iqToSharp.cpp

#include <cstdio>
#include <cstdint>
#include <cmath>
#include <iostream>
#include <unistd.h>

struct WavHeader{
    uint32_t chunkID; // == 'RIFF'
    uint32_t chunkSize;
    uint32_t format; // == 'WAVE'
    uint32_t subchunk1ID; // == 'fmt '
    uint32_t subchunk1Size;
    uint16_t audioFormat;
    uint16_t numChannels;
    uint32_t sampleRate;
    uint32_t byteRate;
    uint16_t blockAlign;
    uint16_t bitsPerSample;
    uint32_t subchunk2ID; // == 'data'
    uint32_t subchunk2Size;
};

template<class T>
struct complex{
    T re;
    T im;
};

void usage(){
    fprintf(stderr,
            "iqToSharp, an I/Q converter for SDRSharp\n\n"
            "Usage:\t -i input file\n"
            "\t[-o output file without .wav extension (default: out)]\n"
            "\t[-b buffer size (default: 2048)]\n"
            "\t[-s samplerate (default: 2048000 Hz)]\n"
            "\t[-f center frequency (default: 0)]\n"
            "\t[-z add 1 sec of silence]\n");

    exit(1);
}

int main(int argc, char **argv){
    const char *inFileName = NULL;
    const char *outFileNameArg = "out";
    uint32_t sampleRate = 2048000;
    const char *centerFreq = "0";
    bool silence = false;

    int c;
    size_t bufsize = 2048;

    while ((c = getopt(argc, argv, "i:b:o:s:f:z")) != -1) {
        switch(c){
            case 'i':
                inFileName = optarg;
                break;
            case 'o':
                outFileNameArg = optarg;
                break;
            case 's':
                sampleRate = atoi(optarg);
                break;
            case 'b':
                bufsize = atoi(optarg);
                break;
            case 'f':
                centerFreq = optarg;
                break;
            case 'z':
                silence = true;
                break;
            default:
                usage();
            break;
        }
    }

    if(optind < argc) usage();

    char outFileName[255] = {0};
    snprintf(outFileName, 255, "%s_%sHz_IQ.wav", outFileNameArg, centerFreq);

    FILE *f;
    FILE *fout;

    f = fopen(inFileName, "rb");

    if(!f){
        puts("failed open input file");
        return 1;
    }

    fout = fopen(outFileName, "wb");

    if(!fout){
        puts("failed open output file");
        return 1;
    }

    printf("Input file: %s\n"
           "Output file: %s\n"
           "Sample rate: %d\n"
           "Frequency: %sHz\n",
           inFileName, outFileName, sampleRate, centerFreq);

    printf("Write samples...");
    fflush(stdout);
    fseek(fout, sizeof(WavHeader), SEEK_SET);

    complex<int8_t> *pctx = (complex<int8_t>*)malloc(sizeof(complex<int8_t>)*bufsize);
    if(pctx == NULL){
        puts("out of memory");
        return 1;
    }

    size_t dataSize = 0;
    size_t elemRead = 0;
    while((elemRead=fread(pctx, sizeof(complex<int8_t>), bufsize, f)) > 0){
        //processing
        fwrite(pctx, sizeof(complex<int8_t>), elemRead, fout);
        dataSize += sizeof(complex<int8_t>)*elemRead;
    }

    printf("DONE\n");
    fflush(stdout);

    if(silence){
        printf("Write silence...");
        fflush(stdout);

        pctx->re = 0; pctx->im = 0;

        for(uint32_t i = 0; i < sampleRate; i++){
            fwrite(pctx, sizeof(complex<int8_t>), 1, fout);
            dataSize += sizeof(complex<int8_t>);
        }

        printf("DONE\n");
        fflush(stdout);
    }

    printf("Write wav header...");
    fflush(stdout);

    size_t fileSize = sizeof(WavHeader) + dataSize;

    WavHeader wav;

    wav.chunkID = 0x46464952; // == 'RIFF'
    wav.chunkSize = fileSize - 8;
    wav.format = 0x45564157; // == 'WAVE'
    wav.subchunk1ID = 0x20746D66; // == 'fmt '
    wav.subchunk1Size = 16;
    wav.audioFormat = 1;
    wav.numChannels = 2;
    wav.sampleRate = sampleRate;

    wav.bitsPerSample = sizeof(pctx->re)*8;

    wav.byteRate = wav.sampleRate *
                   wav.numChannels *
                   wav.bitsPerSample/8;

    wav.blockAlign = wav.numChannels * wav.bitsPerSample/8;
    wav.subchunk2ID = 0x61746164; // == 'data'
    wav.subchunk2Size = dataSize;

    fseek(fout, 0, SEEK_SET);
    fwrite(&wav, sizeof(wav), 1, fout);
    fclose(f);
    fclose(fout);

    printf("DONE\n");
    fflush(stdout);
    free(pctx);
    return 0;
}