/Users/richardeakin/projects/libsms/trunk/src/synthesis.c File Reference

main synthesis routines More...

#include "sms.h"

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Functions
static void	SineSynthIFFT (SMS_Data *pSmsData, SMS_SynthParams *pSynthParams)
	synthesis of one frame of the deterministic component using the IFFT
void	sms_deterministic (SMS_Data *pSmsData, SMS_SynthParams *pSynthParams)
	synthesis of one frame of the deterministic component using the IFFT
static int	StocSynthApprox (SMS_Data *pSmsData, SMS_SynthParams *pSynthParams)
	synthesis of one frame of the stochastic component by apprimating phases
int	sms_stochastic (SMS_Data *pSmsData, SMS_SynthParams *pSynthParams)
	synthesis of one frame of the residual component, modeled as stochastic, by approximating phases
void	sms_synthesize (SMS_Data *pSmsData, sfloat *pFSynthesis, SMS_SynthParams *pSynthParams)
	synthesizes one frame of SMS data

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Detailed Description

main synthesis routines

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Function Documentation

static void SineSynthIFFT	(	SMS_Data *	pSmsData,
		SMS_SynthParams *	pSynthParams
	)			[static]

synthesis of one frame of the deterministic component using the IFFT

Parameters:

	pSmsData	pointer to SMS data structure frame
	pSynthParams	pointer to structure of synthesis parameters

References INV_TWO_PI, SMS_SynthParams::iSamplingRate, SMS_Data::nTracks, SMS_SynthParams::pFDetWindow, SMS_Data::pFSinAmp, SMS_Data::pFSinFreq, SMS_Data::pFSinPha, PI_2, SMS_SynthParams::prevFrame, SMS_SynthParams::pSpectra, SMS_SynthParams::pSynthBuff, sfloat, SMS_SynthParams::sizeHop, sms_ifft(), sms_random(), sms_sinc(), sms_sine(), and TWO_PI.

Referenced by sms_synthesize().

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void sms_deterministic	(	SMS_Data *	pSmsData,
		SMS_SynthParams *	pSynthParams
	)

synthesis of one frame of the deterministic component using the IFFT

I made this function trying to pull the ifft out of the SineSynthIFFT that part of the code is in the main sms_synthesize function below Next would be sms_stochastic, so they could be summed and synthesized with only one fft, but the problem is that it needs to be 'pre-inverse-windowed' before the stochastic can be summed.

Parameters:

	pSmsData	pointer to SMS data structure frame
	pSynthParams	pointer to structure of synthesis parameters

References INV_TWO_PI, SMS_SynthParams::iSamplingRate, SMS_Data::nTracks, SMS_Data::pFSinAmp, SMS_Data::pFSinFreq, SMS_Data::pFSinPha, PI_2, SMS_SynthParams::prevFrame, SMS_SynthParams::pSpectra, sfloat, SMS_SynthParams::sizeHop, sms_random(), sms_sinc(), sms_sine(), and TWO_PI.

Referenced by sms_synthesize().

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int sms_stochastic	(	SMS_Data *	pSmsData,
		SMS_SynthParams *	pSynthParams
	)

synthesis of one frame of the residual component, modeled as stochastic, by approximating phases

computes a linearly interpolated spectral envelope to fit the correct number of output audio samples. Phases are generated randomly.

Todo:

needs to be pre-windowed to match the windowing effect of the deterministic, so when they are summed then they can be ifft'ed and overlap-added properly

Parameters:

	pSmsData	pointer to the current SMS frame
	pSynthParams	pointer to a strucure of synthesis parameters

Returns:

Todo:

why is it also multiplied by 2? Why aren't the coeffecients just stored with gain already multiplied?

References SMS_SynthParams::iOriginalSRate, SMS_SynthParams::iSamplingRate, SMS_Data::nCoeff, SMS_Data::pFStocCoeff, SMS_Data::pFStocGain, SMS_SynthParams::pMagBuff, SMS_SynthParams::pPhaseBuff, SMS_SynthParams::pSpectra, SMS_SynthParams::sizeHop, sms_PolarToRect(), sms_random(), sms_spectralApprox(), and TWO_PI.

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void sms_synthesize	(	SMS_Data *	pSmsData,
		sfloat *	pFSynthesis,
		SMS_SynthParams *	pSynthParams
	)

synthesizes one frame of SMS data

Parameters:

	pSmsData	input SMS data
	pFSynthesis	output sound buffer
	pSynthParams	synthesis parameters

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Todo:

use a comb filter of harmonics to better combine the signal here

References SMS_SynthParams::iDetSynthType, SMS_SynthParams::iSamplingRate, SMS_SynthParams::iStochasticType, SMS_SynthParams::iSynthesisType, SMS_SynthParams::pFDetWindow, SMS_SynthParams::prevFrame, SMS_SynthParams::pSpectra, SMS_SynthParams::pSynthBuff, sfloat, SineSynthIFFT(), SMS_SynthParams::sizeHop, sms_deEmphasis(), SMS_DET_IFFT, sms_deterministic(), sms_ifft(), sms_sineSynthFrame(), SMS_STOC_IFFT, SMS_STYPE_ALL, SMS_STYPE_DET, and StocSynthApprox().

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static int StocSynthApprox	(	SMS_Data *	pSmsData,
		SMS_SynthParams *	pSynthParams
	)			[static]

synthesis of one frame of the stochastic component by apprimating phases

computes a linearly interpolated spectral envelope to fit the correct number of output audio samples. Phases are generated randomly.

Parameters:

	pSmsData	pointer to the current SMS frame
	pSynthParams	pointer to a strucure of synthesis parameters

Returns:

Todo:

cleanup returns and various constant multipliers. check that approximation is ok

References SMS_SynthParams::iOriginalSRate, SMS_SynthParams::iSamplingRate, SMS_Data::nCoeff, SMS_Data::pFStocCoeff, SMS_Data::pFStocGain, SMS_SynthParams::pFStocWindow, SMS_SynthParams::pMagBuff, SMS_SynthParams::pPhaseBuff, SMS_SynthParams::pSynthBuff, SMS_SynthParams::sizeHop, sms_invQuickSpectrumW(), sms_random(), sms_spectralApprox(), and TWO_PI.

Referenced by sms_synthesize().

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