[x264-devel] H264.SVC

[Miljanic Nikola]

On Jan 12, 2010, at 7:55 PM, Jason Garrett-Glaser wrote:

>> 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.

This information would interest me as well.  I completely understand and appreciate the versatility the IRC chat allows for, not to mention rapid discussion and idea exchange.  Unfortunately, it is simply not an option for me, and I'm sure I'm not the only one who monitors this list and is in such situation.  Are such discussions archived anywhere?  Could you please point me (and others interested) to such archives?

Thanks,


Nick