Implement av_find_best_stream.

Originally committed as revision 26104 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 61 insertions, 0 deletions

diff --git a/libavformat/utils.c b/libavformat/utils.c
index e9a8099c95..6f994a1b70 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -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)