On Fri, 29 Oct 2004, Dik Takken wrote:
> > Actually it is mentioned in the toplevel (mjpegtools) manpage:
> >
> > "A quality factor should be chosen that way that the mplex output of
> > Peak bit-rate and average bit-rate differ by about 20-25%\&...
>
> I read this manpage many times, but there is so much information in it
Now that is something new and different - a "complaint" about too
much documentation!
:)
> good to add a line to the mpeg2enc manpage to make it clear that the
> specified bitrate isn't exactly a brick wall. The hint about mplex showing
> the real peak bitrate would also be most valuable there.
Ok - that's easy enough to do. I'll find a little free time this
weekend.
> > Ideally what should be done is get rid of the "-q" concept completely...
>
> Indeed. With the current behavior it's going to be difficult to automate
> the encoding of video material. It would require the script to encode
> multiple times and select the best stream by examining mplex's output.
It hasn't been a big problem for me. I'm usually going for maximum
play time on a disc rather than trying to push towards the limit
the DVD format allows.
One thing that has worked very well is to use the 1/2 encoded frame
size (352x480 for 525line systems and 352x288 for 625line systems).
Then you can let the encoder use as many bits as it wants/needs.
On the typical TVset you really can't see the difference with most
material (especially if the original source is VHS or similar).
> > Another caution is that some DVD players have difficulty placing high
> > bitrate recordable (DVD+R/-R/+RW/-RW) media. I've seen recommendations
> > in Apple's documentation about not using higher than 8000Kb/s in order
>
> Is that a "thou shall not exceed" or a "desired average"?
It's just a "hint" or "advisory limit". Players vary in their ability
to read the recordable media (which is less reflective than the
commercial pressed DVDs).
> I think I'd better use Imagemagick to do that. The frames I generate are
> composed of multiple (partly transparent) layers. Some layers give
I imagine Photoshop could do it too :)
> I guess my little (cough..) DVD menu generating script will need some more
> lines... :)
Something to keep you off the streets at night :-)
Cheers,
Steven Schultz
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