relation between QAudioInput bufferSize() and bytesReady() in QT - c++

Question

I am trying to understand the relation between bufferSize() and bytesReady() for QAudioInput class in QT.
Assume that I have:
m_audioInput = new QAudioInput(m_Inputdevice, m_format, this);
bs = m_audioInput->bufferSize();
br = m_audioInput->bytesReady();
When I look at the values of bs and br (these are default values and I did not change the buffer size), I see that bs is 5 times larger than br. So it looks like there is a buffer that holds 5 blocks of audio input data. My question:
Is this a circular buffer? If I have these:
m_input = m_audioInput->start();
connect(m_input, SIGNAL(readyRead()), SLOT(myFunc()));
Then when I perform a read by:
MainClass::myFunc()
{
qint64 l = m_input->read(m_buffer.data(), br);
.
.
}
Does it read from the buffer in a circular manner? i.e. if I perform read 2 times consequently after a readyRead() is emitted does the buffer pointer moves from 1 block to second block (if it has 5 blocks in total)?
Is there any documentation on the buffer pointer, and if it is a circular buffer, etc.?
Are there automatic read and write pointers to the buffer? Do I need to take care of those, or it is being taken care of automatically?
Any help and pointer related to this is very much appreciated.

Answer 1

I don't really understand your use case. First thing, I suppose when you call
br = m_audioInput->bytesReady();
you are either in QAudio::ActiveState or QAudio::IdleState. Otherwise br is just junk.
So it looks like there is a buffer that holds 5 blocks of audio input data.
A Sample is a unit of audio data. If by that you mean 5 samples then it is not correct. There is also no such thing as block of audio when it comes to non-encoded data.
You can compute how much seconds(or milliseconds) of audio are in your buffer:
Buffer size/ Sample size gives #samples
1/sampling frequency gives you sample size in seconds
sample size x #samples the size of buffer in seconds.
That's in mono mode (one channel). You need to divide by the number of channels
In Qt:
BuffersizeSeconds = (int)((1.0/m_format->sampleRate())
*(m_audioInput->bufferSize()/m_format->sampleSize())
*(1.0/m_format->channelCount())
);