[FFmpeg-user] feature request: warn when video bitrate ignored

[Carl Eugen Hoyos]

Roger Pack <rogerdpack2 <at> gmail.com> writes:

> >> I guess I'm not sure what should happen here...
> >> When I specify 64k for mpeg4, I get an output of
> >>  387.9kbits/s
> >
> > Are you absolutely sure that you can get less than
> > 64k with -qscale 30 (or 100) for your input sample?
> 
> Running it with qscale 100 yields about the same output rate.
> It's odd, though...you'd think it would be able to just 
> pixelate the output more and achieve basically any bitrate.

I unfortunately cannot explain, but I believe you 
misunderstand how MPEG codecs work.
(If I remember a codec comparison once made correctly, 
there once were encoders - Intel - that simply dropped 
frames to reach a low bitrate, but developers here consider 
this bad practice.)

> Anyway, the problem is not that it can't compress more, the 
> problem (in my eyes) is that after specifying a target, it 
> doesn't hit it and doesn't tell you why...leaving you 
> wondering if it accepted the target in the first place, 
> since it appears to be ignoring it...

Did you try 2-pass?
Because I believe it does warn in 2-pass mode if the target 
bitrate is unreachable.

Carl Eugen