Re: [rtcweb] Codec Draft

Ralph Giles <giles@thaumas.net> Sat, 12 November 2011 05:25 UTC

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Date: Fri, 11 Nov 2011 21:25:11 -0800
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From: Ralph Giles <giles@thaumas.net>
To: Miguel Casas-Sanchez <miguelecasassanchez@gmail.com>
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Subject: Re: [rtcweb] Codec Draft
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On 10 November 2011 09:14, Miguel Casas-Sanchez wrote:

> - on the audio codec requirements sec 3.1 , you could be adding as
> optional mp3 (MPEG-2 layer III). I'm sure a large part of the audience
> would like to beat me up after writing this, but WebRTC is about
> interoperability, and there's a whole bunch of servers out there
> cranking mp3.

As has been mentioned before, mp3's fixed frame size of 1152 samples
makes it unsuitable for interactive applications, especially when
combined with the usual 2 or 3 frame encoder latency.

> I'm not too sure if this would not suffer of the same
> problems as g.729 with licensing. MPEG is easier on licensing than
> ITU. Or perhaps this is not the document to discuss this optional
> reqs.

The mp3 format is also believed to be covered by patents through the
end of 2017[1]. While it might be possible to find an encoder profile
which will be free before then, it will be at least 2013 before even
that subset can be considered royalty free.

Unfortunate, I agree, but mp3 and several other more established audio
codecs were considered and discarded prior to this draft.

 -r

[1] http://en.wikipedia.org/wiki/Mp3#Licensing_and_patent_issues