private static AudioFormat FromAdx(CriAdxType codec)
{
switch (codec)
{
case CriAdxType.Fixed:
return(AudioFormat.CriAdxFixed);
case CriAdxType.Linear:
return(AudioFormat.CriAdx);
case CriAdxType.Exponential:
return(AudioFormat.CriAdxExp);
default:
throw new ArgumentOutOfRangeException(nameof(codec), codec, null);
}
}
public static void EncodeFrame(short[] pcm, byte[] adpcmOut, short[] coefs, int samplesPerFrame, CriAdxType type, int version)
{
int maxDistance = 0;
int[] adpcm = new int[samplesPerFrame];
for (int i = 0; i < samplesPerFrame; i++)
{
int predictedSample = (pcm[i + 1] * coefs[0] >> 12) + (pcm[i] * coefs[1] >> 12);
int distance = pcm[i + 2] - predictedSample;
distance = Math.Abs((int)Clamp16(distance));
if (distance > maxDistance)
{
maxDistance = distance;
}
}
int scale = CalculateScale(maxDistance, out double gain, out int scaleOut, type == CriAdxType.Exponential);
for (int i = 0; i < samplesPerFrame; i++)
{
int predictedSample = (pcm[i + 1] * coefs[0] >> 12) + (pcm[i] * coefs[1] >> 12);
int rawDistance = pcm[i + 2] - predictedSample;
int scaledDistance = Clamp16((int)(rawDistance * gain));
int adpcmSample = ScaleShortToNibble(scaledDistance);
adpcm[i] = adpcmSample;
short decodedDistance = Clamp16(scale * adpcmSample);
if (version == 4)
{
predictedSample = (pcm[i + 1] * coefs[0] + pcm[i] * coefs[1]) >> 12;
}
int decodedSample = decodedDistance + predictedSample;
pcm[i + 2] = Clamp16(decodedSample);
}
adpcmOut[0] = (byte)((scaleOut >> 8) & 0x1f);
adpcmOut[1] = (byte)scaleOut;
for (int i = 0; i < samplesPerFrame / 2; i++)
{
adpcmOut[i + 2] = CombineNibbles(adpcm[i * 2], adpcm[i * 2 + 1]);
}
}
public CriAdxFormatBuilder WithEncodingType(CriAdxType type)
{
Type = type;
return(this);
}
