gain reduction from the previous attack for the next
            // samples until we're 1920 samples / 10ms before the peak and then either
            // need to go into attack state if the peak was higher, or stay in sustain
            // state and check for the next peak.

            let mut index = self.limiter_buf_index + smp_cnt * channels;
            if index >= self.limiter_buf.len() {
                index -= self.limiter_buf.len();
            }

            // Sustain the current gain reduction until we're exactly 10ms before
            // the new peak
            let mut s = 0;
            while s < sustain_cnt && smp_cnt < nb_samples {
                // Safety: Index checked below
                let samples = unsafe {
                    self.limiter_buf
                        .get_unchecked_mut(index..(index + channels))
                };
                for sample in samples {
                    *sample *= self.gain_reduction[1];
                }

                index += channels;
                if index >= self.limiter_buf.len() {
                    index -= self.limiter_buf.len();
                }

                smp_cnt += 1;
                s += 1;
            }

            if let Some((_, peak_value)) = peak {
                // If a higher peak than before is found in the next frame need to move
                // into attack state again to reduce the gain smoothly further.
                //
                // Otherwise we stay in sustain mode and smp_cnt is now exactly 10ms before
                // the new peak, i.e. the next call to detect_peak() would find the *next*
                // peak.
                let gain_reduction = self.target_tp / peak_value;
                if gain_reduction < self.gain_reduction[1] {
                    self.limiter_state = LimiterState::Attack;
                    self.env_cnt = 0;
                    self.sustain_cnt = None;
                    self.gain_reduction[0] = self.gain_reduction[1];
                    self.gain_reduction[1] = gain_reduction;

                    gst_debug!(
                                    CAT,
                                    obj: element,
                                    "Found new peak {} at sample {}, going back to attack state at sample {} (gain reduction {}-{})",
                                    peak_value,
                                    smp_cnt + LIMITER_ATTACK_WINDOW,
                                    smp_cnt,
                                    self.gain_reduction[0],
                                    self.gain_reduction[1],
                                );
                } else {
                    gst_debug!(
                                    CAT,
                                    obj: element,
                                    "Found new peak {} at sample {}, going sustain further at sample {} (gain reduction {})",
                                    peak_value,
                                    smp_cnt + LIMITER_ATTACK_WINDOW,
                                    smp_cnt,
                                    self.gain_reduction[1],
                                );
                    // We need to sustain until the peak at least
                    self.sustain_cnt = Some(LIMITER_LOOKAHEAD);
                }
            } else if let Some(ref mut sustain_cnt) = self.sustain_cnt {
                *sustain_cnt -= s;
                if *sustain_cnt == 0 {
                    self.sustain_cnt = None;
                }
            } else {
                unreachable!();
            }
        } else {
            // If no new peak is found, release smoothly over the next 100ms.
            self.limiter_state = LimiterState::Release;
            self.gain_reduction[0] = self.gain_reduction[1];
            self.gain_reduction[1] = 1.;
            self.env_cnt = 0;

            gst_debug!(
                CAT,
                obj: element,
                "Going to release state for sample {} at sample {} (gain reduction {}-1.0)",
                smp_cnt + LIMITER_RELEASE_WINDOW,
                smp_cnt,
                self.gain_reduction[0]
            );
        }

        smp_cnt
    }

    fn true_peak_limiter_release(
        &mut self,
        element: &gst::Element,
        mut smp_cnt: usize,
        nb_samples: usize,
    ) -> usize {
        let channels = self.info.channels() as usize;

        // Smoothly release over the duration of 1 frame (100ms, 19200 samples).

        let mut index = self.limiter_buf_index + smp_cnt * channels;
        if index >= self.limiter_buf.len() {
            index -= self.limiter_buf.len();
        }

        // There might be a new peak during these 100ms, which we will have to detect
        // and in that case go into attack state again if the gain reduction is higher
        // than the current gain reduction we have, or go into sustain mode if it is
        // equal or lower. We don't stay in release mode if a peak is found.
        let peak = self.detect_peak(smp_cnt, nb_samples - smp_cnt);

        if let Some((peak_delta, peak_value)) = peak {
            let gain_reduction = self.target_tp / peak_value;
            let current_gain_reduction = self.gain_reduction[0]
                - (self.env_cnt as f64 / (LIMITER_RELEASE_WINDOW as f64 - 1.0)
                    * (self.gain_reduction[1] - self.gain_reduction[0]));

            if gain_reduction < current_gain_reduction {
                assert!(smp_cnt + peak_delta < nb_samples);

                // Sustain the current gain reduction until we're exactly 10ms before
                // the new peak
                for _ in 0..peak_delta {
                    // Safety: Index checked below
                    let samples = unsafe {
                        self.limiter_buf
                            .get_unchecked_mut(index..(index + channels))
                    };
                    for sample in samples {
                        *sample *= self.gain_reduction[1];
                    }

                    index += channels;
                    if index >= self.limiter_buf.len() {
                        index -= self.limiter_buf.len();
                    }

                    smp_cnt += 1;
                    assert!(smp_cnt < nb_samples);
                }

                self.limiter_state = LimiterState::Attack;
                self.env_cnt = 0;
                self.sustain_cnt = None;
                self.gain_reduction[0] = current_gain_reduction;
                self.gain_reduction[1] = gain_reduction;

                gst_debug!(
                               CAT,
                               obj: element,
                               "Found new peak {} at sample {}, going back to attack state at sample {} (gain reduction {}-{})",
                               peak_value,
                               smp_cnt + LIMITER_ATTACK_WINDOW,
                               smp_cnt,
                               self.gain_reduction[0],
                               self.gain_reduction[1],
                            );
            } else {
                self.gain_reduction[1] = current_gain_reduction;
                gst_debug!(
                                CAT,
                                obj: element,
                                "Going from release to sustain state at sample {} because of low peak {} at sample {} (gain reduction {})",
                                smp_cnt,
                                peak_value,
                                smp_cnt + LIMITER_ATTACK_WINDOW,
                                self.gain_reduction[1]
                            );
                self.limiter_state = LimiterState::Sustain;
            }

            return smp_cnt;
        }

        while self.env_cnt < LIMITER_RELEASE_WINDOW && smp_cnt < nb_samples {
            let env = self.gain_reduction[0]
                - (self.env_cnt as f64 / (LIMITER_RELEASE_WINDOW as f64 - 1.0)
                    * (self.gain_reduction[1] - self.gain_reduction[0]));

            // Safety: Index checked below
            let samples = unsafe {
                self.limiter_buf
                    .get_unchecked_mut(index..(index + channels))
            };
            for sample in samples {
                *sample *= env;
            }

            index += channels;
            if index >= self.limiter_buf.len() {
                index -= self.limiter_buf.len();
            }

            smp_cnt += 1;
            self.env_cnt += 1;
        }

        // If we're done with the release, go to out state
        if smp_cnt < nb_samples {
            self.limiter_state = LimiterState::Out;
            gst_debug!(
                CAT,
                obj: element,
                "Leaving release state and going to out state at sample {}",
                smp_cnt,
            );
        }

        smp_cnt
    }

    fn true_peak_limiter_first_frame(&mut self, element: &gst::Element) {
        let channels = self.info.channels() as usize;

        assert_eq!(self.limiter_buf_index, 0);
        let mut max = 0.;
        for sample in &self.limiter_buf[0..((LIMITER_LOOKAHEAD + 1) * channels)] {
            if sample.abs() > max {
                max = *sample;
            }
        }

        // Initialize the previous sample for peak detection with the last sample we looked at
        // above
        for (o, i) in self
            .prev_smp
            .iter_mut()
            .zip(self.limiter_buf[(LIMITER_LOOKAHEAD * channels)..].iter())
        {
            *o = i.abs();
        }

        if max > self.target_tp {
            // Pretend the first peak was at the last sample so that the sustain code can work
            // as with normal peaks
            self.limiter_state = LimiterState::Sustain;
            self.sustain_cnt = Some(LIMITER_LOOKAHEAD);
            self.gain_reduction[1] = self.target_tp / max;
            gst_debug!(
                CAT,
                obj: element,
                "Reducing gain for start of first frame by {} ({} > {}) and going to sustain state",
                self.gain_reduction[1],
                max,
                self.target_tp
            );

            // The sustain code below will already handle the gain reduction and checking for
            // further peaks.
        }
    }

    fn true_peak_limiter(&mut self, element: &gst::Element, dst: &mut [f64]) {
        let channels = self.info.channels() as usize;
        let nb_samples = dst.len() / channels;

        gst_debug!(
            CAT,
            obj: element,
            "Running limiter for {} samples",
            nb_samples
        );

        // For the first frame we can't adjust the gain before it smoothly anymore so instead
        // apply the gain reduction immediately if we get above the threshold and move to sustain
        // state directly.
        if self.frame_type == FrameType::First {
            self.true_peak_limiter_first_frame(element);
        }

        let mut smp_cnt = 0;
        while smp_cnt < nb_samples {
            match self.limiter_state {
                LimiterState::Out => {
                    smp_cnt = self.true_peak_limiter_out(element, smp_cnt, nb_samples);
                }
                LimiterState::Attack => {
                    smp_cnt = self.true_peak_limiter_attack(element, smp_cnt, nb_samples);
                }
                LimiterState::Sustain => {
                    smp_cnt = self.true_peak_limiter_sustain(element, smp_cnt, nb_samples);
                }
                LimiterState::Release => {
                    smp_cnt = self.true_peak_limiter_release(element, smp_cnt, nb_samples);
                }
            }
        }

        // Copy over the samples into the output buffer, after going through the limiter above.
        let mut index = self.limiter_buf_index;
        for dest_samples in dst.chunks_exact_mut(channels) {
            // Safety: Index checked below
            let in_samples = unsafe {
                self.limiter_buf
                    .get_unchecked_mut(index..(index + channels))
            };

            for (o, i) in dest_samples.iter_mut().zip(in_samples.iter()) {
                *o = *i;
                // Clamp to the maximum for rounding errors above
                if o.abs() > self.target_tp {
                    *o = self.target_tp * o.signum();
                }
            }

            index += channels;
            if index >= self.limiter_buf.len() {
                index -= self.limiter_buf.len();
            }
        }
    }

    // Checks if there is a peak above the threshold 10ms or 1920 samples after the current
    // sample. Returns the peak delta and its value. The peak delta is relative to
    // offset + LIMITER_LOOKAHEAD (10ms), i.e. a peak delta of 0 would be 10ms after the offset.
    //
    // peak delta 0 is never returned, i.e. it is safe to call this 10ms before a peak and it would
    // then return the next peak.
    fn detect_peak(&mut self, offset: usize, samples: usize) -> Option<(usize, f64)> {
        let channels = self.info.channels() as usize;

        // Check for a peak 1920 samples / 10ms in the future
        let mut index = self.limiter_buf_index + (offset + LIMITER_LOOKAHEAD) * channels;
        if index >= self.limiter_buf.len() {
            index -= self.limiter_buf.len();
        }

        for n in 0..samples {
            let mut next_index = index + channels;
            if next_index >= self.limiter_buf.len() {
                next_index -= self.limiter_buf.len();
            }

            // Get the current sample for each channel and the next here
            // Safety: Index checked above
            let (this, next) = unsafe {
                (
                    self.limiter_buf.get_unchecked(index..(index + channels)),
                    self.limiter_buf
                        .get_unchecked(next_index..(next_index + channels)),
                )
            };

            let mut detected = false;
            // Iterate over the previous sample for each channel, the current and the next, i.e.
            // in each iteration we're looking at channel c for those 3 samples.
            for (c, (prev_smp, (this, next))) in self
                .prev_smp
                .iter_mut()
                .zip(this.iter().zip(next.iter()))
                .enumerate()
            {
                let this = this.abs();
                let next = next.abs();

                detected = false;
                // Check if the current sample is the highest peak
                if (*prev_smp <= this) && (this >= next) && (this > self.target_tp) && (n > 0) {
                    detected = true;

                    // Check the 12 following samples, if one of them is higher then that would be
                    // the peak.
                    for i in 2..12 {
                        // Safety: Index checked right here
                        let next = unsafe {
                            let mut next_index = index + c + i * channels;
                            if next_index >= self.limiter_buf.len() {
                                next_index -= self.limiter_buf.len();
                            }

                            self.limiter_buf.get_unchecked(next_index).abs()
                        };

                        if next > this {
                            detected = false;
                            break;
                        }
                    }

                    if detected {
                        break;
                    }
                }

                // Remember as previous sample.
                *prev_smp = this;
            }

            // If this was the highest peak then remember it as the previous sample (as we didn't
            // just above here because of the break!) and return the peak index and value.
            if detected {
                let mut max_peak = 0.0;
                for (c, (prev_smp, this)) in (self.prev_smp.iter_mut().zip(this.iter())).enumerate()
                {
                    if c == 0 || this.abs() > max_peak {
                        max_peak = this.abs();
                    }
                    *prev_smp = this.abs();
                }

                return Some((n, max_peak));
            }

            index = next_index;
        }

        None
    }

    fn gaussian_filter(&self, index: usize) -> f64 {
        let mut result = 0.;

        let index = if index > 10 { index - 10 } else { index + 20 };

        // Apply gaussian filter to the gain adjustments for smoothening them.
        let delta = self.delta[index..].iter().chain(self.delta.iter());
        for (weight, delta) in self.weights.iter().zip(delta) {
            result += delta * weight;
        }

        result
    }
}

impl AudioLoudNorm {
    fn sink_chain(
        &self,
        _pad: &gst::Pad,
        element: &gst::Element,
        buffer: gst::Buffer,
    ) -> Result<gst::FlowSuccess, gst::FlowError> {
        gst_log!(CAT, obj: element, "Handling buffer {:?}", buffer);

        let mut state_guard = self.state.lock().unwrap();
        let state = match *state_guard {
            None => {
                gst_error!(CAT, obj: element, "Not negotiated yet");
                return Err(gst::FlowError::NotNegotiated);
            }
            Some(ref mut state) => state,
        };

        let mut outbufs = vec![];
        if buffer.get_flags().contains(gst::BufferFlags::DISCONT) {
            gst_debug!(CAT, obj: element, "Draining on discontinuity");
            match state.drain(element) {
                Ok(outbuf) => {
                    outbufs.push(outbuf);
                }
                Err(gst::FlowError::Eos) => (),
                Err(err) => return Err(err),
            }

            // Need to reset the state now
            *state = State::new(&*self.settings.lock().unwrap(), state.info.clone());
        }

        state.adapter.push(buffer);
        outbufs.append(&mut state.drain_full_frames(element)?);
        drop(state_guard);

        for buffer in outbufs {
            gst_log!(CAT, obj: element, "Outputting buffer {:?}", buffer);
            self.srcpad.push(buffer)?;
        }

        Ok(gst::FlowSuccess::Ok)
    }

    fn sink_event(&self, pad: &gst::Pad, element: &gst::Element, event: gst::Event) -> bool {
        use gst::EventView;

        gst_log!(CAT, obj: pad, "Handling event {:?}", event);

        match event.view() {
            EventView::Caps(c) => {
                let caps = c.get_caps();
                gst_info!(CAT, obj: pad, "Got caps {:?}", caps);

                let info = match gst_audio::AudioInfo::from_caps(caps) {
                    Ok(info) => info,
                    Err(_) => {
                        gst_error!(CAT, obj: pad, "Failed to parse caps");
                        return false;
                    }
                };

                let mut state = self.state.lock().unwrap();
                let mut outbuf = None;
                if let Some(ref mut state) = &mut *state {
                    outbuf = match state.drain(&element) {
                        Ok(outbuf) => Some(outbuf),
                        Err(gst::FlowError::Eos) => None,
                        Err(_) => return false,
                    };
                }
                *state = Some(State::new(&*self.settings.lock().unwrap(), info));
                drop(state);

                if let Some(outbuf) = outbuf {
                    gst_log!(CAT, obj: element, "Outputting buffer {:?}", outbuf);
                    if let Err(err) = self.srcpad.push(outbuf) {
                        gst_error!(CAT, obj: element, "Failed to push drained data: {}", err);

                        return false;
                    }
                }
            }
            EventView::Eos(_) => {
                let mut state = self.state.lock().unwrap();
                let mut outbuf = None;
                if let Some(ref mut state) = &mut *state {
                    outbuf = match state.drain(&element) {
                        Ok(outbuf) => Some(outbuf),
                        Err(gst::FlowError::Eos) => None,
                        Err(_) => return false,
                    };
                    *state = State::new(&*self.settings.lock().unwrap(), state.info.clone());
                }
                drop(state);

                if let Some(outbuf) = outbuf {
                    gst_log!(CAT, obj: element, "Outputting buffer {:?}", outbuf);
                    if let Err(err) = self.srcpad.push(outbuf) {
                        gst_error!(
                            CAT,
                            obj: element,
                            "Failed to push drained data on EOS: {}",
                            err
                        );

                        return false;
                    }
                }
            }
            EventView::FlushStop(_) => {
                // Resetting our whole state
                let mut state = self.state.lock().unwrap();

                if let Some(info) = state.as_ref().map(|s| s.info.clone()) {
                    let settings = *self.settings.lock().unwrap();
                    *state = Some(State::new(&settings, info));
                } else {
                    *state = None;
                }
            }
            _ => (),
        }

        pad.event_default(Some(element), event)
    }

    fn src_query(&self, pad: &gst::Pad, element: &gst::Element, query: &mut gst::QueryRef) -> bool {
        use gst::QueryView;

        gst_log!(CAT, obj: pad, "Handling query {:?}", query);
        match query.view_mut() {
            QueryView::Latency(ref mut q) => {
1721
                let mut peer_query = gst::query::Latency::new();
1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746
                if self.sinkpad.peer_query(&mut peer_query) {
                    let (live, min_latency, max_latency) = peer_query.get_result();
                    q.set(
                        live,
                        min_latency + 3 * gst::SECOND,
                        max_latency + 3 * gst::SECOND,
                    );
                    true
                } else {
                    false
                }
            }
            _ => pad.query_default(Some(element), query),
        }
    }
}

impl ObjectSubclass for AudioLoudNorm {
    const NAME: &'static str = "RsAudioLoudNorm";
    type ParentType = gst::Element;
    type Instance = gst::subclass::ElementInstanceStruct<Self>;
    type Class = subclass::simple::ClassStruct<Self>;

    glib_object_subclass!();

1747
    fn with_class(klass: &subclass::simple::ClassStruct<Self>) -> Self {
1748
        let templ = klass.get_pad_template("sink").unwrap();
1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765
        let sinkpad = gst::Pad::builder_with_template(&templ, Some("sink"))
            .chain_function(|pad, parent, buffer| {
                Self::catch_panic_pad_function(
                    parent,
                    || Err(gst::FlowError::Error),
                    |this, element| this.sink_chain(pad, element, buffer),
                )
            })
            .event_function(|pad, parent, event| {
                Self::catch_panic_pad_function(
                    parent,
                    || false,
                    |this, element| this.sink_event(pad, element, event),
                )
            })
            .flags(gst::PadFlags::PROXY_CAPS)
            .build();
1766

1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777
        let templ = klass.get_pad_template("src").unwrap();
        let srcpad = gst::Pad::builder_with_template(&templ, Some("src"))
            .query_function(|pad, parent, query| {
                Self::catch_panic_pad_function(
                    parent,
                    || false,
                    |this, element| this.src_query(pad, element, query),
                )
            })
            .flags(gst::PadFlags::PROXY_CAPS)
            .build();
1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799

        Self {
            sinkpad,
            srcpad,
            settings: Mutex::new(Default::default()),
            state: Mutex::new(None),
        }
    }

    fn class_init(klass: &mut subclass::simple::ClassStruct<Self>) {
        klass.set_metadata(
            "Audio loudness normalizer",
            "Filter/Effect/Audio",
            "Normalizes perceived loudness of an audio stream",
            "Sebastian Dröge <sebastian@centricular.com>",
        );

        let caps = gst::Caps::new_simple(
            "audio/x-raw",
            &[
                ("format", &gst_audio::AUDIO_FORMAT_F64.to_str()),
                ("rate", &192_000i32),
1800
                ("channels", &gst::IntRange::<i32>::new(1, std::i32::MAX)),
1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934
                ("layout", &"interleaved"),
            ],
        );
        let src_pad_template = gst::PadTemplate::new(
            "src",
            gst::PadDirection::Src,
            gst::PadPresence::Always,
            &caps,
        )
        .unwrap();
        klass.add_pad_template(src_pad_template);

        let sink_pad_template = gst::PadTemplate::new(
            "sink",
            gst::PadDirection::Sink,
            gst::PadPresence::Always,
            &caps,
        )
        .unwrap();
        klass.add_pad_template(sink_pad_template);

        klass.install_properties(&PROPERTIES);
    }
}

impl ObjectImpl for AudioLoudNorm {
    fn constructed(&self, obj: &glib::Object) {
        self.parent_constructed(obj);

        let element = obj.downcast_ref::<gst::Element>().unwrap();
        element.add_pad(&self.sinkpad).unwrap();
        element.add_pad(&self.srcpad).unwrap();
    }

    fn set_property(&self, _obj: &glib::Object, id: usize, value: &glib::Value) {
        let prop = &PROPERTIES[id];

        match *prop {
            subclass::Property("loudness-target", ..) => {
                let mut settings = self.settings.lock().unwrap();
                settings.loudness_target = value.get_some().expect("type checked upstream");
            }
            subclass::Property("loudness-range-target", ..) => {
                let mut settings = self.settings.lock().unwrap();
                settings.loudness_range_target = value.get_some().expect("type checked upstream");
            }
            subclass::Property("max-true-peak", ..) => {
                let mut settings = self.settings.lock().unwrap();
                settings.max_true_peak = value.get_some().expect("type checked upstream");
            }
            subclass::Property("offset", ..) => {
                let mut settings = self.settings.lock().unwrap();
                settings.offset = value.get_some().expect("type checked upstream");
            }
            _ => unimplemented!(),
        }
    }

    fn get_property(&self, _obj: &glib::Object, id: usize) -> Result<glib::Value, ()> {
        let prop = &PROPERTIES[id];

        match *prop {
            subclass::Property("loudness-target", ..) => {
                let settings = self.settings.lock().unwrap();
                Ok(settings.loudness_target.to_value())
            }
            subclass::Property("loudness-range-target", ..) => {
                let settings = self.settings.lock().unwrap();
                Ok(settings.loudness_range_target.to_value())
            }
            subclass::Property("max-true-peak", ..) => {
                let settings = self.settings.lock().unwrap();
                Ok(settings.max_true_peak.to_value())
            }
            subclass::Property("offset", ..) => {
                let settings = self.settings.lock().unwrap();
                Ok(settings.offset.to_value())
            }
            _ => unimplemented!(),
        }
    }
}

impl ElementImpl for AudioLoudNorm {
    fn change_state(
        &self,
        element: &gst::Element,
        transition: gst::StateChange,
    ) -> Result<gst::StateChangeSuccess, gst::StateChangeError> {
        let res = self.parent_change_state(element, transition);

        match transition {
            gst::StateChange::PausedToReady => {
                // Drop state
                *self.state.lock().unwrap() = None;
            }
            _ => (),
        }

        res
    }
}

pub fn register(plugin: &gst::Plugin) -> Result<(), glib::BoolError> {
    gst::Element::register(
        Some(plugin),
        "rsaudioloudnorm",
        gst::Rank::None,
        AudioLoudNorm::get_type(),
    )
}

fn init_gaussian_filter() -> [f64; 21] {
    let mut weights = [0.0f64; 21];
    let mut total_weight = 0.0f64;
    let sigma = 3.5f64;

    let offset = 21 / 2;
    let c1 = 1.0 / (sigma * f64::sqrt(2.0 * std::f64::consts::PI));
    let c2 = 2.0 * f64::powf(sigma, 2.0);

    for (i, weight) in weights.iter_mut().enumerate() {
        let x = i as f64 - offset as f64;
        *weight = c1 * f64::exp(-(f64::powf(x, 2.0) / c2));
        total_weight += *weight;
    }

    let adjust = 1.0 / total_weight;
    for weight in weights.iter_mut() {
        *weight *= adjust;
    }

    weights
}