private FlacMethod FindBestLpcMethod(int[] channelSamples, int bitsPerSample, FlacEncodingPolicy policy)
{
if (!policy.LpcOrder.HasValue)
{
return(null);
}
int minLpcOrder = policy.LpcOrder.Value.MinValue;
int maxLpcOrder = Math.Min(policy.LpcOrder.Value.MaxValue,
channelSamples.Length - 1);
double[] r = new double[maxLpcOrder + 1];
parallel.For(0, r.Length, i =>
{
double sum = 0;
for (int j = 0, q = channelSamples.Length - i; j < i; j++, q++)
{
sum += (double)channelSamples[j] * channelSamples[q];
}
for (int j = i, q = 0; j < channelSamples.Length; j++, q++)
{
sum += (double)channelSamples[j] * channelSamples[q];
}
r[i] = sum;
});
FlacMethod[] methods = new FlacMethod[maxLpcOrder];
parallel.For(minLpcOrder, maxLpcOrder + 1, order =>
{
double[] coef = SolveLpc(r, order);
int[] integerCoefficients;
int shift;
int precision;
ConvertLpcCoeficientsToIntegers(coef, out integerCoefficients, out precision, out shift);
IPredictor predictor = PredictorFactory.CreateLpcPredictor(integerCoefficients, shift, ArrayUtils.CutArray(channelSamples, 0, order - 1));
FlacResidualCoefficeints residual = FindBestResidual(channelSamples, order, predictor, policy);
FlacLpcMethodCoefficeints lpcCoefficients = new FlacLpcMethodCoefficeints(
precision, integerCoefficients, shift);
FlacMethod method = new FlacLpcMethod(bitsPerSample, lpcCoefficients, residual);
methods[order - 1] = method;
});
return(FindBestMethod(methods));
}
private FlacMethod FindBestFixedMethod(int[] channelSamples, int bitsPerSample, FlacEncodingPolicy policy)
{
if (!policy.FixedOrder.HasValue)
{
return(null);
}
int minFixedOrder = policy.FixedOrder.Value.MinValue;
int maxFixedOrder = Math.Min(channelSamples.Length - 1,
policy.FixedOrder.Value.MaxValue);
FlacMethod[] methods = new FlacMethod[maxFixedOrder + 1];
parallel.For(minFixedOrder, maxFixedOrder + 1, order =>
{
IPredictor predictor = PredictorFactory.CreateFixedPredictor(order, ArrayUtils.CutArray(channelSamples, 0, order - 1));
FlacResidualCoefficeints residual = FindBestResidual(channelSamples, order, predictor, policy);
FlacMethod method = new FlacFixedMethod(bitsPerSample, order, residual);
methods[order] = method;
});
return(FindBestMethod(methods));
}
protected FlacMethodFirBased(SubframeType subframeType, int estimatedSize, int order, FlacResidualCoefficeints residual)
: base(subframeType, estimatedSize)
{
this.order = order;
this.residual = residual;
}
public FlacLpcMethod(int bitsPerSample, FlacLpcMethodCoefficeints coefficients, FlacResidualCoefficeints residual)
: base(SubframeType.SubframeLpc, coefficients.EstimateStorage(bitsPerSample) + residual.EstimatedSize, coefficients.Coefficients.Length, residual)
{
this.coefficients = coefficients;
}
public FlacFixedMethod(int bitsPerSample, int order, FlacResidualCoefficeints residual)
: base(SubframeType.SubframeFixed, bitsPerSample * order + residual.EstimatedSize, order, residual)
{
}
public FlacLpcMethod(int bitsPerSample, FlacLpcMethodCoefficeints coefficients, FlacResidualCoefficeints residual)
: base(SubframeType.SubframeLpc, coefficients.EstimateStorage(bitsPerSample) + residual.EstimatedSize, coefficients.Coefficients.Length, residual)
{
this.coefficients = coefficients;
}
public FlacFixedMethod(int bitsPerSample, int order, FlacResidualCoefficeints residual)
: base(SubframeType.SubframeFixed, bitsPerSample * order + residual.EstimatedSize, order, residual)
{
}
protected FlacMethodFirBased(SubframeType subframeType, int estimatedSize, int order, FlacResidualCoefficeints residual)
: base(subframeType, estimatedSize)
{
this.order = order;
this.residual = residual;
}
private FlacResidualCoefficeints FindBestResidual(int[] channelSamples, int order, IPredictor predictor, FlacEncodingPolicy policy)
{
int[] residual;
if (order > 0)
{
residual = new int[channelSamples.Length];
int lastSample = channelSamples[order - 1];
for (int i = order; i < residual.Length; i++)
{
int nextSample = channelSamples[i];
residual[i] = nextSample - predictor.Next(lastSample);
lastSample = nextSample;
}
}
else
{
residual = channelSamples;
}
int minRiceOrder = policy.RicePartionOrder.MinValue;
int maxRiceOrder = policy.RicePartionOrder.MaxValue;
List <FlacResidualCoefficeints> rices = new List <FlacResidualCoefficeints>();
int samplesPerPartition = channelSamples.Length >> minRiceOrder;
if (samplesPerPartition << minRiceOrder != channelSamples.Length)
{
minRiceOrder = maxRiceOrder = 0; // reset minRiceOrder to zero;
}
for (int riceOrder = minRiceOrder; riceOrder <= maxRiceOrder; riceOrder++)
{
if (samplesPerPartition <= order)
{
break;
}
int partitionCount = 1 << riceOrder;
int[] parameters = new int[partitionCount];
int totalPartitionDataSize = 0;
int j = order;
for (int i = 0; i < partitionCount; i++)
{
int skipAmount = i == 0 ? order : 0;
int estimatedPartitionSize;
int riceParameter;
FindBestResidual(residual, samplesPerPartition * i + skipAmount, samplesPerPartition - skipAmount,
out estimatedPartitionSize, out riceParameter);
totalPartitionDataSize += estimatedPartitionSize;
parameters[i] = riceParameter;
}
const int NormalPrecision = 4;
const int ExtendedPrecision = 5;
const int MinValueForExtendedParameters = 15;
bool isExtended = false;
for (int i = 0; i < parameters.Length && !isExtended; ++i)
{
isExtended = parameters[i] >= MinValueForExtendedParameters;
}
int totalSize = 4 + totalPartitionDataSize +
partitionCount * (isExtended ? ExtendedPrecision : NormalPrecision);
FlacResidualCoefficeints rice = new FlacResidualCoefficeints();
rice.EstimatedSize = totalSize;
rice.IsExtended = isExtended;
rice.RiceParameters = parameters;
rice.Order = riceOrder;
rices.Add(rice);
if ((samplesPerPartition & 1) != 0)
{
break;
}
samplesPerPartition >>= 1;
}
int bestRicePartition = 0;
for (int i = 1; i < rices.Count; i++)
{
if (rices[bestRicePartition].EstimatedSize > rices[i].EstimatedSize)
{
bestRicePartition = i;
}
}
return(rices[bestRicePartition]);
}
private FlacResidualCoefficeints FindBestResidual(int[] channelSamples, int order, IPredictor predictor, FlacEncodingPolicy policy)
{
int[] residual;
if (order > 0)
{
residual = new int[channelSamples.Length];
int lastSample = channelSamples[order - 1];
for (int i = order; i < residual.Length; i++)
{
int nextSample = channelSamples[i];
residual[i] = nextSample - predictor.Next(lastSample);
lastSample = nextSample;
}
}
else
residual = channelSamples;
int minRiceOrder = policy.RicePartionOrder.MinValue;
int maxRiceOrder = policy.RicePartionOrder.MaxValue;
List<FlacResidualCoefficeints> rices = new List<FlacResidualCoefficeints>();
int samplesPerPartition = channelSamples.Length >> minRiceOrder;
if (samplesPerPartition << minRiceOrder != channelSamples.Length)
{
minRiceOrder = maxRiceOrder = 0; // reset minRiceOrder to zero;
}
for (int riceOrder = minRiceOrder; riceOrder <= maxRiceOrder; riceOrder++)
{
if (samplesPerPartition <= order) break;
int partitionCount = 1 << riceOrder;
int[] parameters = new int[partitionCount];
int totalPartitionDataSize = 0;
int j = order;
for (int i = 0; i < partitionCount; i++)
{
int skipAmount = i == 0 ? order : 0;
int estimatedPartitionSize;
int riceParameter;
FindBestResidual(residual, samplesPerPartition * i + skipAmount, samplesPerPartition - skipAmount,
out estimatedPartitionSize, out riceParameter);
totalPartitionDataSize += estimatedPartitionSize;
parameters[i] = riceParameter;
}
const int NormalPrecision = 4;
const int ExtendedPrecision = 5;
const int MinValueForExtendedParameters = 15;
bool isExtended = Array.Exists(parameters, delegate(int x) {
return x >= MinValueForExtendedParameters;
});
int totalSize = 4 + totalPartitionDataSize +
partitionCount * (isExtended ? ExtendedPrecision : NormalPrecision);
FlacResidualCoefficeints rice = new FlacResidualCoefficeints();
rice.EstimatedSize = totalSize;
rice.IsExtended = isExtended;
rice.RiceParameters = parameters;
rice.Order = riceOrder;
rices.Add(rice);
if ((samplesPerPartition & 1) != 0) break;
samplesPerPartition >>= 1;
}
int bestRicePartition = 0;
for (int i = 1; i < rices.Count; i++)
{
if (rices[bestRicePartition].EstimatedSize > rices[i].EstimatedSize)
bestRicePartition = i;
}
return rices[bestRicePartition];
}
