[FFmpeg-cvslog] avformat/mp3dec: Check for occurances of headers within frames during probing

[Limin Wang]

ffmpeg | branch: master | Limin Wang <lance.lmwang at gmail.com> | Fri Nov  8 00:16:22 2019 +0800| [c22665ae691ca313793330bfa7c9a2b70d53cbdf] | committer: Michael Niedermayer

avformat/mp3dec: Check for occurances of headers within frames during probing

Fixes misdetection of zYLx.wav

Reviewed-by: Paul B Mahol <onemda at gmail.com>
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=c22665ae691ca313793330bfa7c9a2b70d53cbdf
---

 libavformat/mp3dec.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/libavformat/mp3dec.c b/libavformat/mp3dec.c
index 4fde920caf..71a4ed706d 100644
--- a/libavformat/mp3dec.c
+++ b/libavformat/mp3dec.c
@@ -71,7 +71,7 @@ static int mp3_read_probe(const AVProbeData *p)
     int frames, ret;
     int framesizes, max_framesizes;
     uint32_t header;
-    const uint8_t *buf, *buf0, *buf2, *end;
+    const uint8_t *buf, *buf0, *buf2, *buf3, *end;
 
     buf0 = p->buf;
     end = p->buf + p->buf_size - sizeof(uint32_t);
@@ -86,11 +86,19 @@ static int mp3_read_probe(const AVProbeData *p)
         buf2 = buf;
         for (framesizes = frames = 0; buf2 < end; frames++) {
             MPADecodeHeader h;
+            int header_emu = 0;
 
             header = AV_RB32(buf2);
             ret = avpriv_mpegaudio_decode_header(&h, header);
             if (ret != 0 || end - buf2 < h.frame_size)
                 break;
+
+            for (buf3 = buf2 + 4; buf3 < buf2 + h.frame_size; buf3++) {
+                uint32_t next_sync = AV_RB32(buf3);
+                header_emu += (next_sync & MP3_MASK) == (header & MP3_MASK);
+            }
+            if (header_emu > 2)
+                break;
             buf2 += h.frame_size;
             framesizes += h.frame_size;
         }