[FFmpeg-devel] Stamping videos with info per download

steward at manscat.com steward
Tue May 12 14:12:28 CEST 2009

First post to this list.
Please forgive and redirect if this is not the right place.

Problem: unauthorized distribution of original material.

Would it be possible for an internet shop to "stamp" a download with
purchaser information? So that later, if the movie turns up at rapidshare,
torrents, free sites etc, we would be be able to identify the rogue?

Problem #1 is finding a place for the info. I tried (without ffmpeg) to
create a "blank space" in the copyright/infor portion of a video, then
write to that space later. The movie failed to load of course. I may have
made a simple mistake but I assumed probably a CRC check of some kind was
in effect.

I'm guessing ffmpeg may provide a solution, rewriting the header and
recalculating whatever magic number is used to check integrity.

Problem #2 would be how to serve more than one copy to different
purchasers at the same time. I guess that is solved by streaming or
temporary copies, or some other way, outside the scope of ffmpeg. But
mention it for completeness.

Even without my particular reason, it seems a reasonable addition to
ffmpeg: inserting text/info as a separate step from rendering/converting.
A kind of ffinject to match ffprobe? Or perhaps it is readily available
and I have not yet stumbled on it?

You guys are doing great work.
Any hints, links, advice much appreciated.

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