On Fri, 7 Jan 2005, Steven M. Schultz wrote:
On Fri, 7 Jan 2005, Nicolas Boos wrote:
Le Thu, 6 Jan 2005 20:27:26 +0100 (CET) Dik Takken <[EMAIL PROTECTED]> écrivait :
Currently, I need to run mpeg2enc 4 or even 5 times in order to find the optimal quantiser number (the -q option) that yields the best quality and uses all available bitrate. That's why I'm currently
Or simply use --cbr and let the encoder vary the -q automatically.
--cbr, is that a new CVS option? I use the last release version, so I assume that omitting the -q option enables CBR mode.
Specify the bitrate that will generate the desired size and the
encoder will do the rest for you. Replace "-q N" with "--cbr" to
use the specified bitrate, the encoder will automatically vary the
effective -q for you without 4 or 5 passes.
CBR mode is *very* cautious with using the available bitrate. When there is little motion, the CBR encoder uses only a tiny fraction of the available bitrate, keeping the -q as high as 8. The result is that lots of detail that could easily fit in the available bandwidth is discarded. When I switch to VBR, I see that I can easily encode the same video with -q 4, resulting in an amazingly detailed MPEG that does not exceed the specified bandwidth. Why does the CBR encoder not use -q 4 to keep the bitrate as high as the requested bitrate?
Cheers,
Dik
