[MPlayer-users] Scaling and expanding when encoding tv

D Richard Felker III dalias at aerifal.cx
Wed Dec 15 16:24:55 CET 2004

On Tue, Dec 14, 2004 at 09:29:10PM -0800, Barton Bosch wrote:
> D Richard Felker III wrote:
> >On Tue, Dec 14, 2004 at 12:36:52PM -0800, Barton Bosch wrote:
> >
> >>D Richard Felker III wrote:
> >><snip>
> >>
> >>>>Is this caused by the 29.97 frame rate?  How do you all deal with 
> >>>>this?  Would it be better to set the tv card's capture rate to 25 or 
> >>>>27 in the -tv options?  To set the fps to 25 or 27 in -lacvopts?  Or 
> >>>>maybe dealing with it on playback with the general mplayer -fps option?
> >>>
> >>>
> >>>Never set the framerate to anything other than the actual correct
> >>>framerate, in this case 30000/1001 aka 29.97. Anything else will give
> >>>horrible results.
> >>
> >>Ok, so is it necessary to pass the frame rate to the tuner card or 
> >>mencoder to get optimal results?  I've noticed that in the intial 
> >>output, mencoder reports the frame rate as 29 fps and that in the 
> >>status line (after it settles out) it reads 30 fps.
> >
> >
> >This is NOT the framerate of the movie, it's the rate you're encoding
> >at, i.e. it's measuring encoding performance. And it's rounded to the
> >nearest whole number anyway..
> Which ?this? are you referring to?  The status line, i.e.:
> Pos:  62.7s   1878f ( 0%)  30fps Trem:   0min   0mb  A-V:0.000 
> [16010:705]

This line above.

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

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.

> That is what the two instances of an fps stat look like if I do not 
> specify an fps value to the -tv option of mencoder.  The somewhat 
> jumpy playback caused me to find and throw the -identify option; 
> it's fps stat on a file encoded without specifying an fps rate looks 
> like:
> ID_VIDEO_FPS=29.000
> The -identify option does not round to whole numbers, correct?  So 
> the file is @ 29 fps and not the 29.97 of the original broadcast? 
> Would this cause playback to be a little jumpy/look like frames had 
> been dropped?


> 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.


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