[MEncoder-users] Re: vf_decimate vs 24p->60p content
dalias at aerifal.cx
Thu Dec 22 19:28:31 CET 2005
On Wed, Dec 21, 2005 at 10:42:24PM -0800, Scott W. Larson wrote:
> Rich Felker wrote:
> >On Wed, Dec 21, 2005 at 04:16:15PM -0800, rob pfile wrote:
> >>so i tried vf_decimate on my tv show, but it didnt work so well. so i
> >>instrumented the code and discovered that it wasnt actually dropping
> >>very many frames.
> >Yes, you'd have to tune the thresholds. :(
> The best decimate parameter I've found so far for turning filmed 720p
> content into 24 fps is "decimate=-1:50:1000:.001". That's the only
> filter I use.
> It's still not perfect. Oddly many duplicate film frames have greater
> differences than non duplicate frames and can easily throw decimate off
> the pattern, especially in dark scenes. When that happens it's ugly.
> This seems to be less of a problem with Fox programs since they're
> encoded by the network instead of being reencoded at your local ABC
> station. I think the ABC stations' encoders are trying to keep a
> constant bit rate and end up encoding extra detail in the duplicate
> frames making them less identical.
> It's a shame they didn't include a "repeat_progressive_frame" flag in
> MPEG-2. :(
They did. It's called a no-change P frame. :) However no one uses it.
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