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App-FfmpegUtils-0.008
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NAME

reencode-video-with-libx264 - Re-encode video (using ffmpeg and libx264)

VERSION

This document describes version 0.008 of reencode-video-with-libx264 (from Perl distribution App-FfmpegUtils), released on 2020-12-12.

SYNOPSIS

Usage:

% reencode-video-with-libx264 [--audio-sample-rate=s] [--config-path=path
    | -c] [--config-profile=profile | -P] [--crf=s] [--debug]
    [--dont-scale] [--dry-run] [--fast] [--faster] [--ffmpeg-path=s]
    [--file=s+] [--files-json=s] [--format=name] [--frame-rate=s] [--json]
    [--log-level=level] [--medium] [--(no)naked-res] [--no-config | -C]
    [--no-env] [--no-scale] [--page-result[=program]] [--preset=s]
    [--quiet] [-r=s] [--sample-rate=s] [--scale=s] [--slow] [--slower]
    [--superfast] [--trace] [--ultrafast] [--verbose] [--veryfast]
    [--veryslow] [--view-result[=program]] <file> ...

Examples:

The default setting is to shrink to 1080p if video is larger than 1080p:

% reencode-video-with-libx264 *

Do not scale/shrink:

% reencode-video-with-libx264 --dont-scale *

Shrink to 480p if video is larger than 480p, but make the reencoding "visually lossless":

% reencode-video-with-libx264 --scale '480^>' --crf 18 *

DESCRIPTION

This utility runs ffmpeg to re-encode your video files using the libx264 codec. It is a wrapper to simplify invocation of ffmpeg. It selects the appropriate ffmpeg options for you, allows you to specify multiple files, and picks appropriate output filenames. It also sports a --dry-run option to let you see ffmpeg options to be used without actually running ffmpeg.

This utility is usually used to reduce the file size (and optionally video width/height) of videos so they are smaller, while minimizing quality loss. Smartphone-produced videos are often high bitrate (e.g. >10-20Mbit) and not yet well compressed, so they make a good input for this utility. The default setting is roughly similar to how Google Photos encodes videos (max 1080p).

The default settings are:

-v:c libx264
-preset veryslow (to get the best compression rate, but with the slowest encoding time)
-crf 28 (0-51, subjectively sane is 18-28, 18 ~ visually lossless, 28 ~ visually acceptable)

when a downsizing is requested (using the --downsize-to option), this utility first checks each input video if it is indeed larger than the requested final size. If it is, then the -vf scale option is added. This utility also calculates a valid size for ffmpeg, since using -vf scale=-1:720 sometimes results in failure due to odd number.

Audio streams are copied, not re-encoded.

Output filenames are:

ORIGINAL_NAME.crf28.mp4

or (if downsizing is done):

ORIGINAL_NAME.480p-crf28.mp4

OPTIONS

* marks required options.

Main options

--audio-sample-rate=s, --sample-rate

Set audio sample rate, in Hz.

--crf=s
--dont-scale

Alias for --scale ''.

See --scale.

--fast

Shortcut for --preset=fast.

See --preset.

--faster

Shortcut for --preset=faster.

See --preset.

--ffmpeg-path=s
--file=s@*

Can be specified multiple times.

--files-json=s

See --file.

--frame-rate=s, -r

Set frame rate, in fps.

--medium

Shortcut for --preset=medium.

See --preset.

--no-scale

Alias for --scale ''.

See --scale.

--preset=s

Default value:

"veryslow"

Valid values:

["ultrafast","superfast","veryfast","faster","fast","medium","slow","slower","veryslow"]
--scale=s

Default value:

"1080^>"

Scale video to specified size. See <pm:Math::Image::CalcResized> or <prog:calc-image-resized-size> for more details on scale specification. Some examples include:

The default is `1080^>` which means to shrink to 1080p if video size is larger than 1080p.

To disable scaling, set `--scale` to '' (empty string), or specify `--dont-scale` on the CLI.

--slow

Shortcut for --preset=slow.

See --preset.

--slower

Shortcut for --preset=slower.

See --preset.

--superfast

Shortcut for --preset=superfast.

See --preset.

--ultrafast

Shortcut for --preset=ultrafast.

See --preset.

--veryfast

Shortcut for --preset=veryfast.

See --preset.

--veryslow

Shortcut for --preset=veryslow.

See --preset.

Configuration options

--config-path=s, -c

Set path to configuration file.

--config-profile=s, -P

Set configuration profile to use.

--no-config, -C

Do not use any configuration file.

Environment options

--no-env

Do not read environment for default options.

Logging options

--debug

Shortcut for --log-level=debug.

--log-level=s

Set log level.

--quiet

Shortcut for --log-level=error.

--trace

Shortcut for --log-level=trace.

--verbose

Shortcut for --log-level=info.

Output options

--format=s

Choose output format, e.g. json, text.

Default value:

undef
--json

Set output format to json.

--naked-res

When outputing as JSON, strip result envelope.

Default value:

0

By default, when outputing as JSON, the full enveloped result is returned, e.g.:

[200,"OK",[1,2,3],{"func.extra"=>4}]

The reason is so you can get the status (1st element), status message (2nd element) as well as result metadata/extra result (4th element) instead of just the result (3rd element). However, sometimes you want just the result, e.g. when you want to pipe the result for more post-processing. In this case you can use `--naked-res` so you just get:

[1,2,3]
--page-result

Filter output through a pager.

--view-result

View output using a viewer.

Other options

--dry-run

Run in simulation mode (also via DRY_RUN=1).

Default value:

""
--help, -h, -?

Display help message and exit.

--version, -v

Display program's version and exit.

COMPLETION

This script has shell tab completion capability with support for several shells.

bash

To activate bash completion for this script, put:

complete -C reencode-video-with-libx264 reencode-video-with-libx264

in your bash startup (e.g. ~/.bashrc). Your next shell session will then recognize tab completion for the command. Or, you can also directly execute the line above in your shell to activate immediately.

It is recommended, however, that you install modules using cpanm-shcompgen which can activate shell completion for scripts immediately.

tcsh

To activate tcsh completion for this script, put:

complete reencode-video-with-libx264 'p/*/`reencode-video-with-libx264`/'

in your tcsh startup (e.g. ~/.tcshrc). Your next shell session will then recognize tab completion for the command. Or, you can also directly execute the line above in your shell to activate immediately.

It is also recommended to install shcompgen (see above).

other shells

For fish and zsh, install shcompgen as described above.

CONFIGURATION FILE

This script can read configuration files. Configuration files are in the format of IOD, which is basically INI with some extra features.

By default, these names are searched for configuration filenames (can be changed using --config-path): ~/.config/reencode-video-with-libx264.conf, ~/reencode-video-with-libx264.conf, or /etc/reencode-video-with-libx264.conf.

All found files will be read and merged.

To disable searching for configuration files, pass --no-config.

You can put multiple profiles in a single file by using section names like [profile=SOMENAME] or [SOMESECTION profile=SOMENAME]. Those sections will only be read if you specify the matching --config-profile SOMENAME.

You can also put configuration for multiple programs inside a single file, and use filter program=NAME in section names, e.g. [program=NAME ...] or [SOMESECTION program=NAME]. The section will then only be used when the reading program matches.

You can also filter a section by environment variable using the filter env=CONDITION in section names. For example if you only want a section to be read if a certain environment variable is true: [env=SOMEVAR ...] or [SOMESECTION env=SOMEVAR ...]. If you only want a section to be read when the value of an environment variable has value equals something: [env=HOSTNAME=blink ...] or [SOMESECTION env=HOSTNAME=blink ...]. If you only want a section to be read when the value of an environment variable does not equal something: [env=HOSTNAME!=blink ...] or [SOMESECTION env=HOSTNAME!=blink ...]. If you only want a section to be read when an environment variable contains something: [env=HOSTNAME*=server ...] or [SOMESECTION env=HOSTNAME*=server ...]. Note that currently due to simplistic parsing, there must not be any whitespace in the value being compared because it marks the beginning of a new section filter or section name.

To load and configure plugins, you can use either the -plugins parameter (e.g. -plugins=DumpArgs or -plugins=DumpArgs@before_validate_args), or use the [plugin=NAME ...] sections, for example:

[plugin=DumpArgs]
-event=before_validate_args
-prio=99

[plugin=Foo]
-event=after_validate_args
arg1=val1
arg2=val2

which is equivalent to setting -plugins=-DumpArgs@before_validate_args@99,-Foo@after_validate_args,arg1,val1,arg2,val2.

List of available configuration parameters:

audio_sample_rate (see --audio-sample-rate)
crf (see --crf)
ffmpeg_path (see --ffmpeg-path)
files (see --file)
format (see --format)
frame_rate (see --frame-rate)
log_level (see --log-level)
naked_res (see --naked-res)
preset (see --preset)
scale (see --scale)

ENVIRONMENT

REENCODE_VIDEO_WITH_LIBX264_OPT => str

Specify additional command-line options.

FILES

~/.config/reencode-video-with-libx264.conf

~/reencode-video-with-libx264.conf

/etc/reencode-video-with-libx264.conf

HOMEPAGE

Please visit the project's homepage at https://metacpan.org/release/App-FfmpegUtils.

SOURCE

Source repository is at https://github.com/perlancar/perl-App-FfmpegUtils.

BUGS

Please report any bugs or feature requests on the bugtracker website https://github.com/perlancar/perl-App-FfmpegUtils/issues

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.

AUTHOR

perlancar <perlancar@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2020 by perlancar@cpan.org.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.