function getMp4Pic{
    param(
        [io.fileinfo]$mp4, 
        [timespan]$startTime = '0:0:0' , 
        [timespan]$endTime = '-1' ,
        [timespan]$step = '0:1:0' ,
        [uint32]$width = 0 ,
        [uint32]$height = 0
    )
    #learn from https://fleexlab.blogspot.com/2018/02/using-winrts-iasyncoperation-in.html
    Add-Type -AssemblyName System.Runtime.WindowsRuntime
    $asTaskGeneric = ([System.WindowsRuntimeSystemExtensions].GetMethods() | 
        ? { $_.Name -eq 'AsTask' -and $_.GetParameters().Count -eq 1 -and 
        $_.GetParameters()[0].ParameterType.Name -eq 'IAsyncOperation`1' }   )[0]
    Function Await($WinRtTask, $ResultType) {
    $asTask = $asTaskGeneric.MakeGenericMethod($ResultType)
    $netTask = $asTask.Invoke($null, @($WinRtTask))
    $netTask.Wait(-1) | Out-Null
    $netTask.Result
    }


    #http://blog.bagusandryan.com/get-video-thumbnail-storagefile-uwp-732/
    #https://docs.microsoft.com/en-us/windows/uwp/audio-video-camera/imaging

    [Windows.Storage.StorageFile , Windows.Storage , ContentType=WindowsRuntime] > $null
    [Windows.Media.Editing.MediaComposition , Windows.Media.Editing , ContentType=WindowsRuntime] > $null
    [Windows.Graphics.Imaging.ImageStream , Windows.Graphics.Imaging , ContentType=WindowsRuntime] > $null

    $xmlPath = Join-Path  $mp4.DirectoryName  "MediaClip11111xml.xml"
    $mp4PathInXml = "$mp4"  -replace  '&','&'
@"
<?xml version="1.0" encoding="UTF-8"?>
<Composition>
<Clips>
    <MediaClip Path="$mp4PathInXml" />
</Clips>
</Composition>
"@ | sc -Literal  $xmlPath  -Enc UTF8
# "@  must at begin of line
    $a = [Windows.Storage.StorageFile]
    $xmlFile = await ($a::GetFileFromPathAsync($xmlPath)) ($a)

    #===== MediaComposition =====
    $a = [Windows.Media.Editing.MediaComposition]
    $m01 = await ($a::LoadAsync($xmlFile)) ($a)

    $NearestKeyFrame = 1
    if ($endTime -eq '-1'){ $endTime = $m01.Clips.OriginalDuration }

    $outFolder = Join-Path $mp4.DirectoryName  ($mp4.BaseName + "_$startTime" -replace ':','_')
    md $outFolder 2>$null >$null
    for ($time = $startTime; $time -le $endTime; $time += $step){
        $a = [Windows.Graphics.Imaging.ImageStream]
        $mp4Thumb = await ($m01.GetThumbnailAsync($time, $width, $height, $NearestKeyFrame)) ($a)

        $reader = [Windows.Storage.Streams.DataReader]::new($mp4Thumb.GetInputStreamAt(0))
        $reader.LoadAsync($mp4Thumb.Size) > $null
        $bytes = new-object byte[] ($mp4Thumb.Size)
        $reader.ReadBytes($bytes)
        
        #out
        $outName = $mp4.BaseName + ("_$time" -replace ':','_') + '.jpg'
        $outPath = Join-Path $outFolder  $outName
        [System.IO.File]::WriteAllBytes($outPath, $bytes)
    }

    del $xmlPath
}
#=======

cd -literal $PSScriptRoot
[Environment]::CurrentDirectory = pwd
$files = @(dir *.mp4,*.mkv -file)
if ($files.count -ne 0){
    getMp4Pic  $files[0]  -start 0:0:5  -end 0:0:5  # -step 0:0:20 -w 640 -h 480
}
复制代码