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Better FIR Filter implementation, correct sample collecting

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This commit is contained in:
Geoffrey Merck 2020-02-04 22:21:57 +01:00
parent 4ba6a77ecc
commit ee1b97a165
1 changed files with 15 additions and 8 deletions
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23
ambed/cfirfilter.cpp
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@ -34,7 +34,7 @@ CFIRFilter::CFIRFilter(const float* taps, int tapsLength)
::memcpy(m_taps, taps, tapsLength * sizeof(float)); ::memcpy(m_taps, taps, tapsLength * sizeof(float));
::memset(m_buffer, 0, tapsLength * sizeof(float)); ::memset(m_buffer, 0, tapsLength * sizeof(float));
m_currentBufferPosition = m_tapsLength -1; m_currentBufferPosition = 0;
} }
CFIRFilter::~CFIRFilter() CFIRFilter::~CFIRFilter()
@ -45,23 +45,30 @@ CFIRFilter::~CFIRFilter()
inline float CFIRFilter::Process(float inputSample) inline float CFIRFilter::Process(float inputSample)
{ {
// Buffer latest sample float output = 0.0f;
int iTaps = 0;
// Buffer latest sample into delay line
m_buffer[m_currentBufferPosition] = inputSample; m_buffer[m_currentBufferPosition] = inputSample;
float outputSample = 0.0f; for(int i = m_currentBufferPosition; i >= 0; i--)
for(int i = 0; i < m_tapsLength; i++)
{ {
outputSample += m_taps[i] * m_buffer[(m_currentBufferPosition + i) % m_tapsLength]; output += m_taps[iTaps++] * m_buffer[i];
} }
m_currentBufferPosition = MAX(0, m_currentBufferPosition - 1); for(int i = m_tapsLength - 1; i > m_currentBufferPosition; i--)
{
output += m_taps[iTaps++] * m_buffer[i];
}
return outputSample; m_currentBufferPosition = (m_currentBufferPosition + 1) % m_tapsLength;
return output;
} }
void CFIRFilter::Process(uint8* voice, int length) void CFIRFilter::Process(uint8* voice, int length)
{ {
for(int i = 0; i < length; i++) for(int i = 0; i < length; i+=2)
{ {
//Get the sample //Get the sample
float input = (float)(short)MAKEWORD(voice[i+1], voice[i]); float input = (float)(short)MAKEWORD(voice[i+1], voice[i]);