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67958ccce8
Various audio formats require an audio lead-in to decode it properly. Most parsers would take care of it, but when a container like matroska is involved, the demuxer handles the seeking and without its own lead-in handling would never even pass the lead-in data to the parser. This commit provides an initial implementation of that for audio/mpeg, audio/x-ac3 and audio/x-eac3 by calculating the worst case lead-in time needed from known samplerate, potential lead-in frames need and the maximum blocksize possible for the format (as we don't parse that out exactly in matroskademux) and seeking that much earlier in case of accurate seeks. This is especially important for NLE use-cases with GES. If accurate seeking to a position that happens to have a video keyframe, it'll go back to the previous keyframe than needed, but with typical video files that's the best we can do anyway without falling back to scanning the clusters, as typically only keyframes are indexed in Cueing Data. If the media doesn't have a CUE, then we bisect for the cluster to seek to with the same modified time as well in case of accurate seeking, ensuring sufficient lead-in. This code path is typically hit only with (suboptimal) audio-only matroska files, e.g. when created with ffmpeg, which doesn't add a CUE for audio-only mkv muxing.
142 lines
4.9 KiB
C
142 lines
4.9 KiB
C
/* GStreamer Matroska muxer/demuxer
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* (c) 2003 Ronald Bultje <rbultje@ronald.bitfreak.net>
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* (c) 2011 Debarshi Ray <rishi@gnu.org>
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*
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* matroska-demux.h: matroska file/stream demuxer definition
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
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* Boston, MA 02110-1301, USA.
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*/
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#ifndef __GST_MATROSKA_DEMUX_H__
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#define __GST_MATROSKA_DEMUX_H__
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#include <gst/gst.h>
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#include <gst/base/gstflowcombiner.h>
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#include "ebml-read.h"
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#include "matroska-ids.h"
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#include "matroska-read-common.h"
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G_BEGIN_DECLS
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#define GST_TYPE_MATROSKA_DEMUX \
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(gst_matroska_demux_get_type ())
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#define GST_MATROSKA_DEMUX(obj) \
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(G_TYPE_CHECK_INSTANCE_CAST ((obj), GST_TYPE_MATROSKA_DEMUX, GstMatroskaDemux))
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#define GST_MATROSKA_DEMUX_CLASS(klass) \
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(G_TYPE_CHECK_CLASS_CAST ((klass), GST_TYPE_MATROSKA_DEMUX, GstMatroskaDemuxClass))
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#define GST_IS_MATROSKA_DEMUX(obj) \
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(G_TYPE_CHECK_INSTANCE_TYPE ((obj), GST_TYPE_MATROSKA_DEMUX))
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#define GST_IS_MATROSKA_DEMUX_CLASS(klass) \
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(G_TYPE_CHECK_CLASS_TYPE ((klass), GST_TYPE_MATROSKA_DEMUX))
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typedef struct _GstMatroskaDemux {
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GstElement parent;
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/* < private > */
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GstMatroskaReadCommon common;
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/* pads */
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GstClock *clock;
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gboolean have_nonintraonly_v_streams;
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guint num_v_streams;
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guint num_a_streams;
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guint num_t_streams;
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guint group_id;
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gboolean have_group_id;
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GstFlowCombiner *flowcombiner;
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/* state */
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gboolean streaming;
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guint64 seek_block;
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gboolean seek_first;
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/* did we parse cues/tracks/segmentinfo already? */
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gboolean tracks_parsed;
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GList *seek_parsed;
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/* cluster positions (optional) */
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GArray *clusters;
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/* keeping track of playback position */
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GstClockTime last_stop_end;
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GstClockTime stream_start_time;
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/* Stop time for reverse playback */
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GstClockTime to_time;
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GstEvent *new_segment;
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/* some state saving */
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GstClockTime cluster_time;
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guint64 cluster_offset;
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guint64 cluster_prevsize; /* 0 if unknown */
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guint64 first_cluster_offset;
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guint64 next_cluster_offset;
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GstClockTime requested_seek_time;
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guint64 seek_offset;
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GstClockTime audio_lead_in_ts;
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/* alternative duration; optionally obtained from last cluster */
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guint64 last_cluster_offset;
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GstClockTime stream_last_time;
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/* index stuff */
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gboolean seekable;
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gboolean building_index;
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guint64 index_offset;
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GstEvent *seek_event;
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GstEvent *deferred_seek_event;
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GstPad *deferred_seek_pad;
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gboolean need_segment;
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guint32 segment_seqnum;
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/* reverse playback */
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GArray *seek_index;
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gint seek_entry;
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gboolean seen_cluster_prevsize; /* We track this because the
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* first cluster won't have
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* this set, so we can't just
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* check cluster_prevsize to
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* determine if it's there
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* or not. We assume if one
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* cluster has it, all but
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* the first will have it. */
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guint max_backtrack_distance; /* in seconds (0 = don't backtrack) */
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/* gap handling */
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guint64 max_gap_time;
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/* for non-finalized files, with invalid segment duration */
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gboolean invalid_duration;
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/* Cached upstream length (default G_MAXUINT64) */
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guint64 cached_length;
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} GstMatroskaDemux;
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typedef struct _GstMatroskaDemuxClass {
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GstElementClass parent;
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} GstMatroskaDemuxClass;
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gboolean gst_matroska_demux_plugin_init (GstPlugin *plugin);
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G_END_DECLS
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#endif /* __GST_MATROSKA_DEMUX_H__ */
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