[Ffmpeg-devel] Incorrect JPEG decoding with patch

Cyril Russo cyril.russo
Fri Nov 17 17:25:02 CET 2006


Hi all,

 I've reported earlier that there was a bug with ffmpeg while decoding 
my pictures.
I've dug into mjpeg.c file, and I've found that ffmpeg didn't support 
multiple scans JPEG.

Well, not yet ;-)

I've modified the JPEG decoder so it can handle multiple scans JPEG too.
Currently, 95% of JPEG file have only one interleaved scan.
Bad luck, the JPEG stream I must decode are 3 single scans (Y, Cr, Cb).

Multiple scans are allowed in JFIF specification 1.02, but lacked until 
now in current mjpeg.c implementation.
I've attached the patch, and I ask the devs for review.
For testing the new features, download and decode from 
http://xryl669ny.free.fr/MyFile000.jpg

BTW, grep for "Cyril Russo" for all modifications I've added in final 
patched file.

I've tried to follow ffmpeg coding guidelines. I haven't subscribe to 
the list, so for reply use cyril dot russo AT nexvision in france ;-)

-- 
Cyril RUSSO
NEXVISION [ www.nexvision.fr ]


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