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hlsdemux2: Add a new method to synchronize two media playlist

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This allows transfering the stream time of the playlist to an updated
variant/rendition.

This allows updating that information without having a "current segment"

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/2679>
This commit is contained in:
Edward Hervey 2022-05-17 07:11:17 +02:00 committed by GStreamer Marge Bot
parent 4eac7f0e06
commit 8fd2dcd266
2 changed files with 108 additions and 44 deletions
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148
subprojects/gst-plugins-good/ext/adaptivedemux2/hls/m3u8.c
View file

@ -943,57 +943,35 @@ gst_hls_media_playlist_find_by_uri (GstHLSMediaPlaylist * playlist,
return NULL;
}
/* Given a media segment (potentially from another media playlist), find the
* equivalent media segment in this playlist.
/* Find the equivalent segment in the given playlist.
*
* This will also recalculate all stream times based on that segment stream
* time (i.e. "sync" the playlist to that previous time).
*
* If an equivalent/identical one is found it is returned with
* the reference count incremented
*
* If the reference segment is *just* before the 1st segment in the playlist, it
* will be inserted and returned. This allows coping with non-overlapping (but
* contiguous) playlist updates.
* The returned segment does *NOT* have increased reference !
*/
GstM3U8MediaSegment *
gst_hls_media_playlist_sync_to_segment (GstHLSMediaPlaylist * playlist,
static GstM3U8MediaSegment *
find_segment_in_playlist (GstHLSMediaPlaylist * playlist,
GstM3U8MediaSegment * segment)
{
guint idx = G_MAXUINT;
GstM3U8MediaSegment *res = NULL;
#ifndef GST_DISABLE_GST_DEBUG
gchar *pdtstring;
#endif
g_return_val_if_fail (playlist, NULL);
g_return_val_if_fail (segment, NULL);
GST_DEBUG ("Re-syncing to segment %" GST_STIME_FORMAT " duration:%"
GST_TIME_FORMAT " sn:%" G_GINT64_FORMAT "/dsn:%" G_GINT64_FORMAT
" uri:%s in playlist %s", GST_STIME_ARGS (segment->stream_time),
GST_TIME_ARGS (segment->duration), segment->sequence,
segment->discont_sequence, segment->uri, playlist->uri);
guint idx;
/* The easy one. Happens when stream times need to be re-synced in an existing
* playlist */
if (g_ptr_array_find (playlist->segments, segment, NULL)) {
GST_DEBUG ("Present as-is in playlist");
res = segment;
goto out;
return segment;
}
/* If there is an identical segment with the same URI and SN, use that one */
res = gst_hls_media_playlist_find_by_uri (playlist, segment);
if (res) {
GST_DEBUG ("Using same URI/DSN/SN match");
goto out;
return res;
}
/* Try with PDT */
if (segment->datetime && playlist->ext_x_pdt_present) {
#ifndef GST_DISABLE_GST_DEBUG
pdtstring = g_date_time_format_iso8601 (segment->datetime);
gchar *pdtstring = g_date_time_format_iso8601 (segment->datetime);
GST_DEBUG ("Search by datetime for %s", pdtstring);
g_free (pdtstring);
#endif
@ -1016,15 +994,19 @@ gst_hls_media_playlist_sync_to_segment (GstHLSMediaPlaylist * playlist,
GST_STIME_ARGS (ddiff));
g_ptr_array_insert (playlist->segments, 0,
gst_m3u8_media_segment_ref (segment));
res = segment;
goto out;
return segment;
}
if (ddiff > 0) {
/* If the reference segment is completely before the first segment, bail out */
GST_DEBUG ("Reference segment ends before first segment");
break;
}
}
if (cand->datetime
&& g_date_time_difference (cand->datetime, segment->datetime) >= 0) {
res = cand;
goto out;
GST_DEBUG ("Picking by date time");
return cand;
}
}
}
@ -1039,15 +1021,13 @@ gst_hls_media_playlist_sync_to_segment (GstHLSMediaPlaylist * playlist,
/* If the candidate starts at or after the previous stream time */
if (cand->stream_time >= segment->stream_time) {
res = cand;
goto out;
return cand;
}
/* If the previous end stream time is before the candidate end stream time */
if ((segment->stream_time + segment->duration) <
(cand->stream_time + cand->duration)) {
res = cand;
goto out;
return cand;
}
}
}
@ -1064,19 +1044,52 @@ gst_hls_media_playlist_sync_to_segment (GstHLSMediaPlaylist * playlist,
GST_DEBUG ("reference segment is just before 1st segment, inserting");
g_ptr_array_insert (playlist->segments, 0,
gst_m3u8_media_segment_ref (segment));
res = segment;
goto out;
return segment;
}
if ((segment->discont_sequence == cand->discont_sequence
|| !playlist->has_ext_x_dsn)
&& (cand->sequence >= segment->sequence)) {
res = cand;
goto out;
&& (cand->sequence == segment->sequence)) {
return cand;
}
}
out:
return NULL;
}
/* Given a media segment (potentially from another media playlist), find the
* equivalent media segment in this playlist.
*
* This will also recalculate all stream times based on that segment stream
* time (i.e. "sync" the playlist to that previous time).
*
* If an equivalent/identical one is found it is returned with
* the reference count incremented
*
* If the reference segment is *just* before the 1st segment in the playlist, it
* will be inserted and returned. This allows coping with non-overlapping (but
* contiguous) playlist updates.
*/
GstM3U8MediaSegment *
gst_hls_media_playlist_sync_to_segment (GstHLSMediaPlaylist * playlist,
GstM3U8MediaSegment * segment)
{
GstM3U8MediaSegment *res = NULL;
#ifndef GST_DISABLE_GST_DEBUG
gchar *pdtstring;
#endif
g_return_val_if_fail (playlist, NULL);
g_return_val_if_fail (segment, NULL);
GST_DEBUG ("Re-syncing to segment %" GST_STIME_FORMAT " duration:%"
GST_TIME_FORMAT " sn:%" G_GINT64_FORMAT "/dsn:%" G_GINT64_FORMAT
" uri:%s in playlist %s", GST_STIME_ARGS (segment->stream_time),
GST_TIME_ARGS (segment->duration), segment->sequence,
segment->discont_sequence, segment->uri, playlist->uri);
res = find_segment_in_playlist (playlist, segment);
/* For live playlists we re-calculate all stream times based on the existing
* stream time. Non-live playlists have their stream time calculated at
* parsing time. */
@ -1137,6 +1150,53 @@ gst_hls_media_playlist_get_starting_segment (GstHLSMediaPlaylist * self)
return res;
}
/* Calls this to carry over stream time, DSN, ... from one playlist to another.
*
* This should be used when a reference media segment couldn't be matched in the
* playlist, but we still want to carry over the information from a reference
* playlist to an updated one. This can happen with live playlists where the
* reference media segment is no longer present but the playlists intersect */
gboolean
gst_hls_media_playlist_sync_to_playlist (GstHLSMediaPlaylist * playlist,
GstHLSMediaPlaylist * reference)
{
GstM3U8MediaSegment *res = NULL;
GstM3U8MediaSegment *cand = NULL;
guint idx;
g_return_val_if_fail (playlist && reference, FALSE);
/* The new playlist is supposed to be an update of the reference playlist,
* therefore we will try from the last segment of the reference playlist and
* go backwards */
for (idx = reference->segments->len - 1; idx; idx--) {
cand = g_ptr_array_index (reference->segments, idx);
res = find_segment_in_playlist (playlist, cand);
if (res)
break;
}
if (res == NULL) {
GST_WARNING ("Could not synchronize media playlists");
return FALSE;
}
/* Carry over reference stream time */
if (res->stream_time == GST_CLOCK_STIME_NONE)
res->stream_time = cand->stream_time;
if (GST_HLS_MEDIA_PLAYLIST_IS_LIVE (playlist))
gst_hls_media_playlist_recalculate_stream_time (playlist, res);
/* If the playlist didn't specify a reference discont sequence number, we
* carry over the one from the reference segment */
if (!playlist->has_ext_x_dsn
&& res->discont_sequence != cand->discont_sequence) {
res->discont_sequence = cand->discont_sequence;
gst_hls_media_playlist_recalculate_dsn (playlist, res);
}
return TRUE;
}
gboolean
gst_hls_media_playlist_has_next_fragment (GstHLSMediaPlaylist * m3u8,
GstM3U8MediaSegment * current, gboolean forward)

4
subprojects/gst-plugins-good/ext/adaptivedemux2/hls/m3u8.h
View file

@ -182,6 +182,10 @@ GstM3U8MediaSegment *
gst_hls_media_playlist_sync_to_segment (GstHLSMediaPlaylist * m3u8,
GstM3U8MediaSegment * segment);
gboolean
gst_hls_media_playlist_sync_to_playlist (GstHLSMediaPlaylist * m3u8,
GstHLSMediaPlaylist * reference);
gboolean
gst_hls_media_playlist_has_next_fragment (GstHLSMediaPlaylist * m3u8,
GstM3U8MediaSegment * current,