BerBevans
commented
5 years ago I have found a way to do this. Basically I mix two stereo sources from microphone and speakers but before mixing the two sources, I pan the audio on each source so the audio is effectively coming from one channel on each source but opposite channels so the channel with audio on one source is mixed with the channel with no audio from the other source.
Note There are two issues that I haven't ironed out but I suspect that they are related.
- The recorded audio is a bit choppy. This seems to be coming from the speaker capture. I am not sure if this is because all of the re-sampling is done real-time and then output to the one, pre-mixed file than recorded to separate files for each source and then after the recording has finished, mix both files into the one mixed file.
- The prompt to start writing to a file is from the speaker source detecting audio. If there is no sound playing from the speakers, the file will not start writing to the disk. This could cause issues with the microphone filling buffers. Having two IWaveSources linked to the same WasapiLoopbackCapture object may be causing the choppy audio mentioned in point 1.
Without further ado, here is my code. To get this working, I modified the 'Recorder' sample project.
// SimpleMixer.cs (copied from the 'SimpleMixerSample' project with the line to remove sources commented out.
using System;
using System.Collections.Generic;
using CSCore;
namespace Recorder
{
public class SimpleMixer : ISampleSource
{
private readonly WaveFormat _waveFormat;
private readonly List<ISampleSource> _sampleSources = new List<ISampleSource>();
private readonly object _lockObj = new object();
private float[] _mixerBuffer;
public bool FillWithZeros { get; set; }
public bool DivideResult { get; set; }
public SimpleMixer(int channelCount, int sampleRate)
{
if(channelCount < 1)
throw new ArgumentOutOfRangeException("channelCount");
if(sampleRate < 1)
throw new ArgumentOutOfRangeException("sampleRate");
_waveFormat = new WaveFormat(sampleRate, 32, channelCount, AudioEncoding.IeeeFloat);
FillWithZeros = false;
}
public void AddSource(ISampleSource source)
{
if (source == null)
throw new ArgumentNullException("source");
if(source.WaveFormat.Channels != WaveFormat.Channels ||
source.WaveFormat.SampleRate != WaveFormat.SampleRate)
throw new ArgumentException("Invalid format.", "source");
lock (_lockObj)
{
if (!Contains(source))
_sampleSources.Add(source);
}
}
public void RemoveSource(ISampleSource source)
{
//don't throw null ex here
lock (_lockObj)
{
if (Contains(source))
_sampleSources.Remove(source);
}
}
public bool Contains(ISampleSource source)
{
if (source == null)
return false;
return _sampleSources.Contains(source);
}
public int Read(float[] buffer, int offset, int count)
{
int numberOfStoredSamples = 0;
if (count > 0 && _sampleSources.Count > 0)
{
lock (_lockObj)
{
_mixerBuffer = _mixerBuffer.CheckBuffer(count);
List<int> numberOfReadSamples = new List<int>();
for (int m = _sampleSources.Count -1; m >= 0; m--)
{
var sampleSource = _sampleSources[m];
int read = sampleSource.Read(_mixerBuffer, 0, count);
for (int i = offset, n = 0; n < read; i++, n++)
{
if (numberOfStoredSamples <= i)
buffer[i] = _mixerBuffer[n];
else
buffer[i] += _mixerBuffer[n];
}
if (read > numberOfStoredSamples)
numberOfStoredSamples = read;
if (read > 0)
numberOfReadSamples.Add(read);
else
{
//raise event here
// RemoveSource(sampleSource); //remove the input to make sure that the event gets only raised once.
// Commented out to stop source being removed
}
}
if (DivideResult)
{
numberOfReadSamples.Sort();
int currentOffset = offset;
int remainingSources = numberOfReadSamples.Count;
foreach (var readSamples in numberOfReadSamples)
{
if (remainingSources == 0)
break;
while (currentOffset < offset + readSamples)
{
buffer[currentOffset] /= remainingSources;
buffer[currentOffset] = Math.Max(-1, Math.Min(1, buffer[currentOffset]));
currentOffset++;
}
remainingSources--;
}
}
}
}
if (FillWithZeros && numberOfStoredSamples != count)
{
Array.Clear(
buffer,
Math.Max(offset + numberOfStoredSamples - 1, 0),
count - numberOfStoredSamples);
return count;
}
return numberOfStoredSamples;
}
public bool CanSeek { get { return false; } }
public WaveFormat WaveFormat
{
get { return _waveFormat; }
}
public long Position
{
get { return 0; }
set
{
throw new NotSupportedException();
}
}
public long Length
{
get { return 0; }
}
public void Dispose()
{
lock (_lockObj)
{
foreach (var sampleSource in _sampleSources.ToArray())
{
sampleSource.Dispose();
_sampleSources.Remove(sampleSource);
}
}
}
}
}
//MainWindow.cs
// Created a new enum (bottom of the file)
public enum PanToChannel { Left = 1, Right = -1, Equal = 0 }
// Changed the global variables
//Change this to CaptureMode.Capture to capture a microphone,...
private const CaptureMode CaptureMode = Recorder.CaptureMode.LoopbackCapture;
private MMDevice _selectedDevice;
private WasapiCapture _speakersIn;
private WasapiCapture _micIn;
private IWaveSource _speakersInSource;
private IWaveSource _micInSource;
private PanSource _speakerPan;
private PanSource _micPan;
private SimpleMixer _mixer;
private IWaveSource _finalSource;
private IWriteable _wavWriter;
private readonly GraphVisualization _graphVisualization = new GraphVisualization();
// Updated 'StopCapture()' to handle new and renamed global valiables.
private void StopCapture()
{
if (_speakersIn != null)
{
// clean up all global properties
_speakersIn.Stop();
_speakersIn.Dispose();
_speakersIn = null;
if (_micIn != null)
{
_micIn.Stop();
_micIn.Dispose();
_micIn = null;
}
if (_speakersInSource != null)
_speakersInSource.Dispose();
if (_micInSource != null)
_micInSource.Dispose();
if (_speakerPan != null)
_speakerPan.Dispose();
if (_micPan != null)
_micPan.Dispose();
if (_mixer != null)
_mixer.Dispose();
if (_finalSource != null)
_finalSource.Dispose();
if (_wavWriter is IDisposable)
((IDisposable)_wavWriter).Dispose();
btnStop.Enabled = false;
btnStart.Enabled = true;
}
}// Updated 'StartCapture(string fileName)' and created some extra functions
private void StartCapture(string fileName)
{
if (SelectedDevice == null)
return;
SetupInputDevices();
#region set Pan sources
// All sources need to be the same sample rate so take the speaker sample rate which is generally higher.
int speakerSampleRate = _speakersInSource.WaveFormat.SampleRate;
// Just in case speakers are recording a stereo sound, merge left and right channels so all sound is heard when the source is panned to one side.
_speakerPan = ConfigurePanSource(_speakersInSource, speakerSampleRate, true, PanToChannel.Left);
_micPan = ConfigurePanSource(_micInSource, speakerSampleRate, false, PanToChannel.Right);
#endregion
#region mix wave sources together
// mix both sources into one
MixMultipleSources(new List<ISampleSource>() { _speakerPan }, speakerSampleRate);
MixMultipleSources(new List<ISampleSource>() { _speakerPan, _micPan }, speakerSampleRate);
#endregion
#region read from wave streams and write to file
// need to create this sound in source so the 'DataAvailable' event will fire and start writing to file.
var speakerInSource = new SoundInSource(_speakersIn);
var singleBlockNotificationStream = new SingleBlockNotificationStream(_mixer);
_finalSource = singleBlockNotificationStream.ToWaveSource();
_wavWriter = new WaveWriter(fileName, _finalSource.WaveFormat);
byte[] buffer = new byte[_finalSource.WaveFormat.BytesPerSecond / 2];
speakerInSource.DataAvailable += (s, e) =>
{
int read;
while ((read = _finalSource.Read(buffer, 0, buffer.Length)) > 0)
_wavWriter.Write(buffer, 0, read);
};
#endregion
// populate visulaion tool
singleBlockNotificationStream.SingleBlockRead += SingleBlockNotificationStreamOnSingleBlockRead;
// start the sound input sources
_speakersIn.Start();
_micIn.Start();
}
private void SetupInputDevices()
{
_speakersIn = new WasapiLoopbackCapture();
_speakersIn.Device = SelectedDevice;
_speakersIn.Initialize();
// configure mic capture (system default)
_micIn = new WasapiCapture(true, AudioClientShareMode.Shared, 30);
_micIn.Initialize();
// Assign wave sources
_speakersInSource = new SoundInSource(_speakersIn) { FillWithZeros = false };
_micInSource = new SoundInSource(_micIn) { FillWithZeros = false };
}
private PanSource ConfigurePanSource(IWaveSource inputSource, int sampleRate, bool makeLeftAndRightChannelsEqualBeforePan, PanToChannel panDirection)
{
if (sampleRate != inputSource.WaveFormat.SampleRate)
inputSource = inputSource.ChangeSampleRate(sampleRate);
if (makeLeftAndRightChannelsEqualBeforePan)
inputSource = inputSource.ToMono().ToStereo();
var panSource = new PanSource(inputSource.ToSampleSource());
panSource.Pan = (int)panDirection;
return panSource;
}
private void MixMultipleSources(List<ISampleSource> waveSources, int sampleRate)
{
_mixer = new SimpleMixer(2, sampleRate) //output: stereo, 44,1kHz
{
FillWithZeros = false,
DivideResult = true // you may play around with this
};
foreach(var source in waveSources)
{
_mixer.AddSource(source);
}
}
oo-dev17
filoe
Just in case anyone else is looking to do this, I have found how to do it and the solution is posted below.
I will start this question by saying that I am very new (started today) with audio manipulation so I apologise in advance if this is an obvious misunderstanding from my side.
I need to write a utility that will record the microphone and the speakers to the same wav file but the wave sources need to be on different channels. E.g. Mic on the left channel, speakers on the right. The reason being is we are recording phone calls and analysing the content through speech recognition. Using the staff member on the left channel and the customer on the right, we can establish who is talking.
Using two of your sample projects and some code posted in https://github.com/filoe/cscore/issues/335 I have come up with the following example which will mix both wave sources and record to a file, but the same audio is recorded to each channel effectively making it a 2 channel mono file. Can you please point me in the right direction to be able to correctly record the sources to separate channels.
Thank you in advance.
Ben
` // Most of this taken from sample code private void StartCapture(string fileName) { if (SelectedDevice == null) return;
`