[FFmpeg-user] dv => mp4: deinterlace or not, and how?

[bouke]

----- Original Message ----- 
From: "Tim Nicholson" <tim.nicholson at bbc.co.uk>
To: "FFmpeg user questions and RTFMs" <ffmpeg-user at ffmpeg.org>
Sent: Monday, May 09, 2011 10:29 AM
Subject: Re: [FFmpeg-user] dv => mp4: deinterlace or not, and how?


> On 09/05/11 09:02, Bouke wrote:
>>
>> ---- Original Message -----
>> From: "Tim Nicholson"<tim.nicholson at bbc.co.uk>
>> To: "FFmpeg user questions and RTFMs"<ffmpeg-user at ffmpeg.org>
>> Sent: Monday, May 09, 2011 9:57 AM
>> Subject: Re: [FFmpeg-user] dv =>  mp4: deinterlace or not, and how?
>>
>>
>>> On 06/05/11 20:03, Baptiste Coudurier wrote:
>>>> On 05/06/2011 11:35 AM, sean darcy wrote:
>>> [...]
>>>
>>>>> Why would anyone ever use yadif=1 "bob" deinterlacing?
>>>>
>>>> You can do 1080i25 to 720p50 for example, but I'm sure there are other
>>>> usage since the feature is there.
>>>>
>>>
>>> But what I would really like is to go from 720p50 to 576i25 (SD) ;)
>>
>> Tim,
>> You know that AE can do this?
>> (Perhaps you don't like the downscaler in AE, but it is a handy tool to
>> split fields to frames and vice versa, and it can be scripted)
>>
>
> But difficult to justify the cost of AE on a media mangling box just to do 
> this....
>
>> Or, otherwise a trip to AviSynth Forrest?
>
> Possibly but OS dependant and everything else is X of some flavour..

Ok, you want cheap, you get cheap.
Found a way with QT to do it.
(Old trick to send two images over one interlaced pipe, used in the old days 
of expensive video conferencing)
Export your clip as 25 fps and get rid of the last frame.
>From the original, remove the first frame and export again.
QT will omit one frame every frame if you go from 50 to 25

Pick one of the two and apply a interlaced key signal as mask.
(One line black / white alternating)
Paste that clip over the other, and you got an interlaced composition.
Reverse the mask if you have the wrong field dominance, or apply the mask to 
the other clip.

Bouke

> -- 
> Tim
>
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