[Libav-user] Implementing MPEG-1 Real-Time Video Encryption

Robert Krüger krueger at lesspain.de
Wed Sep 25 09:24:09 CEST 2013

On Tue, Sep 24, 2013 at 6:14 PM, Houle, Elijah Js
<elijah.houle at email.wsu.edu> wrote:
> I'd like to implement the encryption algorithm from this paper (www.cs.purdue.edu/homes/bb/security99.ps), where only the sign bits for the DC/AC coefficients are selected and encrypted. This requires selecting bits in a zigzag order from each block (Y1, Y2, Y3, Y4, Cb, Cr). Not wanting to write an MPEG-1 encoder from scratch, my first thought was to modify the mpeg12enc.c file, but I can't figure out whether/where it distinguishes among the different blocks of the macroblock, especially because I'm unfamiliar with some of the terminology implicit in the variable names. Am I close to the right track, or is there a better approach?

please try the ffmpeg-devel list as your question seems to be about
extending/modifying the core functionality of ffmpeg rather than
building an application using its libs.

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