[FFmpeg-devel] [PATCH] RoQ video encoder (take 4)

[Loren Merritt]

On Thu, 14 Jun 2007, Eric Lasota wrote:
>
> By the way, why does the rate control target rate lambda instead of
> total distortion, since base distortion can vary and cause quality to
> shift while lambda remains the same?

Lambda (or equivalently, quantizer) is the only thing that a ratecontrol 
algorithm can decide. Distortion isn't known until after you encode the 
frame. Now, a ratecontrol algorithm could use some heuristic to guess a 
lambda that might provide a given distortion, rather than guess a lambda 
that might provide a given bitrate. The reason no such mode exists is 
that you haven't written it.

--Loren Merritt