[FFmpeg-devel] support for reading / writing encrypted MP4 files

[Eran Kornblau]

Hi all,

We're thinking about adding support for MP4 files encrypted using the CENC scheme to ffmpeg (such as the ones supported by GPAC -
https://gpac.wp.mines-telecom.fr/mp4box/encryption/common-encryption/)
The motivation is to be able to transcode files without having the media ever resident in the clear on disk (some of our customers have
security regulations that forbid that).

We'll probably add to movenc.c a parameter of encryption-scheme, supporting only the value cenc for now, and another parameter
that will contain the encryption key.
Similarly, mov.c will be added a parameter of encryption-key to enable reading encrypted MP4s.
At first phase, only AAC / AVC codecs will be supported (this change is not codec agnostic since for AVC for example, the contents
of the NAL units is encrypted, while the NAL size + type are not)

Before we start working on this feature, since we really prefer not to manage our own fork of the code, we wanted to check with you
whether you will be willing to merge such a feature ?
(assuming it conforms to the coding standards, naturally)

Thank you

Eran