Multichannel

panda

Hello all,

i am really a newbie on bela.
i would like to simulate a 440 Hz tone of the left side of my headphone and on the right side the 660 Hz tone. So i have at the end of my script two separate audioWrite() commends. But when i play the script i can only listen on one side of my headphone. it will be greate when you can help me. Thanks in advance. In the following you can find my script. And an additional question is, how can i control the individual input and audio channels exactly?

#include <Bela.h>
#include <libraries/Scope/Scope.h>
#include <cmath>

float gFrequency = 660.0;	// Frequency of the sine wave in 440 Hz
float gAmplitude = 0.6;		// Amplitude of the sine wave (1.0 is maximum)
float gFrequencyr = 100.0;   // Frequency of the sine wave in 660 Hz

float gPhase =0;			// Keep track of the phase 
float gPhaser =0;			// Keep track of the phase 
float gInverseSampleRate;

// setup() runs once at the beginning of your program
//bool setup(BelaContext *context, void *userData)
//{
//    return true;
//}



// instantiate the scope
Scope scope;

bool setup(BelaContext *context, void *userData)
{
	// tell the scope how many channels and the sample rate
	scope.setup(2, context->audioSampleRate);
	//gPhase = 0;
	gInverseSampleRate = 1.0f/context->audioSampleRate;
	return true;
}

// render() is called repeatedly by Bela for each audio block
void render(BelaContext *context, void *userData)
{
   	// This for() loop goes through all the samples in the block
	for (unsigned int n = 0; n < context->audioFrames; n++) {
		// Increment the phase by one samples worth at the frequency
		gPhase += 2.0 * M_PI * gFrequency / context->audioSampleRate;
		if(gPhase >= 2.0 * M_PI)
		   gPhase -= 2.0 * M_PI;
		   
		gPhaser += 2.0 * M_PI * gFrequencyr / context->audioSampleRate;
		if(gPhaser >= 2.0 * M_PI)
		   gPhaser -= 2.0 * M_PI;
	
	    // TODO: Calculate a sample of the sine wave
	    //       Start by copying the calculation from the 'sine-generator' project
	//	float out = gAmplitude * sin(2.0 * M_PI * gTotalSamples * gFrequency / context->audioSampleRate);
		float out = gAmplitude * sin(gPhase);
		float outr = gAmplitude * sin(gPhaser);
		
		scope.log(out, outr);
		
		// This part is done for you: store the sample in the
		// audio output buffer
		
		//for(unsigned int channel = 0; channel < context->audioOutChannels; channel++) {
		//    audioWrite(context, n, channel, out);
		
		audioWrite(context, n, 1, outr); 
	        audioWrite(context, n, 0, out);
		
    }
}

// cleanup() runs once at the end of the program
void cleanup(BelaContext *context, void *userData)
{
	// Nothing to do here
}

giuliomoro

please include your code within triple backticks (```). I amended your post accordingly.

panda i would like to simulate a 440 Hz tone of the left side of my headphone and on the right side the 660 Hz tone.

this project is sending a 660Hz sinewave to the left channel and a 100Hz sinewave to the right channel and it's working OK as such.

panda ds. But when i play the script i can only listen on one side of my headphone.

It works for me. It's possible that your headphones or the audio adapter cables are damaged. It's also possible that the 100 Hz sinewave is too low for your headphones to reproduce it properly (any decent headphone/headset should do it) ... It's also possible if you are using a headset/earphones with a TRRS jack (i.e.: any that would have a built in microphone) that it may not work OK with the TRS stereo socket we provide.

panda how can i control the individual input and audio channels exactly?

you can access audio inputs with audioRead(context, frame, channel);. See some of the examples such as Fundamentals/passthrough and several of those in Audio

panda

Thank you for your answer. However, unfortunately it still does not work. I am using a CTAG Starter Beast (without bela). I think it has to do with the PIN assignment. The headphones do not have an integrated microphone, i.e. a TRS connection. I have connected it to the audio out 0-1. Do I need a separate Bela for my channel splitting problem?

giuliomoro e some of the examples such as Fundamentals/passthrou

giuliomoro

What channel are you hearing the 660Hz through? Is that right or left? Can you try and listen to the other channels and see if you can "find" the missing tone? May it be the that the channels are off by 1?

panda

Only on the left channel i can listen the 660 Hz tone. When i switch my output commends to

audioWrite(context, n, 1, out); 
audioWrite(context, n, 0, outr);

than i listen on my left channel the 100 Hz tone. But i never can listen any tone on my right channel.

giuliomoro

Can you try and listen to the other channels?

panda

I have tried all channels with the following result. When I put in my first output commend "1"

audioWrite(context, n, 1, outr); 
audioWrite(context, n, 7, out);

than i only listen the 660 Hz on the left speaker of my headphone tone. But when i switch the channel to "0"

audioWrite(context, n, 0, outr); 
audioWrite(context, n, 7, out);

than I listen the 660 Hz and 100 Hz both together on the left speaker. But still nothing on the right speaker.
Maybe it depands on the hardware. In the Attachment yiu can see the CTAG Beast with the connected headphones

alt text

giuliomoro

The breakouts where the molex connectors are is upside down

panda

Ah great. Now it´s working fine. Thank you very much.