amr: Set the codec->bit_rate field based on the last packet

This allows libavformat to guess an estimated duration for
amr files.

For streams with varying bit rates (or with silence descriptors
or "no frame" blocks) the guess is, of course, inaccurate.

1 files changed, 3 insertions, 0 deletions

diff --git a/libavformat/amr.c b/libavformat/amr.c
index ba2ed4f30c..f2fecf3ee1 100644
--- a/libavformat/amr.c
+++ b/libavformat/amr.c
@@ -153,6 +153,9 @@ static int amr_read_packet(AVFormatContext *s,
         return AVERROR(EIO);
     }
 
+    /* Both AMR formats have 50 frames per second */
+    s->streams[0]->codec->bit_rate = size*8*50;
+
     pkt->stream_index = 0;
     pkt->pos= avio_tell(s->pb);
     pkt->data[0]=toc;