public void Decode(Frame fr, StreamInfo streamInfo, BitReader str, int bitsPerSample, int channelNum)
{
byte header;
this.channelNum = channelNum;
header = (byte) str.ReadByte();
if ((header & 0x80) != 0)
{
//TODO: handle corrupt bit
return;
}
byte subtype = (byte)((header & 0x7E) >> 1);
if (subtype == 0)
{
type = SubframeType.Constant;
}
else if (subtype == 1)
{
type = SubframeType.Verbatim;
}
else if ((subtype >= 8)&&(subtype<=12))
{
type = SubframeType.Fixed;
order = (uint)(subtype & 0x7);
}
else if ((subtype & 0x20) != 0)
{
type = SubframeType.LPC;
order = (uint)(subtype & 0x1F) + 1;
}
else
{
//TODO: handle reserved frame types
return;
}
wastedBits = 0;
if ((header & 0x1) != 0)
{
int buff = 0;
do
{
str.ReadBit(ref buff);
wastedBits++;
} while (buff == 0);
}
numSamples = 0;
numResiduals = 0;
switch (type)
{
case SubframeType.Constant:
ProcessConstant(fr, str, bitsPerSample);
break;
case SubframeType.Verbatim:
ProcessVerbatim(fr, str, bitsPerSample);
break;
case SubframeType.Fixed:
ProcessFixed(fr, str, bitsPerSample);
break;
case SubframeType.LPC:
ProcessLPC(fr, str, bitsPerSample);
break;
}
}
private void MultiplexFrame(Frame fr, MultiplexedFrame mfr, int numSamples, ulong fromSample)
{
long startBuffer = mfr.BufferUsed;
for (int chan = 0; chan < mfr.NumChannels; chan++)
{
mfr.BufferUsed = startBuffer;
for (int sampleNum = 0; sampleNum < numSamples; sampleNum++)
{
int sampleToMultiplex = fr.output[chan, sampleNum+(int)(fromSample-fr.FirstSampleNumber)];
int bitsLeft = streamInfo.BitsPerSample;
int bitsRead = 0;
while (bitsLeft > 0)
{
int bitsToAdd = 0;
if (bitsLeft > 8 - mfr.BitOffset)
{
bitsToAdd = 8 - mfr.BitOffset;
}
else
{
bitsToAdd = bitsLeft;
}
mfr.Buffer[chan, mfr.BufferUsed] |= //(byte)(((byte)(sampleToMultiplex << bitsRead)) >> (8 - bitsToAdd));
(byte)(sampleToMultiplex >> streamInfo.BitsPerSample - bitsRead - bitsToAdd);
bitsRead += bitsToAdd;
mfr.BitOffset += bitsToAdd;
bitsLeft -= bitsToAdd;
if (mfr.BitOffset == 8)
{
mfr.BufferUsed++;
mfr.BitOffset = 0;
}
}
}
}
mfr.SampleCount += (ulong)numSamples;
}
private void ReadRice(Frame fr, BitReader str)
{
int riceType = str.ReadBits(2);
int riceParam = 0;
int riceParamLen = 0;
int partOrder = 0;
int partSize = 0;
switch (riceType)
{
case 0:
riceParamLen = 4;
break;
case 1:
riceParamLen = 5;
break;
default:
//TODO: exception, handle reserved rice types
return;
}
partOrder = str.ReadBits(4);
int numPartitions = 1 << partOrder;
int fullMask = (1 << (riceParamLen + 1)) - 1;
for (int i = 0; i < numPartitions; i++)
{
riceParam = str.ReadBits(riceParamLen);
if (partOrder == 0)
{
partSize = (int) ((int)fr.Blocksize - order);
}
else if (i == 0)
{
partSize = (int)(Math.Floor(fr.Blocksize / (double)(1 << partOrder))) - (int)(order);
}
else
{
partSize = (int)(Math.Floor(fr.Blocksize / (double)(1 << partOrder)));
}
if (riceParam == fullMask)
{
//unencoded
int residualLen = str.ReadBits(5);
for (int j = 0; j < partSize; j++)
{
residuals[numResiduals++] = str.ReadBits(residualLen);
}
}
else
{
uint uRiceParam = (uint)riceParam;
for (int j = 0; j < partSize; j++)
{
residuals[numResiduals++] = str.ReadRice(riceParam);
}
}
}
}
private void ProcessVerbatim(Frame fr, BitReader str, int bitsPerSample)
{
for (ulong i = 0; i < fr.Blocksize; i++)
{
fr.output[channelNum, (int)i] = TruncateTC(str.ReadBits(bitsPerSample),bitsPerSample);
}
}
private void ProcessLPC(Frame fr, BitReader str, int bitsPerSample)
{
for (int i = 0; i < order; i++)
{
samples[numSamples] = TruncateTC(str.ReadBits(bitsPerSample),bitsPerSample);
fr.output[channelNum, (int)numSamples] = samples[numSamples];
numSamples++;
}
int precision = str.ReadBits(4) + 1;
int shift = TruncateTC(str.ReadBits(5),5);
int[] coefficients = new int[32]; //there cannot be more than 32 LPC coefficients
for (int i = 0; i < order; i++)
{
coefficients[i] = TruncateTC(str.ReadBits(precision),precision);
}
ReadRice(fr, str);
//TODO: restore signal, bunch of checks
for (int i = 0; i < numResiduals; i++)
{
long signal = 0;
for (int j = 0; j < order; j++)
{
signal += (long)coefficients[j] * (long)fr.output[channelNum, numSamples - j - 1];
}
fr.output[channelNum, numSamples++] = (int)((long)residuals[i] + (signal >> shift));
if (numSamples == 264)
{
//breakpoint
}
}
}
private void ProcessFixed(Frame fr, BitReader str, int bitsPerSample)
{
for (int i = 0; i < order; i++)
{
samples[numSamples] = TruncateTC(str.ReadBits(bitsPerSample),bitsPerSample);
fr.output[channelNum, (int)numSamples] = samples[numSamples];
numSamples++;
}
ReadRice(fr, str);
//TODO: restore signal, bunch of checks
for (int i = 0; i < numResiduals; i++)
{
switch (order)
{
case 0:
//x[i] = residual[i]
fr.output[channelNum, (int)numSamples++] = residuals[i];
break;
case 1:
//x[i] = residual[i] + x[i-1]
fr.output[channelNum, (int)numSamples] = (residuals[i] + fr.output[channelNum, (int)numSamples - 1]);
numSamples++;
break;
case 2:
//x[i] = residual[i] + 2x[i-1] - x[i-2]
fr.output[channelNum, (int)numSamples] = (residuals[i] + 2 * fr.output[channelNum, (int)numSamples - 1] - fr.output[channelNum, (int)numSamples - 2]);
numSamples++;
break;
case 3:
//x[i] = residual[i] + 3x[i-1] - 3x[i-2] + x[i-3]
fr.output[channelNum, (int)numSamples] = (residuals[i] + 3 * fr.output[channelNum, (int)numSamples - 1] - 3 * fr.output[channelNum, (int)numSamples - 2] + fr.output[channelNum, (int)numSamples - 3]);
numSamples++;
break;
case 4:
//x[i] = residual[i] + 4x[i-1] - 6x[i-2] + 4x[i-3] - x[i-4]
fr.output[channelNum, (int)numSamples] = (residuals[i] + 4 * fr.output[channelNum, (int)numSamples - 1] - 6 * fr.output[channelNum, (int)numSamples - 2] + 4 * fr.output[channelNum, (int)numSamples - 3] - fr.output[channelNum, (int)numSamples - 4]);
numSamples++;
break;
}
}
}
private void ProcessConstant(Frame fr, BitReader str, int bitsPerSample)
{
int value = 0;
value = TruncateTC(str.ReadBits(bitsPerSample),bitsPerSample);
for (ulong i = 0; i < fr.Blocksize; i++)
{
fr.output[channelNum, (int)i] = value;
}
}
