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Add resampler support for downsampling with variable-input constant-output buffering mode

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This commit is contained in:
Ken Cooke 2016-08-12 11:31:06 -07:00
parent 3355a90e7d
commit d9f12e44dc
2 changed files with 20 additions and 0 deletions
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18
libraries/audio/src/AudioSRC.cpp
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@ -1030,3 +1030,21 @@ int AudioSRC::getMaxInput(int outputFrames) {
return (int)(((int64_t)outputFrames * _step) >> 32);
}
}
// the input frames that will produce exactly outputFrames
int AudioSRC::getExactInput(int outputFrames) {
//
// For upsampling, a correct implementation is more complicated
// because it requires early exit of the multirate filter.
// This is not currently supported.
//
if (_upFactor > _downFactor) {
return -1;
}
if (_step == 0) {
int64_t offset = ((int64_t)_phase * _downFactor) % _upFactor;
return (int)(((int64_t)outputFrames * _downFactor + offset) / _upFactor);
} else {
return (int)(((int64_t)outputFrames * _step + _offset) >> 32);
}
}

2
libraries/audio/src/AudioSRC.h
View file

@ -48,6 +48,8 @@ public:
int getMinInput(int outputFrames);
int getMaxInput(int outputFrames);
int getExactInput(int outputFrames);
private:
float* _polyphaseFilter;
int* _stepTable;