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Added EncodeADPCM, optimised DecodeADPCM

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dexy 2020-02-07 22:22:40 +11:00
parent 84419cc2b7
commit 6c1afda9a2
1 changed files with 93 additions and 14 deletions
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107
CodeWalker.Core/GameFiles/FileTypes/AwcFile.cs
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@ -1048,23 +1048,18 @@ namespace CodeWalker.GameFiles
public static byte[] DecodeADPCM(byte[] data, int sampleCount)
{
byte[] dataPCM = new byte[data.Length * 4];
int predictor = 0, step_index = 0, step = 0;
int predictor = 0, stepIndex = 0;
int readingOffset = 0, writingOffset = 0, bytesInBlock = 0;
void parseNibble(byte nibble)
{
step_index = clip(step_index + ima_index_table[nibble], 0, 88);
int diff = step >> 3;
if ((nibble & 4) > 0) diff += step;
if ((nibble & 2) > 0) diff += step >> 1;
if ((nibble & 1) > 0) diff += step >> 2;
if ((nibble & 8) > 0) predictor -= diff;
else predictor += diff;
step = ima_step_table[step_index];
var step = ima_step_table[stepIndex];
int diff = ((((nibble & 7) << 1) + 1) * step) >> 3;
if ((nibble & 8) != 0) diff = -diff;
predictor = predictor + diff;
stepIndex = clip(stepIndex + ima_index_table[nibble], 0, 88);
int samplePCM = clip(predictor, -32768, 32767);
dataPCM[writingOffset] = (byte)(samplePCM & 0xFF);
dataPCM[writingOffset + 1] = (byte)((samplePCM >> 8) & 0xFF);
writingOffset += 2;
@ -1074,9 +1069,8 @@ namespace CodeWalker.GameFiles
{
if (bytesInBlock == 0)
{
step_index = clip(data[readingOffset], 0, 88);
stepIndex = clip(data[readingOffset], 0, 88);
predictor = BitConverter.ToInt16(data, readingOffset + 2);
step = ima_step_table[step_index];
bytesInBlock = 2044;
readingOffset += 4;
}
@ -1093,6 +1087,91 @@ namespace CodeWalker.GameFiles
return dataPCM;
}
public static byte[] EncodeADPCM(byte[] data, int sampleCount)
{
byte[] dataPCM = new byte[data.Length / 4];
int predictor = 0, stepIndex = 0;
int readingOffset = 0, writingOffset = 0, bytesInBlock = 0;
short readSample()
{
var s = BitConverter.ToInt16(data, readingOffset);
readingOffset += 2;
return s;
}
void writeInt16(short v)
{
var ba = BitConverter.GetBytes(v);
dataPCM[writingOffset++] = ba[0];
dataPCM[writingOffset++] = ba[1];
}
byte encodeNibble(int pcm16)
{
int delta = pcm16 - predictor;
uint value = 0;
if (delta < 0)
{
value = 8;
delta = -delta;
}
var step = ima_step_table[stepIndex];
var diff = step >> 3;
if (delta > step)
{
value |= 4;
delta -= step;
diff += step;
}
step >>= 1;
if (delta > step)
{
value |= 2;
delta -= step;
diff += step;
}
step >>= 1;
if (delta > step)
{
value |= 1;
diff += step;
}
predictor += (((value & 8) != 0) ? -diff : diff);
predictor = clip(predictor, short.MinValue, short.MaxValue);
stepIndex += ima_index_table[value & 7];
stepIndex = clip(stepIndex, 0, 88);
return (byte)value;
}
while ((writingOffset < dataPCM.Length) && (sampleCount > 0))
{
if (bytesInBlock == 0)
{
writeInt16((short)stepIndex);
writeInt16((short)predictor);
bytesInBlock = 2044;
}
else
{
var s0 = readSample();
var s1 = readSample();
var b0 = encodeNibble(s0);
var b1 = encodeNibble(s1);
var b = (b0 & 0x0F) + ((b1 & 0x0F) << 4);
dataPCM[writingOffset++] = (byte)b;
bytesInBlock--;
sampleCount -= 2;
}
}
return dataPCM;
}
}