Spectrum analyzer demo, the HZ is 0 ~ 1000, how to change this?

xhsoldier

Yes. I change all the value.
SpectrumNumBands is the 10, that's fine for me.

when I debug I notice that all the frequency will result a bar index, either 0 or 1.
So I think there may be a bug in the Spectrograph::updateBars()

goetz

I can't help on that. You'll have to check the sources. They seem quite simple to me.

grisza50

I have the following :

Where exactly in spectrumanalyser demo is a code for getting the RAW PCM data from .wav file? and how to use this demo's functions to get it.

i'm working on sound processing system and i'm new with qt.

I would be grateful if someone could paste small example how to do get pcm data ;)

thanks for your reply ;)

shoyeb

hey can you please elaborate your problem this way we cant help u out be specific with your problem....

then only we can help you...

grisza50

thanks,
Ok, so I want to open the .wav file, get audio (PCM) data, and do some signal processing using external library (for example mel-cepstrum coefficients analysis)
so i open the wav file using:
@showFileDialog(){
}@
this function calls m_engine->loadFile(fileNames.front()); function
In next step i would like to create the buffer/vector for audio data and write this data to it and then analyse them. I don't know how to create this buffer and get the pcm data.
i look for adequate functions and find this:
@if (m_file) {
m_file->seek(0);
m_bufferPosition = 0;
m_dataLength = 0;
if (isPCMS16LE(m_file->fileFormat())) {
result = initialize();
}if(m_spectrumAnalyser.isReady()) {
m_spectrumBuffer = QByteArray::fromRawData(m_buffer.constData() + position m_bufferPosition, m_spectrumBufferLength);
m_spectrumPosition = position;
m_spectrumAnalyser.calculate(m_spectrumBuffer, m_format);
}@
so i see that i have to get some kind of m_buffer and m_format from .wav file and i don't see the proper way to do it. It would be great if someone could paste some simple code with solution to open .wav file, creating the buffer, getting the necessary parameters from this file (for example number of samples, m_format?), writting pcm data to the buffer, and how to read this data. In MATLAB there is wavread function for reading this kind of data.
thanks for your reply ;)

shoyeb

spectrum analyser is having that functuionality u dont have to write anything for that...

when u say,

@result = initialize();@

this method automatically initialises tha m_buffer and m_format..

check it properly..

grisza50

Thank you shoyeb ;)

ok, I created the pushbutton and and i want to calculate the spectrum of 30000 us with step of 10000 us. how can i set up this values for my use?
I connected my slot to this button and this work properly spectrum. How to enable that the spectrum is calculated only if the position of calculating is less than the signal? - my program is still crushing after a few click ;(
@my function{
if (isPCMS16LE(m_file->fileFormat())) {
result = initialize();
}
if (m_file) {
m_file->seek(0);
m_bufferPosition = 0;
m_dataLength = 0;
}

        //bufor itd
        if(m_spectrumAnalyser.isReady()) {
            m_spectrumBuffer = QByteArray::fromRawData(m_buffer.constData() + classify_position - m_bufferPosition,
                                                       m_spectrumBufferLength);
            m_spectrumPosition = classify_position + 10000;// step of windowing

            m_spectrumAnalyser.calculate(m_spectrumBuffer, m_format);

}
}

@ how to initialize m_spectrumBufferLength and position to the values i mentioned?
and where/how i can add spectrumanalyser functions to calculate the spectrum only if the position is less than duration of signal?

please help me

shoyeb

in engine.cpp file on top there are two constants..

@const qint64 BufferDurationUs = 1 * 1000000;
const int NotifyIntervalMs = 10;@

where first value is amount of data to be processed in microseconds and second one is to set the notify interval, watever value u set in notify interval after that duration only ur data processing is done...

m_spectrumBufferLength is fixed and its value is initialized in utils.h or utils.h u dat can check ...

grisza50

and how can i add the functionality of computing spectrum only if the position of computing is less than duration of whole signal,

or mayby how can i get the info about duration of whole signal (in microseconds or sample number )?

shoyeb

the first line tells you the duration of entire signal i.e

@const qint64 BufferDurationUs = 1 * 1000000;@

this tells that the duration of entire singnal is one second...

grisza50

yes, but i mean not recorded signal but opened and played wave file, how to obtain this information.
thanks

shoyeb

check this...

@if (isPCMS16LE(m_file->fileFormat())) {
result = initialize();@

and

if (result) {
m_analysisFile = new WavFile(this);
m_analysisFile->open(fileName);
}