[MPlayer-dev-eng] enhancement for yuv4mpeg output driver

[Trent Piepho]

On Wed, 19 Jan 2005, D Richard Felker III wrote:
> > +	fprintf(yuv_out, "YUV4MPEG2 W%d H%d ", image_width, image_height);
> > +	if(image_fps>23.975973976 && image_fps<23.976073976) 
> > +		fprintf(yuv_out, "F24000:1001 ");
> > +	else if(image_fps>29.96997997 && image_fps<29.97007997) 
> > +		fprintf(yuv_out, "F30000:1001 ");
> 
> There are already good fraction reducing routines in mplayer (or
> lavc?) that let you specify maximum magnitude for the denominator.
> They'll make mplayer's stupid float crap into correct values like
> 30000/1001.

I found av_reduce() in lavc, but it doesn't work for this.  Depending on what
I specify for the max, it turns 23.976 into 2996973/125000, 983/41,
456427/19037, or 16831/702.  There doesn't seem to be any way to get the
correct value of 24000/1001.

Is it acceptable for the vo_yuv4mpeg module to call a routine from libavcodec? 
Is there a problem with the new dependency?  If it's ok, I'll make a new patch
that uses it to reduce fraction, but it's still necessary to make a special
case to detect NTSC x/1001 framerates.