[FFmpeg-devel] [DOC] FFSERVER Configuration Files.

[Piero Bugoni]

> > 
> > There is no option mentioned in the documentation for "VideoBitRateRange".
> 
> the documentation is in ISO c format
> 

Nice.


> > 
> > If no "VideoQMin/Max" settings are mentioned will the Q vary automatically
> up
> > to the limit allowed for the bitrate? Or, Between .1 and 31, or something
> like
> > that?
> 
> yes

OK, so the best quality image for a given bitrate will be used, and the lower
the bitrate specified, the higher the "Q" value will be set, up to a maximum of
31.


> > 
> > As I have said before, 
> > 1) No image with a "Q" more than 12 did I consider worthwhile for anything.
> > 2) Security camera applications mean that a face must be recognizable.
> 
> look, if your connection can transmit at 500kbit/sec and you set max rate
> 500 and bitrate somewhat lower and libavcodec chooses lets say qp=20 that
> means libavcodec cannot encode the images within the bitrate at a lower qp
> if you force qp=5 your stream will end up needing maybe 5000kbit/sec and you
> will not recognize any faces because you will not see anything simply
> because your network is too slow

So use the bitrate as the throttling mechanism and as much as possible, match
it to network speeds.

What happens when the network becomes temporarily loaded, and won't support
your bitrate setting? If "VideoBitRateRange" is set from 0-N, the stream will
use up to "N" if available, and down to no transmission whatsoever if no
bandwidth is available?

The issue with "Q" is this:
Higher "Q" values make the image look more and more like a mosaic. With files
at least, any "Q" beyond 12 produces an image that I do not want to even look
at. (I typically watch full-screen). So the goal at this point is to
incorporate  the method you suggest, but set a limit on the image-crappiness
that is allowed. So the way to do this would be use VideoBitRateRange, do not
specify Qmin, but do specify Qmax?

Finally, where does the rate control buffer fit in all this, and how does one
arrive at a setting, (other than by trial and error, as I did).


P. 





> what VideoQMin=Max=3 is saying is like
> i want the 3rd best car
> while VideoBitRateRange is saying i want the best car
> which i can afford with the money i have available
> 
> (i dont need to mention that you wont get the 3rd best car if you dont pay
> for it)
> 



       
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