How to trim audio (MP3) files

Summary: PowerShell script to trim beginning and end of the audio (MP3, etc) files.

The following PowerShell script will remove the specified number of seconds from the beginning and/or end of every audio file with the given extension (.mp3 in this case) under the specified folder and all subfolders unerneath (requires FFmpeg binaries):

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# Input folder holding audio files. $inputDir = "Z:\Lectures"   # Seconds to trim from beginning of file. $trimStart = 0.0   # Seconds to trim from the end of file. $trimEnd = 9.0   # Path to the directory holding FFMPEG tools. $ffmpegDir = "c:\ffmpeg\bin"   # Extension of the audio files. $ext = ".mp3"   # Extension for temporary files. $tmpExt = ".TMP$ext"   # Paths to FFMPEG tools. $ffmpeg  = Join-Path $ffmpegDir "ffmpeg.exe" $ffprobe = Join-Path $ffmpegDir "ffprobe.exe"   # Process all audio files in the directory and subdirectories. Get-ChildItem -LiteralPath $inputDir -Filter "*$ext" -Recurse -File | ForEach-Object {     # Original file path.     $oldFile = $_.FullName       # Original file name.     $oldName = $_.Name       # Temp file path will be in the same folder named after the original file.     $tmpFile = "$oldFile$tmpExt"       # Get the length of the audio track (it's a sting holding a floating number with possible new line).     $duration = (& $ffprobe -v 0 -show_entries format=duration -of compact=p=0:nk=1 $oldFile) | Out-String       $duration = $duration.Trim()       # Set new length of the audio by removing the trimmed parts.     $duration -= ($trimEnd + $trimStart)       # Trim the file.     & $ffmpeg -ss $trimStart -t $duration -i $oldFile -acodec copy $tmpFile       # Delete the original file.     Remove-Item -LiteralPath $oldFile -Force       # Rename the temp file to the original.     Rename-Item -LiteralPath $tmpFile $oldName -Force }