Issue when using the IMRSourceReader.ReadSample function in async mode

[raphael-work]

Hello,

First of all, thank you for your work it's really amazing.
I'm implementing a C# WinForm application (.NET 9.0) and referencing your package Vortice.MediaFoundation (3.6.2).
I'm facing an exception when calling the ReadSample from a SourceReader instance with an AsyncCallback setted

private void RenderCameraDeviceFootageAsync(RenderCameraDeviceFootageArgs args)
{
	try
	{
		using (IMFAttributes attributesMediaSession = MediaFactory.MFCreateAttributes(1))
		{
			attributesMediaSession.SourceType = CaptureDeviceAttributeKeys.SourceTypeVidcap;
			attributesMediaSession.SymbolicLink = args.Camera.Id;
			using (IMFMediaSource mediaSource = MediaFactory.MFCreateDeviceSource(attributesMediaSession))
			{
				using (IMFAttributes attributes = MediaFactory.MFCreateAttributes(1))
				{
					attributes.SourceType = CaptureDeviceAttributeKeys.SourceTypeVidcap;
					attributes.VideoDeviceCategory = CaptureDeviceAttributeKeys.SourceTypeVidcap;
					attributes.AsyncCallback = new CameraMediaTypeSourceReaderCallback();
					using (IMFSourceReader reader = MediaFactory.MFCreateSourceReaderFromMediaSource(mediaSource, attributes))
					{
						using (IMFMediaType mediaType = reader.GetNativeMediaType(SourceReaderIndex.FirstVideoStream, (int)args.CameraMediaType.MediaTypeIndex))
						{   
							reader.SetCurrentMediaType(SourceReaderIndex.FirstVideoStream, mediaType);

							int actualStreamIndex = 0;
							SourceReaderFlag flags = SourceReaderFlag.None;
							long timestamp = 0;

							using (IMFSample sample = reader.ReadSample(SourceReaderIndex.FirstVideoStream, SourceReaderControlFlag.None,
								out actualStreamIndex, out flags, out timestamp))
							{                                            
							}
						}
					}
				}                        
			}
		}
	}
	catch (Exception ex)
	{
		_logger.LogError(ex, $"An error occured !");
	}        
}

internal class CameraMediaTypeSourceReaderCallback : IMFSourceReaderCallbackBase
{
	internal CameraMediaTypeSourceReaderCallback(ILogger<VideoController> logger)
	{
	}

	public override void OnEvent(SourceReaderIndex streamIndex, IMFMediaEvent @event)
	{
	}

	public override void OnFlush(SourceReaderIndex streamIndex)
	{
	}

	public override void OnReadSample(Result hrStatus,
		SourceReaderIndex streamIndex,
		SourceReaderFlag streamFlags, long llTimestamp, IMFSample sample)
	{
	}
}

You can find below the details of the Exception.

SharpGen.Runtime.SharpGenException
  HResult=0x80070057
  Message=HRESULT: [0x80070057], Module: [General], ApiCode: [E_INVALIDARG/Invalid arguments], Message: [Paramètre incorrect.
]
  Source=SharpGen.Runtime
  StackTrace:
   at SharpGen.Runtime.Result.ThrowFailureException()
   at SharpGen.Runtime.Result.CheckError()
   at Vortice.MediaFoundation.IMFSourceReader.ReadSample(Int32 streamIndex, SourceReaderControlFlag controlFlags, Int32& pdwActualStreamIndex, SourceReaderFlag& pdwStreamFlags, Int64& pllTimestamp)
   at Vortice.MediaFoundation.IMFSourceReader.ReadSample(SourceReaderIndex dwStreamIndex, SourceReaderControlFlag dwControlFlags, Int32& dwActualStreamIndexRef, SourceReaderFlag& dwStreamFlagsRef, Int64& llTimestampRef)

The documentation of the ReadSample method (probably coming from the Win32 API ?) explain this : "In asynchronous mode: All of the [out] parameters must be null. Otherwise, the method returns E_INVALIDARG"
But the [out] directive disallow this prerequisite with integer, enum flags or long.

May I ask you to provide a solution for this issue please ? Or is there another possibility to read a sample asynchronously ?

[amerkoleci]

Hi,
Can you share an example on github so I can track it?

[raphael-work]

Hello,

You can find the repository here => WinFormsAppAsyncMode.

King regards