[FFmpeg-devel] MP4 VFR

Baptiste Coudurier baptiste.coudurier at gmail.com
Wed Mar 13 01:36:29 CET 2013

On 03/06/2013 12:17 PM, Reimar Döffinger wrote:
> On Wed, Mar 06, 2013 at 08:52:39PM +0100, Nicolas George wrote:
>> I personally do not know and do not care about the MP4 format, but a lot of
>> users seem to want to use it and get trouble for it.
>> Does someone know what the status of variable frame rate in MP4 is? I know
>> it is not supported, but is it a limitation of the format, or just missing
>> code in lavf?
> I think it should be working fine, we just disabled it because it's not really
> allowed and causes issues with some players.
> Or do I remember incorrectly?

I think the problem lies in that track timestamps have to start at 0 or be compensated by
an edit list, and that was not working 100% correctly so it was safer to force CFR which
would trigger frame duplication and therefore guarantee that track timestamps start at 0.

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