[MEncoder-users] x264 [error]: no ratecontrol method specified

[Corey Hickey]

Duane Evenson wrote:
> Most examples I've found don't specify any ratecontrol. After reading 
> the manual, I have tried setting bitrate and qp (3000 and 18 
> respectively), but not at the same time. Either solution solves the
> error, but I've also heard it counters the benefits of multipass encoding.

Roughly, 'qp' sets a constant quality per frame, making multipass
encoding useless--if the quality is constant, each pass is identical,
since there's no way to control how many bits each frame uses.
Specifiying 'bitrate', however, is the usual method for multipass--x264
will "learn" how to distribute the given bits for the best overall
quality, and the quality of individual frames will vary.

The two options are mutually exclusive, so using them both at the same
time makes no sense. A brief test indicates that x264 simply ignores
'bitrate' when 'qp' is specified; I'm too lazy to peer at the code for
such an academic issue. Just remember to use 'qp' or 'bitrate', but not
both.

-Corey