Re: [rtcweb] Plan for MTI video codec?

Randell Jesup <> Fri, 24 October 2014 05:11 UTC

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Date: Fri, 24 Oct 2014 01:11:08 -0400
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Subject: Re: [rtcweb] Plan for MTI video codec?
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On 10/20/2014 3:09 AM, Cavigioli, Chris wrote:
> No, not 2 discussions ... but 2 MTI codecs.
> Given:
> -Industry is polarized c. 40% VP8 vs. c. 40% H.264
> -Unlikely this will change
> -Every single mobile device (100%) of the billions out there running a 
> mobile OS (iOS, Android, Windows, BB OS, etc) will already support 
> H.264, AMR-xx since those are MTI for 3GPP and for the OS
> Then:
> -Why not support both:  VP8, Opus = web; H.264, AMR/AMR-WB = LTE
> -Every single mobile device and OS already deals with H.264+AMR 
> licensing for many years.
> -Being royalty free, incrementally adding VP8 and Opus shouldn't be a 
> major additional impact

I should note that many H.264 HW implementations (or the software 
driving them) in mobile devices are NOT usable for WebRTC (or for video 
communication in general).  The bugs I've seen..... <shudder>.  You can 
certify specific sets of hardware or base chipset code, but until they 
actually get tested *well* in interactive, error-recovery, variable 
bandwidth use you have no clue if they'll work.  (And without such 
testing, generally the answer would be 'no').  Can you say "IDR to 
change bitrate"?  Learn.... OMX has *many* options, most of which are 
not supported on a given implementation, which makes generic use 
'interesting' when you go past the well-traveled (and still rocky) 
decode path.

So if Mozilla distributes Firefox to Android devices, what are we to 
do?  We can't simply assume the encoder/decoder will work for WebRTC at 
this point.  Even getting streaming video decode to leverage HW decoders 
was a massive pain with whitelists, blacklists, evil device-specific 
hacks, etc.  It has gotten better over time - but not great.

I'll note that for WebRTC we currently support OpenH264 on desktop, and 
HW H.264 on specific FxOS devices/chipsets/versions (the default for 
FxOS WebRTC OMX H.264 support is false).  As of today we support only 
VP8 on Android.

And I'll echo Bernard's comments about AMR and licensing/open APIs.

<gripe> When did people forget how to edit out irrelevant repetition of 
old messages?  Ah, yes, when everyone started top-replying.... </gripe>  
Makes searching archives much less fun.  :-/

Randell Jesup -- rjesup a t mozilla d o t com