how to reinterlace using ffmpeg

[hydra3333]

Hello.
I have a PAL TFF 1080i mpeg2 TV capture .mpg source and wish to convert it to 576i (yes "i" so as not to lose "motion fluidity") h.264/.mp4.
I also have similar sources from other TV channels as captured h.264/.mp4.

I have used avisynth for years to resize by deinterlacing/resizing/re-interlacing.

# LAST is deinterlaced to double framerate using QTGMC ie incoming is 50fps progressive
AssumeTFF() #choose the SAME field order like before deinterlacing
Blur(0,0.5).SeparateFields().SelectEvery(4,0,3).Weave()   #reinterlace PAL TFF from from PAL 576p50 assuming original source was TFF
AssumeTFF() #choose the SAME field order like before deinterlacing
AssumeFPS(25) >> "%avs1%"

Is it possible to re-interlace natively in ffmpeg ?

So far I have this in the commandline to resize from PAL TFF 1080i into PAL 576p50, but of course it is now progressive:

"%ffmpegexex64%" -loglevel error -i "%inputfile_1080i%" -map_metadata -1 -an -sws_flags lanczos -filter:v yadif=1:0:0,setdar=dar=16/9,scale=720:576,colormatrix=bt709:bt601,unsharp -r 50

Can some kind soul please indicate how to use ffmpeg commandline to reinterlace the PAL 576p50 into PAL TFF 576i25.

[KarMa]

Why can't you keep it at 50fps, as going to 25i will just cut the vertical information in half while doing nothing for "motion fluidity" compared to 50fps.

[hydra3333]

I'd thought of that too.
- media player handles 576i (not P50)
- TV handles 576i (not P50)

I could keep it as 1080i however the desired result of 576i .mp4 file is much smaller and retains "motion fluidity"

[smrpix]

-flags +ildct+ilme

[hydra3333]

-flags +ildct+ilme

Thanks. I did some goggling and testing and there were a few more settings to set, since the re-interlacing step was also needed

"tinterlace=4:flags=vlpf" and ":interl=0:in_color_matrix=bt709:out_color_matrix=bt601"

This seems to do the trick, piping to x264 for encoding (some time ago I saw problems with ffmpeg interlaced h.264 encoding whereas x264 worked) :

set PARF1fc=.\framecount.txt
"C:\software\mediainfo\mediainfo.exe" --Inform=Video;%%FrameCount%% "%inputfile_1080i%" > "%PARF1fc%"
FOR /F "usebackq tokens=1" %%G IN ( "%PARF1fc%" ) DO SET FRAMES=%%G
DEL "%PARF1fc%"
REM --frames "%FRAMES%" 

"%ffmpegexex64%" -loglevel error -i "%inputfile_1080i%" -map_metadata -1 -an -sws_flags lanczos+accurate_rnd+full_chroma_int+full_chroma_inp -filter:v yadif=1:0:0,setdar=dar=16/9,scale=720:576:interl=0:in_color_matrix=bt709:out_color_matrix=bt601,unsharp,tinterlace=4:flags=vlpf -r 25 -flags +ildct+ilme -ildctcmp satd -top 1 -f yuv4mpegpipe - | "%X264EXEx64%" - --stdin y4m --thread-input --threads 8 --frames "%FRAMES%" --preset slow --interlaced --tff --profile high --level 4.1 --no-cabac --crf 18 --sar 64:45 --colormatrix bt470bg -o "%PARtemph264%"

[pandy]

Albeit tinterlace is newer and recommended filter, older http://ffmpeg.org/ffmpeg-filters.html#interlace should work also:

interlace=lowpass=0:scan=tff

vertical lowpass may give suboptimal results - you can disable it and give a chance to other approaches (at least i prefer sometimes to control how it is applied).

[hydra3333]

and give a chance to other approaches (at least i prefer sometimes to control how it is applied).

OK. What do you use instead ?

[pandy]

and give a chance to other approaches (at least i prefer sometimes to control how it is applied).

OK. What do you use instead ?

Both - depends what is target for aliasing reduction but usually some tricks - it can be more refined trough http://avisynth.nl/index.php/External_filters#Anti-aliasing - vertical low pass filter implemented in ffmpeg is quite crude in terms how it reducing vertical resolution...