[x264-devel] H264.SVC

[Jason Garrett-Glaser]

> Bandwidth management in multi-party situations is the main reason I have
> been looking at SVC. Take a 3 way conference between hypothetical users in
> Japan (20mbit downstream), the US (2mbit downstream) and outback Australia
> (256kbit downstream). I'm not looking to target multiple devices from QCIF
> to 1080p but my example, while contrived, is typical of today's Internet. I
> am on 50mbit fibre but I know people on 256kbit ADSL. Thats a factor of 200x
> the bandwidth. In 2 party conferences I agree with your sentiment entirely
> but in 3,4,5 party scenarios, "lowest-common-denominator" bit-rate seems
> quite disappointing. In this situation it would result in a 20x loss of
> potential bitrate and thus 20x loss in video quality for the US user over a
> solution that could target the available bandwidth of each user
> individually.

In this case it doesn't seem like there's a good reason to use SVC.
The potential benefit of SVC is based on the following formula:

(total bitrate of all streams) / (bitrate of higher stream)

The larger this fraction, the more SVC would help.

In your case, the fraction is 22.256 / 20, which is barely over 1: not
enough to justify SVC in my opinion.

By the way, if you're interested in advice using x264 for
videoconferencing, we already have at least three companies doing
similar things, so I can pass on the advice I gave them to you.  Drop
by #x264 on Freenode IRC if you have any questions.

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