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Improve performance for wav read sample #117

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Improve performance for wav read sample #117

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08eae12
improve performance of Wav.ReadCallback
hoxily Aug 4, 2021
5b7a0f3
ignore .vs directory
hoxily Aug 4, 2021
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1 change: 1 addition & 0 deletions .gitignore
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Original file line number Diff line number Diff line change
Expand Up @@ -38,3 +38,4 @@ UpgradeLog*
*.mpq

.idea
/.vs
21 changes: 17 additions & 4 deletions Assets/Scripts/Diablerie/Engine/IO/Wav.cs
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Expand Up @@ -59,10 +59,10 @@ private void ReadCallback(float[] data)
var chunk = _chunks[_chunkIndex];
int samplesAvailable = chunk.sampleCount + chunk.sampleOffset - _sampleIndex;
int samplesToRead = Math.Min(data.Length - i, samplesAvailable);
for (int j = 0; j < samplesToRead; ++j, ++i)
{
data[i] = ReadSample(_reader);
}
// When smaplesToRead reaches 35000 or above, reading a float a time will consumes about 3 seconds, which stalls the whole game.
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// Use bunch read to spped up.
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ReadSample(_reader, data, i, samplesToRead);
i += samplesToRead;
_sampleIndex += samplesToRead;
if (i < data.Length)
++_chunkIndex;
Expand Down Expand Up @@ -130,6 +130,19 @@ private static float ReadSample(BinaryReader reader)
return BytesToFloat(byte1, byte2);
}

private static void ReadSample(BinaryReader reader, float[] sampleBuffer, int startIndex, int sampleCount)
{
byte[] buffer = new byte[sampleCount * 2];
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Could we reuse the buffer array somehow to avoid frequent allocations and excessive garbage collector work?

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How about create a reuseable fixed length byte[] buffer when new Wav(), and transfer this buffer to ReadSample method. Works like a Stream's internal buffer.

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Sounds good

reader.BaseStream.Read(buffer, 0, buffer.Length);
for (int i = 0; i < buffer.Length; i += 2)
{
byte byte1 = buffer[i];
byte byte2 = buffer[i + 1];
short s = (short)((byte2 << 8) | byte1);
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Let's reuse BytesToFloat here to avoid the transformation logic duplication, please.

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Maybe we shall test the performances of the following two solutions:

  1. reuse BytesToFloat method;
  2. directly insert body of BytesToFloat;

After performance test, choose the fastest one.

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Do you expect significant function call overhead? In this case, I like your idea to test both of them. If the inlined version works faster I think it's a reasonable cost to duplicate the code.

sampleBuffer[startIndex + i / 2] = s / 32768.0F;
}
}

private static float BytesToFloat(byte byte1, byte byte2)
{
// convert two bytes to one short (little endian)
Expand Down