Trim multiple mp3 files at once

I know four methods: mp3DirectCut, Mp3splt-GTK, Mp3splt or ffmpeg

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mp3DirectCut (GUI version, best choice for quick results)

• After starting, go to File » Batch processing

• Add your mp3 folder, select Auto crop and press Start

  

Hints

• Choose a different folder as output to test some result files. After verifying, rerun it and choose Overwrite originals. You should be done in a couple of seconds since the program doesn't re-encode your mp3 files
• You probably want to enable Settings » Keep date on overwriting source files

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Mp3splt-gtk (GUI version, available for all major OS platforms)

• Download $ start the program, click on Batch & automatic split

• Select Trim using silence detection and press Batch split

  

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mp3splt (Command Line version, available for all major OS platforms)

Download mp3splt, open your PowerShell ISE, change both paths and run the following code:

$files = Get-ChildItem "C:\my\musicfolder" -Recurse -Include *.mp3,*.ogg,*.flac
$exe = "C:\path\to\mp3splt.exe"

ForEach ($file in $files) {    
    If ($file.BaseName -notmatch "_trimmed$" ) {        

        $newFile = $file.DirectoryName + "\" + $file.BaseName + "_trimmed" + $file.Extension
        If (Test-Path $newFile) {Remove-Item $newFile }

        & $exe -r -p "th=-48,min=2" `"$file`" | Out-Null

        Remove $file.Fullname
        Rename $($file.DirectoryName + "\" + $file.BaseName + "_trimmed" + $file.Extension) $file.Fullname
    }
}

Hints

• -r -p th=-48, min=2 is the option to remove silence at the start/end of your file. th defines the threshold level in dB. Everything below is considered as silence. min=2 sets the minimum silence in seconds. Only silence longer then 2 seconds will be truncated
• You could pretend a test run by adding an uppercase -P at the end of mp3splt command. It outputs errors or says everything went well. If used, comment out Remove and Rename since no new files are created to process them

• For testing, you could also use -d FOLDERPATH to choose a single output folder and -o@f to use the original filename as output (otherwise _trimmed will be appended)

  Documentation explaining all available options

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FFmpeg (Command Line version, available for all major OS platforms)

FFmpeg's audio filter -af silenceremove should not be used since it always re-encodes your files and you cannot for gods sake keep the same audio quality as your input file. -acodec copy can not be used here. You can only choose one fixed bit rate even if you process multiple files with different qualities.

However, there is another ffmpeg option: -af silencedetect. The theory is already explained at StackOverflow. I adopted it to Windows and PowerShell.

Download ffmpeg, open your PowerShell ISE, change both paths and run the following code:

$files = Get-ChildItem "C:\path\to\musicfolder" -Recurse -Include *.mp3,*.ogg,*.flac
$ffmpeg = "C:\path\to\ffmpeg.exe"

ForEach ($file in $files) {
    If ($file.BaseName -notmatch "_trimmed$" ) {

        # Detect silence with ffmpeg and "silencedetect". Save the complete output to variable $log
        $log = & $ffmpeg -hide_banner -i `"$file`" -af "silencedetect=duration=1:noise=-50dB" -f null - 2>&1

        $totalLength = [string]$log | where {$_ -match '(?<= Duration:.*)[\d:\.]+' } | % {$matches[0]}        
        $totalLength = ([TimeSpan]::Parse($totalLength)).TotalSeconds

        # Use regex to search all numbers after string "silence_end". Save them as string array in the format XXX.XXX
        # Check if any 'silence_end' was found. If yes, save the first silence ending time as mp3 start time        
        [string[]]$silenceEnd = $log | where {$_ -match '(?<=silence_end: )[-\d\.]+' } | % {$matches[0]}            
        If ($silenceEnd.count -gt 0 -And [double]$silenceEnd[0] -lt $totalLength/2) {
            [double]$trackStart = $silenceEnd[0]
        } else {
            [double]$trackStart = 0
        }

        # Do the same again but for silence starting times. Save the last one as mp3 end time
        [string[]]$silenceStart = $log | where {$_ -match '(?<=silence_start: )[-\d\.]+' } | % {$matches[0]}                
        If ($silenceStart.count -gt 0 -And $silenceStart[$silenceStart.count-1] -gt $totalLength/2) {
            [double]$trackEnd = $silenceStart[$silenceStart.count-1]
        } else {        
            [double]$trackEnd = $totalLength
        } 

        # calculate duration since ffmpeg's -t option wants a duration and not a timestamp
        $duration = $trackEnd - $trackStart

        # Put together the new file name. If file already exists from  previous run, delete it
        $newFile = $file.DirectoryName + "\" + $file.BaseName + "_trimmed" + $file.Extension
        If (Test-Path $newFile) {Remove-Item $newFile }                        

        # Run ffmpeg with our calculated start and duration times to remove silence at start and end
        write-host "$ffmpeg -i `"$file`" -ss $trackStart -t $duration -acodec copy `"$newFile`"  2>&1"
        & $ffmpeg -i `"$file`" -ss $trackStart -t $duration -acodec copy `"$newFile`"  2>&1

        # Delete the original mp3 file and rename the new mp3 file to the original name
        Remove-Item $file.Fullname   
        Rename-Item $newFile $file.Fullname
    }
}