[FFmpeg-user] aes-ctr cipher

Moritz Barsnick barsnick at gmx.net
Tue Aug 9 22:33:10 EEST 2016

Hi Saelis,

On Tue, Aug 09, 2016 at 06:31:58 -0700, Saelis wrote:
> I see that aes-ctr support is included in FFmpeg since commit
> 23ac99dc17b0c4ff43bb56c1f8cbe7feb34bada5
> (https://ffmpeg.org/pipermail/ffmpeg-cvslog/2015-December/096510.html).
> I can't find documentation on how to use this feature.

The relevant commit for you as a user is this:

It seems the options are not documented separately. You can read about
them in that commit diff, or with
$ ffmpeg -h muxer=mov
  -encryption_scheme <string>     E....... Configures the encryption scheme, allowed values are none, cenc-aes-ctr
  -encryption_key    <binary>     E....... The media encryption key (hex)
  -encryption_kid    <binary>     E....... The media encryption key identifier (hex)

The demuxer also supports it.

I do recall reading an email (on a mailing list) or some web page
explaining how to do it. I don't *think* ffmpeg extracts or inserts the
keys into HLS by itself, you need to extract them.

Unlike Anatol, I'm not sure it's limited to MP4. The code doesn't
indicate that this shouldn't apply to mov (or flv) as well. Just try!


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