I’m developing a UWP application ( for Windows 10) which works with audio data. It receives samples buffer at the start in the form of a float array of samples, which items are changing from -1f to 1f. Earlier I used NAudio.dll 1.8.0 that gives all necessary functionality. Worked with WaveFileReader, waveBuffer.FloatBuffer, WaveFileWriter classes. However, when I finished this app and tried to build Release version, got this error: ILT0042: Arrays of pointer types are not currently supported: 'System.Int32*[]'.
I’ve tried to solve it:
There is advice to remove the link to .dll, but I need it.
I’ve tried to install NAudio the same version using Manage NuGet Packages, but WaveFileReader, WaveFileWriter is not available.
In NAudio developer’s answer (How to store a .wav file in Windows 10 with NAudio) I’ve read about using AudioGraph, but I can build float array of samples only in the realtime playback, but I need get the full samples to pack right after the audio file uploading. Example of getting samples during the recording process or playback: https://docs.microsoft.com/ru-ru/windows/uwp/audio-video-camera/audio-graphs
That’s why I need help: how to get FloatBuffer for working with samples after audio file uploading? For example, for building audio waves or calculation for audio effects applying.
Thank you in advance.
I’ve tried to use FileStream and BitConverter.ToSingle(), however, I had a different result compared to NAudio. In other words, I’m still looking for a solution.
private float[] GetBufferArray()
{
string _path = ApplicationData.Current.LocalFolder.Path.ToString() + "/track_1.mp3";
FileStream _stream = new FileStream(_path, FileMode.Open);
BinaryReader _binaryReader = new BinaryReader(_stream);
int _dataSize = _binaryReader.ReadInt32();
byte[] _byteBuffer = _binaryReader.ReadBytes(_dataSize);
int _sizeFloat = sizeof(float);
float[] _floatBuffer = new float[_byteBuffer.Length / _sizeFloat];
for (int i = 0, j = 0; i < _byteBuffer.Length - _sizeFloat; i += _sizeFloat, j++)
{
_floatBuffer[j] = BitConverter.ToSingle(_byteBuffer, i);
}
return _floatBuffer;
}
Another way to read samples from an audio file in UWP is using AudioGraph API. It will work for all audio formats that Windows10 supports
Here is a sample code
namespace AudioGraphAPI_read_samples_from_file
{
// App opens a file using FileOpenPicker and reads samples into array of
// floats using AudioGragh API
// Declare COM interface to access AudioBuffer
[ComImport]
[Guid("5B0D3235-4DBA-4D44-865E-8F1D0E4FD04D")]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
unsafe interface IMemoryBufferByteAccess
{
void GetBuffer(out byte* buffer, out uint capacity);
}
public sealed partial class MainPage : Page
{
StorageFile mediaFile;
AudioGraph audioGraph;
AudioFileInputNode fileInputNode;
AudioFrameOutputNode frameOutputNode;
/// <summary>
/// We are going to fill this array with audio samples
/// This app loads only one channel
/// </summary>
float[] audioData;
/// <summary>
/// Current position in audioData array for loading audio samples
/// </summary>
int audioDataCurrentPosition = 0;
public MainPage()
{
this.InitializeComponent();
}
private async void Open_Button_Click(object sender, RoutedEventArgs e)
{
// We ask user to pick an audio file
FileOpenPicker filePicker = new FileOpenPicker();
filePicker.SuggestedStartLocation = PickerLocationId.MusicLibrary;
filePicker.FileTypeFilter.Add(".mp3");
filePicker.FileTypeFilter.Add(".wav");
filePicker.FileTypeFilter.Add(".wma");
filePicker.FileTypeFilter.Add(".m4a");
filePicker.ViewMode = PickerViewMode.Thumbnail;
mediaFile = await filePicker.PickSingleFileAsync();
if (mediaFile == null)
{
return;
}
// We load samples from file
await LoadAudioFromFile(mediaFile);
// We wait 5 sec
await Task.Delay(5000);
if (audioData == null)
{
ShowMessage("Error loading samples");
return;
}
// After LoadAudioFromFile method finished we can use audioData
// For example we can find max amplitude
float max = audioData[0];
for (int i = 1; i < audioData.Length; i++)
if (Math.Abs(audioData[i]) > Math.Abs(max))
max = audioData[i];
ShowMessage("Maximum is " + max.ToString());
}
private async void ShowMessage(string Message)
{
var dialog = new MessageDialog(Message);
await dialog.ShowAsync();
}
private async Task LoadAudioFromFile(StorageFile file)
{
// We initialize an instance of AudioGraph
AudioGraphSettings settings =
new AudioGraphSettings(
Windows.Media.Render.AudioRenderCategory.Media
);
CreateAudioGraphResult result1 = await AudioGraph.CreateAsync(settings);
if (result1.Status != AudioGraphCreationStatus.Success)
{
ShowMessage("AudioGraph creation error: " + result1.Status.ToString());
}
audioGraph = result1.Graph;
if (audioGraph == null)
return;
// We initialize FileInputNode
CreateAudioFileInputNodeResult result2 =
await audioGraph.CreateFileInputNodeAsync(file);
if (result2.Status != AudioFileNodeCreationStatus.Success)
{
ShowMessage("FileInputNode creation error: " + result2.Status.ToString());
}
fileInputNode = result2.FileInputNode;
if (fileInputNode == null)
return;
// We read audio file encoding properties to pass them to FrameOutputNode creator
AudioEncodingProperties audioEncodingProperties = fileInputNode.EncodingProperties;
// We initialize FrameOutputNode and connect it to fileInputNode
frameOutputNode = audioGraph.CreateFrameOutputNode(audioEncodingProperties);
fileInputNode.AddOutgoingConnection(frameOutputNode);
// We add a handler achiving the end of a file
fileInputNode.FileCompleted += FileInput_FileCompleted;
// We add a handler which will transfer every audio frame into audioData
audioGraph.QuantumStarted += AudioGraph_QuantumStarted;
// We initialize audioData
int numOfSamples = (int)Math.Ceiling(
(decimal)0.0000001
* fileInputNode.Duration.Ticks
* fileInputNode.EncodingProperties.SampleRate
);
audioData = new float[numOfSamples];
audioDataCurrentPosition = 0;
// We start process which will read audio file frame by frame
// and will generated events QuantumStarted when a frame is in memory
audioGraph.Start();
}
private void FileInput_FileCompleted(AudioFileInputNode sender, object args)
{
audioGraph.Stop();
}
private void AudioGraph_QuantumStarted(AudioGraph sender, object args)
{
AudioFrame frame = frameOutputNode.GetFrame();
ProcessInputFrame(frame);
}
unsafe private void ProcessInputFrame(AudioFrame frame)
{
using (AudioBuffer buffer = frame.LockBuffer(AudioBufferAccessMode.Read))
using (IMemoryBufferReference reference = buffer.CreateReference())
{
// We get data from current buffer
((IMemoryBufferByteAccess)reference).GetBuffer(
out byte* dataInBytes,
out uint capacityInBytes
);
// We discard first frame; it's full of zeros because of latency
if (audioGraph.CompletedQuantumCount == 1) return;
float* dataInFloat = (float*)dataInBytes;
uint capacityInFloat = capacityInBytes / sizeof(float);
// Number of channels defines step between samples in buffer
uint step = fileInputNode.EncodingProperties.ChannelCount;
// We transfer audio samples from buffer into audioData
for (uint i = 0; i < capacityInFloat; i += step)
{
if (audioDataCurrentPosition < audioData.Length)
{
audioData[audioDataCurrentPosition] = dataInFloat[i];
audioDataCurrentPosition++;
}
}
}
}
}
}
Edited: It solves the problem because it reads samples from a file into a float array
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With