Help needed with IMFSourceReaderCallback

[andreysaf]

I am trying to implement a custom call back for reading a stream. For now, I took the decompiled class and copied it exactly.

using SharpGen.Runtime;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using SharpGen.Runtime;
using Vortice.MediaFoundation;

namespace GetDevices
{
    [Guid("deec8d99-fa1d-4d82-84c2-2c8969944867")]
    public class Media : IMFSourceReaderCallback, IUnknown
    {
        public Media(nint nativePtr)
        : base(nativePtr)
        {
            Console.WriteLine("Media Class");
        }

        public static explicit operator Media(nint nativePtr)
        {
            if (nativePtr != IntPtr.Zero)
            {
                return new Media(nativePtr);
            }

            return null;
        }

        public unsafe void OnReadSample(Result hrStatus, int streamIndex, int streamFlags, long llTimestamp, IMFSample sample)
        {
            Console.WriteLine("OnReadSample");
            nint zero = IntPtr.Zero;
            zero = sample?.NativePointer ?? IntPtr.Zero;
            Result result = ((delegate* unmanaged[Stdcall]<nint, Result, int, int, long, void*, int>)base[3])(base.NativePointer, hrStatus, streamIndex, streamFlags, llTimestamp, (void*)zero);
            GC.KeepAlive(sample);
            result.CheckError();
        }

        public unsafe void OnFlush(int streamIndex)
        {
            ((Result)((delegate* unmanaged[Stdcall]<nint, int, int>)base[4])(base.NativePointer, streamIndex)).CheckError();
        }

        public unsafe void OnEvent(int streamIndex, IMFMediaEvent @event)
        {
            nint zero = IntPtr.Zero;
            zero = @event?.NativePointer ?? IntPtr.Zero;
            Result result = ((delegate* unmanaged[Stdcall]<nint, int, void*, int>)base[5])(base.NativePointer, streamIndex, (void*)zero);
            GC.KeepAlive(@event);
            result.CheckError();
        }
    }

}

And after trying to use it as follows:

IMFMediaSource mediaSource = device.ActivateObject<IMFMediaSource>();
IMFAttributes attributes = MFCreateAttributes(2);
attributes.SetUInt32(Vortice.MediaFoundation.SinkWriterAttributeKeys.ReadwriteDisableConverters, 1);
GetDevices.Media media = new GetDevices.Media(1);
attributes.Set(Vortice.MediaFoundation.SourceReaderAttributeKeys.AsyncCallback, media);
IMFSourceReader sourceReader = MFCreateSourceReaderFromMediaSource(mediaSource, attributes);

However, running into the Fatal error. System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

I believe it is stemming from the initialization of the Media class. I could not find the documentation on what nativeptr I should initialize with. Could you please point me in the right direction? Thank you!

[amerkoleci]

Thats not how callbacks works, once I'm back from vacation will take a look.

Cheers

[amerkoleci]

This was fixed by f17b551 and version 3.5.12-beta is being released on nuget.

You can now subclass from IMFSourceReaderCallbackBase and assing the AsyncCallback property of IMFAttributes class.

Cheers

[andreysaf]

Thank you so much!!!