[Ffmpeg-devel] libavcodec h264 decoder

Loren Merritt lorenm
Fri Dec 15 21:49:52 CET 2006

On Fri, 15 Dec 2006, michael benzon chua wrote:
> On 12/15/06, Stefan Gehrer <stefan.gehrer at gmx.de> wrote:
>> Interesting concept, but as soon as you use some real cryptography instead
>> of just toggling the sign I think the bitstream size will increase as some
>> seemingly random coefficients will be harder to compress than what the
>> encoder outputs. Or am I missing something?
> I think this is the case as well. The size of the output .264 file increased
> when I changed the dct values. I'm hoping the effect isn't too significant,
> and that the encryption is still reversible.

The size of the .264 shouldn't change if you just toggle the coefficient's 
sign, because sign isn't compressed.
Why do you want to mess with the guts of the codec, rather than encrypting 
the whole stream?

--Loren Merritt

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