void UpdateSound()
{
// Try to keep 1/10 seconds of sound in the buffer, to avoid both dropouts and unnecessary latency
float targetLength = 1.0f / 10.0f;
float requiredLength = targetLength - soundStream.BufferLength;
if (requiredLength < 0.0f)
{
return;
}
uint numSamples = (uint)(soundStream.Frequency * requiredLength);
if (numSamples == 0)
{
return;
}
// Allocate a new buffer and fill it with a simple two-oscillator algorithm. The sound is over-amplified
// (distorted), clamped to the 16-bit range, and finally lowpass-filtered according to the coefficient
var newData = new short[numSamples];
for (int i = 0; i < numSamples; ++i)
{
osc1 = osc1 + 1.0f % 360.0f;
osc2 = osc2 + 1.002f % 360.0f;
float newValue = MathHelper.Clamp((float)((Math.Sin(osc1) + Math.Sin(osc2)) * 100000.0f), -32767.0f, 32767.0f);
accumulator = MathHelper.Lerp(accumulator, newValue, filter);
newData[i] = (short)accumulator;
}
// Queue buffer to the stream for playback
soundStream.AddData(newData, 0, newData.Length);
}
// https://github.com/microsoft/MixedRealityCompanionKit/blob/master/LegacySpectatorView/Samples/SharedHolograms/Assets/HoloToolkit/Utilities/Scripts/TextToSpeech.cs
private async Task <BufferedSoundStream> SpeechStreamToSoundStream(SpeechSynthesisStream inStream)
{
var outStream = new BufferedSoundStream();
uint size = (uint)inStream.Size;
byte[] wavAudio = new byte[size];
using (var inputStream = inStream.GetInputStreamAt(0)) {
inStream.Dispose();
using (var reader = new DataReader(inputStream)) {
await reader.LoadAsync(size);
reader.ReadBytes(wavAudio);
}
}
int channelCount = wavAudio[22];
int frequency = BytesToInt(wavAudio, 24);
outStream.SetFormat((uint)frequency, true, channelCount == 2);
// Get past all the other sub chunks to get to the data subchunk:
int pos = 12; // First subchunk ID from 12 to 16
// Keep iterating until we find the data chunk (i.e. 64 61 74 61 ...... (i.e. 100 97 116 97 in decimal))
while (!(wavAudio[pos] == 100 && wavAudio[pos + 1] == 97 && wavAudio[pos + 2] == 116 && wavAudio[pos + 3] == 97))
{
pos += 4;
int chunkSize = wavAudio[pos] + wavAudio[pos + 1] * 256 + wavAudio[pos + 2] * 65536 + wavAudio[pos + 3] * 16777216;
pos += 4 + chunkSize;
}
pos += 8;
// Pos is now positioned to start of actual sound data.
int sampleCount = (wavAudio.Length - pos) / 2; // 2 bytes per sample (16 bit sound mono)
if (channelCount == 2)
{
sampleCount /= 2;
} // 4 bytes per sample (16 bit stereo)
outStream.AddData(wavAudio, pos);
return(outStream);
}