Re: [rmcat] Scenarios as input for new feedback format design

[Randell Jesup <[e-mail]>]

On 8/23/2016 11:09 AM, Stefan Holmer wrote:
> Hi,
>
> As was requested in Berlin, here are a set of scenarios where we 
> (Google) are of interested in using thefeedback format 
> <https://tools.ietf.org/html/draft-dt-rmcat-feedback-message-00>. It 
> would be great to analyze what would be needed to achieve this and 
> discuss how we can improve the current design to possibly accommodate 
> these scenarios.
>
> *Very low bitrate, audio only*
> If a mobile connection becomes really bad for a period of time, we'd 
> like to be able to gracefully degrade to audio only at a low bitrate. 
> This is an extreme, but valid if the connection degrades to 2G for a 
> while.
> - Uplink: 20 kbps
> - Downlink: 20 kbps
> - Audio packet rate: 17 packets/second

These scenarios look good.  I'll add a few which may or may not be 
covered already:

* Audio-only, variable bandwidth (perhaps in place of the above)
- Uplink 16Kbps to 500Kbps (assumes 8Kbps codec @ 40ms with no SRTP auth 
tag (unencrypted or at least unauthenticated; encrypted would be ~18Kbps)
- Downlink 16Kbps to 500Kbps
- Audio packet rate: 26 to 110(?) (assumes max ptime of 40ms)

I include unencrypted  because this isn't just a webrtc spec. Bandwidth 
includes RTP/UDP/IP overhead.

* Screensharing (likely understood already)
- uplink 100Kbps to 10Mbps
- Downlink 70Kbps to 2Mbps
- Audio packet rate 50 packets/s (audio may be optional in some cases)
- Video framerate: <1fps to 30fps (variable, depending on content - may 
be regular or very bursty)
This is especially nasty as the output rate is VERY bursty in some 
low-fps cases, and even in high-fps cases the bitrate will still be very 
bursty (screen transitions or window changes, alternating with small 
changes or animations).  Lack of content means the algorithm can't 
maintain an estimate easily, and may need time to push others to give it 
a fair share.

>
> *Low bitrate audio and video*
> - Uplink: 70-100 kbps
> - Downlink: 70-100 kbps
> - Audio packet rate: 50 packets/second
> - Video framerate: 7-15 fps
>
> *ADSL conference, 10 small thumbnail streams, 1 main stream*
> - Uplink: 500 kbps
>     - Audio packet rate: 50 packets/second
>     - Video framerate: 30 fps
> - Downlink: 8000 kbps
>     - Thumbnail streams: 15 x 7 fps
>     - Main stream: 30 fps

-- 
Randell Jesup -- rjesup a t mozilla d o t com
Please please please don't email [e-mail]!  Way too much spam