[FFmpeg-devel] [PATCH] skip ##ix chunks reading as video/audio data

[Maksym Veremeyenko]

Hi!

I was investigating an errors happens during transcoding huge DV avi 
files. The error messages from DV decoder:
[...]
AC EOB marker is absent pos=91
AC EOB marker is absent pos=64
AC EOB marker is absent pos=67
AC EOB marker is absent pos=64
[...]
show that frame is broken. After locating that frame i found it contains 
a part of avi index table instead of DV data. Attached screenshot show 
that avi file used a ##ix chunk for pointing to further index. ffmpeg 
reads that chunk (00ix #14100) as frame data....

Same problem happens also to https://trac.videolan.org/vlc/ticket/964

Skipping ##ix chunk was done in the same manner as it was done for ix## 
chunks. The minor changes i removed
n < s->nb_streams
condition, because n is 100 in all cases it found 00ix:

FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF 30 
2146511652 805240575 100
FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF 30 30 2146511653 
808451839 100
FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF 30 30 69 2146511654 
1764765695 100
FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF 30 30 69 78 2146511655 2020159536 100
FFFFFFFF FFFFFFFF FFFFFFFF 30 30 69 78 30 2146511656 813197616 100
FFFFFFFF FFFFFFFF 30 30 69 78 30 FA 2146511657 -97486743 0
FFFFFFFF 30 30 69 78 30 FA 1 2146511658 33173624 100
30 30 69 78 30 FA 1 0 2146511659 129584 100
                                         ^^^

or 01ix :

FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF 30 
2146641244 805240575 100
FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF 30 31 2146641245 
825229055 100
FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF 30 31 69 2146641246 
1764831231 100
FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF 30 31 69 78 2146641247 2020159792 100
FFFFFFFF FFFFFFFF FFFFFFFF 30 31 69 78 38 2146641248 947415345 100
FFFFFFFF FFFFFFFF 30 31 69 78 38 FA 2146641249 -96962455 1
FFFFFFFF 30 31 69 78 38 FA 1 2146641250 33175672 100
30 31 69 78 38 FA 1 0 2146641251 129592 100
                                         ^^^

Is this patch OK?


-- 
________________________________________
Maksym Veremeyenko

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