public static byte[] Encode(short[] pcm, CriAdxParameters config)
{
var c = config;
int sampleCount = pcm.Length + c.Padding;
int samplesPerFrame = (c.FrameSize - 2) * 2;
int frameCount = sampleCount.DivideByRoundUp(samplesPerFrame);
int paddingRemaining = c.Padding;
short[] coefs = c.Type == CriAdxType.Fixed ? Coefs[c.Filter] : CalculateCoefficients(500, c.SampleRate);
var pcmBuffer = new short[samplesPerFrame + 2];
var adpcmBuffer = new byte[c.FrameSize];
var adpcmOut = new byte[frameCount * c.FrameSize];
if (c.Version == 4 && c.Padding == 0)
{
pcmBuffer[0] = pcm[0];
pcmBuffer[1] = pcm[0];
c.History = pcm[0];
}
for (int i = 0; i < frameCount; i++)
{
int samplesToCopy = Math.Min(sampleCount - i * samplesPerFrame, samplesPerFrame);
int pcmBufferStart = 2;
if (paddingRemaining != 0)
{
while (paddingRemaining > 0 && samplesToCopy > 0)
{
paddingRemaining--;
samplesToCopy--;
pcmBufferStart++;
}
if (samplesToCopy == 0)
{
continue;
}
}
Array.Copy(pcm, Math.Max(i * samplesPerFrame - c.Padding, 0), pcmBuffer, pcmBufferStart, samplesToCopy);
Array.Clear(pcmBuffer, pcmBufferStart + samplesToCopy, samplesPerFrame - samplesToCopy - pcmBufferStart + 2);
EncodeFrame(pcmBuffer, adpcmBuffer, coefs, samplesPerFrame, c.Type, c.Version);
if (c.Type == CriAdxType.Fixed)
{
adpcmBuffer[0] |= (byte)(c.Filter << 5);
}
Array.Copy(adpcmBuffer, 0, adpcmOut, i * c.FrameSize, c.FrameSize);
pcmBuffer[0] = pcmBuffer[samplesPerFrame];
pcmBuffer[1] = pcmBuffer[samplesPerFrame + 1];
config.Progress?.ReportAdd(1);
}
return(adpcmOut);
}
public static short[] Decode(byte[] adpcm, int sampleCount, CriAdxParameters config = null)
{
CriAdxParameters c = config ?? new CriAdxParameters();
int samplesPerFrame = (c.FrameSize - 2) * 2;
short[][] coefs = c.Type == CriAdxType.Fixed ? Coefs : new[] { CalculateCoefficients(c.HighpassFrequency, c.SampleRate) };
var pcm = new short[sampleCount];
int hist1 = c.History;
int hist2 = c.History;
int frameCount = sampleCount.DivideByRoundUp(samplesPerFrame);
int currentSample = 0;
int startSample = c.Padding > 0 ? c.Padding % samplesPerFrame : 0;
int inIndex = c.Padding / samplesPerFrame * c.FrameSize;
for (int i = 0; i < frameCount; i++)
{
int filterNum = GetHighNibble(adpcm[inIndex]) >> 1;
short scale = (short)((adpcm[inIndex] << 8 | adpcm[inIndex + 1]) & 0x1FFF);
scale = (short)(c.Type == CriAdxType.Exponential ? 1 << (12 - scale) : scale + 1);
inIndex += 2 + startSample / 2;
int samplesToRead = Math.Min(samplesPerFrame, sampleCount - currentSample);
for (int s = startSample; s < samplesToRead; s++)
{
int sample = s % 2 == 0 ? GetHighNibbleSigned(adpcm[inIndex]) : GetLowNibbleSigned(adpcm[inIndex++]);
if (c.Version == 4)
{
sample = scale * sample + ((hist1 * coefs[filterNum][0] + hist2 * coefs[filterNum][1]) >> 12);
}
else
{
sample = scale * sample + (hist1 * coefs[filterNum][0] >> 12) + (hist2 * coefs[filterNum][1] >> 12);
}
short finalSample = Clamp16(sample);
hist2 = hist1;
hist1 = finalSample;
pcm[currentSample++] = finalSample;
}
startSample = 0;
}
return(pcm);
}
