avformat/mp3dec: optimize mp3_seek() for dir < 0

this minimizes the amount of protocol seeks and reading needed in that case

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

diff --git a/libavformat/mp3dec.c b/libavformat/mp3dec.c
index c1ce17373777414144c2a16715b9ade6300041e1..ba77bce2380a7fb22f5207ccc6af6eec1df0f5d3 100644 (file)
--- a/libavformat/mp3dec.c
+++ b/libavformat/mp3dec.c
@@ -318,6 +318,8 @@ static int mp3_seek(AVFormatContext *s, int stream_index, int64_t timestamp,
         return -1;
     }
 
+    if (dir < 0)
+        avio_seek(s->pb, FFMAX(ie->pos - 4096, 0), SEEK_SET);
     ret = avio_seek(s->pb, ie->pos, SEEK_SET);
     if (ret < 0)
         return ret;