[FFmpeg-user] separatefields, select=eq(mod(n, 4), 0)+eq(mod(n, 4), 3), weave

[Mark Filipak (ffmpeg)]

Here:
https://ffmpeg.org/ffmpeg-filters.html#Examples-121
is this example:
"11.237.1 Examples
"    Interlace video using select and separatefields filter:
"    separatefields,select=eq(mod(n,4),0)+eq(mod(n,4),3),weave"

Why does it not work?
Thanks!

ffmpeg -report -loglevel info -i "source.VOB" -ss 1:00 -to 2:00 -vf 
"separatefields,select=eq(mod(n,4),0)+eq(mod(n,4),3),weave" -codec:v libx265 -x265-params 
crf=16:qcomp=1.00 -codec:a copy -codec:s copy -dn "target 
separatefields,select=eq(mod(n,4),0)+eq(mod(n,4),3),weave .mkv"
ffmpeg started on 2020-12-28 at 12:44:59
Report written to "ffmpeg-20201228-124459.log"
Log level: 48
ffmpeg version N-100461-gb0a882cc93 Copyright (c) 2000-2020 the FFmpeg developers
   built with gcc 9.3-win32 (GCC) 20200320
   configuration: --prefix=/ffbuild/prefix --pkg-config-flags=--static --pkg-config=pkg-config 
--cross-prefix=x86_64-w64-mingw32- --arch=x86_64 --target-os=mingw32 --enable-gpl --enable-version3 
--disable-debug --disable-w32threads --enable-pthreads --enable-iconv --enable-zlib --enable-libxml2 
--enable-libfreetype --enable-libfribidi --enable-gmp --enable-lzma --enable-fontconfig 
--enable-opencl --enable-libvmaf --enable-vulkan --enable-libvorbis --enable-amf --enable-libaom 
--enable-avisynth --enable-libdav1d --enable-libdavs2 --enable-ffnvcodec --enable-cuda-llvm 
--enable-libglslang --enable-libass --enable-libbluray --enable-libmp3lame --enable-libopus 
--enable-libtheora --enable-libvpx --enable-libwebp --enable-libmfx --enable-libopencore-amrnb 
--enable-libopencore-amrwb --enable-libopenjpeg --enable-librav1e --enable-librubberband 
--enable-schannel --enable-sdl2 --enable-libsoxr --enable-libsrt --enable-libsvtav1 
--enable-libtwolame --enable-libuavs3d --enable-libvidstab --enable-libx264 --enable-libx265 
--enable-libxavs2 --enable-libxvid --enable-libzimg --extra-cflags=-DLIBTWOLAME_STATIC 
--extra-cxxflags= --extra-ldflags=-pthread --extra-libs=-lgomp
   libavutil      56. 62.100 / 56. 62.100
   libavcodec     58.115.102 / 58.115.102
   libavformat    58. 65.100 / 58. 65.100
   libavdevice    58. 11.103 / 58. 11.103
   libavfilter     7. 94.100 /  7. 94.100
   libswscale      5.  8.100 /  5.  8.100
   libswresample   3.  8.100 /  3.  8.100
   libpostproc    55.  8.100 / 55.  8.100
Input #0, mpeg, from 'source.VOB':
   Duration: 01:58:04.70, start: 0.300300, bitrate: 4795 kb/s
     Stream #0:0[0x1bf]: Data: dvd_nav_packet
     Stream #0:1[0x1e0]: Video: mpeg2video (Main), yuv420p(tv, bottom first), 720x480 [SAR 8:9 DAR 
4:3], 4500 kb/s, 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc
     Side data:
       cpb: bitrate max/min/avg: 4500000/0/0 buffer size: 1835008 vbv_delay: N/A
     Stream #0:2[0x80]: Audio: ac3, 48000 Hz, stereo, fltp, 192 kb/s
Stream mapping:
   Stream #0:1 -> #0:0 (mpeg2video (native) -> hevc (libx265))
   Stream #0:2 -> #0:1 (copy)
Press [q] to stop, [?] for help
[Parsed_select_1 @ 00000272f3b3a9c0] [Eval @ 000000f7843fdf10] Missing ')' or too many args in 'mod(n'
[Parsed_select_1 @ 00000272f3b3a9c0] Error while parsing expression 'eq(mod(n'
[AVFilterGraph @ 00000272f3b3f8c0] Error initializing filter 'select' with args 'eq(mod(n'
Error reinitializing filters!
Failed to inject frame into filter network: Invalid argument
Error while processing the decoded data for stream #0:1
Conversion failed!