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matroskadec: defer parsing of cues element until we seek. 

This decreases startup latency.

Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
Signed-off-by: Anton Khirnov <anton@khirnov.net>
This commit is contained in:
Aaron Colwell 2011-07-09 07:48:43 +02:00 committed by Anton Khirnov
parent 84626b364b
commit 31ad14c21e
1 changed files with 86 additions and 45 deletions
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131
libavformat/matroskadec.c
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@ -244,6 +244,9 @@ typedef struct {
/* What to skip before effectively reading a packet. */
int skip_to_keyframe;
uint64_t skip_to_timecode;
/* File has a CUES element, but we defer parsing until it is needed. */
int cues_parsing_deferred;
} MatroskaDemuxContext;
typedef struct {
@ -1110,7 +1113,7 @@ static void matroska_convert_tags(AVFormatContext *s)
}
}
static void matroska_execute_seekhead(MatroskaDemuxContext *matroska)
static int matroska_parse_seekhead_entry(MatroskaDemuxContext *matroska, int idx)
{
EbmlList *seekhead_list = &matroska->seekhead;
MatroskaSeekhead *seekhead = seekhead_list->elem;
@ -1118,34 +1121,25 @@ static void matroska_execute_seekhead(MatroskaDemuxContext *matroska)
int64_t before_pos = avio_tell(matroska->ctx->pb);
uint32_t saved_id = matroska->current_id;
MatroskaLevel level;
int i;
int64_t offset;
int ret = 0;
// we should not do any seeking in the streaming case
if (!matroska->ctx->pb->seekable ||
(matroska->ctx->flags & AVFMT_FLAG_IGNIDX))
return;
for (i=0; i<seekhead_list->nb_elem; i++) {
int64_t offset = seekhead[i].pos + matroska->segment_start;
if (seekhead[i].pos <= before_pos
|| seekhead[i].id == MATROSKA_ID_SEEKHEAD
|| seekhead[i].id == MATROSKA_ID_CLUSTER)
continue;
if (idx >= seekhead_list->nb_elem
|| seekhead[idx].id == MATROSKA_ID_SEEKHEAD
|| seekhead[idx].id == MATROSKA_ID_CLUSTER)
return 0;
/* seek */
if (avio_seek(matroska->ctx->pb, offset, SEEK_SET) != offset)
continue;
offset = seekhead[idx].pos + matroska->segment_start;
if (avio_seek(matroska->ctx->pb, offset, SEEK_SET) == offset) {
/* We don't want to lose our seekhead level, so we add
* a dummy. This is a crude hack. */
if (matroska->num_levels == EBML_MAX_DEPTH) {
av_log(matroska->ctx, AV_LOG_INFO,
"Max EBML element depth (%d) reached, "
"cannot parse further.\n", EBML_MAX_DEPTH);
break;
}
ret = AVERROR_INVALIDDATA;
} else {
level.start = 0;
level.length = (uint64_t)-1;
matroska->levels[matroska->num_levels] = level;
@ -1161,11 +1155,76 @@ static void matroska_execute_seekhead(MatroskaDemuxContext *matroska)
break;
}
}
}
/* seek back */
avio_seek(matroska->ctx->pb, before_pos, SEEK_SET);
matroska->level_up = level_up;
matroska->current_id = saved_id;
return ret;
}
static void matroska_execute_seekhead(MatroskaDemuxContext *matroska)
{
EbmlList *seekhead_list = &matroska->seekhead;
MatroskaSeekhead *seekhead = seekhead_list->elem;
int64_t before_pos = avio_tell(matroska->ctx->pb);
int i;
// we should not do any seeking in the streaming case
if (!matroska->ctx->pb->seekable ||
(matroska->ctx->flags & AVFMT_FLAG_IGNIDX))
return;
for (i = 0; i < seekhead_list->nb_elem; i++) {
if (seekhead[i].pos <= before_pos)
continue;
// defer cues parsing until we actually need cue data.
if (seekhead[i].id == MATROSKA_ID_CUES) {
matroska->cues_parsing_deferred = 1;
continue;
}
if (matroska_parse_seekhead_entry(matroska, i) < 0)
break;
}
}
static void matroska_parse_cues(MatroskaDemuxContext *matroska) {
EbmlList *seekhead_list = &matroska->seekhead;
MatroskaSeekhead *seekhead = seekhead_list->elem;
EbmlList *index_list;
MatroskaIndex *index;
int index_scale = 1;
int i, j;
for (i = 0; i < seekhead_list->nb_elem; i++)
if (seekhead[i].id != MATROSKA_ID_CUES)
break;
assert(i <= seekhead_list->nb_elem);
matroska_parse_seekhead_entry(matroska, i);
index_list = &matroska->index;
index = index_list->elem;
if (index_list->nb_elem
&& index[0].time > 1E14/matroska->time_scale) {
av_log(matroska->ctx, AV_LOG_WARNING, "Working around broken index.\n");
index_scale = matroska->time_scale;
}
for (i = 0; i < index_list->nb_elem; i++) {
EbmlList *pos_list = &index[i].pos;
MatroskaIndexPos *pos = pos_list->elem;
for (j = 0; j < pos_list->nb_elem; j++) {
MatroskaTrack *track = matroska_find_track_by_num(matroska, pos[j].track);
if (track && track->stream)
av_add_index_entry(track->stream,
pos[j].pos + matroska->segment_start,
index[i].time/index_scale, 0, 0,
AVINDEX_KEYFRAME);
}
}
}
static int matroska_aac_profile(char *codec_id)
@ -1197,9 +1256,6 @@ static int matroska_read_header(AVFormatContext *s, AVFormatParameters *ap)
EbmlList *chapters_list = &matroska->chapters;
MatroskaChapter *chapters;
MatroskaTrack *tracks;
EbmlList *index_list;
MatroskaIndex *index;
int index_scale = 1;
uint64_t max_start = 0;
Ebml ebml = { 0 };
AVStream *st;
@ -1529,27 +1585,6 @@ static int matroska_read_header(AVFormatContext *s, AVFormatParameters *ap)
max_start = chapters[i].start;
}
index_list = &matroska->index;
index = index_list->elem;
if (index_list->nb_elem
&& index[0].time > 100000000000000/matroska->time_scale) {
av_log(matroska->ctx, AV_LOG_WARNING, "Working around broken index.\n");
index_scale = matroska->time_scale;
}
for (i=0; i<index_list->nb_elem; i++) {
EbmlList *pos_list = &index[i].pos;
MatroskaIndexPos *pos = pos_list->elem;
for (j=0; j<pos_list->nb_elem; j++) {
MatroskaTrack *track = matroska_find_track_by_num(matroska,
pos[j].track);
if (track && track->stream)
av_add_index_entry(track->stream,
pos[j].pos + matroska->segment_start,
index[i].time/index_scale, 0, 0,
AVINDEX_KEYFRAME);
}
}
matroska_convert_tags(s);
return 0;
@ -1898,6 +1933,12 @@ static int matroska_read_seek(AVFormatContext *s, int stream_index,
AVStream *st = s->streams[stream_index];
int i, index, index_sub, index_min;
/* Parse the CUES now since we need the index data to seek. */
if (matroska->cues_parsing_deferred) {
matroska_parse_cues(matroska);
matroska->cues_parsing_deferred = 0;
}
if (!st->nb_index_entries)
return 0;
timestamp = FFMAX(timestamp, st->index_entries[0].timestamp);