[FFmpeg-user] muxing confusion
Clayton Macleod
cherrytwist at gmail.com
Tue Feb 22 00:40:02 EET 2022
I've written a batch file to split up a source file into individual files
by GOP. I'm using an input file that has only a single video stream, as
audio and other streams seemed to only make other problems arise, or
perhaps was simply making this same issue have even worse consequences.
The splitting is done via this command:
ffmpeg -i input.mkv -c copy -map 0 -segment_time 00:00:01 -f segment
-reset_timestamps 1 .\split\output%%06d.mkv
Once I have those I do a slightly modified binary search encode job to hit
a target VMAF score on all the individual GOPs. All those encoding jobs
and subsequent VMAF comparisons all execute successfully. Once that is
done I merge the results back into a single result file. Then, just to
confirm, I run VMAF on the complete final result. Here's where the problem
comes up. The file that I mux via these commands:
for /f %%G in ('dir /b/on output*.mkv') do echo file '%%G' >> splitlist.txt
ffmpeg -loglevel info -f concat -safe 0 -i splitlist.txt -c copy
..\finalresult.mkv
seems to have some kind of problem. If I encode with a target VMAF of 97,
and all the individual GOP files did indeed get encoded such that they all
individually have a VMAF of 97, then it only follows naturally that the
final result file will also have a VMAF of 97. However, the file that's
been merged by ffmpeg in this fashion returns an absolutely horrible VMAF
score. But if I take the same individual results files and use the
mkvmerge GUI instead and then run it through VMAF it does indeed return a
score of 97.x, as it should.
finalresult.mkvmerge.VMAF 97.020162.mkv
finalresult.ffmpeg.VMAF 47.014416 WTF.mkv
ffmpeg is apparently doing something different, but I can't figure out what
I might do to solve it. I would prefer to merge the files with ffmpeg
simply because I can script that easily. Scripting that part of the job
with mkvmerge is slightly more complicated and I'd hope to not have to go
that route if I can avoid it.
C:\temp2\Blade Runner 720x480 test>ffprobe "finalresult.mkvmerge.VMAF
97.020162.mkv"
ffprobe version 2022-01-30-git-1530b3f566-full_build-www.gyan.dev Copyright
(c) 2007-2022 the FFmpeg developers
built with gcc 11.2.0 (Rev7, Built by MSYS2 project)
configuration: --enable-gpl --enable-version3 --enable-static
--disable-w32threads --disable-autodetect --enable-fontconfig
--enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib
--enable-lzma --enable-libsnappy --enable-zlib --enable-librist
--enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth
--enable-libbluray --enable-libcaca --enable-sdl2 --enable-libdav1d
--enable-libdavs2 --enable-libuavs3d --enable-libzvbi --enable-librav1e
--enable-libsvtav1 --enable-libwebp --enable-libx264 --enable-libx265
--enable-libxavs2 --enable-libxvid --enable-libaom --enable-libopenjpeg
--enable-libvpx --enable-mediafoundation --enable-libass --enable-frei0r
--enable-libfreetype --enable-libfribidi --enable-libvidstab
--enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm
--enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc
--enable-d3d11va --enable-dxva2 --enable-libmfx --enable-libshaderc
--enable-vulkan --enable-libplacebo --enable-opencl --enable-libcdio
--enable-libgme --enable-libmodplug --enable-libopenmpt
--enable-libopencore-amrwb --enable-libmp3lame --enable-libshine
--enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc
--enable-libilbc --enable-libgsm --enable-libopencore-amrnb
--enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa
--enable-libbs2b --enable-libflite --enable-libmysofa
--enable-librubberband --enable-libsoxr --enable-chromaprint
libavutil 57. 19.100 / 57. 19.100
libavcodec 59. 20.100 / 59. 20.100
libavformat 59. 17.101 / 59. 17.101
libavdevice 59. 5.100 / 59. 5.100
libavfilter 8. 26.101 / 8. 26.101
libswscale 6. 5.100 / 6. 5.100
libswresample 4. 4.100 / 4. 4.100
libpostproc 56. 4.100 / 56. 4.100
Input #0, matroska,webm, from 'finalresult.mkvmerge.VMAF 97.020162.mkv':
Metadata:
title :
Blade.Runner.1982.The.Final.Cut.2160p.BluRay.REMUX.HEVC.DTS-HD.MA.TrueHD.7.1.Atmos-FGT
encoder : libebml v1.4.2 + libmatroska v1.6.4
creation_time : 2022-02-20T23:29:29.000000Z
Duration: 01:57:31.33, start: 0.000000, bitrate: 3243 kb/s
Stream #0:0: Video: hevc (Main), yuv420p(tv, smpte170m/smpte170m/bt709),
720x480 [SAR 32:27 DAR 16:9], 23.98 fps, 23.98 tbr, 1k tbn (default)
Metadata:
BPS : 3242258
DURATION : 01:57:31.326000000
NUMBER_OF_FRAMES: 169064
NUMBER_OF_BYTES : 2857777985
_STATISTICS_WRITING_APP: mkvmerge v65.0.0 ('Too Much') 64-bit
_STATISTICS_WRITING_DATE_UTC: 2022-02-20 23:29:29
_STATISTICS_TAGS: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
C:\temp2\Blade Runner 720x480 test>ffprobe "finalresult.ffmpeg.VMAF
47.014416 WTF.mkv"
ffprobe version 2022-01-30-git-1530b3f566-full_build-www.gyan.dev Copyright
(c) 2007-2022 the FFmpeg developers
built with gcc 11.2.0 (Rev7, Built by MSYS2 project)
configuration: --enable-gpl --enable-version3 --enable-static
--disable-w32threads --disable-autodetect --enable-fontconfig
--enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib
--enable-lzma --enable-libsnappy --enable-zlib --enable-librist
--enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth
--enable-libbluray --enable-libcaca --enable-sdl2 --enable-libdav1d
--enable-libdavs2 --enable-libuavs3d --enable-libzvbi --enable-librav1e
--enable-libsvtav1 --enable-libwebp --enable-libx264 --enable-libx265
--enable-libxavs2 --enable-libxvid --enable-libaom --enable-libopenjpeg
--enable-libvpx --enable-mediafoundation --enable-libass --enable-frei0r
--enable-libfreetype --enable-libfribidi --enable-libvidstab
--enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm
--enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc
--enable-d3d11va --enable-dxva2 --enable-libmfx --enable-libshaderc
--enable-vulkan --enable-libplacebo --enable-opencl --enable-libcdio
--enable-libgme --enable-libmodplug --enable-libopenmpt
--enable-libopencore-amrwb --enable-libmp3lame --enable-libshine
--enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc
--enable-libilbc --enable-libgsm --enable-libopencore-amrnb
--enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa
--enable-libbs2b --enable-libflite --enable-libmysofa
--enable-librubberband --enable-libsoxr --enable-chromaprint
libavutil 57. 19.100 / 57. 19.100
libavcodec 59. 20.100 / 59. 20.100
libavformat 59. 17.101 / 59. 17.101
libavdevice 59. 5.100 / 59. 5.100
libavfilter 8. 26.101 / 8. 26.101
libswscale 6. 5.100 / 6. 5.100
libswresample 4. 4.100 / 4. 4.100
libpostproc 56. 4.100 / 56. 4.100
Input #0, matroska,webm, from 'finalresult.ffmpeg.VMAF 47.014416 WTF.mkv':
Metadata:
ENCODER : Lavf59.17.101
Duration: 01:57:31.80, start: 0.000000, bitrate: 3243 kb/s
Stream #0:0: Video: hevc (Main), yuv420p(tv, smpte170m/smpte170m/bt709,
progressive), 720x480 [SAR 32:27 DAR 16:9], 23.98 fps, 23.98 tbr, 1k tbn
Metadata:
ENCODER : Lavc59.20.100 libx265
DURATION : 01:57:31.795000000
They're showing as different durations for some reason. And I'm not sure
why the one that's been merged via ffmpeg doesn't display as much info via
ffprobe. All I know is the ffmpeg version seems to start comparing in VMAF
ok but at some point during the comparison it just falls off the rails as
if the data suddenly has fallen out of step, akin to comparing two
completely different video streams after that point. (Phantom frames
making their way in somehow? Both VMAF output files list the same number
of frames, though, so I guess not.) I've been trying to find something in
ffmpeg's command line options that I could change or add, but so far I
haven't seen anything obvious to me that I should do. Is there something I
should have in this merging command that I'm missing, or am I simply stuck
having to manually merge it with the mkvmerge GUI? Thanks.
(Yes, I'm aware of av1an. Couldn't get it to do what I'd like under
Windows, and I don't feel like setting up linux just for this task in hopes
of the linux av1an package behaving better. I'm hitting my VMAF target
within 0.1 already, and just hope I can sort out this merging automation
issue.)
--
Clayton Macleod
If no one comes from the future to stop you from doing it, then how bad of
a decision can it really be?
More information about the ffmpeg-user
mailing list