[x265] Dynamic rate control

[Ralf Globisch]

Joshua, just checking if I'm understanding you correctly: are you suggesting I change the x265_param::vbvBufferSize parameter before calling x265_encoder_reconfig?

Currently I am only setting x265_param::bitrate. If I need to set vbvBufferSize what 
sort of values should it contain in relation to the desired bitrate in kbps?

Thanks,
Ralf

>>> Joshua Bowman <silverbacknet at gmail.com> 10/13/15 12:47 PM >>>
You should be able to use x265_encoder_reconfig to continually change the VBV
as you get updated on how much bandwidth & congestion you have. By adjusting VBV you
can achieve the fine-grained rate control you want; scalable encoding is little more
than the standardized encoding of several streams, RTSP-style, and switching between
them, so I don't think it'd be applicable to your case.


> On 10/13/2015 3:00 AM, Ralf Globisch wrote:
> Mario, thanks for the reply.
>
> > So you are using a client-to-server feedback control, trying to control  
> > the video bitrate based on the download speed, in a real-time encode  
> > scenario?
>
> Yes, exactly.
> > The usual approach I knew so far was providing several video streams with  
> > different setups and switching between them (like in MPEG DASH, as used by  
> > YouTube for HD video features).
>
> I am familiar with the bitstream switching approach, but am looking at rate control 
> in e.g. video conferencing/WebRTC scenarios where this is not really an option. 
> Perhaps the scalable extension is a better fit for such use cases. 
> Are there any plans for implementing SHVC in x265?
>
> > I don't know the interna, but I could imagine that reconfiguring the  
> > bitrate control will have a quite slow effect, probably only from the next  
> > GOP on, when it comes to effect at all. I wonder if you may have to force  
> > a kind of encoder reset after reconfiguring... Just a thought.
>
> Ok, thanks, I was hoping there might be another way as resetting an encoder 
> when adjusting to network congestion will likely have an adverse effect.
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