[FFmpeg-user] audio/video obfuscation

[Micael Silva]

On Wed, Jun 19, 2019 at 10:10 AM Madovsky <infos at madovsky.org> wrote:

>
> On 6/19/2019 5:20 AM, Madovsky wrote:
> >
> > On 6/19/2019 5:15 AM, Moritz Barsnick wrote:
> >> On Wed, Jun 19, 2019 at 05:02:36 -0700, Madovsky wrote:
> >>> I just tried it, works well but unfortunately the player cannot play
> >>> the
> >>> video at all with this option.
> >>> what I'm looking for is if the player does not have the key to
> >>> decode it
> >>> still can play the movie
> >>> with audio and video obfuscated, like audio with frequencies modified
> >>> and pixel noise.
> >> Ah, so that it's still a legal stream that canb be played, but plays
> >> junk?
> >>
> >> I'm not aware of any standardized method to do this, nor of any way to
> >> achieve this with ffmpeg. The "geq" filter can apply a function to
> >> pixels (as some other filter probably can with audio), but you would
> >> need a way to pass it an encryption scheme. I don't think something like
> >> this is implemented or even in consideration - but I might be wrong.
> >>
> >> Moritz
> > a kind of encryption as when it plays without decrypt it plays junk yes.
> > if anyone knows a way to do it please share thanks
> practically I would like to make an obfuscation type like this
> https://www.youtube.com/watch?v=cGTJEjLmx8s
> _______________________________________________
>
> That kind of visual is possible on analog formats not because of the
source but how the receptor. It keep trying to decode the signal and some
how it can because some parts still present like sync pulses. The
'encryption' used in this analog example for instance randomize the lines
of video but some structure remains to make possible the 'decryption'.
Digital encryption works somehow different since a good encrypted content
looks like a background noise, since that the player doesnt even know how
to display anything ("what is the size? the frame rate? the colospace?")