Re: [rtcweb] Support of video with different resolutions

[Gunnar Hellström <[e-mail]>]

On 2012-12-21 16:40, Bernard Aboba wrote:
> SVC supports multiple scalability mechanisms: temporal, spatial and 
> quality.  Temporal is the most widely implemented in software (at 
> least for H.264/SVC), although there is an open source implementation 
> that supports all modes.  In hardware, support for spatial or quality 
> scaling is not common. As a result, a browser on a mobile device could 
> have difficulty complying with a mandate to support spatial scaling 
> within the encoder.
>
This is sad. For good usability of video, maintained frame rate is 
usually much more important than maintained spatial resolution. E.g. for 
sign language or lip reading usage with a single person in image, a 
frame rate under 20 fps introduces loss of language contents, and 
requires the users to try to fill in the gaps by imagination, while 
spatial resolution reduction down to QCIF causes much less harm to 
language perception possibilities.

Gunnar