Here's my personal FFMPEG command line collection (for transcoding automation .e.g and many other usefull use cases) for You
using many undocumented parameters for those who are interested:
Have Fun!
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ffmpeg -c:v h264_crystalhd -i in.mp4 -c:a copy -vf mp=stereo3d=17:7 -qscale:v 6 out.mp4
ffmpeg -c:v h264_crystalhd -i "/mnt/data/filme/Final Destination 4 2009 1080p 3D HOU BRRip x264 aac vice.mp4" -c:a copy -vf mp=stereo3d=20:7 -r 65535/2733 -qscale:v 6 /mnt/data/filme/Final.Destination.4.2009.1080p.3D.agmd.sbs2l.mp4
ffmpeg -c:v h264_crystalhd -i in.mp4 -c:a copy -vf mp=stereo3d=17:7 -qscale:v 6 out.mp4
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You need Green/Magenta glasses cheaply available on ebay or amazon to view,
this model should meet the requirements:
https://www.ebay.de/itm/204310688348
(It's featuring the most advanced , highest quality and eye friendly dubois anaglyph system I've made for (contributed a very complex patch to, no known bugs) the stereo3d filter
See FFMPEG Developer Mailing list archives and
which Your eyes and brain will accept the acceptable irritation after only ca. 15 minutes of viewing,
You can watch this good example Video to test if Your glasses colors are matching, if You see shadows Your glasses color is too diffrent, just buy 10 several models at once at no cost.:
You can also use the easy to use and very user friendly OSS Bino 3D player or (s)mplayer supporting HDMI output in many 3D formats and with its 3D output conversion filter with many useful 3D adjustment features for (pre)viewing, testing, and live decoding of 3D input files of many 3D systems, like side-by-side, above-down and other source picture formats.
I guarantee You the effect is bombastic like 3D Cinema!
No need to waste money for expensive shutter glasses 3D TV sets.
ffmpeg -f concat -i mylist.txt -c copy justiz-arschloecher-down-main-full-bh.mp4
ffmpeg -i justiz-arschloecher-down-main2.mp4 -i Kartoffelbauern-Gericht-small.png -filter_complex overlay=main_w-overlay_w-500:main_h-overlay_h-400 -c:v mpeg4 -c:a copy justiz-arschloecher-down-main2-bh.mp4
$ ffmpeg -i The.Scribbler.2014.544p.x264.DEENDD51.mkv -metadata title="" -metadata:s title="" -map 0 -c copy The.Scribbler.2014.544p.x264.DEENDD51.delmeta.mkv
-map_metadata -1 (del all)
for f in /mnt/data/filme/IN_THIS*; do echo $f; ffmpeg -n -i $f -c:a copy -c:v mpeg4 -q:v 10 $f.FMP4.mp4; done
for f in *; do echo $f; ffmpeg -n -i "$f" -c:a copy -c:v mpeg4 -q:v 10 "$f.FMP4.mp4"; done
ffmpeg -ss 00:22:04 -i "/mnt/vdr1-aux/Olympus Has Fallen 2013 720p BRRip x264 AC3-JYK.mkv" -t 21 -c:a copy -c:v mpeg4 justiz-arschloecher-down-main.mp4
for f in *; do echo $f; ffmpeg -i "$f" -vn -map 0:1 -c copy "$f.aac"; echo; done
for f in *; do echo $f; ffmpeg -i "$f" -vn -map 0:1 -c libmp3lame -q:a 0 "$f.mp3"; echo; done
ffmpeg -ss 1.5 -i The.Family.2013.720p.BluRay.x264.YIFY.mp4 -i The.Family.2013.dvd.XviD.DD51.ac3 -map 0:0 -map 1:0 -c:v copy -af atempo=0.959641255 -c:a ac3_fixed -b:a 384k The.Family.2013.536p.x264.DD51.mkv naja
ffmpeg -ss 1.5 -i The.Family.2013.720p.BluRay.x264.YIFY.mp4 -i The.Family.2013.dvd.XviD.DD51.ac3 -map 0:0 -map 1:0 -c:v copy -af aresample=async=1000 -c:a ac3_fixed -b:a 384k The.Family.2013.536p.x264.DD51.mkv nein
ffmpeg -i The.Family.2013.720p.BluRay.x264.YIFY.mp4 -i The.Family.2013.dvd.XviD.DD51.ac3 -map 0:0 -map 1:0 -c:v copy -af aresample=first_pts=240000:async=5000 -c:a ac3_fixed -b:a 384k The.Family.2013.536p.x264.DD51.mkv no
ffmpeg -i The.Family.2013.720p.BluRay.x264.YIFY.mp4 -i The.Family.2013.dvd.XviD.DD51.ac3 -map 0:0 -c:v copy -map 1:0 -af aresample=first_pts=0:async=1 -c:a ac3_fixed -b:a 384k The.Family.2013.536p.x264.DD51.mkv nö
ffmpeg -ss 5 -i The.Family.2013.720p.BluRay.x264.YIFY.mp4 -i The.Family.2013.dvd.XviD.DD51.avi -map 0:0 -c:v copy -map 1:1 -af aresample=async=5000 -c:a ac3_fixed -b:a 384k The.Family.2013.536p.x264.DD51.mp4 nö
ffmpeg -ss 1.5 -i The.Family.2013.720p.BluRay.x264.YIFY.mp4 -i The.Family.2013.dvd.XviD.DD51.ac3 -map 0:0 -map 1:0 -c:v copy -af atempo=0.96 -c:a ac3_fixed -b:a 384k The.Family.2013.536p.x264.DD51.mkv zum ab 30 min -2s audio
ffmpeg -itsoffset -1.5 -i The.Family.2013.536p.x264.video.mp4 -i The.Family.2013.dvd.XviD.DD51.ac3 -c:v copy -af atempo=0.959641255,aresample=swr_flags=res:async=1:min_comp=0.000100:min_hard_comp=0.010000:comp_duration=5:max_soft_comp=1.5 -c:a ac3 The.Family.2013.536p.x264.DD51.mkv grrrr
$ ffmpeg -i /mnt/vdr1-aux/Escape.Plan.2013.528p.x264.DD51-192.mp4 -vn -filter_complex "channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR], [FL]silencedetect; [FR]silencedetect; [FC]silencedetect; [LFE]silencedetect; [SL]silencedetect; [SR]silencedetect" -f null -
ffmpeg -v verbose -i The.Family.2013.536p.x264.mp4 -i The.Family.2013.536p.x264.DD51.mp4 -map 1:0,1:0 -map 1:1 -map 0:1 -c copy /mnt/vdr1-aux/The.Family.2013.536p.x264.DD51.AAC20.mp4
atempo=0.9589 für 23,96 -> 25 fps
for f in /mnt/data/aux2/*; do echo $f; ffmpeg -i $f 2>&1 |grep Stream |grep aac |grep -i 5.1; done
$ ffmpeg -hwaccel vaapi -hwaccel_output_format vaapi -i 'Avatar The Way Of Water (2022) [1080p] [WEBRip] [5.1] [YTS.MX]/Avatar.The.Way.Of.Water.2022.1080p.WEBRip.x264.AAC5.1-[YTS.MX].mp4' -an -f null -
$ ffmpeg -hwaccel vaapi -hwaccel_output_format vaapi -hwaccel_device /dev/dri/renderD128 -i 'Avatar The Way Of Water (2022) [1080p] [WEBRip] [5.1] [YTS.MX]/Avatar.The.Way.Of.Water.2022.1080p.WEBRip.x264.AAC5.1-[YTS.MX].mp4' -c:v hevc_vaapi -qp 30 -c:a copy -c:s copy output.mkv
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This command will create and record a graphical scope for analysis of detection, channel separation, and of the audio stereo qualty in AV files, especially for detection of low qualty fake- stereo or joint stereo in AAC (MP4A) files and streams:
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ffmpeg -v debug -i CHILDREN_OF_BODOM_Morrigan_hd720.mp4 -filter_complex "[0:a]avectorscope=s=1280x720,format=yuv420p[vid]" -map "[vid]" -map 0:a -codec:v mpeg4 -q:v 10 -codec:a mp2 output.mp4
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Lucky You don't need to download illegally with file sharing anymore since bluray AACS copy protection has been broken 
But there's still missing a 3D x264/5 MVC decoder in FFMPEG, someone of libx264/5 - developers please make one for it, if You got the time, all 3D fans please request this feature on their and the FFMPEG users mailinglists and please donate enough money for it to them especially if You're rich and can afford it, just donate the money You would pay for a 10x as expensive shutter TV set as anaglyph 3D which works on any cheap display to them instead, thank You.
Oh, looks like 3D MPEG4/libx264/5 HSBS encoding is already available:
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$ ffmpeg -f rawvideo -video_size 640x480 -i MVCDS-1_ViewId0000.yuv -f rawvideo -video_size 640x480 -i MVCDS-1_ViewId0001.yuv -filter_complex "pad=in_w*2:in_h, overlay=main_w/2:0, scale=in_w/2:in_h, scale=-1:1080" -an -c:v mpeg4 -q:v 8 stereo3d.mp4
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It maybe be possible to derive a MVC to agmd encoder from this command,
Your Homework, 
"But I don't know if it's even solvable", like my Math Professor always said about his tests and exams 
Since there have been already 3D bluray rips using those closed source decoders it should be possible,
You could also try to reverse engineer their assembler machine code
like it has been done with closed source ntfs-, wireless-, and webcam-, paper scanner- drivers
Some say makemkv should work:
MakeMKV 1.17.7 for Linux is available - www.makemkv.com
Hmm, which Linux can run this?
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makemkvcon: /lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.33' not found (required by makemkvcon)
makemkvcon: /lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.34' not found (required by makemkvcon)
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looks like a missing configure check.
And the windows version is crashing wine.
OK it runs fine on debian bookworm 
BIG FAT WARNING: EXTREMLY DANGEROUS: NEVER trust all those https -fake- websites like 1337x.* , thepiratebay.* on google and ANY tor onion links to any "piratebay" dark net websites, those are all run by cybercriminals who may hack You and break in even Torbrowser (NEVER in any case disable its noscript addon or allow exceptions for those malware sites!) and damage Your hard and Software and they may also be run by FBI/BKA to get Your uncool niece jailed, one hop VPN s are absolutely useless, too, they do not offer any protection of either security or privacy (they only want Your credit card number to misuse it) !
BUGS: The above commands may not work with every FFMPEG version or codec acceleration hardware.