Commit d8f1a6c5 authored by Edward Hervey's avatar Edward Hervey 🤘 Committed by Sebastian Dröge

qtdemux: Add/Fix comments on the various structure variables

No variables were added/removed. This was just a good excuse to:
* Comment what most variables are used for (and when)
* Order them in such a way as to show first the common variables used
  in all cases, followed by those only used in push-mode
parent 6f1eed7f
......@@ -219,7 +219,10 @@ struct _QtDemuxStream
guint32 fourcc;
gboolean sparse;
gboolean new_caps;
gboolean new_caps; /* If TRUE, caps need to be generated (by
* calling _configure_stream()) This happens
* for MSS and fragmented streams */
gboolean new_stream; /* signals that a stream_start is required */
gboolean on_keyframe; /* if this stream last pushed buffer was a
* keyframe. This is important to identify
......@@ -233,7 +236,7 @@ struct _QtDemuxStream
guint track_id;
/* duration/scale */
guint64 duration; /* in timescale */
guint64 duration; /* in timescale units */
guint32 timescale;
/* language */
......@@ -244,12 +247,17 @@ struct _QtDemuxStream
QtDemuxSample *samples;
gboolean all_keyframe; /* TRUE when all samples are keyframes (no stss) */
guint32 first_duration; /* duration in timescale of first sample, used for figuring out
the framerate, in timescale units */
the framerate */
guint32 n_samples_moof; /* sample count in a moof */
guint64 duration_moof; /* duration in timescale of a moof, used for figure out
* the framerate of fragmented format stream */
guint32 offset_in_sample;
guint32 max_buffer_size;
guint32 offset_in_sample; /* Offset in the current sample, used for
* streams which have got exceedingly big
* sample size (such as 24s of raw audio).
* Only used when max_buffer_size is non-NULL */
guint32 max_buffer_size; /* Maximum allowed size for output buffers.
* Currently only set for raw audio streams*/
/* if we use chunks or samples */
gboolean sampled;
......@@ -9173,7 +9181,7 @@ qtdemux_parse_trak (GstQTDemux * qtdemux, GNode * trak)
/* HACK:
* some of those trailers, nowadays, have prologue images that are
* themselves vide tracks as well. I haven't really found a way to
* themselves video tracks as well. I haven't really found a way to
* identify those yet, except for just looking at their duration. */
if (tdur1 != 0 && (tdur2 * 10 / tdur1) < 2) {
GST_WARNING_OBJECT (qtdemux,
......@@ -12212,7 +12220,7 @@ qtdemux_add_container_format (GstQTDemux * qtdemux, GstTagList * tags)
return tags;
}
/* we have read th complete moov node now.
/* we have read the complete moov node now.
* This function parses all of the relevant info, creates the traks and
* prepares all data structures for playback
*/
......
......@@ -57,9 +57,17 @@ typedef struct _QtDemuxStream QtDemuxStream;
struct _GstQTDemux {
GstElement element;
/* pads */
/* Global state */
enum QtDemuxState state;
/* static sink pad */
GstPad *sinkpad;
/* TRUE if pull-based */
gboolean pullbased;
gboolean posted_redirect;
QtDemuxStream *streams[GST_QTDEMUX_MAX_STREAMS];
gint n_streams;
gint n_video_streams;
......@@ -68,62 +76,130 @@ struct _GstQTDemux {
GstFlowCombiner *flowcombiner;
/* Incoming stream group-id to set on downstream STREAM_START events.
* If upstream doesn't contain one, a global one will be generated */
gboolean have_group_id;
guint group_id;
guint major_brand;
GstBuffer *comp_brands;
/* [moov] header.
* FIXME : This is discarded just after it's created. Just move it
* to a temporary variable ? */
GNode *moov_node;
/* FIXME : This is never freed. It is only assigned once. memleak ? */
GNode *moov_node_compressed;
/* Set to TRUE when the [moov] header has been fully parsed */
gboolean got_moov;
/* Global timescale for the incoming stream. Use the QTTIME macros
* to convert values to/from GstClockTime */
guint32 timescale;
GstClockTime duration;
/* Global duration (in global timescale). Use QTTIME macros to get GstClockTime */
guint64 duration;
/* Total size of header atoms. Used to calculate fallback overall bitrate */
guint header_size;
GstTagList *tag_list;
/* configured playback region */
GstSegment segment;
/* The SEGMENT_EVENT from upstream *OR* generated from segment (above) */
GstEvent *pending_newsegment;
guint32 segment_seqnum;
/* flag to indicate that we're working with a smoothstreaming fragment
* Mss doesn't have 'moov' or any information about the streams format,
* requiring qtdemux to expose and create the streams */
gboolean mss_mode;
/* Set to TRUE if the incoming stream is either a MSS stream or
* a Fragmented MP4 (containing the [mvex] atom in the header) */
gboolean fragmented;
/* PULL-BASED only : If TRUE there is a pending seek */
gboolean fragmented_seek_pending;
/* PULL-BASED : offset of first [moof] or of fragment to seek to
* PUSH-BASED : offset of latest [moof] */
guint64 moof_offset;
gint state;
/* MSS streams have a single media that is unspecified at the atoms, so
* upstream provides it at the caps */
GstCaps *media_caps;
gboolean pullbased;
gboolean posted_redirect;
/* Set to TRUE when all streams have been exposed */
gboolean exposed;
gint64 chapters_track_id;
/* push based variables */
/* protection support */
GPtrArray *protection_system_ids; /* Holds identifiers of all content protection systems for all tracks */
GQueue protection_event_queue; /* holds copy of upstream protection events */
guint64 cenc_aux_info_offset;
guint8 *cenc_aux_info_sizes;
guint32 cenc_aux_sample_count;
/*
* ALL VARIABLES BELOW ARE ONLY USED IN PUSH-BASED MODE
*/
GstAdapter *adapter;
guint neededbytes;
guint todrop;
GstAdapter *adapter;
/* Used to store data if [mdat] is before the headers */
GstBuffer *mdatbuffer;
/* Amount of bytes left to read in the current [mdat] */
guint64 mdatleft;
/* When restoring the mdat to the adatpter, this buffer
* stores any trailing data that was after the last atom parsed as it
* has to be restored later along with the correct offset. Used in
* fragmented scenario where mdat/moof are one after the other
* in any order.
/* When restoring the mdat to the adapter, this buffer stores any
* trailing data that was after the last atom parsed as it has to be
* restored later along with the correct offset. Used in fragmented
* scenario where mdat/moof are one after the other in any order.
*
* Check https://bugzilla.gnome.org/show_bug.cgi?id=710623 */
GstBuffer *restoredata_buffer;
guint64 restoredata_offset;
/* The current offset in bytes from upstream.
* Note: While it makes complete sense when we are PULL-BASED (pulling
* in BYTES from upstream) and PUSH-BASED with a BYTE SEGMENT (receiving
* buffers with actual offsets), it is undefined in PUSH-BASED with a
* TIME SEGMENT */
guint64 offset;
/* offset of the mdat atom */
guint64 mdatoffset;
/* Offset of the first mdat */
guint64 first_mdat;
gboolean got_moov;
/* offset of last [moov] seen */
guint64 last_moov_offset;
guint header_size;
GstTagList *tag_list;
/* If TRUE, qtdemux received upstream newsegment in TIME format
* which likely means that upstream is driving the pipeline (such as
* adaptive demuxers or dlna sources) */
gboolean upstream_format_is_time;
/* configured playback region */
GstSegment segment;
GstEvent *pending_newsegment;
guint32 segment_seqnum;
gboolean upstream_format_is_time; /* qtdemux received upstream
* newsegment in TIME format which likely
* means that upstream is driving the pipeline
* (adaptive demuxers / dlna) */
/* Seqnum of the seek event sent upstream. Will be used to
* detect incoming FLUSH events corresponding to that */
guint32 offset_seek_seqnum;
/* UPSTREAM BYTE: Requested upstream byte seek offset.
* Currently it is only used to check if an incoming BYTE SEGMENT
* corresponds to a seek event that was sent upstream */
gint64 seek_offset;
/* UPSTREAM BYTE: Requested start/stop TIME values from
* downstream.
* Used to set on the downstream segment once the corresponding upstream
* BYTE SEEK has succeeded */
gint64 push_seek_start;
gint64 push_seek_stop;
......@@ -133,28 +209,21 @@ struct _GstQTDemux {
gint index_id;
#endif
/* Whether upstream is seekable in BYTES */
gboolean upstream_seekable;
/* UPSTREAM BYTE: Size of upstream content.
* Note : This is only computed once ! If upstream grows in the meantime
* it will not be updated */
gint64 upstream_size;
/* MSS streams have a single media that is unspecified at the atoms, so
* upstream provides it at the caps */
GstCaps *media_caps;
gboolean exposed;
gboolean mss_mode; /* flag to indicate that we're working with a smoothstreaming fragment
* Mss doesn't have 'moov' or any information about the streams format,
* requiring qtdemux to expose and create the streams */
/* UPSTREAM TIME : Contains the PTS (if any) of the
* buffer that contains a [moof] header. Will be used to establish
* the actual PTS of the samples contained within that fragment. */
guint64 fragment_start;
/* UPSTREAM TIME : The offset in bytes of the [moof]
* header start.
* Note : This is not computed from the GST_BUFFER_OFFSET field */
guint64 fragment_start_offset;
gint64 chapters_track_id;
/* protection support */
GPtrArray *protection_system_ids; /* Holds identifiers of all content protection systems for all tracks */
GQueue protection_event_queue; /* holds copy of upstream protection events */
guint64 cenc_aux_info_offset;
guint8 *cenc_aux_info_sizes;
guint32 cenc_aux_sample_count;
};
struct _GstQTDemuxClass {
......
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