[FFmpeg-cvslog] r20552 - trunk/libavcodec/mjpegdec.c

Michael Niedermayer michaelni
Sun Nov 22 12:26:26 CET 2009

On Fri, Nov 20, 2009 at 03:57:59PM +0100, Reimar D?ffinger wrote:
> On Fri, Nov 20, 2009 at 02:21:53PM +0100, Michael Niedermayer wrote:
> > I dont think this is correct
> > The test should be s->height % (s->v_max*8)
> > 
> > besides this the fliped code also looks suspect
> Hmm. Does anyone actually have or can create a sample that should be flipped
> and where the height is not divisible by 8 or so?

you can just set flipped = 1 with a normal jpeg to test it i guess 

> Either way, I am quite confident that the check here should be exactly
> for the same thing as whatever is used for the flipping code.

i doubt (height / 3) % 8 is correct
example: height=25
height/3 == 8
actually written height= 48
yes we have code that blocks v_max=3 ..

another example: (height /2) %8
height=1 ...

> I suspect that your code is more correct, however I also think that
> the 8*mb_height is completely bogus and should have particularly funny
> effects if someone created a lossless JPEG (where mb_width is never
> initialized) that somehow triggers flipped.

mjpeg_decode_scan() is under if(!lossless)
or did you mean something else?

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Concerning the gods, I have no means of knowing whether they exist or not
or of what sort they may be, because of the obscurity of the subject, and
the brevity of human life -- Protagoras
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