Quick Tips

Cinemagoer Extract

imdbpy search movie "12 Monkeys"
python ../../util/test.py 0114746 > 12_Monkeys.json

Image Stabilization

FFMPEG

ffmpeg -i input.mp4 -vf vidstabdetect=shakiness=10:accuracy=15 -f null -
ffmpeg -i input.mp4 -vf vidstabtransform=smoothing=30:zoom=0 output.mp4

First command generates the convolution file, second command applies it.

Remove Subtitles

ffmpeg -i series_launch_english.mp4 -c copy -sn series_launch_english_nosubs.mp4

See Also: https://start.duckduckgo.com/?q=Advanced+SubStation+Alpha&ia=web

FFMpeg

Concat

cat > list.txt
file 'file1.mkv'
file 'file2.mkv'
^d
ffmpeg -f concat -safe 0 -i list.txt -map 0 -c copy output.mkv

or

ffmpeg -f concat -safe 0 -i list.txt \
  -map 0:v -map 0:a -map 0:s -map 1:v -map 1:a -map 1:s \
  -c copy output.mkv

Resize

Scale, Match Vertical to Suit 720

ffmpeg -i input.avi -filter:v scale=720:-1 -c:a copy output.mkv

Time

ffmpeg -i foo.avi -ss 01:23:45 -to 02:34:56 out.avi

Players

MPV

Prefer French audio:

$ mpv ./Futurama-S0[123]*mkv --alang=fr,fre,en --loop-playlist

Use two sets of subtitles:

$ mpv kaamelott_book_1_volume_2.webm --sid=1 --secondary-sid=2

Specify a subtitle file and run two sets of subtitles:

$ mpv kaamelott_book_1_volume_1.webm --sub-file=kaamelott_book_1_volume_1.en-GB.vtt --sid=1 --secondary-sid=2

Subtitle Processing

Embed .vtt into .mkv

ffmpeg -i input.mkv -i subtitles.vtt -c:v copy -c:a copy -c:s mov_text -map 0 -map 1 -metadata:s:s:0 language=fre output.mkv

ffmpeg -i subtitles.vtt subtitles.srt
ffmpeg -i input.mkv -i subtitles.srt -c:v copy -c:a copy -c:s srt -map 0 -map 1 -metadata:s:s:0 language=fre output.mkv

Dual Subtitles

Option 1: Use secondary-sid

mpv has a secondary-sid option, which lets you specify a second subtitle track to render alongside the primary one.

For example:

Where:

• --sid=1 → the main subtitle track (e.g., English)
• --secondary-sid=2 → the secondary subtitle track (e.g., French)

You can check the track IDs by running:

or just mpv video.mkv and press j to cycle through tracks and note their IDs.

Option 2: External subtitle files

If you have separate .srt or .vtt files for English and French:

You can also use .vtt files this way.

Option 3: Config file

If you often want this behavior, add to your ~/.config/mpv/mpv.conf:

You may need to adjust the numbers (sid) to match your preferred language tracks.

More Options

You are correct: in mpv 0.35.1, there is support for --secondary-sid (to select a second subtitle track already present in the media), but there is no option called --secondary-sub-file.

This is because mpv’s “secondary subtitle” system only applies to subtitle streams already loaded, either from the container or from a single external subtitle file loaded as primary.

What works:

If your video already contains both English and French subtitle tracks:

You can enable them both like this:

This renders both subtitle tracks simultaneously. They will stack in the same position unless you adjust one of them with options like sub-pos or sub-margin-y.

If you have two separate external subtitle files (.srt or .vtt):

By default, mpv will only load one external subtitle file, even if you specify multiple --sub-file arguments — it ignores the rest.

Workarounds:

1. Mux both subtitle files into the video container (e.g., .mkv) Use mkvmerge:

1. This displays both lines in one cue.
2. Use an mpv Lua script to load two external subtitle files. There are community Lua scripts that let you load and display two external subtitles, one at the top and one at the bottom. See the mpv Lua script resources page: https://mpv.io/resources/

Summary:

• --secondary-sub-file is not implemented.
• --secondary-sid works, but only with embedded tracks.
• For external files: either mux them into the video file, combine them manually, or use a Lua script.

If you’d like, I can help you:

• Write a shell script to mux .srt files into .mkv automatically.
• Write a minimal Lua script to load and render two .srt files in mpv.

• Then you can use --sid and --secondary-sid as above.
• Manually combine them into one subtitle file. Example:

Voice Acting

• 10 Voice Tones: https://old.reddit.com/r/TikTokCringe/comments/1at3n7a/voiceover_actor_explains10_tones_used_during_reads/
  • "im an audio for video engineer, im the person directly communicating with the voice actor to make sure the producer is happy during recording, and it really is wild the amount of times they give what is a really over the top read from their point of view, and we have to prop then up to get them to go even bigger and more exaggerated. It feels unnatural, and bizarre, but it plays well in a VO"
    • "It's like that for stage plays and performances. a persons delivery really flattens out the farther it travels so you gotta make it over-the-top"