Re: [Mjpeg-developer] mpeg2enc with MJPEG Tools 1.9.0rc2 buggy !

[Steven M. S. <sm...@2B...>]

On Mon, 19 Mar 2007, stefan wrote:

> > Ideally and eventually '-q' should go away completely...
> >   
> Huh? I don't regard this to be a good idea. There is no harm, if an 
> encoder uses less bits than specified by the bitrate. Imagine a 

	Why?  Your sugessions say the same thing - just using different words ;)

> I think, mpeg2enc needs two bitrate-modes:
> 
> 1) variable bitrate-mode: A local and short second pass is just used to 
> chop off bitrate-spikes. That is, whenever the encoder realizes that 
> there was a spike, it goes back some frames (a GOP?) and reencodes them 
> with a lower q-scale again. But only for that spike...

	So if the encoder is going to compute the -q why bother with the
	user specifying it?

> 2) average-bitrate-mode or "filesize-mode": Here it makes some sense to 
> specify an upper-bound-tolerance, only. The encoder must not go beyond 
> this. If not possible otherwise, then use 2 passes... This mode should 
> fit a file as close as possible to a given file-size/average-bitrate...
	
	Again, where is -q?

	In BOTH cases you have set the bitrate or filesize and let the
	ENCODER COMPUTE the effective -q?

	WHY does the user have to specify both the rate and the initial q?
	Give a bitrate and let the encoder do the job.

> hmm,... seems like I must use ffmpeg, currently...

	Or Compressor2 - that's what I'm doing until mpeg2enc is trustworthy
	once again :(

	Cheers,
	Steven Schultz