Processing large files with libsndfile

Question

Currently I've written a program (in Visual Studio C++) based on the available example code of "libsndfile" in which I've just added a subtraction-function to subtract one (channel of a) WAV-file with another.

The program worked perfectly for files with a limit of 4 channels.

The problem is that as soon as I upload a file with as many as 5 channels or more, the program refuses to execute the function. This is independent of the frame-size as I've managed to process 4-channel files which were many times larger than some 5/6-channel-files which I have used.

Has anyone encountered this or a similar problem before? If requested I will provide the source code.

My apologies for the bad structure, I don't really optimize until I get the whole deal working.

Code:

#include <sndfile.hh>
#include <tinyxml2.h>
#include <iostream>
#include <fstream>

#define BLOCK_SIZE 32

using TiXmlDocument = tinyxml2::XMLDocument;
using CStdStringA = std::string;

int main(int argc, char* argv[])

{
    SNDFILE *infile  = NULL;
    SNDFILE *infile2 = NULL;
    SNDFILE *outfile = NULL;
    SF_INFO    sfinfo;
    SF_INFO    sfinfo2;
    SF_INFO    sfinfoOut;
    sf_count_t readcount;
    //int filetype = SF_FORMAT_WAV | SF_FORMAT_PCM_24;                  // 24-bit Wav-Files
    TiXmlDocument iDoc;                                               // Init tinyXML
    int i;                                                            // Iteration-var;
    short BufferIn[BLOCK_SIZE];                                       // Buffer1
    short BufferIn2[BLOCK_SIZE];                                      // Buffer2
    short BufferOut[BLOCK_SIZE];
    CStdStringA FileLoc, FileName, FileLocWav, FileLocTxt,FileLocRaw; // OutputFile locationstring
    CStdStringA WavName, WavName2, FileIn, FileIn2;
    FileLoc = "C:\\Testfiles\\";
    //TextTitle(FileLoc);                                             // Print console-header
    printf("Name Wavefile 1:\n");
    std::cin >> WavName;
    FileIn = FileLoc + WavName + ".wav";
    if((infile = sf_open(FileIn.c_str(),SFM_READ,&sfinfo)) == NULL)   // Open Wav-file 2 instance
    {
        printf("Not able to open input file 1\n");
        printf("\n\nPress any key to exit.");                         // Exit-text if file not present
        puts(sf_strerror(NULL)) ;
        return 1;
    }
    std::cout << "Wav file 1 succesfully opened." <<  std::endl;
    std::cout << "\nChannels: " << sfinfo.channels << "\nFrames: " << sfinfo.frames << std::endl; // Print Channels & Frames
    std::cout << "Samplerate: " << sfinfo.samplerate << "\n\n" <<  std::endl;// Print Samplerate
    printf("Name Wavefile 2:\n");
    std::cin >> WavName2;
    FileIn2 = FileLoc + WavName2 + ".wav";
    if((infile2 = sf_open(FileIn2.c_str(),SFM_READ,&sfinfo2)) == NULL) // Open Wav-file 2 instance
    {
        printf("Not able to open input file 2\n");
        printf("\n\nPress any key to exit.");                          // Exit-text if file not present
        puts(sf_strerror(NULL)) ;
        return 1;
    }
    std::cout << "Wav file 2 succesfully opened." <<  std::endl;
    std::cout << "\nChannels: " << sfinfo2.channels << "\nFrames: " << sfinfo2.frames  << std::endl; // Print Channels & Frames
    std::cout << "Samplerate: " << sfinfo2.samplerate << "\n\n" <<  std::endl;// Print Samplerate
//{
    //std::cout << "Format differs from eachother, abort program.";
    //printf("\n\nPress any key to exit.");                     // Exit-text
    //return 1;
//}
    if(sfinfo.channels != sfinfo2.channels)                                // Abort if channels not the same
    {
        std::cout << "Channelammount differs from eachother, abort program.";
        printf("\n\nPress any key to exit.");                     // Exit-text
        return 1;
    }
    if(sfinfo.samplerate != sfinfo2.samplerate)                   // Abort if samplerate not the same
    {
        std::cout << "Samplerate differs from eachother, abort program.";
        printf("\n\nPress any key to exit.");                     // Exit-text
        return 1;
    }
    std::cout << "Give a filename for Txt- & Wav-file: ";
    std::cin >> FileName;
    FileLoc += FileName;                                          // Fuse Filelocation with given name
    FileLocTxt = FileLoc + ".txt";
    FileLocWav = FileLoc + ".wav";
    FileLocRaw = FileLoc + "Raw.txt";
    sfinfoOut.channels = sfinfo.channels;
    sfinfoOut.format = sfinfo.format;
    sfinfoOut.samplerate = sfinfo.samplerate;
    if((outfile = sf_open(FileLocWav.c_str(),SFM_WRITE,&sfinfoOut)) == NULL)      // Open Wav-file 2 instance
    {
        printf("Not able to create output file \n");
        printf("\n\nPress any key to exit.");                      // Exit-text if file not present
        puts(sf_strerror(NULL)) ;
        return 1;
    }
    std::ofstream myfile;
    myfile.open(FileLocTxt.c_str(),std::ios::app);
    std::ofstream myfileRaw;
    myfileRaw.open(FileLocRaw.c_str(),std::ios::app);
    while((readcount = sf_read_short(infile, BufferIn, BLOCK_SIZE)))     // While there are still frames to be processed
    {
        //process_data (data, readcount, sfinfo.channels) ;
        auto readcount2 = sf_read_short(infile2, BufferIn2, BLOCK_SIZE);
        for(i = 0; i < BLOCK_SIZE; i++)                                  // BLOCK_SIZE decides the chunk-size
        {
            BufferOut[i] = BufferIn[i] - BufferIn2[i];
            myfileRaw << BufferOut[i];
        }
        sf_write_short(outfile, BufferOut, BLOCK_SIZE) ;                 // Write the data to a new file
    }
    sf_close(infile);                                                    // Close Wav-file handlers
    sf_close(infile2);
    sf_close(outfile);
    myfile.close();                                                      // Close text-file handlers
    printf("\n\nPress any key to exit.");                                // Exit-text
    return 0;
}

Answer 1

The documentation states:

File Read Functions (Items)

sf_count_t  sf_read_short   (SNDFILE *sndfile, short *ptr, sf_count_t items) ;
sf_count_t  sf_read_int     (SNDFILE *sndfile, int *ptr, sf_count_t items) ;
sf_count_t  sf_read_float   (SNDFILE *sndfile, float *ptr, sf_count_t items) ;
sf_count_t  sf_read_double  (SNDFILE *sndfile, double *ptr, sf_count_t items) ;

The file read items functions fill the array pointed to by ptr with the requested number of items. The items parameter must be an integer product of the number of channels or an error will occur

There's your problem, since BLOCK_SIZE is a multiple of 1,2,4 but not of 3 and 5 - so that would fail.

About the problem that program completes as if calculations had taken place: add appropriate error handling.