[FFmpeg-user] DASH and Variable framerate

Alfred E. Heggestad alfred.heggestad at gmail.com
Sat Aug 8 16:02:44 EEST 2020

On 07/08/2020 13:25, Moritz Barsnick wrote:
> On Thu, Aug 06, 2020 at 15:00:55 +0200, Alfred E. Heggestad wrote:
>> I am wondering if DASH muxer supports variable framerate.
> [...]
>> What I have seen is that DASH and HLS behaves differently
>> regarding variable framerate input.
>>     muxer:               format:   audio delay:
>>     DASH:                m4s       yes
>>     DASH w HLS playlist: m4s       yes
>>     HLS muxer:           mpegts    no
> I suspect this is due to the fact that ffmpeg does not handle variable
> framerate in MOV/MP4 well (which m4s is a variant of, IIUC).

Thanks for the answer. Yes m4s is fragmented MP4.

This also seems to match my observations.


>> in m4s the audio and video track is stored in separate .m4s files.
>> after some time they become out of sync.
> I don't think the separate files are the issue. HLS can also separate
> video and audio into separate files, as far as I remember.
> Cheers,
> Moritz
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