[MPlayer-users] Scaling and expanding when encoding tv

[Barton Bosch]

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]


or the initial output, i.e.:

[V] filefmt:9  fourcc:0x32315659  size:640x480  fps:29.00  ftime:=0.0345


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?

It turns out that mencoder -tv's fps option does accept float values 
and fractions so the next thing to do is to record another long file 
  with fps=30000/1001 thrown and see if that fixes the prob.  I just 
thought that someone here might know the answer off the top of their 
head.

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.



Thanks again,

Barton