audioutilities.cpp

Go to the documentation of this file.

/* SPDX-License-Identifier: MIT */
#include "common.h"
#include "audioutilities.h"
#include <math.h>
 
#ifndef M_PI
#define M_PI (3.14159265358979323846)
#endif
 
uint32_t AJA_GenerateAudioTone (uint32_t*   audioBuffer,
                                uint32_t    numSamples,
                                uint32_t    numChannels,
                                uint32_t    numBits,
                                uint32_t&   cycleSample,
                                double      sampleRate,
                                double*     amplitude,
                                double*     frequency,
                                bool        endianConvert)
{
    double cycleCurrent[AJA_MAX_AUDIO_CHANNELS];
    double cycleLength[AJA_MAX_AUDIO_CHANNELS];
    double scale = (double)((uint32_t)(1<<(numBits-1)));
    scale -= 1.0;
 
    uint32_t sample;
    uint32_t channel;
    for (channel = 0; channel < numChannels; channel++)
    {
        cycleLength[channel] = sampleRate / frequency[channel];
        cycleCurrent[channel] = cycleSample;
    }
 
    for (sample = 0; sample < numSamples; sample++)
    {
        for (channel = 0; channel < numChannels; channel++)
        {
            float nextFloat = (float)(sin(cycleCurrent[channel] / cycleLength[channel] * (M_PI * 2.0)) * amplitude[channel]);
            uint32_t value = static_cast<uint32_t>((nextFloat * scale) + 0.5);
 
            if (endianConvert)
            {
                value = AJA_ENDIAN_SWAP32(value);
            }
            *audioBuffer++ = value;
 
            cycleCurrent[channel] += 1.0;
            if (cycleCurrent[channel] > cycleLength[channel])
            {
                cycleCurrent[channel] -= cycleLength[channel];
            }
        }
        cycleSample++;
    }
 
    return numSamples*4*numChannels;
}