[FFmpeg-devel] [PATCH 0/3] WebM in dashenc

Jeyapal, Karthick kjeyapal at akamai.com
Fri May 4 09:49:56 EEST 2018


On 5/3/18 10:11 PM, Jan Ekström wrote:
> On Fri, Apr 27, 2018 at 3:51 AM, Jan Ekström <jeebjp at gmail.com> wrote:
>> Personally I would be for removal of the WebM muxing feature in dashenc
>> altogether, since the dashenc feature has never seemingly worked, and
>> since there is a whole separate WebM-specific DASH meta muxer in
>> webmdashenc.
>>
>> But these patches should at least make the thing not crash, and put it
>> under FF_COMPLIANCE_EXPERIMENTAL strictness. That way nobody should be
>> accidentally utilizing it.
>>
>
> For the record, I wrote this at around 4AM under the impression that
> the "WebM DASH" muxer was actually what you would expect from its
> name.. (and by quickly checking that it seemed to be writing a DASH
> manifest)
>
> It most certainly is not that, it just writes a DASH manifest. Does
> not actually mux anything. So yes, dashenc is the thing to poke for
> both ISOBMFF and WebM DASH.
OMG! I was also not aware of that. Oops! 
Thanks for the info.
>
> Accordingly, I have found out that someone actually utilized WebM dash
> for audio, and they mentioned that it worked for them on Chromium,
> Firefox and Edge. The muxer seems to have worked without crashing at
> least during release/3.4. I asked them to verify some video as well,
> and if it works then the FF_COMPLIANCE_EXPERIMENTAL limitation can be
> removed.
I have sent a new patch to make the output format configurable as suggested by you sometime back.
http://ffmpeg.org/pipermail/ffmpeg-devel/2018-May/229436.html
I have tested the WebM output with the following results
VP8 - Works both in Chrome and Firefox
Opus - Works both in Chrome and Firefox
VP9 - Works in Chrome. But not in Firefox.
Since most of it working I have also removed the FF_COMPLIANCE_EXPERIMENTAL limitation and replaced it with just a warning in case of segment extension mismatch.  
>
> Kind of glad adding that made someone notice something, and report
> that they were actually utilizing the feature. They seemed to be happy
> about the thing no longer crashing, as well as the pass-through of
> compliance mode to the sub-muxer.
Yes, that is a really useful feature. 
>
> Best regards,
> Jan
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