[MPlayer-advusers] lavc ratecontrol bug

[Corey Hickey]

RC wrote:
> Okay, this bug is VERY specific.  It's no wonder nobody noticed it, even
> though it's been around for at least a month...

Can you identify the commit that caused it? If you don't get a quick
answer, finding the commit would be helpful.

> If using scplx_mask (eg. =0.1) while encoding with mpeg1/mpeg2 video,
> the video bitrate will quickly climb extremely high (3000) and stay
> there, despite the vbitrate setting (700 in my case). 
> 
> Simple to reproduce:  mencoder -ovc lavc -lavcopts
> vcodec=mpeg1video:vbitrate=700:scplx_mask=0.1
> 
> This does NOT happen with the mpeg4 codec, or if "trell" is
> used in with mpeg1/2.  It's only because "turbo" turns off trell for
> vpass=1 that I experienced the bug myself.

I can confirm that. Lots of messages:
[mpeg1video @ 0xe52ec0]warning, clipping 1 dct coefficients to -255..255

If anybody has trouble reproducing this, I can give more information,
but I don't have time now.

-Corey