Often, one wants to reprocess a video file using some basic operations, such as removing certain segments. Rather than opening a video editor, it is nice to be able to define a text file (the editlist) with processing instructions, and then run it. This allows collaboration in the processing, for example sharing the editlist file via git.
This utility takes a YAML definition of an editlist (segments to cut out and re-assemble into a file), and does the re-assembling using the ffmpeg command line utility.
This is currently an alpha-level utility: it works, but expect it may not exactly fit your use case without a bit of work. Documentation is minimal but still needs improvement. However, it has been used for several large events.
Video demonstration: https://youtu.be/thvMNTBJg2Y
Features include:
- YAML edit list definition.
- Select segments to stitch together in the final video file.
Segments are either copied raw or re-encoded (
--reencode). - Give Table of Contents times (for example, '16:45: Lesson 2 begins') relative to the source video, output mapped to times in the output video automatically.
- Cover certain areas of video (for example, when an audience member appears).
- Everything scripted and non-interactive.
- Cutting and re-splicing subtitles, too.
This is on PyPI, may be installed with pip install ffmpeg-editlist.
The only dependency is PyYAML so it might be reasonable to install
with pip install --user. This creates a ffmpeg-editlist command
in your environment.
For usage without installing, ffmpeg_editlist.py works as
stand-alone with only pyyaml.
It depends on the ffmpeg command line utility, which must be
installed through the operating system. Version requirements of
ffmpeg are currently unknown.
Start with a directory of your videos (example: day1-raw.mkv).
Create an edit list file (described in next section). A minimal example is:
- input: day1-raw.mkv
- output: part1.mkv
title: This is the title of part1
description: >-
This is the multi-line description
of part 1.
editlist:
- start: 00:00 # These are time segments to include
- 4:00: Begin exercise 1
- stop: 5:00
- start: 6:13
- -: Going over the exercises # '-' means "latest start time".
- stop: 99:00The general usage is then:
python ffmpeg-editlist.py EDITLIST.yaml INPUT-DIR [-o OUTPUT-DIR]
Where INPUT-DIR is the search path for input files and OUTPUT-DIR
(default .) is the output path for files. You can use the --limit PATTERN option to reprocess only a few videos (example: --limit part1).
Because of the way keyframes work, there may be missing segments
around the transition points. After you have tested that your timings
seem reasonable, re-run with --reencode and it will do a full
re-encoding and make a seamless videos. The default encoding settings
are designed to be slow but good enough for all practical purposes:
python ffmpeg-editlist.py EDITLIST.yaml --reencode INPUT-DIR [-o OUTPUT-DIR]
OUTPUT-DIR will get the encoded files, and .txt files with the
video descriptions ready to upload to your video hosting site.
Subtitles: The option --srt will make ffmpeg-editlist reprocess
subtitles just like video segments (cut to the segments and adjust
timestamps). A .srt file is expected alongside each input file
(input file's extension replaced with .srt), and an output is
similarly placed alongside each output. Warning: make sure that no
segment's declared stop time goes beyond the actual file length. It's
possible that there will be some weird effects around the
beginning/end of the segments if subtitles go beyond the start/stop.
# Input is taken from command line argument `input`.
- output: output.mp4
title: This is the title
description: >-
This is the multi-line description.
editlist:
- start: 00:00 # These are time segments to include
- stop: 5:00
- start: 6:13
- stop: 99:00Run with python ffmpeg-editlist.py editlist.yaml input.mkv.
- input: raw-day1.mkv
output: day1-part1.mkv
editlist:
- start: 1:12
- stop: 55:30
# Previous input file is used if no new input is defined
- output: day1-part2.mkv
editlist:
- start: 1:00:12
- stop: 1:54:00Run with python ffmpeg-editlist.py editlist.yaml $input_directory.
This is a full example that demonstrates all features.
- workshop_description: >
If this exists, it will be appended to the bottom of every video
description. For example, it can be general information about the
overall workshop.
# This input will be used for all segments until redefined
# Input relative to the input-dir command line argument.
# If not given, use the raw input-dir argument as a filename.
- input: cr-2021may-day1-obs.mov
# A basic example
# Output is relative to the output-dir command line argument.
- output: day1-welcome.mp4
# If given, do not reencode this segment even if --reencode is given
# (useful for segments that start at 00:00). 'reencode: true' does
# nothing, this is the default and --reencode must still be
# specified on the command line.
#reencode: false
editlist:
- start: 12:20
- stop: 31:14
# Git-intro day 1
- output: day1-git-intro-1.mp4 # Output filename
title: YouTube Video Title
description: >
Description of the video.
editlist:
# These pairs are times to *include*
- start: 31:14
- stop: 38:13
- start: 41:28
- stop: 1:04:45
# A sample including table of contents entries.
# You need to map times from the raw file, to the output file, in
# order to make a clickable YouTube table of contents.
# They are times in the
# original video, and they are converted to the equivalent times in
# the processed videos. They must be within the ranges above (and
# you get a unhandled error if they aren't):
# segment_start <= toc_time < segment_stop.
# These can be interspersed with the segment definitions.
# Example:
- output: day2-git-intro-2.mp4
editlist:
- start: 31:14
# TOC entry:
- 31:14: Overview of the day
- 33:25: Motivation to version control
- stop: 38:13
- start: 41:28
- -: Basics of version control # '-' is an alias for "last start"
- 48:35: "Exercise: record changes" # has a ':', so must be quoted
- stop: 1:04:45
#- 1:18:22: This will fail, timestamp after the end
# This syntax is used to cover a segment of the video:
- output: day3-has-audience-visible.mp4
editlist:
- start: 00:00
# Cover an area. begin/end are clear. w and h are width and
# height. x and y are offset (left, down) from the top-left corner
- cover: {begin: "1:15:29", end: "1:51:34", w: 840, h: 300, x: 360}
- stop: 5:00
Alongside the .mp4 output file, a .mp4.info.txt file is created
with these contents. This is designed for easy copying and pasting
into hosting sites:
Title of Video
Video description.
01:53 Table of contents entry 1
15:45 Table of contents entry 2
...
Workshop description.
Multiple inputs in one segment might be useful when you are attaching an introduction to the main video. Note that things might go wrong if the video sizes and codecs do not align perfectly. (TODO: does this work as expected?)
- output: output.mp4
editlist:
- input: intro.mkv
- start: 00:00
- stop: 99:00
- input: main.mkv
- start: 0:00
- stop: 99:00
- input: outro.mkv
- start: 0:00
- stop: 99:00
- https://trac.ffmpeg.org/wiki/Concatenate
- https://stackoverflow.com/q/7333232
- Inspired by https://github.com/mvdoc/budapest-fmri-data/blob/master/scripts/preprocessing-stimulus/split_movie.sh
- mpv (https://mpv.io/) is a video player with good command line
interface, keyboard shortcuts, and scriptable so that you can make a
hotkey that copies the current time.
- script for the mpv video player, which can copy the time when you push a button. Might need some modification: https://github.com/Kr4is/mpv-copy-time
[and]change the playback speed.Ocauses time to be permanently shown.→and←seek,↑and↓seek longer, and--hr-seekallows seeking exactly.Control+→,Control+←allow seeking to the next/previous subtitle.
Alpha/beta, under development, it is starting to become reusable but still development is for a few use cases. In order to use this you probably have to read some code / work around some bugs since it isn't well tested yet.
Bug reports or improvements welcome, but it is kind of a mess now.
Test with pytest ffmpeg-editlist.py, but note that main
functionality is not tested right now.