Converting audio/video tracks to AAC format in C# app.

Question

I try convert audio/video tracks to AAC format using qaac lib. In CMD it works and output information about progress of convertation. In my C# app it works too, but I can't get information about progress, i try use these events: OutputDataReceived, ErrorDataReceived. In handler of ErrorDataReceived I don't get needed information, in handler of OutputDataReceived I get received.Data like null value. How can I get conversion progress information during conversion in C# code?

Creating process for converting:

string arguments = $"\"{engineParameters.InputFile.Filename}\" -no-delay -o \"{engineParameters.OutputFile.Filename}\"";

processStartInfo = new ProcessStartInfo
{
    FileName = QaacFilePath,
    Arguments = arguments,
    RedirectStandardOutput = true,
    UseShellExecute = false,
    CreateNoWindow = true,
    WindowStyle = ProcessWindowStyle.Hidden
};

Also i call these methods for process:

BeginOutputReadLine();
BeginErrorReadLine();
WaitForExit();

Handlers:

this.Process.OutputDataReceived += (sender, received) =>
{
    if (received.Data == null) return;
    //Some code...
}

this.Process.ErrorDataReceived += (sender, received) =>
{
    if (received.Data == null) return;
    //Some code...
}

Answer 1

You don't need any external library; you can use MediaTranscoder

A test :

// Add reference to C:\Program Files (x86)\Windows Kits\10\UnionMetadata\10.0.19041.0\Windows.winmd
// Add reference to C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETCore\v4.5\System.Runtime.WindowsRuntime.dll

string sInputFile = "E:\\Sources\\CSharp_ConvertToAAC\\sample_1280x720_surfing_with_audio.mp4";
string sOutputFile = "E:\\Sources\\CSharp_ConvertToAAC\\sample_1280x720_surfing_with_audio.m4a";

var cts = new CancellationTokenSource();
try
{    
    await ConvertToAacAsync(sInputFile, sOutputFile, cts.Token);
}
catch (TaskCanceledException)
{
    System.Diagnostics.Debug.WriteLine("Conversion canceled.");
}

       static async Task ConvertToAacAsync(string sInputFile, string sOutputFile, CancellationToken cancellationToken)
       {
           StorageFile inputFile = await StorageFile.GetFileFromPathAsync(sInputFile);

           string sOutputFolderPath = System.IO.Path.GetDirectoryName(sOutputFile);
           string sOutputFileName = System.IO.Path.GetFileName(sOutputFile);
           StorageFolder outputFolder = await StorageFolder.GetFolderFromPathAsync(sOutputFolderPath);
           StorageFile outputFile = await outputFolder.CreateFileAsync(sOutputFileName, CreationCollisionOption.ReplaceExisting);

           var transcoder = new MediaTranscoder();
           transcoder.VideoProcessingAlgorithm = MediaVideoProcessingAlgorithm.Default; // No video processing needed
  
           var profile = Windows.Media.MediaProperties.MediaEncodingProfile.CreateM4a(Windows.Media.MediaProperties.AudioEncodingQuality.High); // AAC inside .m4a container
           
           var prepared = await transcoder.PrepareFileTranscodeAsync(inputFile, outputFile, profile);
           if (!prepared.CanTranscode)
           {
               System.Diagnostics.Debug.WriteLine($"Transcoding not possible: {prepared.FailureReason}");
               return;
           }

           System.Diagnostics.Debug.WriteLine("Conversion started...");
           var progressHandler = new Progress<double>(progress =>
           {
               System.Diagnostics.Debug.WriteLine($"Progress: {progress}%");
           });

           await prepared.TranscodeAsync().AsTask(cancellationToken, progressHandler);
           System.Diagnostics.Debug.WriteLine("Conversion completed!");
       }