Question

I have some code written in C++ and when I compile it on my laptop, the results show, however, I have tried to compile and run the code onto the RPI and I get the error:

Segmentation fault

How the program (currently) works:

• Reads in a (.wav) file into a vector of doubles (“rawData”)
• Splits the rawData into blocks (blockked)

The segmentation fault happens when I try and split the data into blocks. The sizes:

rawData – 57884
blockked – 112800

Now I know the RPI only has 256MB and this could possibly be the problem, or, i’m not handling the data properly. I have included some code as well, to help demonstrate how things are running:

(main.cpp):

int main()
{
int N = 600;
int M = 200;

float sumthresh = 0.035;
float zerocorssthres = 0.060;

Wav sampleWave;

if(!sampleWave.readAudio("repositry/example.wav", DOUBLE))
{
    cout << "Cannot open the file BOOM";

}

// Return the data
vector<double> rawData = sampleWave.returnRaw();
// THIS segments (typedef vector<double> iniMatrix;)
vector<iniMatrix> blockked = sampleWave.something(rawData, N, M);


cout << rawData.size();

return EXIT_SUCCESS;   
}

(function: something)

int n = theData.size();
int maxblockstart = n - N;
int lastblockstart = maxblockstart - (maxblockstart % M);

int numblocks = (lastblockstart)/M + 1;
vector< vector<double> > subBlock;
vector<double> temp;
this->width = N;
this->height = numblocks;

subBlock.resize(600*187);
for(int i=0; (i < 600); i++)
{
    subBlock.push_back(vector<double>());
    for(int j=0; (j < 187); j++)
    {   
        subBlock[i].push_back(theData[i*N+j]);
    } 
}    
return subBlock;

Any suggestions would be greatly appreciated :)! Hopefully this is enough description.

Answer 1

You’re probably overrunning an array somewhere (Maybe not even in the code you posted). I’m not really sure what you’re trying to do with the blocking either, but I guess you want to split your wave file into 600 sample chunks?

If so, I think you want something more like the following:

std::vector<std::vector<double>>
SimpleWav::something(const std::vector<double>& data, int N) {

    //How many blocks of size N can we get?
    int num_blocks = data.size() / N;

    //Create the vector with enough empty slots for num_blocks blocks
    std::vector<std::vector<double>> blocked(num_blocks);

    //Loop over all the blocks
    for(int i = 0; i < num_blocks; i++) {
        //Resize the inner vector to fit this block            
        blocked[i].resize(N);

        //Pull each sample for this block
        for(int j = 0; j < N; j++) {
            blocked[i][j] = data[i*N + j];
        }
    }

    return blocked;
}