[MEncoder-users] Re: vf_decimate vs 24p->60p content

Scott W. Larson scowl at pacifier.com
Thu Dec 22 07:42:24 CET 2005

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. :(

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