我试图将503,196字节的wav文件的内容写入另一个文件，并将samplerate / byterate加倍，以使速度加倍。但是，我无法从输入文件中读取数据并将其写入输出文件。这是我的代码：
#include <stdio.h>
int main() {
struct WAVE {
char ChunkID[4];
unsigned int ChunkSize;
char Format[4];
char Subchunk1ID[4];
unsigned int Subchunk1Size;
unsigned short int AudioFormat;
unsigned short int NumChannels;
unsigned int SampleRate;
unsigned int ByteRate;
unsigned short int BlockAlign;
unsigned short int BitsPerSample;
char Subchunk2ID[4];
unsigned int Subchunk2Size;
} wav;
FILE *original, *fast;
original = fopen("Alejandro_project.wav", "rb");
fast = fopen("Alejandro_fast.wav", "wb");
if (original == NULL) {
printf("File does not exist.\n");
return 0;
}
fread(&wav, 1, 44, original);
unsigned short int data[12 * wav.SampleRate]
int i;
for (i = 0; i < Subchunk2Size / 2; i++)
fread(&data[i], 1, 2, original);
fwrite(&wav, 1, 44, fast);
unsigned int fastSampleRate = wav.SampleRate * 2;
unsigned int fastByteRate = 2 * fastSampleRate;
fseek(fast, 24, SEEK_SET);
fwrite(&fastSampleRate, 4, 1, fast);
fseek(fast, 28, SEEK_SET);
fwrite(&fastByteRate, 4, 1, fast);
fwrite(data, 1, 2, original);
fclose(fast);
fclose(original);
}
答案 0 :(得分：0)
有几个问题..对于初学者，你需要确保你的WAVE标头的结构被打包，这样在结构中不会出现意外的填充，这会导致某些字段不对齐并增加结构的大小。否则，您可能会在每个unsigned short int成员之后获得两个字节的额外填充。
#pragma pack(push,1) /* for VC, may also work for GCC */
struct WAVE {
/* ...struct contents... */
} wav;
#pragma pack(pop)
其次，看起来你试图简单地覆盖新文件中的SampleRate和ByteRate成员，而其余部分保持不变。这仅在新文件已经是旧文件的副本时才有效。如果是这样，您还需要将打开新文件的模式更改为“r + b”（读取模式+写入）而不是“wb”（写入模式），以便不会丢弃现有文件内容。 / p>
尝试编写标题时也会出错。这一行：
fread(original, 1, 44, fast);
应该是：
fwrite(&wav, 44, 1, fast);
将wav的44个字节写入新文件，而不是从新文件中读取并使用旧文件的FILE *作为目标。
如果新文件不已经是旧文件的副本，则需要复制文件的其余部分（包括标题的其他部分）。在这种情况下，（一旦打开文件）可能最容易：
将旧文件中的标题读入wav
fread(&wav, sizeof(wav), 1, original);
修改SampleRate和ByteRate字段
wav.SampleRate *= 2;
wav.ByteRate *= 2;
将整个修改后的wav标头写入新文件
fwrite(&wav, sizeof(wav), 1, fast);
将旧文件的其余部分复制到循环中的新文件
char buf[1024];
int count;
while ((count = fread(buf, 1, sizeof(buf), original)) > 0)
fwrite(buf, 1, count, fast);
..然后关闭文件并返回。
答案 1 :(得分：0)
我明白了。我删除了结构只是为了看看我在做什么。我完成最后的项目后，我将把结构合并到一起。
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main() {
FILE *original, *fast, *slow, *slowdown;
unsigned int ChunkSize, Subchunk1Size, Subchunk2Size, RIFFSize, fmtSize, dataSize, SampleRate, ByteRate;
unsigned short int AudioFormat, NumChannels, BlockAlign, BitsPerSample;
char ChunkID[5], Format[5], Subchunk1ID[5], Subchunk2ID[5];
ChunkID[4] = '\0';
Format[4] = '\0';
Subchunk1ID[4] = '\0';
Subchunk2ID[4] = '\0';
char path[FILENAME_MAX], dfast[FILENAME_MAX], dslow[FILENAME_MAX], dslowdown[FILENAME_MAX];
printf("Enter path to Alejandro_project.wav file: ");
scanf("%s", path);
strcpy(dfast, path);
dfast[strlen(path) - 21] = '\0';
strcpy(dslow, dfast);
strcpy(dslowdown, dslow);
strcat(dfast, "Alejandro_fast.wav");
strcat(dslow, "Alejandro_slow.wav");
strcat(dslowdown, "Alejandro_slowdown.wav");
original = fopen(path, "rb");
if (!original) {
printf("Error: file does not exist.\n");
return EXIT_FAILURE;
}
fread(ChunkID, 4, 1, original);
fread(&ChunkSize, 4, 1, original);
fread(Format, 4, 1, original);
fread(Subchunk1ID, 4, 1, original);
fread(&Subchunk1Size, 4, 1, original);
fread(&AudioFormat, 2, 1, original);
fread(&NumChannels, 2, 1, original);
fread(&SampleRate, 4, 1, original);
fread(&ByteRate, 4, 1, original);
fread(&BlockAlign, 2, 1, original);
fread(&BitsPerSample, 2, 1, original);
fread(Subchunk2ID, 4, 1, original);
fread(&Subchunk2Size, 4, 1, original);
fmtSize = Subchunk1Size + 8;
dataSize = Subchunk2Size + 8;
RIFFSize = ChunkSize + 8 - (fmtSize + dataSize);
printf("RIFF Size: %d\n", RIFFSize);
printf("fmt Size: %d\n", fmtSize);
printf("data Size: %d\n\n", dataSize);
printf("ChunkID: %s\n", ChunkID);
printf("ChunkSize: %d\n", ChunkSize);
printf("Format: %s\n\n", Format);
printf("Subchunk1ID: %s\n", Subchunk1ID);
printf("Subchunk1Size: %d\n", Subchunk1Size);
printf("AudioFormat: %d\n", AudioFormat);
printf("NumChannels: %d\n", NumChannels);
printf("SampleRate: %d\n", SampleRate);
printf("ByteRate: %d\n", ByteRate);
printf("BlockAlign: %d\n", BlockAlign);
printf("BitsPerSample: %d\n\n", BitsPerSample);
printf("Subchunk2ID: %s\n", Subchunk2ID);
printf("Subchunk2Size: %d\n", Subchunk2Size);
fseek(original, 0, SEEK_SET);
fast = fopen(dfast, "wb");
unsigned int fastSampleRate = SampleRate * 2;
unsigned int fastByteRate = 2 * fastSampleRate;
fwrite(ChunkID, 4, 1, fast);
fwrite(&ChunkSize, 4, 1, fast);
fwrite(Format, 4, 1, fast);
fwrite(Subchunk1ID, 4, 1, fast);
fwrite(&Subchunk1Size, 4, 1, fast);
fwrite(&AudioFormat, 2, 1, fast);
fwrite(&NumChannels, 2, 1, fast);
fwrite(&fastSampleRate, 4, 1, fast);
fwrite(&fastByteRate, 4, 1, fast);
fwrite(&BlockAlign, 2, 1, fast);
fwrite(&BitsPerSample, 2, 1, fast);
fwrite(Subchunk2ID, 4, 1, fast);
fwrite(&Subchunk2Size, 4, 1, fast);
short int data;
unsigned int i;
for (i = 0; i < Subchunk2Size / 2; i++) {
fread(&data, 2, 1, original);
fwrite(&data, 2, 1, fast);
}
fclose(fast);
fseek(original, 0, SEEK_SET);
slow = fopen(dslow, "wb");
unsigned int slowSampleRate = SampleRate / 2;
unsigned int slowByteRate = 2 * slowSampleRate;
fwrite(ChunkID, 4, 1, slow);
fwrite(&ChunkSize, 4, 1, slow);
fwrite(Format, 4, 1, slow);
fwrite(Subchunk1ID, 4, 1, slow);
fwrite(&Subchunk1Size, 4, 1, slow);
fwrite(&AudioFormat, 2, 1, slow);
fwrite(&NumChannels, 2, 1, slow);
fwrite(&slowSampleRate, 4, 1, slow);
fwrite(&slowByteRate, 4, 1, slow);
fwrite(&BlockAlign, 2, 1, slow);
fwrite(&BitsPerSample, 2, 1, slow);
fwrite(Subchunk2ID, 4, 1, slow);
fwrite(&Subchunk2Size, 4, 1, slow);
for (i = 0; i < Subchunk2Size / 2; i++) {
fread(&data, 2, 1, original);
fwrite(&data, 2, 1, slow);
}
fclose(slow);
fclose(original);
system("pause");
return EXIT_SUCCESS;
}
答案 2 :(得分：0)
要使速度加倍，您不能只更改WAV标头中的sample rate或byte-rate。如果你这样做，它会播放得很快，但由于音调错误会听起来很奇怪。相反，您需要使用正确的采样率转换（SRC）库将输入WAV文件转换为具有更快采样率的输出WAV文件。