[MEncoder-users] mencoder apparently not obeying video bitrate settings

[RC]

On Mon, 21 Jul 2008 03:57:28 -0600
Eric Anopolsky <erpo41 at gmail.com> wrote:

> I think perhaps I miscommunicated. 

You did not.

> > What do you expect
> > MEncoder to do with the extra bits after it's reached the point
> > where it has encoded the video perfectly(*)? Pad the file with
> > zeros?
> 
> Since MPEG2 is lossy, I expect the encoder to reproduce the input as
> accurately as it can at the given bitrate. 

That wasn't the question.  At a high enough bitrate, a video can be
re-encoded without (practically) any loss.  If you specify a bitrate
higher than the one needed for (practically) "perfect" encoding, what
else would you like it to do with the extra bits you're allowing it to
use?

> The subjective quality of the input shouldn't affect the encoder's
> ability to do this, should it?

Yes.  The less complex the video, the easier it is to compress.

 
> When I use vqscale=2, here's what I get:

> Video stream: 3340.625 kbit/s  (417578 B/s)  size: 225073300 bytes
> 538.997 secs  12923 frames

Proving my point.  At about 3,000 kbit/s, MEncoder is reproducing the
input at the maximum possible quality.  When you tell it to use a
bitrate higher than it needs to perfectly reproduce the input video,
what could it possibly do with the rest of the bits?  How would you
prefer it to waste them?