[FFmpeg-devel] [PATCH 2/5] fate: avoid framemd5, use framecrc its faster

Michael Niedermayer michaelni at gmx.at
Wed May 8 19:05:08 CEST 2013

On Wed, May 08, 2013 at 06:24:25PM +0200, Reimar Döffinger wrote:
> Michael Niedermayer <michaelni at gmx.at> wrote:
> >Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
> I disagree with this, CRC can easily miss structural changes,

Can you give an example of a structural change that has occured over
the lifetime of ffmpeg in one of its output files that would have
failed to be detected with CRC (or rather adler32)?

The question is not if you can construct a pattern that gives a
crc equal to some other because noone sits there and tries to generate
such collisions, the checks are there to detect unintended bugs.

> particularly with "only" 32 bit, so I have doubts it is really suitable for this purpose.
> Also the speed difference seems not all that relevant to me.

Sure thats because you run fate maybe once a day, i run it maybe 50
times or more a day. The time it takes is definitly relevant to me.

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Breaking DRM is a little like attempting to break through a door even
though the window is wide open and the only thing in the house is a bunch
of things you dont want and which you would get tomorrow for free anyway
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