[MPlayer-users] looking for good starting values for vf_decimate

[D Richard Felker III]

On Mon, Jun 23, 2003 at 11:24:48AM -0400, Brian J. Murrell wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> I have a stream I captured from NTSC television in MJPEG format.  I want
> to convert it to MPEG4 using mencoder (CVS).  I have noticed that the
> origiinal must have been 24fps but rather than telecining it for NTSC,
> they simply duplicated 1 frame out 4 to increase the framerate to NTSC.

Are you sure you didn't just capture at ???x240 rather than ???x480? :)

> It looks like I can use the vf_decimate filter to eliminate the duplicate
> frames, but I am not quite sure of what to use for the the values of
> max:hi:lo:frac.  max=1 seems like a sane value, but what to use for hi,
> lo, and frac considering this was captured from analog cable (probably
> fairly noisy, although visually it looks quite acceptable).

Max should be set to -5 (drop at most once every 5 frames). I'm not
really sure what values are optimal for hi/lo/frac... Try playing with
them until you get something you're happy with. Keep in mind that "hi"
controls the degree to which very isolated local changes can force a
frame not to be dropped, whereas "lo" and "frac" specify a threshold
of change that must be present in a large portion of the frame...

If you find good values, post them here! My defaults were tuned mostly
to generating super-low-bitrate output, not fixing this sort of
pseudo-telecine...

Rich