[FFmpeg-devel] [FFmpeg-cvslog] lavf/cafenc: Allow muxing opus.

James Almer jamrial at gmail.com
Wed Oct 18 00:48:21 EEST 2017

On 10/17/2017 6:20 PM, Carl Eugen Hoyos wrote:
> 2017-10-17 22:20 GMT+02:00 James Almer <jamrial at gmail.com>:
>>> ffmpeg | branch: master | Carl Eugen Hoyos <ceffmpeg at gmail.com <http://ffmpeg.org/mailman/listinfo/ffmpeg-cvslog>> | Tue Oct 17 21:35:28 2017 +0200| [a3accd0c3768933f15422c9dec596da0f436d786] | committer: Carl Eugen Hoyos
>>> lavf/cafenc: Allow muxing opus.
>>> QuickTime does not require the (unknown) kuki chunk for decoding.
>> This at the very least requires limiting muxing to mono and stereo
>> streams (The only kind of streams that work without channel mapping
>> information in extradata),
> Done, thank you!
>> and a check for -strict experimental.
> Why?

Because we're creating these files blindly, without a proper RE attempt
or following any kind of encapsulation spec. And considering the
official encoder/muxer adds a codec specific chunk we don't, the more
reason to consider a muxing as barebones as this as something
potentially non-compliant.

>> Also, I'd have rather waited for Apple to update their docs about Opus
>> in CAF.
> As in: Until Godot arrives?
> Sorry, I don't think it makes much sense to wait for a
> specification that to best of our knowledge may never
> appear.

Apple published the spec for CAF, detailing encapsulation details for
the codecs it supports, including the contents of the kuki chunk for
most of them. It's to be expected that eventually they'll update it for
While I'm not asking you to revert this addition, I'd prefer if you keep
the muxing code under the experimental check until we're 100% sure it's
correct, or until enough time has passed without the spec being updated.
See how VP9 in Mov was under such a check until the encapsulation spec
was frozen and made official.

PS: Maintainers lists Peter Ross as the CAF maintainer, but that seems
to refer to the demuxer seeing you're the author of the muxer. So
assuming you're maintaining it, could you list yourself there?

> Thank you, Carl Eugen
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