mpv-cut

This extension allows you to:

• Quickly cut videos both losslessly and re-encoded-ly.

• Specify custom actions in a config.lua file to support your own use cases without having to modify the script itself or write your own extension.

• Bookmark timestamps to a .book file and load them as chapters.

• Save cut information to a .list file for backup and make cuts later.

• Choose meaningful channel names to organize the aforementioned actions.

All directly in the fantastic media player mpv.

Requirements

Besides mpv, you must have ffmpeg in your PATH.

If you're launching mpv from Finder/Explorer, FFmpeg must be in your actual system environment's PATH as opposed to your shell environment. This means that changes to ~/.profile or the like will not suffice. As such, on my newest Macbook, after installing ffmpeg with homebrew I had to run the following:

sudo ln -s /opt/homebrew/bin/ffmpeg /usr/local/bin/ffmpeg

Tips

To debug when launching from Finder/Explorer, use ` to display a terminal with output.

Installation

Linux/MacOS

git clone -b release --single-branch "https://github.com/familyfriendlymikey/mpv-cut.git" ~/.config/mpv/scripts/mpv-cut

Windows

In %AppData%\Roaming\mpv\scripts or Users\user\scoop\persist\mpv\scripts run:

git clone -b release --single-branch "https://github.com/familyfriendlymikey/mpv-cut.git"

That's all you have to do, next time you run mpv the script will be automatically loaded.

Usage

Cutting A Video Losslessly

• Press c to begin a cut.

• Seek to a later time in the video.

• Press c again to make the cut.

The resulting cut will be placed in the same directory as the source file.

You can press C to cancel a cut.

Actions

You can press a to cycle between three default actions:

• Copy (lossless cut, rounds to keyframes).

• Encode (re-encoded cut, exact).

• List (simply add the timestamps for the cut to a .list file).

More details in Custom Actions.

Bookmarking

Press i to append the current timestamp to a .book file. This automatically reloads the timestamps as chapters in mpv. You can navigate between these chapters with the default mpv bindings, ! and @.

Channels

The resulting cuts and bookmark files will be prefixed a channel number. This is to help you categorize cuts and bookmarks. You can press - to decrement the channel and = to increment the channel.

You can configure a name for each channel as shown in config.

Utils

This plugin includes a utils script that you can source in your shell's startup file. In my ~/.zshrc I have this line:

source ~/.config/mpv/scripts/mpv-cut/utils

Now when you open new terminals, you'll have access to the functions inside of the utils script, which are used as follows:

Making Cuts

The make_cuts function takes a .list file and ffmpeg output options except for an output filename. To make cuts without reencoding:

make_cuts some_video.mp4.list -c copy

Concatenate, Merge, Combine, Join Cuts

The concat function takes a prefix and ffmpeg output options. Any file in the current directory starting with the prefix will be included. For example, to concatenate all files in the current directory whose filename starts with CUT without reencoding:

concat CUT -c copy output.mp4

Config

You can configure settings by creating a config.lua file in ~/.config/mpv-cut or in the same directory as main.lua.

You can include or omit any of the following:

-- Key config
KEY_CUT = "c"
KEY_CANCEL_CUT = "C"
KEY_CYCLE_ACTION = "a"
KEY_BOOKMARK_ADD = "i"
KEY_CHANNEL_INC = "="
KEY_CHANNEL_DEC = "-"

-- The list of channel names, you can choose whatever you want.
CHANNEL_NAMES[1] = "FUNNY"

-- The default channel
CHANNEL = 1

-- The default action
ACTION = "COPY"

-- Delete a default action
ACTIONS.LIST = nil

Custom Actions

In the config file you can also specify custom actions. Even if you don't know Lua, it should be pretty straightforward to take the following example and tune it to your needs. I think this is a very powerful abstraction. All of the default actions are implemented the same way you'd implement custom actions.

You can essentially define an arbitrary callback to run whenever an action is invoked (the second time you press c in mpv). The callback function gets passed a table with the following properties:

inpath, indir, infile, infile_noext, ext
channel
start_time, end_time, duration
start_time_hms, end_time_hms, duration_hms

Here is an example overwriting the default ENCODE action:

ACTIONS.ENCODE = function(d)
	local args = {
		"ffmpeg",
		"-nostdin", "-y",
		"-loglevel", "error",
		"-i", d.inpath,
		"-ss", d.start_time,
		"-t", d.duration,
		"-pix_fmt", "yuv420p",
		"-crf", "16",
		"-preset", "superfast",
		utils.join_path(d.indir, "ENCODE_" .. d.channel .. "_" .. d.infile_noext .. "_FROM_" .. d.start_time_hms .. "_TO_" .. d.end_time_hms .. d.ext)
	}
	mp.command_native_async({
		name = "subprocess",
		args = args,
		playback_only = false,
	}, function() print("Done") end)
end

Optimized MPV Input Config

This is my input.conf file, and it is optimized for both normal playback and quickly editing videos.

RIGHT seek 2 exact
LEFT seek -2 exact
UP seek 2 keyframes
DOWN seek -2 keyframes

] add speed 0.5
[ add speed -0.5
} add speed 0.25
{ add speed -0.25
\ set speed 1

BS script-binding osc/visibility

Alt+= add video-zoom 0.1

You may also want to change your key repeat delay and rate by tweaking input-ar-delay and input-ar-rate to your liking in mpv.conf.

FAQ

What Is The Point Of A Cut List?

There are plenty of reasons, but to give some examples:

• In my opinion, video is extremely complex and tools around video can be unreliable. One video file may cause certain issues, and another may not, which makes writing an ffmpeg command that accounts for all scenarios difficult. If you spend a ton of time making many cuts in a long movie only to find that the colors look off because of some 10-bit h265 dolby mega surround whatever the fuck, with a cut list it's trivial to edit the ffmpeg command and re-make the cuts.

• Maybe you forget that the foreign language video you're cutting has softsubs rather than hardsubs, and you make a bunch of encode cuts resulting in cuts that have no subtitles.

• You might move the source video to somewhere else for storage but still want to have a back up of the cut timestamps in the event you need to remake the cuts from source quality.

Why Would I Bookmark Instead Of Cutting?

Suppose you're watching a movie or show for your own enjoyment, but you also want to compile funny moments to post online or send to your friends. It would ruin your viewing experience to wait for a funny moment to be over in order to make a cut. Instead, you can quickly make a bookmark whenever you laugh, and once you're done watching you can go back and make actual cuts.

Why Would I Re-Encode A Video?

• As mentioned above, copying the input stream is very fast and lossless but the cuts are not exact. Sometimes you want a cut to be exact.

• If you want to change the framerate.

• If you want to encode hardsubs.

• If the video's compression isn't efficient enough to upload to a messaging platform or something, you may want to compress it more.

Can I Make Seeking And Reverse Playback Faster?

Depending on the encoding of the video file being played, the following may be quite slow:

• The use of exact in input.conf.

• The use of the . and , keys to go frame by frame.

• The holding down of the , key to play the video in reverse.

Long story short, if the video uses an encoding that is difficult for mpv to decode, exact seeking and backwards playback won't be smooth, which for normal playback is not a problem at all, since by default mpv very quickly seeks keyframe-wise when you press left arrow or right arrow.

However if we are very intensively cutting a video, it may be useful to be able to quickly seek to an exact time, and to quickly play in reverse. In this case, it is useful to first make a proxy of the original video which is very easy to decode, generate a cut list with the proxy, and then apply the cut list to the original video.

To create a proxy which will be very easy to decode, you can use this ffmpeg command:

ffmpeg -noautorotate -i input.mp4 -pix_fmt yuv420p -g 1 -sn -an -vf colormatrix=bt601:bt709,scale=w=1280:h=1280:force_original_aspect_ratio=decrease:force_divisible_by=2 -c:v libx264 -crf 16 -preset superfast -tune fastdecode proxy.mp4

The important options here are the -g 1 and the scale filter. The other options are more or less irrelevant. The resulting video file should seek extremely quickly and play backwards just fine.

Once you are done generating the cut list, simply open the cut_list.txt file, substitute the proxy file name for the original file name, and run make_cuts on it.

Why Is Lossless Cutting Called "Copy"?

This refers to ffmpeg's -copy flag which copies the input stream instead of re-encoding it, meaning that the cut will process extremely quickly and the resulting video will retain 100% of the original quality. The main drawback is that the cut may have some extra video at the beginning and end, and as a result of that there may be some slightly wonky behavior with video players and editors.