查看“︁Ca”︁的源代码

{{DISPLAYTITLE:{{spmono|ca}}}}
A tiny little Windows Batch script used for converting media files into MPEG4 Audio files. It requires the following software to be properly put into {{spmono|%PATH%}} (here in my case is <code>C:<wbr />\<wbr />_<wbr />c<wbr />\</code>, and the last two are actually {{spmono|qaac}}’s ‘dependencies’):
* [https://github.com/yt-dlp/FFmpeg-Builds/releases/latest/download/ffmpeg-master-latest-win64-gpl-shared.zip {{spmono|ffmpeg}}];
* [https://rarewares.org/others.php#SoX-repo {{spmono|sox}}];
* [https://github.com/nu774/qaac/releases/latest {{spmono|qaac}}];
* [https://drive.google.com/file/d/1Xp5TnAye_lqZv3W8Ye7iuQAB5JlHbdi2/ {{spmono|QTFiles}} for {{spmono|qaac}}]; and
* [https://github.com/xiph/flac/releases/latest {{spmono|flac}}].
By default, the script will take any given media file with at least one audiotrack and convert the first audiotrack (or the only audiotrack) of it into an MPEG4 Audio file with .{{spmono|m4a}} being used as the container; if the input audiotrack has more than two channels (for instance, it’s a ‘5.1 surround sound’ track), it will be automatically downmixed into a two-channel stereo by using {{spmono|ffmpeg}}’s <code>-ac 2</code>.

The script accepts optional switches to alter its functions as follows:
* <code>'''-t''' '''''n'''''</code>: directs the script to use the ''n'' th audiotrack of the given file;
* <code>'''-ss''' '''''x'''''</code> and <code>'''-to''' '''''y'''''</code>: function identical to {{spmono|ffmpeg}}’s <code>-ss</code> and <code>-to</code> switches, which define the beginning and the ending timestamps of a clip that was cut from the given file;
* <code>'''-f'''</code>: adds both a fade-in and a fade-out of 0.06 ''s'' to the clip cut from the given file—this serves as a way to avoid the clickings at the beginning or the end of the clip, and is not intended to apply a real fade-in or fade-out effect to the clip, which is controlled by the switch below;
* <code>'''-ff''' '''''x''''' '''''y'''''</code>: adds a fade-in and / or a fade-out of ''customised'' lengths to the clip cut where ''x'' stands for the length in seconds of the fade-in effect, and the ''y'' likewise is for the fade-out;
* <code>'''-q'''</code>: directs the script to use a customised audio filter in the ‘downmixing into stereo’ process to achieve quieter background sounds with human voices boosted;
* <code>'''-m'''</code>: downmixes the output file to a one-channel mono;
* <code>'''-v'''</code>: directs {{spmono|qaac}} to use <code>-V 127</code> instead of <code>-v 0</code> to achieve a more frugal filesize;
* <code>'''-c'''</code>: copies or tries to copy metadata from the input file into the output one; if <code>'''-cc'''</code> is ''added'' to <code>-c</code>, then the script will also try to copy the metadata for chapters from the original into the output—a practice that is strongly dissuaded and is bound to go wrong unless the conversion was made for the whole track without clipping it; and
* <code>'''-n'''</code>: removes all the processing-denoting suffixes from the final output file.
A rather lengthy {{spmono|REG}} file is attached below to inject some of the commonly used commands into shell.
==The batch==
{{ca-win}}
==The {{spmono|REG}} file==
{{ca-reg}}