On Tuesday 06 November 2007 07:59:35 Florin Andrei wrote:
> -A|--ratecontroller
> What's the difference between 0 and 1?
>
> Ever played with larger values for -r when the source is a fairly good
> (new) DV camcorder? Worth bumping it up?
None (at present).
-A 0 currently selects a limited local single-GOP look-ahead two pass encoding
rate control. Here basically if simple heuristics used for the first
encoding pass produced erratic quantisation with frames varying wildly in
quantity or GOP boundaries in bad places a second pass is switched in to use
the information from the first pass to do a better job. There will
eventually also be a 'pass 1.5' where if lots of action means blockiness is
likely the encoder will re-encode with low-pass filtered source material to
allow blockiness to be eliminated.
-A 1 will (when its done) do statistical look-ahead rate control. This will
basically run an entire 1st pass, or 1st pass over a statistical sample of
GOPs, to work out the pattern of image complexity in the encoding. A second
pass will the encode using that information to accurately hit an average
bit-rate / size target trying to trade bits as much as the decoder buffers
allow between GOPs to maintain the best perceived image quality.
The major changes / bugs in the 1.9 revision of mpeg2enc relate to major
internal changes needed to support this internal encoding and re-encoding of
images (and provided hooks for improving multi-core scalability).
cheers,
Andrew
--
Dr Andrew Stevens
Erdingerstrasse 23
85464 Neufinsing
Germany
Home: +49 8121 883672
Mobile: +49 173 5397553
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