c中的聲波鋸齒

Question

我正試圖在c中產生鋸齒波。 我已經接近我的工作，但我有一個必須解決的問題。 我在下面附上了clode。

#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <tgmath.h>

/******************************
*  Magic file format strings. *
******************************/
const char fChunkID[]     = {'R', 'I', 'F', 'F'};
const char fFormat[]      = {'W', 'A', 'V', 'E'};
const char fSubchunk1ID[] = {'f', 'm', 't', ' '};
const char fSubchunk2ID[] = {'d', 'a', 't', 'a'};

/********************************
* WriteWavePCM() configuration: *
* - 2 channels,                 *
* - frequency 44100 Hz.         *
********************************/
const unsigned short N_CHANNELS = 2;
const unsigned int SAMPLE_RATE = 48000;
const unsigned short BITS_PER_BYTE = 8;

bool WriteWavePCM(short* sound, size_t pairAmount, char* fileName){
    const static unsigned int fSubchunk1Size = 16;
    const static unsigned short fAudioFormat = 1;
    const static unsigned short fBitsPerSample = 16;

    unsigned int fByteRate = SAMPLE_RATE * N_CHANNELS * fBitsPerSample / BITS_PER_BYTE;

    unsigned short fBlockAlign = N_CHANNELS * fBitsPerSample / BITS_PER_BYTE;
    unsigned int fSubchunk2Size;
    unsigned int fChunkSize;

    FILE* fout;
    size_t ws;

    if (!sound || !fileName || !(fout = fopen( fileName, "w" ))) return false;

    fSubchunk2Size = pairAmount * N_CHANNELS * fBitsPerSample / BITS_PER_BYTE;
    fChunkSize = 36 + fSubchunk2Size;

    // Writing the RIFF header:
    fwrite(&fChunkID, 1, sizeof(fChunkID),      fout);
    fwrite(&fChunkSize,  sizeof(fChunkSize), 1, fout);
    fwrite(&fFormat, 1,  sizeof(fFormat),       fout);

    // "fmt" chunk:
    fwrite(&fSubchunk1ID, 1, sizeof(fSubchunk1ID),      fout);
    fwrite(&fSubchunk1Size,  sizeof(fSubchunk1Size), 1, fout);
    fwrite(&fAudioFormat,    sizeof(fAudioFormat),   1, fout);
    fwrite(&N_CHANNELS,      sizeof(N_CHANNELS),     1, fout);
    fwrite(&SAMPLE_RATE,     sizeof(SAMPLE_RATE),    1, fout);
    fwrite(&fByteRate,       sizeof(fByteRate),      1, fout);
    fwrite(&fBlockAlign,     sizeof(fBlockAlign),    1, fout);
    fwrite(&fBitsPerSample,  sizeof(fBitsPerSample), 1, fout);

    /* "data" chunk: */
    fwrite(&fSubchunk2ID, 1, sizeof(fSubchunk2ID),      fout);
    fwrite(&fSubchunk2Size,  sizeof(fSubchunk2Size), 1, fout);

    /* sound data: */
    ws = fwrite(sound, sizeof(short), pairAmount * N_CHANNELS, fout);
    fclose(fout);
    return true;
}

////////////////////////////////////////////////

const unsigned int N_SAMPLE_PAIRS = 50000;

int main(int argc, char* argv[]){
    short* sound;
    int i;
    int j;
    bool status;
    char* file_name;
    int l; // dodane

    sound = (int*) malloc(sizeof(int) * N_SAMPLE_PAIRS * N_CHANNELS );

    if (!sound)
    {
        puts("Could not allocate space for the sound data.");
        return (EXIT_FAILURE);
    }

    int amplitude = 10000;
    int frequency = 80;
    short record = 0;
    short waveNumber = 1;
    int samplesPerWavelength = SAMPLE_RATE / (frequency/N_CHANNELS);
    int soundLen = 10 * samplesPerWavelength;
    int ampStep = (int)((amplitude*2)/(int)samplesPerWavelength);
    short step = 5*samplesPerWavelength;
    short muteRate = amplitude/(soundLen/samplesPerWavelength);
    int totalSamplesWritten = 0;
    int tempSample =0;

    for (i=0, j=0; i<N_SAMPLE_PAIRS*N_CHANNELS; i+=2, j++) {
        ampStep = (int)((amplitude*2)/(int)samplesPerWavelength);
        tempSample = (int)((totalSamplesWritten%samplesPerWavelength)*ampStep);
        sound[i] = tempSample;
        sound[i+1] = tempSample;
        totalSamplesWritten++;
    }


    file_name = argc > 1 ? argv[1] : "Default2.wav";
    status = WriteWavePCM(sound, N_SAMPLE_PAIRS, file_name);


    free(sound);

    if (status)
    {
        printf("Discotheque is ready in \"%s\"\n", file_name);
    }
    else
    {
        puts( "Something seems to have gone wrong." );
        return (EXIT_FAILURE);
    }

    return 0;
}

這是我的結果。 有鋸齒但有奇怪的行為。 我不知道為什么會這樣。 我檢查了一系列樣品，一切都很好看。

有人能幫我嗎？ 我被困住了，我不知道該怎么做。 我在兩個不同的程序中檢查了它：audiocity和wavepadaudio，然后在這兩個程序中都存在這種行為。 所以我的代碼確實存在問題。 請幫幫我。

Answer 1

當我查看文件轉儲（MSVC編譯）時，我注意到了一些0D 0A數據對。 然后我改變了這個

fout = fopen( fileName, "w" )

指定二進制文件

fout = fopen( fileName, "wb" )

現在故障已經消失了。

注意

如果未在mode給出t或b ，則默認轉換模式由全局變量_fmode定義。

因此默認翻譯模式必須是“文本”。

Answer 2

以下是我獲得的輸出的一些屏幕截圖。 對我來說似乎很好。

使用內置規格。 COLLECT_GCC = gcc COLLECT_LTO_WRAPPER = / usr / lib / gcc / i686-pc-cygwin / 5.4.0 / lto-wrapper.exe目標：i686-pc-cygwin配置：/ cygdrive / i / szsz / tmpp / gcc / gcc- 5.4.0-1.i686 / src / gcc-5.4.0 / configure --srcdir = / cygdrive / i / szsz / tmpp / gcc / gcc-5.4.0-1.i686 / src / gcc-5.4.0 - -prefix = / usr --exec-prefix = / usr --localstatedir = / var --sysconfdir = / etc --docdir = / usr / share / doc / gcc --htmldir = / usr / share / doc / gcc / h tml -C --build = i686-pc-cygwin --host = i686-pc-cygwin --target = i686-pc-cygwin --without-libiconv-prefix --without-libintl-prefix --libexecdir = / usr / lib --enable-shared --enable-shared-libgcc --enable-static --enable-version-specific-runtime-libs --enable-bootstrap --enable -__ cxa_ate xit --with-dwarf2 --with -arch = i686 --with-tune = generic --disable-sjlj-exceptions --enable-languages = ada，c，c ++，fortran，java，lto，objc，obj-c ++ --enable-graphite --enable- threads = posix --enable-libatomic --enable-libcilkrts --enable-libgomp --enable-libitm --enable-libquadmath --enab le-libquadmath-support --enable-libssp --enabl e-libada --enable-libjava --enable-libgcj-sublibs --disable-java-awt --disable-symvers --with- ecj-jar = / usr / share / java / ecj.jar --with-gnu -ld --with-gnu-as --with-cloog-include = / usr / include / cloog-isl --without-libiconv-prefix --without- libintl-prefix --with-system-zlib --enable- linker-build-id --with-default-libstdcxx-abi = gcc4-compatible線程模型：posix gcc版本5.4.0（GCC）

uname -a CYGWIN_NT-6.1-WOW DE-E03895 2.8.0（0.309 / 5/3）2017-04-01 20:42 i686 Cygwin

這是輸出中損壞樣本的屏幕截圖;