RtAudio - Playing samples from wav file - c++

Question

I am currently trying to learn audio programming. My goal is to open a wav file, extract everything and play the samples with RtAudio.
I made a WaveLoader class which let's me extract the samples and meta data. I used this guide to do that and I checked that everything is correct with 010 editor. Here is a snapshot of 010 editor showing the structure and data.
And this is how i store the raw samples inside WaveLoader class:
data = new short[wave_data.payloadSize]; // - Allocates memory size of chunk size
if (!fread(data, 1, wave_data.payloadSize, sound_file))
{
throw ("Could not read wav data");
}
If i print out each sample I get : 1, -3, 4, -5 ... which seems ok.
The problem is that I am not sure how I can play them. This is what I've done:
/*
* Using PortAudio to play samples
*/
bool Player::Play()
{
ShowDevices();
rt.showWarnings(true);
RtAudio::StreamParameters oParameters; //, iParameters;
oParameters.deviceId = rt.getDefaultOutputDevice();
oParameters.firstChannel = 0;
oParameters.nChannels = mAudio.channels;
//iParameters.deviceId = rt.getDefaultInputDevice();
//iParameters.nChannels = 2;
unsigned int sampleRate = mAudio.sampleRate;
// Use a buffer of 512, we need to feed callback with 512 bytes everytime!
unsigned int nBufferFrames = 512;
RtAudio::StreamOptions options;
options.flags = RTAUDIO_SCHEDULE_REALTIME;
options.flags = RTAUDIO_NONINTERLEAVED;
//&parameters, NULL, RTAUDIO_FLOAT64,sampleRate, &bufferFrames, &mCallback, (void *)&rawData
try {
rt.openStream(&oParameters, NULL, RTAUDIO_SINT16, sampleRate, &nBufferFrames, &mCallback, (void*) &mAudio);
rt.startStream();
}
catch (RtAudioError& e) {
std::cout << e.getMessage() << std::endl;
return false;
}
return true;
}
/*
* RtAudio Callback
*
*/
int mCallback(void * outputBuffer, void * inputBuffer, unsigned int nBufferFrames, double streamTime, RtAudioStreamStatus status, void * userData)
{
unsigned int i = 0;
short *out = static_cast<short*>(outputBuffer);
auto *data = static_cast<Player::AUDIO_DATA*>(userData);
// if i is more than our data size, we are done!
if (i > data->dataSize) return 1;
// First time callback is called data->ptr is 0, this means that the offset is 0
// Second time data->ptr is 1, this means offset = nBufferFrames (512) * 1 = 512
unsigned int offset = nBufferFrames * data->ptr++;
printf("Offset: %i\n", offset);
// First time callback is called offset is 0, we are starting from 0 and looping nBufferFrames (512) times, this gives us 512 bytes
// Second time, the offset is 1, we are starting from 512 bytes and looping to 512 + 512 = 1024
for (i = offset; i < offset + nBufferFrames; ++i)
{
short sample = data->rawData[i]; // Get raw sample from our struct
*out++ = sample; // Pass to output buffer for playback
printf("Current sample value: %i\n", sample); // this is showing 1, -3, 4, -5 check 010 editor
}
printf("Current time: %f\n", streamTime);
return 0;
}
Inside callback function, when I print out sample values I get exactly like 010 editor? Why isnt rtaudio playing them. What is wrong here? Do I need to normalize sample values to between -1 and 1?
Edit:
The wav file I am trying to play:
Chunksize: 16
Format: 1
Channel: 1
SampleRate: 48000
ByteRate: 96000
BlockAlign: 2
BitPerSample: 16
Size of raw samples total: 2217044 bytes

Answer 1

For some reason it works when I pass input parameters to the openStream()
RtAudio::StreamParameters oParameters, iParameters;
oParameters.deviceId = rt.getDefaultOutputDevice();
oParameters.firstChannel = 0;
//oParameters.nChannels = mAudio.channels;
oParameters.nChannels = mAudio.channels;
iParameters.deviceId = rt.getDefaultInputDevice();
iParameters.nChannels = 1;
unsigned int sampleRate = mAudio.sampleRate;
// Use a buffer of 512, we need to feed callback with 512 bytes everytime!
unsigned int nBufferFrames = 512;
RtAudio::StreamOptions options;
options.flags = RTAUDIO_SCHEDULE_REALTIME;
options.flags = RTAUDIO_NONINTERLEAVED;
//&parameters, NULL, RTAUDIO_FLOAT64,sampleRate, &bufferFrames, &mCallback, (void *)&rawData
try {
rt.openStream(&oParameters, &iParameters, RTAUDIO_SINT16, sampleRate, &nBufferFrames, &mCallback, (void*) &mAudio);
rt.startStream();
}
catch (RtAudioError& e) {
std::cout << e.getMessage() << std::endl;
return false;
}
return true;
It was so random when I was trying to playback my mic. I left input parameters and my wav file was suddenly playing. Is this is a bug?