[FFmpeg-user] converting 1080p50 to PAL interlaced dv format

[Konrad Karl]

Hi,

On Tue, Jan 24, 2012 at 08:01:51PM +0100, Bo??tjan Strojan wrote:
> I don't have a command line ready, but the filter order might be:
> 
> 1. crop width
> 2. resize width to final size
> 3. bob deinterlace (maybe yadif) to get double frame rate

this I don't understand: why would I need double frame rate?

1080p50 is already 50 full frames per second and the output should
be interlaced to have 25 full frames per second using two fields,
lower field first.

from http://www.dvmp.co.uk/digital-video.htm (DV & DVCAM)

"Consequently in both systems field 1 is the "lower" field .
Field 1 dominance effectively means that the field order of DV material
is "lower field first" for both PAL and NTSC, which is nice! "

So after steps 1 and 2 above the video already has correct size with
50 full frames per second and now interlacing should produce two frames
of 1/50 second duration each (assuming  non-interlaced lines are numbered 1..576):

lower  frame: taking lines 2,4,6....576  from the first  50p frame
higher frame: lines 1,3,4....575         from the second 50p frame 
and so on.

I think the DV pixels are not quadratic (dont know for sure yet) then this should 
be taken into account during step 1 and 2.

Does this make sense so far?

> 4. resize height to final/2
> 5. reinterlace (maybe using tinterlace)

Thanks for mentioning tinterlace, did not know about it.

> or maybe just
> 
> 1. crop width
> 2. crop height (keeping in mind line scan order)
> 3. resize (use interl=1 with scale command)
> 
> can you upload a short sample (the one that has a lot of motion)?

I have put a very short example 1080p50 video here:

http://140.78.117.254:88/avchd/out.mts.bin
(~ 3.5MB)

it has been extracted from a longer clip:

ffmpeg -i 00023.MTS -ss 00:00:03.5 -t 00:00:01.500 -acodec copy -vcodec copy -f mpegts out.mts

since I was unable to get a short enough clip by using the record button :-)

will experiment using your suggestions tomorrow which forces me to read
the man page a couple of times I think. A command line example about
using "resize (use interl=1 with scale command)" and/or "(maybe using
tinterlace)" will let me reach my goal a lot faster, I guess.

Many thanks,

Konrad

> b.
> 
> On Tue, Jan 24, 2012 at 6:47 PM, Konrad Karl <kk_konrad at gmx.at> wrote:
> > Dear all,
> >
> > is this possible with current ffmpeg (Fedora 16, but I can compile myself)?
> > Google did not help so far, "interlaced" triggers lots of search results
> > about de-interlacing....
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