[FFmpeg-cvslog] avcodec/dvdec: skip 3rd stage ac decoding when the headers indicates that the data is inconsistent

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Sat Jul 25 00:18:05 2015 +0200| [dee551bbd280c5f43b9f100d944944c27f188549] | committer: Michael Niedermayer

avcodec/dvdec: skip 3rd stage ac decoding when the headers indicates that the data is inconsistent

Fixes Ticket1589

Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=dee551bbd280c5f43b9f100d944944c27f188549
---

 libavcodec/dvdec.c |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/libavcodec/dvdec.c b/libavcodec/dvdec.c
index 656110e..2a241ab 100644
--- a/libavcodec/dvdec.c
+++ b/libavcodec/dvdec.c
@@ -294,6 +294,7 @@ static int dv_decode_video_segment(AVCodecContext *avctx, void *arg)
     int vs_bit_buffer_damaged = 0;
     int mb_bit_buffer_damaged[5] = {0};
     int retried = 0;
+    int sta;
 
     av_assert1((((int) mb_bit_buffer) & 7) == 0);
     av_assert1((((int) vs_bit_buffer) & 7) == 0);
@@ -310,6 +311,12 @@ retry:
     for (mb_index = 0; mb_index < 5; mb_index++, mb1 += s->sys->bpm, block1 += s->sys->bpm * 64) {
         /* skip header */
         quant    = buf_ptr[3] & 0x0f;
+        if ((buf_ptr[3] >> 4) == 0x0E)
+            vs_bit_buffer_damaged = 1;
+        if (!mb_index) {
+            sta = buf_ptr[3] >> 4;
+        } else if (sta != (buf_ptr[3] >> 4))
+            vs_bit_buffer_damaged = 1;
         buf_ptr += 4;
         init_put_bits(&pb, mb_bit_buffer, 80);
         mb    = mb1;