comparison core/RTAudio.cpp @ 12:a6beeba3a648

Initial support for higher matrix sample rates by reducing the number of channels. Input not tested yet, and not all examples updated to new format.

 // initAudio() prepares the infrastructure for running PRU-based real-time
 // audio, but does not actually start the calculations.
 // periodSize indicates the number of _sensor_ frames per period: the audio period size
 // is twice this value. In total, the audio latency in frames will be 4*periodSize,
 // plus any latency inherent in the ADCs and DACs themselves.
-// useMatrix indicates whether to use the ADC and DAC or just the audio codec.
+// useMatrix indicates whether to enable the ADC and DAC or just use the audio codec.
+// numMatrixChannels indicates how many ADC and DAC channels to use.
 // userData is an opaque pointer which will be passed through to the initialise_render()
 // function for application-specific use
 //
 // Returns 0 on success.
 

 				cout << "Couldn't set value on amplifier mute pin\n";
 			return -1;
 		}
 	}
 
+	// Limit the matrix channels to sane values
+	if(settings->numMatrixChannels >= 8)
+		settings->numMatrixChannels = 8;
+	else if(settings->numMatrixChannels >= 4)
+		settings->numMatrixChannels = 4;
+	else
+		settings->numMatrixChannels = 2;
+
+	// Sanity check the combination of channels and period size
+	if(settings->numMatrixChannels <= 4 && settings->periodSize < 2) {
+		cout << "Error: " << settings->numMatrixChannels << " channels and period size of " << settings->periodSize << " not supported.\n";
+		return 1;
+	}
+	if(settings->numMatrixChannels <= 2 && settings->periodSize < 4) {
+		cout << "Error: " << settings->numMatrixChannels << " channels and period size of " << settings->periodSize << " not supported.\n";
+		return 1;
+	}
+
 	// Use PRU for audio
 	gPRU = new PRU();
 	gAudioCodec = new I2c_Codec();
 
 	if(gPRU->prepareGPIO(settings->useMatrix, 1, 1)) {
 		cout << "Error: unable to prepare GPIO for PRU audio\n";
 		return 1;
 	}
-	if(gPRU->initialise(0, settings->periodSize, true)) {
+	if(gPRU->initialise(0, settings->periodSize, settings->numMatrixChannels, true)) {
 		cout << "Error: unable to initialise PRU\n";
 		return 1;
 	}
 	if(gAudioCodec->initI2C_RW(2, settings->codecI2CAddress, -1)) {
 		cout << "Unable to open codec I2C\n";

 	// Set default volume levels
 	BeagleRT_setDACLevel(settings->dacLevel);
 	BeagleRT_setADCLevel(settings->adcLevel);
 	BeagleRT_setHeadphoneLevel(settings->headphoneLevel);
 
-	if(!initialise_render(2, settings->useMatrix ? settings->periodSize : 0, settings->periodSize * 2, 22050.0, 44100.0, userData)) {
+	// Initialise the rendering environment: pass the number of audio and matrix
+	// channels, the period size for matrix and audio, and the sample rates
+
+	int audioPeriodSize = settings->periodSize * 2;
+	float audioSampleRate = 44100.0;
+	float matrixSampleRate = 22050.0;
+	if(settings->useMatrix) {
+		audioPeriodSize = settings->periodSize * settings->numMatrixChannels / 4;
+		matrixSampleRate = audioSampleRate * 4.0 / (float)settings->numMatrixChannels;
+	}
+
+	if(!initialise_render(settings->useMatrix ? settings->numMatrixChannels : 0, /* matrix channels */
+						  2, /* audio channels */
+				          settings->useMatrix ? settings->periodSize : 0, /* matrix period size */
+				          audioPeriodSize,
+				          matrixSampleRate, audioSampleRate,
+				          userData)) {
 		cout << "Couldn't initialise audio rendering\n";
 		return 1;
 	}
 
 	return 0;