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Implement av_find_best_stream.

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Originally committed as revision 26104 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Nicolas George 2010-12-27 09:08:20 +00:00
parent 107a7e3e7b
commit 9128ae08b3
3 changed files with 96 additions and 1 deletions
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3
doc/APIchanges
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@ -13,6 +13,9 @@ libavutil: 2009-03-08
API changes, most recent first:
2010-12-XX - r26104 - lavformat 52.91.0 - av_find_best_stream()
Add av_find_best_stream to libavformat/avformat.h.
2010-12-27 - r26103 - lavf 52.90.0
Add AVFMT_NOSTREAMS flag for formats with no streams,
like e.g. text metadata.

33
libavformat/avformat.h
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@ -22,7 +22,7 @@
#define AVFORMAT_AVFORMAT_H
#define LIBAVFORMAT_VERSION_MAJOR 52
#define LIBAVFORMAT_VERSION_MINOR 90
#define LIBAVFORMAT_VERSION_MINOR 91
#define LIBAVFORMAT_VERSION_MICRO 0
#define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
@ -1140,6 +1140,37 @@ AVFormatContext *avformat_alloc_context(void);
*/
int av_find_stream_info(AVFormatContext *ic);
/**
* Find the "best" stream in the file.
* The best stream is determined according to various heuristics as the most
* likely to be what the user expects.
* If the decoder parameter is non-NULL, av_find_best_stream will find the
* default decoder for the stream's codec; streams for which no decoder can
* be found are ignored.
*
* @param ic media file handle
* @param type stream type: video, audio, subtitles, etc.
* @param wanted_stream_nb user-requested stream number,
* or -1 for automatic selection
* @param related_stream try to find a stream related (eg. in the same
* program) to this one, or -1 if none
* @param decoder_ret if non-NULL, returns the decoder for the
* selected stream
* @param flags flags; none are currently defined
* @return the non-negative stream number in case of success,
* AVERROR_STREAM_NOT_FOUND if no stream with the requested type
* could be found,
* AVERROR_DECODER_NOT_FOUND if streams were found but no decoder
* @note If av_find_best_stream returns successfully and decoder_ret is not
* NULL, then *decoder_ret is guaranteed to be set to a valid AVCodec.
*/
int av_find_best_stream(AVFormatContext *ic,
enum AVMediaType type,
int wanted_stream_nb,
int related_stream,
AVCodec **decoder_ret,
int flags);
/**
* Read a transport packet from a media file.
*

61
libavformat/utils.c
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@ -2458,6 +2458,67 @@ int av_find_stream_info(AVFormatContext *ic)
return ret;
}
static AVProgram *find_program_from_stream(AVFormatContext *ic, int s)
{
int i, j;
for (i = 0; i < ic->nb_programs; i++)
for (j = 0; j < ic->programs[i]->nb_stream_indexes; j++)
if (ic->programs[i]->stream_index[j] == s)
return ic->programs[i];
return NULL;
}
int av_find_best_stream(AVFormatContext *ic,
enum AVMediaType type,
int wanted_stream_nb,
int related_stream,
AVCodec **decoder_ret,
int flags)
{
int i, nb_streams = ic->nb_streams, stream_number = 0;
int ret = AVERROR_STREAM_NOT_FOUND, best_count = -1;
unsigned *program = NULL;
AVCodec *decoder = NULL, *best_decoder = NULL;
if (related_stream >= 0 && wanted_stream_nb < 0) {
AVProgram *p = find_program_from_stream(ic, related_stream);
if (p) {
program = p->stream_index;
nb_streams = p->nb_stream_indexes;
}
}
for (i = 0; i < nb_streams; i++) {
AVStream *st = ic->streams[program ? program[i] : i];
AVCodecContext *avctx = st->codec;
if (avctx->codec_type != type)
continue;
if (wanted_stream_nb >= 0 && stream_number++ != wanted_stream_nb)
continue;
if (decoder_ret) {
decoder = avcodec_find_decoder(ic->streams[i]->codec->codec_id);
if (!decoder) {
if (ret < 0)
ret = AVERROR_DECODER_NOT_FOUND;
continue;
}
}
if (best_count >= st->codec_info_nb_frames)
continue;
best_count = st->codec_info_nb_frames;
ret = i;
best_decoder = decoder;
if (program && i == nb_streams - 1 && ret < 0) {
program = NULL;
nb_streams = ic->nb_streams;
i = 0; /* no related stream found, try again with everything */
}
}
if (decoder_ret)
*decoder_ret = best_decoder;
return ret;
}
/*******************************************************/
int av_read_play(AVFormatContext *s)