Subject: Re: [rtcweb] MTI motion JPEG

From: Harald Alvestrand <[email-masked]>
Date: Mon, 02 Dec 2013 10:50:04 +0100

Designing new video codecs is something that I don't think we should do 
in this WG at this time.

On 12/01/2013 12:46 AM, Maik Merten wrote:
> Am 30.11.2013 01:49, schrieb Ralph Giles:
>> I'd like propose motion JPEG as the manditory-to-implement video codec,
>> per RFC 2435 or similar.
>
> Is it feasible to extend the RFC with, e.g., a run-length coded list 
> of skipped MCUs ("macroblocks")? Picture data for those would be 
> copied over from the last frame. This may even work with unmodified 
> JPEG decoders (either by filling in stub data for the skipped MCUs at 
> the receiving end or by encoding skipped MCUs compact run of zeroed 
> coefficents) and a postprocessing step.
>
> (If coding an explicit list of skipped MCUs is not practical, one can 
> regard MCUs with all-zero coefficients as "skipped". An encoder will 
> have to take this into account so no MCUs are skipped by accident, 
> though.)
>
> This contradicts the minimal-effort argument to some degree, but at 
> least this would enable efficient transmission of screencasts, 
> increase coding efficiency for "talking head" content, and offer 
> additional means for bitrate management (partial screen updates).
>
>
>
> Maik
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> [email-masked]
> https://www.ietf.org/mailman/listinfo/rtcweb

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From: Maik Merten <[email-masked]>
Date: Mon, 02 Dec 2013 11:28:49 +0100

Yes, I guess you're right, this is out of scope. It's just that its 
tempting to come up with ideas for improvements, given the low-hanging 
fruits in case of MJPEG are basically touching the ground.

Maik

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From: Basil Mohamed Gohar <[email-masked]>
Date: Mon, 02 Dec 2013 14:50:13 -0500

For what it's worth, what you described sounds a lot like the "Smoke"
video codec, which, as far as I know, exists only on the OLPC project
via gstreamer.  At least, that's about the only reference I've ever
found for it.

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