mpg123 decode mp3 to pcm in C++

Question

I want to decode a mp3 file to pcm :

#include <iostream>
#include <mpg123.h>
#include <out123.h>
using namespace std;
int main()
{
mpg123_handle *mh;
unsigned char *buffer;
size_t buffer_size;
size_t done;
int err;
int channels, encoding;
long rate;
buffer_size = mpg123_outblock(mh);
buffer = (unsigned char*) malloc(buffer_size * sizeof(unsigned char));

mpg123_init();
mh = mpg123_new(NULL, &err);

mpg123_open(mh, "/home/abbas/Desktop/nastaran.mp3");
// mpg123_getformat(mh, &rate, &channels, &encoding);



while (mpg123_read(mh, buffer, buffer_size, &done) == MPG123_OK)
    cout << buffer ;

free(buffer);
mpg123_close(mh);
mpg123_delete(mh);
mpg123_exit();
return 0;
}

But it gives me this error:

The program has unexpectedly finished.

This error says nothing about the reason. Where is the problem?

Is it something about the OS?

cmake file:

project(echoprint2)
cmake_minimum_required(VERSION 2.8)

aux_source_directory(. SRC_LIST)
add_executable(${PROJECT_NAME} ${SRC_LIST})

add_library(mpg123 SHARED IMPORTED )
set_target_properties(mpg123 PROPERTIES IMPORTED_LOCATION  /usr/local     /lib/libmpg123.so)
TARGET_LINK_LIBRARIES(echoprint2 mpg123)

Answer 1

I fixed some errors and got some numeric values to be produced. I leave it to you to check if the waveform produced is correct. Suggest using Excel and Audacity to visualize it and confirm that the waveforms look alright.

#include <fstream>
#include <iostream>
#include <mpg123.h>
#include <out123.h>

int main(){
    mpg123_init();

    int err;
    mpg123_handle *mh = mpg123_new(NULL, &err);
    unsigned char *buffer;
    size_t buffer_size;
    size_t done;

    int channels, encoding;
    long rate;
    buffer_size = mpg123_outblock(mh);
    buffer = (unsigned char*)malloc(buffer_size * sizeof(unsigned char));

    mpg123_open(mh, "/home/abbas/Desktop/nastaran.mp3");
    mpg123_getformat(mh, &rate, &channels, &encoding);
    
    std::ofstream out("res.txt");
    unsigned int counter = 0;

    for (int totalBtyes = 0; mpg123_read(mh, buffer, buffer_size, &done) == MPG123_OK; ) {
        short* tst = reinterpret_cast<short*>(buffer);
        for (auto i = 0; i < buffer_size / 2; i++) {
            out<< counter + i<<"\t"<< tst[i] << "\n";
        }
        counter += buffer_size/2;
        totalBtyes += done;
    }
    out.close();
    free(buffer);
    mpg123_close(mh);
    mpg123_delete(mh);
    mpg123_exit();
    return 0;
}