Re: [rtcweb] MTI motion JPEG

[Maik Merten <[e-mail]>]

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