[MPlayer-users] Scaling and expanding when encoding tv

[Barton Bosch]

RC wrote:

<snip>

> Encoding a TV signal at a reduced frame-rate will cause a multitude of
> problems, glitches, artifacts, etc.  No one can conclusively say that
> the problem you are seeing is only a result of this issue, though,
> without much more information.
> 
> 
>>So what are the best options for recording tv at less than full file 
>>size (either compressed or scaled or ?) so as to encode them to 
>>dvd/mpeg2?
> 
> 
> There's no such thing as "best".  People have very different priorities.
>  It's all going to depend on whether you want to save disk space, CPU
> time, or want the very best quality you can manage.

Yeah, 'best' wasn't well defined here.  I suppose I meant very best 
quality manageable within reason (>1GB/min not being within that 
definition, <g>).


> First, you can encode to a lossless codec (huff, ffv1), or use a very
> high-bitrate with a lossy codec (mpeg2, mpeg4), and re-encode that in
> 2-pass mode to your normal bitrate.  

Lossless compression sounds interesting, thanks for the tip.



D Richard Felker III wrote:
 >or the initial output, i.e.:
 >>
 >> [V] filefmt:9  fourcc:0x32315659  size:640x480  fps:29.00 
ftime:=0.0345


DRF:This is VERY VERY BAD!!! Where did the 29.00 come from?!? Are you
using MPlayer 0.92 or something still??? There was a bug like this
once, but it was fixed a long time ago. This is definitely why you're
getting bad choppy output.

BB:The 29 fps in the initial readout appears every time I play a 
file captured from my tv card unless I specify -tv fps=30000/1001. 
I'm currently running 1.0pre5-2...  The readout appears in the 
section of mplayer output just before the audio codec info:

Playing fb2.avi.
AVI file format detected.
VIDEO:  [DIVX]  608x464  24bpp  25.000 fps  11649.6 kbps (1422.1 
kbyte/s)
Clip info:
  Software: MEncoder 1.0pre5-RPM-3.3.3
==========================================================================
Opening audio decoder: [pcm] Uncompressed PCM audio decoder


FWIW the particular framedrop/jumpcut problem seems to have been 
resolved by setting the tuner card's fps rate.  There is still a 
little choppiness @ fullscreen (esp in big swooping crane pans) but 
as it doesn't occur @ regular (unscaled) resolution I'm guessing 
that it is a result of some combination of video filters and the x11 
driver.


 >> So what are the best options for recording tv at less than full 
file
 >> size (either compressed or scaled or ?) so as to encode them to
 >> dvd/mpeg2?  I'd just -ovc copy the 640x480 29.97 fps signal to disk
 >> but >1GB/min is a stretch.


  :)

Try huffyuv or ffv1 if you insist on lossless. Otherwise mjpeg with
qscale=1 is a good choice.



Thanks,

Barton