[MEncoder-users] Near-lossless MPEG-2 (Was: High bitrate mpeg2 encoding problem)

[Rich Felker]

On Mon, Sep 03, 2007 at 11:13:37AM +0200, Reimar Döffinger wrote:
> Hello,
> On Mon, Sep 03, 2007 at 10:49:25AM +0200, Moritz Barsnick wrote:
> > Are there any encoding (lavc) options recommended for least-lossy
> > MPEG-2 compression, or do I just need to let mencoder do its best job
> > (with whatever tweaks) within the given rate? Bitrate is not really an
> > issue, as hinted above, but it should be possible in realtime (as it's
> > TV capture) on a 2.8 GHz Pentium 4. Though encoding to MPEG-2 has never
> > really max'd out my CPU.
> 
> vqscale=2 for high quality. vqscale=1 is also possible but the
> documentation suggests it might lead to encoding errors.
> keyint=1 encodes all frames as I-frames which usually increases quality
> and encoding speed, but also size (by a lot).

IMO using I-frames-only decreases encoding quality, at least when
quality is not already extremely high (low quantization). Motion
vectors are not just more efficient; they're also more accurate, or at
least keep the errors consistent between frames (they move with the
motion of the video).

Rich