Decoding Sound Using MediaStreamSource

Question

I have a UWP project and I want to use the Windows.Media.Audio API to play the file. Instead of using FileInputNode, I want to transfer the file so that I can pinpoint the various temporary properties.

I found the MediaStreamSource API and made the following code in an attempt to decode the 16-bit PCM channel .wav file

public async Task<Windows.Storage.Streams.Buffer> GetBuffer() { // check if the sample requested byte offset is within the file size if (byteOffset + BufferSize <= mssStream.Size) { inputStream = mssStream.GetInputStreamAt(byteOffset); // create the MediaStreamSample and assign to the request object. // You could also create the MediaStreamSample using createFromBuffer(...) MediaStreamSample sample = await MediaStreamSample.CreateFromStreamAsync(inputStream, BufferSize, timeOffset); sample.Duration = sampleDuration; sample.KeyFrame = true; // increment the time and byte offset byteOffset += BufferSize; timeOffset = timeOffset.Add(sampleDuration); return sample.Buffer; } else { return null; } } 

Instead of using the Event system, I created a method that runs whenever my AudioFrameInputNode needs a new AudioFrame.

Now it seems that the resulting byte array in MediaStreamSample is exactly the same as when I was just reading my StorageFile using the DataReader.

Does MediaStreamSample.CreateFromStreamAsync create decoding of an audio file into a byte array with a float? Or is this done in MediaElement when it reproduces a sample?

And if so, how can I decode an audio file so that I can return the resulting AudioBuffer to my FrameInputNode?

Answer 1

When MediaStreamSample.CreateFromStreamAsync completes, it returns a new file as MediaStreamSample.

If I understand what you want here, and an example of what you can do to execute it.

 function sampleRequestedHandler(e) { var request = e.request; if (!MyCustomFormatParser.IsAtEndOfStream(randomAccessStream)) { var deferral = request.getDeferral(); var inputStream = MyCustomFormatParser.getInputStream(randomAccessStream); MediaStreamSample.createFromStreamAsync(inputStream, sampleSize, timeOffset). then(function(sample) { sample.duration = sampleDuration; sample.keyFrame = true; request.sample = sample; deferral.complete(); }); } } 

When a sample request is requested, your custom parser extracts audio data from RandomAccessStream and returns only sound samples as InputStream.