[FFmpeg-devel] [PATCH 1/2] Add experimental muxing support for FLAC in ISO BMFF (MP4).

James Almer jamrial at gmail.com
Mon Nov 21 20:56:23 EET 2016

On 11/18/2016 12:25 AM, Matthew Gregan wrote:
> At 2016-11-17T22:57:49-0300, James Almer wrote:
>>> > > @@ -345,6 +346,7 @@ const AVCodecTag ff_codec_movaudio_tags[] = {
>>> > > +    { AV_CODEC_ID_FLAC,            MKTAG('f', 'L', 'a', 'C') }, /* nonstandard */
>> > 
>> > This is enables muxing into mov, which bypasses the experimental check below
>> > since mov isn't MODE_MP4.
> Thanks.  Updated the check to reject non-MP4 as invalid before checking the
> experimental flag.  I based the original check on the VP9/MP4 muxing, which
> has the same bug, should I send a patch to restrict that to MP4 too?
> Updated patch attached.
> 0001-Add-experimental-muxing-support-for-FLAC-in-ISO-BMFF.patch
> From 6309c0c60835a843a846915c7534a61786291ad3 Mon Sep 17 00:00:00 2001
> From: Matthew Gregan <kinetik at flim.org>
> Date: Thu, 20 Oct 2016 17:28:11 +1300
> Subject: Add experimental muxing support for FLAC in ISO BMFF (MP4).
> Based on the draft spec at https://git.xiph.org/?p=flac.git;a=blob;f=doc/isoflac.txt
> '-strict -2' is required to create files in this format.

Seeing the maintainer hasn't replied, i have pushed it. Seems to adhere to
the (draft) spec correctly, and is under an experimental strict check.

I tried creating some FLAC only files and they play fine on Firefox 51 b1,
which is the first version with FLAC support. However an h264+flac file
gave me audio only and no video. Do you know if it's a bug that should be
reported to Mozilla, or just expected behavior as they only mention support
for h264+aac and no other specific AV combination?

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