Picking audio track in a multi-audio files

[Bearmancer]

I want to transcribe the director's commentary in a particular mkv file instead of the default audio. How do I choose a different audio track in Whisper?

[glangford]

You can extract the relevant audio track using ffmpeg. See this gist for examples.

• https://gist.github.com/cdeath/1f8fdd96ead3829465897e413188190a

Other tools are also available. whisper itself does not support track selection.

[Bearmancer]

The help page was confusing so I asked ChatGPT for help and made a pwsh script to extract the second audio track whenever applicable as a 16-bit FLAC file in a directory for MKV files.

For those interested, here is the script:

`function ExtractCommentaryAudio() {
$videoFiles = Get-ChildItem -Path . -Recurse -Filter "*.mkv"

foreach ($file in $videoFiles) {
    $audioTrackCount = (ffmpeg -i $file.FullName -hide_banner 2>&1 | Select-String "Stream #.*: Audio").Count

    if ($audioTrackCount -gt 1) {
        $outputFile = Join-Path $PWD.Path ("$($file.BaseName) - Audio Commentary.flac")
        ffmpeg -i $file.FullName -map 0:a:1 -sample_fmt s16 -acodec flac $outputFile
    
    }
}

}`