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

L. Lee llee040 at sbcglobal.net
Wed Dec 18 21:10:39 CET 2013

On 12/17/13, 4:30 PM, "Nicholas Robbins" <nickrobbins at yahoo.com> wrote:
>> 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
>>>  the encoding results might be entirely different.
>>>  Laine Lee
>> I'm not sugesting that it would be identical, but it seems that the
>> is between fieldmatch and yadif so tacking ,decimate onto the end would
>> 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
>> [Parsed_fieldmatch_1 @ 0x306d9d4f20] Frame #8160 at 272.272 is still
>> Furthermore, if decimate does its job right the frame rate is already
>> 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
>> fps filter at the end should change things. Also, I just checked, and
>> 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

I would surely like to get a sample. I shouldn’t need more than 20-30
seconds to see what results I’m able to produce. You might be able to
email me such an excerpt. I don’t see how any conversion to deinterlaced
30 fps would result in optimal output. Nearly any smooth horizontal
panning is like getting slapped in the face 6 times per second. If output
is deinterlaced, all 4th and 5th frames are duplicates. If not
deinterlaced, those frames are interlaced complements which still take
twice as long as a normal frame to play. Thanks.

Laine Lee


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