Powershell module for converting flv files to mp4. I use it for the output of OpenBroadcaster.

gistfile1.txt

<#
    .Synopsis
    Converts a video from flv to mp4.
    
    .Description
    Calls ffmpeg to convert a video from flv to mp4.
    
    .Parameter InputFile
    Name of the flv file to convert.
    
    .Parameter OutputFile
    Name of the mp4 file. Defaults to the InputFile.
    
    .Example
    # Convert a file
    Convert-Video -InputFile "myInputFile.flv" -OutputFile "myOutputFile.mp4"
    
#>
function Convert-Video {
    param(
        [string] $inputFile,
        [string] $outputFile = $inputFile
    )

    if(!$inputFile.ToUpper().EndsWith(".FLV"))
    {
        $inputFile = $inputFile + ".flv"
    }

    $inputFile



    if($outputFile.ToUpper().EndsWith(".FLV"))
    {

        $outputFile = $outputFile.Substring(0, $outputFile.ToUpper().IndexOf(".FLV"))
    }

    if(!$outputFile.ToUpper().EndsWith(".MP4"))
    {
        $outputFile = $outputFile + ".mp4"
    }
    
    $outputFile
    
    & ffmpeg -i $inputFile -c copy -copyts $outputFile
}