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App-FfmpegUtils-0.008
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/ App::FfmpegUtils

NAME

App::FfmpegUtils - Utilities related to ffmpeg

VERSION

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

FUNCTIONS

reencode_video_with_libx264

Usage:

reencode_video_with_libx264(%args) -> [status, msg, payload, meta]

Re-encode video (using ffmpeg and libx264).

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

This function is not exported.

This function supports dry-run operation.

Arguments ('*' denotes required arguments):

  • audio_sample_rate => uint

    Set audio sample rate, in Hz.

  • crf => int

  • ffmpeg_path => filename

  • files* => array[filename]

  • frame_rate => ufloat

    Set frame rate, in fps.

  • preset => str (default: "veryslow")

  • scale => str (default: "1080^>")

    Scale video to specified size. See Math::Image::CalcResized or 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.

Special arguments:

  • -dry_run => bool

    Pass -dry_run=>1 to enable simulation mode.

Returns an enveloped result (an array).

First element (status) is an integer containing HTTP status code (200 means OK, 4xx caller error, 5xx function error). Second element (msg) is a string containing error message, or 'OK' if status is 200. Third element (payload) is optional, the actual result. Fourth element (meta) is called result metadata and is optional, a hash that contains extra information.

Return value: (any)

split_video_by_duration

Usage:

split_video_by_duration(%args) -> [status, msg, payload, meta]

Split video by duration into parts.

This utility uses ffmpeg (particularly the -t and -ss) option to split a longer video into shorter videos. For example, if you have long.mp4 with duration of 1h12m and you run it through this utility with --every 15min then you will have 5 new video files: long.1of5.mp4 (15min), long.2of5.mp4 (15min), long.3of5.mp4 (15min), long.4of5.mp4 (15min), and long.5of5.mp4 (12min).

Currently this utility uses -c copy ffmpeg option, so there might be a few of seconds of glitches around the cut points. An option to use other codec will be provided in the future.

This function is not exported.

This function supports dry-run operation.

Arguments ('*' denotes required arguments):

  • every* => duration

  • file* => filename

Special arguments:

  • -dry_run => bool

    Pass -dry_run=>1 to enable simulation mode.

Returns an enveloped result (an array).

First element (status) is an integer containing HTTP status code (200 means OK, 4xx caller error, 5xx function error). Second element (msg) is a string containing error message, or 'OK' if status is 200. Third element (payload) is optional, the actual result. Fourth element (meta) is called result metadata and is optional, a hash that contains extra information.

Return value: (any)

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.