Commit 133913a1 authored by George Kiagiadakis's avatar George Kiagiadakis Committed by Wim Taymans

rtprtxsend: run a new GstTask on the src pad

The reason behind this is to minimize the retransmission delay.
Previously, when a NACK was received, rtprtxsend would put a
retransmission packet in a queue and it would send it from chain(),
i.e. only after a new buffer would arrive.

This unfortunately was causing big delays, in the order of 60-100 ms,
which can be critical for the receiver side.

By having a separate GstTask for pushing buffers out of rtxsend,
we can push buffers out right after receiving the event, without
waiting for chain() to get called.
parent 4480a258
......@@ -77,6 +77,9 @@ static GstStaticPadTemplate sink_factory = GST_STATIC_PAD_TEMPLATE ("sink",
GST_STATIC_CAPS ("application/x-rtp")
);
static gboolean gst_rtp_rtx_send_queue_check_full (GstDataQueue * queue,
guint visible, guint bytes, guint64 time, gpointer checkdata);
static gboolean gst_rtp_rtx_send_src_event (GstPad * pad, GstObject * parent,
GstEvent * event);
static gboolean gst_rtp_rtx_send_sink_event (GstPad * pad, GstObject * parent,
......@@ -84,6 +87,10 @@ static gboolean gst_rtp_rtx_send_sink_event (GstPad * pad, GstObject * parent,
static GstFlowReturn gst_rtp_rtx_send_chain (GstPad * pad, GstObject * parent,
GstBuffer * buffer);
static void gst_rtp_rtx_send_src_loop (GstRtpRtxSend * rtx);
static gboolean gst_rtp_rtx_send_activate_mode (GstPad * pad,
GstObject * parent, GstPadMode mode, gboolean active);
static GstStateChangeReturn gst_rtp_rtx_send_change_state (GstElement *
element, GstStateChange transition);
......@@ -201,8 +208,7 @@ static void
gst_rtp_rtx_send_reset (GstRtpRtxSend * rtx)
{
GST_OBJECT_LOCK (rtx);
g_queue_foreach (rtx->pending, (GFunc) gst_buffer_unref, NULL);
g_queue_clear (rtx->pending);
gst_data_queue_flush (rtx->queue);
g_hash_table_remove_all (rtx->ssrc_data);
g_hash_table_remove_all (rtx->rtx_ssrcs);
rtx->num_rtx_requests = 0;
......@@ -222,7 +228,7 @@ gst_rtp_rtx_send_finalize (GObject * object)
g_hash_table_unref (rtx->rtx_pt_map);
if (rtx->rtx_pt_map_structure)
gst_structure_free (rtx->rtx_pt_map_structure);
g_queue_free_full (rtx->pending, (GDestroyNotify) gst_buffer_unref);
g_object_unref (rtx->queue);
G_OBJECT_CLASS (gst_rtp_rtx_send_parent_class)->finalize (object);
}
......@@ -239,6 +245,8 @@ gst_rtp_rtx_send_init (GstRtpRtxSend * rtx)
GST_PAD_SET_PROXY_ALLOCATION (rtx->srcpad);
gst_pad_set_event_function (rtx->srcpad,
GST_DEBUG_FUNCPTR (gst_rtp_rtx_send_src_event));
gst_pad_set_activatemode_function (rtx->srcpad,
GST_DEBUG_FUNCPTR (gst_rtp_rtx_send_activate_mode));
gst_element_add_pad (GST_ELEMENT (rtx), rtx->srcpad);
rtx->sinkpad =
......@@ -252,7 +260,8 @@ gst_rtp_rtx_send_init (GstRtpRtxSend * rtx)
GST_DEBUG_FUNCPTR (gst_rtp_rtx_send_chain));
gst_element_add_pad (GST_ELEMENT (rtx), rtx->sinkpad);
rtx->pending = g_queue_new ();
rtx->queue = gst_data_queue_new (gst_rtp_rtx_send_queue_check_full, NULL,
NULL, rtx);
rtx->ssrc_data = g_hash_table_new_full (g_direct_hash, g_direct_equal,
NULL, (GDestroyNotify) ssrc_rtx_data_free);
rtx->rtx_ssrcs = g_hash_table_new (g_direct_hash, g_direct_equal);
......@@ -262,6 +271,52 @@ gst_rtp_rtx_send_init (GstRtpRtxSend * rtx)
rtx->max_size_packets = DEFAULT_MAX_SIZE_PACKETS;
}
static void
gst_rtp_rtx_send_set_flushing (GstRtpRtxSend * rtx, gboolean flush)
{
GST_OBJECT_LOCK (rtx);
gst_data_queue_set_flushing (rtx->queue, flush);
gst_data_queue_flush (rtx->queue);
GST_OBJECT_UNLOCK (rtx);
}
static gboolean
gst_rtp_rtx_send_queue_check_full (GstDataQueue * queue,
guint visible, guint bytes, guint64 time, gpointer checkdata)
{
return FALSE;
}
static void
gst_rtp_rtx_data_queue_item_free (gpointer item)
{
GstDataQueueItem *data = item;
if (data->object)
gst_mini_object_unref (data->object);
g_slice_free (GstDataQueueItem, data);
}
static gboolean
gst_rtp_rtx_send_push_out (GstRtpRtxSend * rtx, gpointer object)
{
GstDataQueueItem *data;
gboolean success;
data = g_slice_new0 (GstDataQueueItem);
data->object = GST_MINI_OBJECT (object);
data->size = 1;
data->duration = 1;
data->visible = TRUE;
data->destroy = gst_rtp_rtx_data_queue_item_free;
success = gst_data_queue_push (rtx->queue, data);
if (!success)
data->destroy (data);
return success;
}
static guint32
gst_rtp_rtx_send_choose_ssrc (GstRtpRtxSend * rtx, guint32 choice,
gboolean consider_choice)
......@@ -399,6 +454,7 @@ gst_rtp_rtx_send_src_event (GstPad * pad, GstObject * parent, GstEvent * event)
if (gst_structure_has_name (s, "GstRTPRetransmissionRequest")) {
guint seqnum = 0;
guint ssrc = 0;
GstBuffer *rtx_buf = NULL;
/* retrieve seqnum of the packet that need to be restransmisted */
if (!gst_structure_get_uint (s, "seqnum", &seqnum))
......@@ -430,12 +486,14 @@ gst_rtp_rtx_send_src_event (GstPad * pad, GstObject * parent, GstEvent * event)
if (iter) {
BufferQueueItem *item = g_sequence_get (iter);
GST_DEBUG_OBJECT (rtx, "found %" G_GUINT16_FORMAT, item->seqnum);
g_queue_push_tail (rtx->pending,
gst_rtp_rtx_buffer_new (rtx, item->buffer));
rtx_buf = gst_rtp_rtx_buffer_new (rtx, item->buffer);
}
}
GST_OBJECT_UNLOCK (rtx);
if (rtx_buf)
gst_rtp_rtx_send_push_out (rtx, rtx_buf);
gst_event_unref (event);
res = TRUE;
......@@ -508,6 +566,17 @@ gst_rtp_rtx_send_sink_event (GstPad * pad, GstObject * parent, GstEvent * event)
GstRtpRtxSend *rtx = GST_RTP_RTX_SEND (parent);
switch (GST_EVENT_TYPE (event)) {
case GST_EVENT_FLUSH_START:
gst_pad_push_event (rtx->srcpad, event);
gst_rtp_rtx_send_set_flushing (rtx, TRUE);
gst_pad_pause_task (rtx->srcpad);
return TRUE;
case GST_EVENT_FLUSH_STOP:
gst_pad_push_event (rtx->srcpad, event);
gst_rtp_rtx_send_set_flushing (rtx, FALSE);
gst_pad_start_task (rtx->srcpad,
(GstTaskFunction) gst_rtp_rtx_send_src_loop, rtx, NULL);
return TRUE;
case GST_EVENT_CAPS:
{
GstCaps *caps;
......@@ -566,20 +635,11 @@ gst_rtp_rtx_send_get_ts_diff (SSRCRtxData * data)
return (guint32) gst_util_uint64_scale_int (result, 1000, data->clock_rate);
}
/* push pending retransmission packet.
* it constructs rtx packet from original packets */
static void
do_push (GstBuffer * buffer, GstRtpRtxSend * rtx)
{
gst_pad_push (rtx->srcpad, buffer);
}
static GstFlowReturn
gst_rtp_rtx_send_chain (GstPad * pad, GstObject * parent, GstBuffer * buffer)
{
GstRtpRtxSend *rtx = GST_RTP_RTX_SEND (parent);
GstFlowReturn ret = GST_FLOW_ERROR;
GQueue *pending = NULL;
GstRTPBuffer rtp = GST_RTP_BUFFER_INIT;
BufferQueueItem *item;
SSRCRtxData *data;
......@@ -619,34 +679,64 @@ gst_rtp_rtx_send_chain (GstPad * pad, GstObject * parent, GstBuffer * buffer)
}
}
/* within lock, get packets that have to be retransmited */
if (g_queue_get_length (rtx->pending) > 0) {
pending = rtx->pending;
rtx->pending = g_queue_new ();
/* update statistics - assume we will succeed to retransmit those packets */
rtx->num_rtx_packets += g_queue_get_length (pending);
}
/* no need to hold the lock to push rtx packets */
GST_OBJECT_UNLOCK (rtx);
/* retransmit requested packets */
if (pending) {
g_queue_foreach (pending, (GFunc) do_push, rtx);
g_queue_free (pending);
}
GST_LOG_OBJECT (rtx,
"push seqnum: %" G_GUINT16_FORMAT ", ssrc: %" G_GUINT32_FORMAT, seqnum,
ssrc);
/* push current rtp packet */
ret = gst_pad_push (rtx->srcpad, buffer);
return ret;
}
static void
gst_rtp_rtx_send_src_loop (GstRtpRtxSend * rtx)
{
GstDataQueueItem *data;
if (gst_data_queue_pop (rtx->queue, &data)) {
GST_LOG_OBJECT (rtx, "pushing rtx buffer %p", data->object);
gst_pad_push (rtx->srcpad, GST_BUFFER (data->object));
GST_OBJECT_LOCK (rtx);
rtx->num_rtx_packets++;
GST_OBJECT_UNLOCK (rtx);
data->object = NULL; /* we no longer own that object */
data->destroy (data);
} else {
GST_LOG_OBJECT (rtx, "flushing");
gst_pad_pause_task (rtx->srcpad);
}
}
static gboolean
gst_rtp_rtx_send_activate_mode (GstPad * pad, GstObject * parent,
GstPadMode mode, gboolean active)
{
GstRtpRtxSend *rtx = GST_RTP_RTX_SEND (parent);
gboolean ret = FALSE;
switch (mode) {
case GST_PAD_MODE_PUSH:
if (active) {
gst_rtp_rtx_send_set_flushing (rtx, FALSE);
ret = gst_pad_start_task (rtx->srcpad,
(GstTaskFunction) gst_rtp_rtx_send_src_loop, rtx, NULL);
} else {
gst_rtp_rtx_send_set_flushing (rtx, TRUE);
ret = gst_pad_stop_task (rtx->srcpad);
}
GST_INFO_OBJECT (rtx, "activate_mode: active %d, ret %d", active, ret);
break;
default:
break;
}
return ret;
}
static void
gst_rtp_rtx_send_get_property (GObject * object,
guint prop_id, GValue * value, GParamSpec * pspec)
......
......@@ -26,6 +26,7 @@
#include <gst/gst.h>
#include <gst/rtp/gstrtpbuffer.h>
#include <gst/base/gstdataqueue.h>
G_BEGIN_DECLS
#define GST_TYPE_RTP_RTX_SEND (gst_rtp_rtx_send_get_type())
......@@ -45,8 +46,8 @@ struct _GstRtpRtxSend
GstPad *sinkpad;
GstPad *srcpad;
/* rtp packets that will be pushed upon next buffer */
GQueue *pending;
/* rtp packets that will be pushed out */
GstDataQueue *queue;
/* ssrc -> SSRCRtxData */
GHashTable *ssrc_data;
......
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