[MPlayer-users] Reencoding a broadcast HD-ATSC stream

[Vladimir Mosgalin]

Hi Philip Prindeville!

 On 2005.11.21 at 14:49:02 -0700, Philip Prindeville wrote next:

> Why place pp after? Because I don't want to have non-display (CC) lines
> (the bottom 8 lines) being included in the post-processing computation,
> as they will lead to artifacts in the adjacent cells...

That's stupid, because you'll lose qp of original video, and won't be
able to postprocess it correctly.

Am I understanding right that postprocessing bottom 8 lines leads to
artifact in bottom 16 lines or you are speculating things?


You also don't need scale filter there, after crop the dimensions are
1920:1080. And use aspect=16/9 instead of autoaspect.

> >conclusion: something like pp=ac/lb,crop=...,scale=...
> >You may also think about denoising filter, something like hqdn3d=2:2:3
> >or stronger one.
> > 
> >
> 
> Actually, I'd rather just crop and de-interlace, and nothing more...
> Keeping the source material as close to original as possible... and do
> the post-processing at playback instead (that way, you can change the
> options until you find what looks best).

No. If you need to postprocess at all, you have to do it on encoding
stage. The vital information for good postprocessing will be lost after
that. You can postprocess second time if your encoding will add visible
artifact, but at that bitrate it shouldn't be a problem.

> >About your problem: don't use bitrate of 20000. If you want to specify
> >2 mbit/s, use 2000. If you want to specify 20 mbit/s, use 20000000. Read
> >man page for details.
> Well that's perfectly intuitive... ;-)

Mplayer's authors never supposed that someone will encode at average
bitrates higher than 16 mbit/s. You should think twice before doing so,
really. It is WAY to high. The encoded hdtv streams I saw had excellent
quality (without postprocessing) at bitrates of 7-9 mbit/s. You'd better
tweak your encoding parameters. Good candidates are v4mv,
vqmin=1:lmin=1, mbd2, mpeg_quant, mv0 and trell options. You can turn
them all together, they never hurt. Then use bitrate of 10000 (if you
feel like wasting disk space) or lower and two-pass encoding.

-- 

Vladimir