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adaptivedemux2: Don't send FLUSH_{START|STOP} when losing sync

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The initial goal was to support the case where we are paused watching a live
stream, and when we resume we can no longer resume from the previously
downloaded position. In that case we internally do a flushing seek back to the
"current live head position". This was also extended since to be able to
handle (utterly broken) servers when we can't really figure out where we are
anymore and therefore trigger that lost sync so we can try to get back on our
feet.

This does fix the issue... but results in spurious FLUSH_{START|STOP} events
being sent downstream. While that's fine for regular playback scenarios, it's a
bit of a wild scenario since a lot of pipelines/applications don't expect such
events when it wasn't triggered by downstream/application.

Fixes #3605

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/7005>
This commit is contained in:
Edward Hervey 2024-06-07 15:26:00 +02:00 committed by GStreamer Marge Bot
parent c5a39f2dfa
commit 98e4d90519
3 changed files with 63 additions and 15 deletions
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6
subprojects/gst-plugins-good/ext/adaptivedemux2/gstadaptivedemux-private.h
View file

@ -146,6 +146,12 @@ struct _GstAdaptiveDemuxPrivate
guint32 current_selection_seqnum;
/* Current output position (in running time) */
GstClockTime global_output_position;
/* NOTE: The two following variables are to handle lost-sync internal flushing
* and transposing the base time */
/* Initial output position (in running time) */
GstClockTime initial_output_position;
/* Offset to apply to outgoing segments (in running time) */
GstClockTime base_offset;
/* End of fields protected by output_lock */
gint n_audio_streams, n_video_streams, n_subtitle_streams;

18
subprojects/gst-plugins-good/ext/adaptivedemux2/gstadaptivedemux-track.c
View file

@ -269,6 +269,24 @@ handle_event:
/* Replace the stored sticky event with this one */
is_pending_sticky = FALSE;
}
if (demux->priv->base_offset != 0) {
GstSegment ev_segment;
GstEvent *new_event;
GST_DEBUG_ID (track->id,
"Offsetting segment base by %" GST_TIME_FORMAT,
GST_TIME_ARGS (demux->priv->base_offset));
gst_event_copy_segment (event, &ev_segment);
ev_segment.base += demux->priv->base_offset;
new_event = gst_event_new_segment (&ev_segment);
gst_event_set_seqnum (new_event, gst_event_get_seqnum (event));
gst_mini_object_unref (res);
event = new_event;
res = (GstMiniObject *) event;
/* Replace the stored sticky event with this one */
is_pending_sticky = FALSE;
}
break;
default:
break;

54
subprojects/gst-plugins-good/ext/adaptivedemux2/gstadaptivedemux.c
View file

@ -213,7 +213,7 @@ static gboolean gst_adaptive_demux_src_query (GstPad * pad, GstObject * parent,
static gboolean gst_adaptive_demux_src_event (GstPad * pad, GstObject * parent,
GstEvent * event);
static gboolean gst_adaptive_demux_handle_seek_event (GstAdaptiveDemux * demux,
GstEvent * event);
GstEvent * event, gboolean lost_sync);
static gboolean gst_adaptive_demux_handle_select_streams_event (GstAdaptiveDemux
* demux, GstEvent * event);
@ -1406,6 +1406,8 @@ gst_adaptive_demux_reset (GstAdaptiveDemux * demux)
demux->priv->segment_seqnum = gst_util_seqnum_next ();
demux->priv->global_output_position = 0;
demux->priv->initial_output_position = 0;
demux->priv->base_offset = 0;
demux->priv->n_audio_streams = 0;
demux->priv->n_video_streams = 0;
@ -1425,7 +1427,7 @@ gst_adaptive_demux_send_event (GstElement * element, GstEvent * event)
switch (GST_EVENT_TYPE (event)) {
case GST_EVENT_SEEK:
{
res = gst_adaptive_demux_handle_seek_event (demux, event);
res = gst_adaptive_demux_handle_seek_event (demux, event, FALSE);
break;
}
case GST_EVENT_SELECT_STREAMS:
@ -2008,9 +2010,16 @@ gst_adaptive_demux_setup_streams_for_restart (GstAdaptiveDemux * demux,
GST_SEEK_FLAG_SNAP_AFTER | \
GST_SEEK_FLAG_SNAP_NEAREST))
/**
* gst_adaptive_demux_handle_seek_event:
* @demux:
* @event: The seek event
* @lost_sync: TRUE if this triggered by a "lost sync" and not an external seek
*
*/
static gboolean
gst_adaptive_demux_handle_seek_event (GstAdaptiveDemux * demux,
GstEvent * event)
GstEvent * event, gboolean lost_sync)
{
GstAdaptiveDemuxClass *demux_class = GST_ADAPTIVE_DEMUX_GET_CLASS (demux);
gdouble rate;
@ -2183,11 +2192,13 @@ gst_adaptive_demux_handle_seek_event (GstAdaptiveDemux * demux,
/* have a backup in case seek fails */
gst_segment_copy_into (&demux->segment, &oldsegment);
GST_DEBUG_OBJECT (demux, "sending flush start");
flush_event = gst_event_new_flush_start ();
gst_event_set_seqnum (flush_event, seqnum);
if (!lost_sync) {
GST_DEBUG_OBJECT (demux, "sending flush start");
flush_event = gst_event_new_flush_start ();
gst_event_set_seqnum (flush_event, seqnum);
gst_adaptive_demux_push_src_event (demux, flush_event);
gst_adaptive_demux_push_src_event (demux, flush_event);
}
gst_adaptive_demux_stop_tasks (demux, FALSE);
gst_adaptive_demux_reset_tracks (demux);
@ -2307,10 +2318,12 @@ gst_adaptive_demux_handle_seek_event (GstAdaptiveDemux * demux,
/* Resetting flow combiner */
gst_flow_combiner_reset (demux->priv->flowcombiner);
GST_DEBUG_OBJECT (demux, "Sending flush stop on all pad");
flush_event = gst_event_new_flush_stop (TRUE);
gst_event_set_seqnum (flush_event, seqnum);
gst_adaptive_demux_push_src_event (demux, flush_event);
if (!lost_sync) {
GST_DEBUG_OBJECT (demux, "Sending flush stop on all pad");
flush_event = gst_event_new_flush_stop (TRUE);
gst_event_set_seqnum (flush_event, seqnum);
gst_adaptive_demux_push_src_event (demux, flush_event);
}
/* If the seek generated a new period, prepare it */
if (!demux->input_period->prepared) {
@ -2325,8 +2338,19 @@ gst_adaptive_demux_handle_seek_event (GstAdaptiveDemux * demux,
gst_adaptive_demux_setup_streams_for_restart (demux, start_type, stop_type);
demux->priv->qos_earliest_time = GST_CLOCK_TIME_NONE;
/* Reset the global output position (running time) for when the output loop restarts */
demux->priv->global_output_position = 0;
if (!lost_sync) {
/* Reset the global output position (running time) for when the output loop restarts */
demux->priv->global_output_position = 0;
demux->priv->initial_output_position = demux->priv->base_offset = 0;
} else {
/* When dealing with lost-sync, we don't reset the global output position
* (running time), but we do need to take into account how much was played
* previously to add it to the outgoing segment base */
demux->priv->base_offset =
demux->priv->global_output_position -
demux->priv->initial_output_position;
demux->priv->initial_output_position = demux->priv->global_output_position;
}
/* After a flushing seek, any instant-rate override is undone */
demux->instant_rate_multiplier = 1.0;
@ -2519,7 +2543,7 @@ gst_adaptive_demux_src_event (GstPad * pad, GstObject * parent,
gst_event_unref (event);
return TRUE;
}
return gst_adaptive_demux_handle_seek_event (demux, event);
return gst_adaptive_demux_handle_seek_event (demux, event, FALSE);
}
case GST_EVENT_LATENCY:{
/* Upstream and our internal source are irrelevant
@ -2747,7 +2771,7 @@ gst_adaptive_demux_handle_lost_sync (GstAdaptiveDemux * demux)
gst_event_new_seek (1.0, GST_FORMAT_TIME,
GST_SEEK_FLAG_FLUSH | GST_SEEK_FLAG_KEY_UNIT, GST_SEEK_TYPE_END, 0,
GST_SEEK_TYPE_NONE, 0);
gst_adaptive_demux_handle_seek_event (demux, seek);
gst_adaptive_demux_handle_seek_event (demux, seek, TRUE);
return FALSE;
}