I'm trying to write a class that implements IRandomAccessStream that I can feed to a MediaElement via SetSource, but no matter what I do the MediaElement either rejects the stream format or crashes.
As a control, I tried making a simple wrapper that takes a Stream and implements IRandomAccessStream. The implementation of ReadAsync just does this:
IAsyncOperationWithProgress<IBuffer, uint> IInputStream.ReadAsync(IBuffer buffer, uint count, InputStreamOptions options)
{
Func<CancellationToken, IProgress<uint>, Task<IBuffer>> taskProvider =
(token, progress) =>
{
Func<IBuffer> readFunc = () =>
{
int bytesRead;
byte[] result = new byte[count];
bytesRead = this._Stream.Read(result, 0, (int)count);
this.Position += bytesRead;
result.CopyTo(buffer);
buffer.Length = (uint)bytesRead;
return buffer;
};
return Task.Run(readFunc);
};
return AsyncInfo.Run(taskProvider);
}
The code works perfectly fine to set the source for BitmapImage's, but for inexplicable reasons, not for MediaElement.
I've read elsewhere that MediaElement cannot work with an in-memory stream (which makes no sense...) but this is not even that case. Even if I seed my custom IRandomAccessStream with a normal Stream obtained from a StorageFile, the MediaElement still fails
to accept the stream source.
I should also add that debugging shows the MediaElement is acting very oddly. For example, it first reads 1024 bytes, then seeks back to position 0, then reads 2048 bytes, then again seeks back to position 0, then reads 4108 bytes, then AGAIN seeks back
to position 0, etc...
Again, the class works fine in other contexts requiring an IRandomAccessStream, including BitmapImage, so it has to be something unique to MediaElement.
Can anyone explain what's going wrong here? Thanks much!
