How to recode video without losing quality? / Remux to mkv

[NaufalAriqS21]

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Question

Hello, I want to ask. Is it possible to do that?
I found something similiar, #25296 , but the feature is not implemented yet.
I have tried it with --merge-output-format mkv with no success. The file output is still in mp4.

Here the log, I tried it with no account needed:

C:\Users\Administrator\Downloads>youtube-dl --version
2020.07.28

C:\Users\Administrator\Downloads>youtube-dl -v --merge-output-format mkv -f 240p-https --all-subs --embed-subs https://www.viki.com/videos/1160375v
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: ['-v', '--merge-output-format', 'mkv', '-f', '240p-https', '--all-subs', '--embed-subs', 'https://www.viki.com/videos/1160375v']
[debug] Encodings: locale cp1252, fs mbcs, out cp437, pref cp1252
[debug] youtube-dl version 2020.07.28
[debug] Python version 3.4.4 (CPython) - Windows-10-10.0.14393
[debug] exe versions: ffmpeg N-86383-g4705edb
[debug] Proxy map: {}
[viki] 1160375v: Downloading video JSON
[viki] 1160375v: Downloading video streams JSON
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.ca.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.pl.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.fi.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.es.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.ro.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.hr.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.sr.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.nl.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.ar.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.ru.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.hi.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.pt.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.hu.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.id.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.fr.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.el.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.it.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.sv.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.th.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.ko.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.tr.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.cs.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.ja.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.et.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.en.vtt
[info] Writing video subtitles to: I'll Go to You When the Weather is Nice - Episode 1-1160375v.de.vtt
[debug] Invoking downloader on 'https://v4.viki.io/1160375v/1160375v_high_240p_c82eff_2002280345.mp4?e=1596783101&h=1769071f2ee6cc33b6543099ff2d32c6'
[download] Destination: I'll Go to You When the Weather is Nice - Episode 1-1160375v.mp4
[download] 100% of 91.00MiB in 00:10
[ffmpeg] Embedding subtitles in 'I'll Go to You When the Weather is Nice - Episode 1-1160375v.mp4'
[debug] ffmpeg command line: ffmpeg -y -loglevel "repeat+info" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.mp4" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.ca.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.pl.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.fi.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.es.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.ro.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.hr.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.sr.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.nl.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.ar.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.ru.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.hi.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.pt.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.hu.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.id.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.fr.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.el.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.it.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.sv.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.th.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.ko.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.tr.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.cs.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.ja.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.et.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.en.vtt" -i "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.de.vtt" -map 0 -c copy -map "-0:s" -map "-0:d" "-c:s" mov_text -map "1:0" "-metadata:s:s:0" "language=cat" -map "2:0" "-metadata:s:s:1" "language=pol" -map "3:0" "-metadata:s:s:2" "language=fin" -map "4:0" "-metadata:s:s:3" "language=spa" -map "5:0" "-metadata:s:s:4" "language=ron" -map "6:0" "-metadata:s:s:5" "language=hrv" -map "7:0" "-metadata:s:s:6" "language=srp" -map "8:0" "-metadata:s:s:7" "language=nld" -map "9:0" "-metadata:s:s:8" "language=ara" -map "10:0" "-metadata:s:s:9" "language=rus" -map "11:0" "-metadata:s:s:10" "language=hin" -map "12:0" "-metadata:s:s:11" "language=por" -map "13:0" "-metadata:s:s:12" "language=hun" -map "14:0" "-metadata:s:s:13" "language=ind" -map "15:0" "-metadata:s:s:14" "language=fra" -map "16:0" "-metadata:s:s:15" "language=ell" -map "17:0" "-metadata:s:s:16" "language=ita" -map "18:0" "-metadata:s:s:17" "language=swe" -map "19:0" "-metadata:s:s:18" "language=tha" -map "20:0" "-metadata:s:s:19" "language=kor" -map "21:0" "-metadata:s:s:20" "language=tur" -map "22:0" "-metadata:s:s:21" "language=ces" -map "23:0" "-metadata:s:s:22" "language=jpn" -map "24:0" "-metadata:s:s:23" "language=est" -map "25:0" "-metadata:s:s:24" "language=eng" -map "26:0" "-metadata:s:s:25" "language=deu" "file:I'll Go to You When the Weather is Nice - Episode 1-1160375v.temp.mp4"
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.ca.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.pl.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.fi.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.es.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.ro.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.hr.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.sr.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.nl.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.ar.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.ru.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.hi.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.pt.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.hu.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.id.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.fr.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.el.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.it.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.sv.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.th.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.ko.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.tr.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.cs.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.ja.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.et.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.en.vtt (pass -k to keep)
Deleting original file I'll Go to You When the Weather is Nice - Episode 1-1160375v.de.vtt (pass -k to keep)