Opening mp3 files using the audiere library

как открыть mp3-файл, звук, audiere, обработка звука, аудио

The audiere library allows you to work with audio files of various formats (wav, mp3, etc.). To work, we need the files audiere.h, audiere.lib, audiere.dll. h-file is included in the program code

#include "audiere.h"

lib-file is linked to .pro

LIBS += audiere.lib

dll we drag behind the program.
In RuNet it is easy to find information on how to play sound with it. But there is absolutely no information on how to get audio data for further processing. Therefore, I will write, especially since it is quite simple.

1 open file

    QString name = "D:/qtProg/audioprocessor/test2.mp3"; 
    name.replace("/","\\");
    SampleSourcePtr source;
    source = OpenSampleSource( name.toLocal8Bit() ); 
    if(!source)
    {
        ui->statusBar->showMessage("файл не открыт");
        return;
    }
    else
    {
        ui->statusBar->showMessage(name);
    }

2 read audio parameters

    int ccount; // число каналов
    int samplerate; // частота дискретизации
    SampleFormat format; // формат данных
 
    source->getFormat(ccount, samplerate, format);
    int l = source->getLength(); // число отсчётов одного канала

For typical audio recordings, the number of channels is two, single-channel recordings are quite common, I have not seen others, but it should work on the same principle. Note that the number of samples obtained with getLength() corresponds to one channel. Sampling frequency (if you don't know what it is, check out the Kotelnikov theorem or the Nyquist theorem). Format - determines the number of bits that encode one sample (usually 16).

3 create buffer and suitable storage

    int w = 256; // размер временного окна
    qint16 buf[w*ccount];
 
    QVector<qint16> data; // хранилище данных для одного канала

4 read data

    int row = l/w; // число временных фрагментов
 
    for(int j = 0; j < row; j++)
    {
        source->read(w, buf); // считывание фрагмента
        for(int i=0; i<w; i++)
        {
            data.append(buf[i*ccount]);
        }
    }
    source->read(w, buf); // считывание последнего фрагмента
    for(int i=0; i < l%w; i++)
    {
        data.append(buf[i*ccount]);
    }

Now the extracted data can be processed...
The text of the program can be downloaded here