[MPlayer-dev-eng] [PATCH] synch to new x264 revision

[Jeff Clagg]

On Wed, Sep 22, 2004 at 11:35:04AM -0400, Nico Sabbi wrote:
> can you write some docs about high quality settings, please?
> I made some test using only the bitrate parameter but I wasn't very 
> impressed,
> except that I expected much lower speed  than the 12 fps I obtained.

First, the ratecontrol in x264 may not be as well-disciplined as what
you're used to. Using 2-pass probably helps a lot.

There are some options that are especially deserving of comment:

* iframe. Default is 60. Usually this is much too low.

* deblockalpha. For encodes that are intended to be reasonably high
quality, I usually turn this down a little. However, if your source
material already has some blocking or noise which you would like to
remove, or if it's animation, it may be a good idea to turn it up some.

* cabac. There's really not much reason not to use it. It's off by default.

* subq. In all cases I've seen, it helps significantly.

These are options I'm a little mystified by:

* fullinter. I've seen this cause changes in both directions, and never
did pin down why. But afair none of the changes were very large.

* frameref. This happens to work very well on the foreman test sample, but
more often it has almost no effect at all. I have a guess that it could be
a big win on scenes with rapid flashing, but I never tested this idea out.

I never did much serious sytematic testing, and didn't save the results
from the tiny amount of testing I have done, so I won't venture to
suggest what kind of bitrate or quality differences any of the above
options might give you.