[FFmpeg-user] Confusion about fieldmatch, decimate and framerate (now with yadif)

Nicholas Robbins nickrobbins at yahoo.com
Tue Dec 17 23:30:51 CET 2013

> On Thursday, December 12, 2013 1:02 PM, Nicholas Robbins <nickrobbins at yahoo.com> wrote:
> >>  On Thursday, December 12, 2013 11:25 AM, L. Lee 
> <llee040 at sbcglobal.net> wrote:
>>  > On 12/9/13, 8:44 PM, "Nicholas Robbins" 
> <nickrobbins at yahoo.com> 
>>  wrote:
>>>  The 'decimate' filter after fieldmatch would take care of the 
> frame 
>>  rate
>>>  coversion, but it just throws out the extra frame, so it wouldn't 
> change
>>>  the fact that fieldmatch was labeling frames as interlaced, but yadif
>>>  wasn't deinterlacing them.
>>  That hasn¹t been my experience at all. The frame rate of the output may be
>>  the same, but unless the filter chain and all other options are the same,
>>  the encoding results might be entirely different.
>>  Laine Lee
> I'm not sugesting that it would be identical, but it seems that the problem 
> is between fieldmatch and yadif so tacking ,decimate onto the end would not 
> change if yadif caught the frames. I tested and the I get the "still 
> interlaced" frames at the same places.
> Frame #8158 at 272.205 is still interlaced time=00:04:31.96 
> bitrate=2607.8kbits/s    
> [Parsed_fieldmatch_1 @ 0x306d9d4f20] Frame #8159 at 272.239 is still interlaced
> [Parsed_fieldmatch_1 @ 0x306d9d4f20] Frame #8160 at 272.272 is still interlaced
> Furthermore, if decimate does its job right the frame rate is already 24000/1001 
> since it was 30000/1001 and decimate drops every fifth frame. I checked and the 
> decimated version has a frame rate of 23.97. So I don't thinking adding the 
> fps filter at the end should change things. Also, I just checked, and it 
> doesn't. Same output and error.
> -Nick

So unless someone has some other option or advice, I think I will just 

fps=fps=30000/1001,fieldmatch,decimate,yadif (which will yadif everything.) should get rid of the combing, but it will blurr everything a bit too. U


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