avformat: increase first_frames threshold for mp3,ac3

Fixes Ticket4723
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/ac3dec.c

@@ -80,7 +80,7 @@ static int ac3_eac3_probe(AVProbeData *p, enum AVCodecID expected_codec_id)
     if(codec_id != expected_codec_id) return 0;
     // keep this in sync with mp3 probe, both need to avoid
     // issues with MPEG-files!
-    if   (first_frames>=4) return AVPROBE_SCORE_EXTENSION + 1;
+    if   (first_frames>=7) return AVPROBE_SCORE_EXTENSION + 1;
     else if(max_frames>200)return AVPROBE_SCORE_EXTENSION;
     else if(max_frames>=4) return AVPROBE_SCORE_EXTENSION/2;
     else if(max_frames>=1) return 1;

libavformat/mp3dec.c

@@ -98,7 +98,7 @@ static int mp3_read_probe(AVProbeData *p)
     avcodec_free_context(&avctx);
     // keep this in sync with ac3 probe, both need to avoid
     // issues with MPEG-files!
-    if   (first_frames>=4) return AVPROBE_SCORE_EXTENSION + 1;
+    if   (first_frames>=7) return AVPROBE_SCORE_EXTENSION + 1;
     else if(max_frames>200)return AVPROBE_SCORE_EXTENSION;
     else if(max_frames>=4 && max_frames >= p->buf_size/10000) return AVPROBE_SCORE_EXTENSION / 2;
     else if(ff_id3v2_match(buf0, ID3v2_DEFAULT_MAGIC) && 2*ff_id3v2_tag_len(buf0) >= p->buf_size)