使用C创建立体声WAV文件
我正在考虑用C语言创建一个使用C创建立体声WAV文件,c,file,audio,wav,C,File,Audio,Wav,我正在考虑用C语言创建一个WAV文件,并且已经看到了一个示例 这看起来不错,但我有兴趣添加两个缓冲区,使音频立体声(每个耳朵可能有不同的声音)。如果我将频道数设置为2,则音频仅从左声道播放(显然是右声道,因为左声道是第一个声道)。我已经读过了,我必须把它和正确的频道交错 不幸的是,我还没有在网上找到太多帮助创建立体声WAV的东西 write_little_endian((unsigned int)(data[i]),bytes_per_sample, wav_file); 我试着创建第二个缓
WAV文件
,并且已经看到了一个示例
这看起来不错,但我有兴趣添加两个缓冲区,使音频立体声(每个耳朵可能有不同的声音)。如果我将频道数设置为2,则音频仅从左声道播放(显然是右声道,因为左声道是第一个声道)。我已经读过了,我必须把它和正确的频道交错
不幸的是,我还没有在网上找到太多帮助创建立体声WAV的东西
write_little_endian((unsigned int)(data[i]),bytes_per_sample, wav_file);
我试着创建第二个缓冲区,用一半的振幅看看我是否可以交错
for (j=0; i<BUF_SIZE; i++) {
phase +=freq_radians_per_sample;
buffertwo[i] = (int)((amplitude/2) * sin(phase));;
}
write_wav("test.wav", BUF_SIZE, buffer, buffertwo, S_RATE);
但这是行不通的。理论上应该是交错的。我认为问题在于函数“write\u little\u endian”。你不需要在笔记本电脑上使用它 Endianness是特定于架构的。最初的例子可能是Arduino微控制器板。Arduino板使用的Atmel微控制器是big-endian。这就是为什么您所引用的代码需要显式地将16位整数转换为little endian格式 另一方面,您的笔记本电脑使用的x86处理器已经是小端,因此不需要转换。如果希望使用健壮的可移植代码来转换endianness,可以在Linux中使用函数
htole16
。查阅手册页以了解有关此功能的更多信息
对于一个快速但不可移植的修复,我会说只需写出整个16位值
此外,我认为从单声道到立体声不需要将振幅减半。因此我决定尝试一下,以获得乐趣,这里有一种编写.wav文件的替代方法。它生成一个名为
sawtooth\u test.wav
的文件。当你播放时,你应该听到左右两种不同的频率。(不要放得太大声,太烦人了。)
/*使用gcc-Wall-O2-o wavwrite.c编译*/
#包括
#包括
#包括
#包括
/*
wav文件的标头基于:
https://ccrma.stanford.edu/courses/422/projects/WaveFormat/
*/
类型定义结构文件头
{
char ChunkID[4];/*4*/
int32\u t ChunkSize;/*4*/
字符格式[4];/*4*/
char Subchunk1ID[4];/*4*/
int32_t Subchunk1Size;/*4*/
int16_t AudioFormat;/*2*/
int16\u t数字通道;/*2*/
int32_t采样器;/*4*/
int32_t ByteRate;/*4*/
int16\u t BlockAlign;/*2*/
int16_t BitsPerSample;/*2*/
char Subchunk2ID[4];
int32_t次chunk2尺寸;
}wavfile_头文件;
/*CD质量音频的标准值*/
#定义子chunk1大小(16)
#为PCM定义音频格式(1)/**/
#定义NUM_通道(2)
#定义采样率(44100)
#定义每个样本的位(16)
#定义字节速率(采样速率*通道数*每采样位数/8)
#定义块对齐(每个采样的通道数*位/8)
/*成功时返回0,失败时返回-1*/
int write_PCM16_立体声_头(文件*文件),
int32_t采样器,
int32(帧计数)
{
int ret;
wavfile_头\u t wav_头;
int32_t subchunk2_尺寸;
int32块大小;
大小\不写入\计数;
subchunk2_size=帧数*通道数*每采样位数/8;
块大小=4+(8+次块大小)+(8+次块大小);
wav_header.ChunkID[0]=“R”;
wav_header.ChunkID[1]=“I”;
wav_header.ChunkID[2]=“F”;
wav_header.ChunkID[3]=“F”;
wav_header.ChunkSize=块大小;
wav_头。格式[0]=“W”;
wav_header.Format[1]=“A”;
wav_header.Format[2]=“V”;
wav_header.Format[3]=“E”;
wav_头.Subchunk1ID[0]=“f”;
wav_header.Subchunk1ID[1]=“m”;
wav_header.Subchunk1ID[2]=“t”;
wav_header.Subchunk1ID[3]='';
wav_header.Subchunk1Size=Subchunk1Size;
wav_header.AudioFormat=音频_格式;
wav_header.NumChannels=NUM_通道;
wav_header.SampleRate=采样器;
wav_header.ByteRate=字节率;
wav_header.BlockAlign=块对齐;
wav_header.BitsPerSample=每个样本的位;
wav_header.Subchunk2ID[0]=“d”;
wav_header.Subchunk2ID[1]=“a”;
wav_header.Subchunk2ID[2]=“t”;
wav_header.Subchunk2ID[3]=“a”;
wav_header.Subchunk2Size=subchunk2_size;
写入计数=写入(&wav)头,
sizeof(wavfile\u头文件),1,
文件(p),;
ret=(1!=写入计数)?-1:0;
返回ret;
}
/*使用两个通道保存单个帧的数据结构*/
typedef结构PCM16_立体声
{
int16_t左;
国际权利;
}PCM16_立体声;
PCM16立体声*分配PCM16立体声缓冲区(int32帧计数)
{
返回(PCM16_立体声*)malloc(sizeof(PCM16_立体声)*帧数);
}
/*返回成功写入的音频帧数*/
大小写入PCM16wav数据(文件*文件),
int32_t帧计数,
PCM16(立体声*缓冲区)
{
尺寸(单位);;
ret=fwrite(缓冲区),
sizeof(PCM16立体声),帧数,
文件(p),;
返回ret;
}
/*以两个频率和振幅生成两个锯齿信号*/
int生成双锯齿(双频1,
双振幅1,
双频2,
双振幅2,
int32_t采样器,
int32_t帧计数,
PCM16(立体声*缓冲区)
{
int-ret=0;
双采样器d=(双)采样器;
双采样周期=1.0/SampleRate\u d;
双周期1,周期2;
双相1,相2;
双斜率1,斜率2;
int32_t k;
/*检查是否违反奈奎斯特极限*/
如果((频率1*2>=采样器d)| |(频率2*2>=采样器d))
{
ret=-1;
write_little_endian((unsigned int)(data[i]),bytes_per_sample, wav_file);
write_little_endian((unsigned int)(datatwo[i]),bytes_per_sample, wav_file);
/*Compiles with gcc -Wall -O2 -o wavwrite wavwrite.c*/
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <limits.h>
/*
The header of a wav file Based on:
https://ccrma.stanford.edu/courses/422/projects/WaveFormat/
*/
typedef struct wavfile_header_s
{
char ChunkID[4]; /* 4 */
int32_t ChunkSize; /* 4 */
char Format[4]; /* 4 */
char Subchunk1ID[4]; /* 4 */
int32_t Subchunk1Size; /* 4 */
int16_t AudioFormat; /* 2 */
int16_t NumChannels; /* 2 */
int32_t SampleRate; /* 4 */
int32_t ByteRate; /* 4 */
int16_t BlockAlign; /* 2 */
int16_t BitsPerSample; /* 2 */
char Subchunk2ID[4];
int32_t Subchunk2Size;
} wavfile_header_t;
/*Standard values for CD-quality audio*/
#define SUBCHUNK1SIZE (16)
#define AUDIO_FORMAT (1) /*For PCM*/
#define NUM_CHANNELS (2)
#define SAMPLE_RATE (44100)
#define BITS_PER_SAMPLE (16)
#define BYTE_RATE (SAMPLE_RATE * NUM_CHANNELS * BITS_PER_SAMPLE/8)
#define BLOCK_ALIGN (NUM_CHANNELS * BITS_PER_SAMPLE/8)
/*Return 0 on success and -1 on failure*/
int write_PCM16_stereo_header( FILE* file_p,
int32_t SampleRate,
int32_t FrameCount)
{
int ret;
wavfile_header_t wav_header;
int32_t subchunk2_size;
int32_t chunk_size;
size_t write_count;
subchunk2_size = FrameCount * NUM_CHANNELS * BITS_PER_SAMPLE/8;
chunk_size = 4 + (8 + SUBCHUNK1SIZE) + (8 + subchunk2_size);
wav_header.ChunkID[0] = 'R';
wav_header.ChunkID[1] = 'I';
wav_header.ChunkID[2] = 'F';
wav_header.ChunkID[3] = 'F';
wav_header.ChunkSize = chunk_size;
wav_header.Format[0] = 'W';
wav_header.Format[1] = 'A';
wav_header.Format[2] = 'V';
wav_header.Format[3] = 'E';
wav_header.Subchunk1ID[0] = 'f';
wav_header.Subchunk1ID[1] = 'm';
wav_header.Subchunk1ID[2] = 't';
wav_header.Subchunk1ID[3] = ' ';
wav_header.Subchunk1Size = SUBCHUNK1SIZE;
wav_header.AudioFormat = AUDIO_FORMAT;
wav_header.NumChannels = NUM_CHANNELS;
wav_header.SampleRate = SampleRate;
wav_header.ByteRate = BYTE_RATE;
wav_header.BlockAlign = BLOCK_ALIGN;
wav_header.BitsPerSample = BITS_PER_SAMPLE;
wav_header.Subchunk2ID[0] = 'd';
wav_header.Subchunk2ID[1] = 'a';
wav_header.Subchunk2ID[2] = 't';
wav_header.Subchunk2ID[3] = 'a';
wav_header.Subchunk2Size = subchunk2_size;
write_count = fwrite( &wav_header,
sizeof(wavfile_header_t), 1,
file_p);
ret = (1 != write_count)? -1 : 0;
return ret;
}
/*Data structure to hold a single frame with two channels*/
typedef struct PCM16_stereo_s
{
int16_t left;
int16_t right;
} PCM16_stereo_t;
PCM16_stereo_t *allocate_PCM16_stereo_buffer( int32_t FrameCount)
{
return (PCM16_stereo_t *)malloc(sizeof(PCM16_stereo_t) * FrameCount);
}
/*Return the number of audio frames sucessfully written*/
size_t write_PCM16wav_data(FILE* file_p,
int32_t FrameCount,
PCM16_stereo_t *buffer_p)
{
size_t ret;
ret = fwrite( buffer_p,
sizeof(PCM16_stereo_t), FrameCount,
file_p);
return ret;
}
/*Generate two saw-tooth signals at two frequencies and amplitudes*/
int generate_dual_sawtooth( double frequency1,
double amplitude1,
double frequency2,
double amplitude2,
int32_t SampleRate,
int32_t FrameCount,
PCM16_stereo_t *buffer_p)
{
int ret = 0;
double SampleRate_d = (double)SampleRate;
double SamplePeriod = 1.0/SampleRate_d;
double Period1, Period2;
double phase1, phase2;
double Slope1, Slope2;
int32_t k;
/*Check for the violation of the Nyquist limit*/
if( (frequency1*2 >= SampleRate_d) || (frequency2*2 >= SampleRate_d) )
{
ret = -1;
goto error0;
}
/*Compute the period*/
Period1 = 1.0/frequency1;
Period2 = 1.0/frequency2;
/*Compute the slope*/
Slope1 = amplitude1/Period1;
Slope2 = amplitude2/Period2;
for(k = 0, phase1 = 0.0, phase2 = 0.0;
k < FrameCount;
k++)
{
phase1 += SamplePeriod;
phase1 = (phase1 > Period1)? (phase1 - Period1) : phase1;
phase2 += SamplePeriod;
phase2 = (phase2 > Period2)? (phase2 - Period2) : phase2;
buffer_p[k].left = (int16_t)(phase1 * Slope1);
buffer_p[k].right = (int16_t)(phase2 * Slope2);
}
error0:
return ret;
}
int main(void)
{
int ret;
FILE* file_p;
double frequency1 = 493.9; /*B4*/
double amplitude1 = 0.65 * (double)SHRT_MAX;
double frequency2 = 392.0; /*G4*/
double amplitude2 = 0.75 * (double)SHRT_MAX;
double duration = 10; /*seconds*/
int32_t FrameCount = duration * SAMPLE_RATE;
PCM16_stereo_t *buffer_p = NULL;
size_t written;
/*Open the wav file*/
file_p = fopen("./sawtooth_test.wav", "w");
if(NULL == file_p)
{
perror("fopen failed in main");
ret = -1;
goto error0;
}
/*Allocate the data buffer*/
buffer_p = allocate_PCM16_stereo_buffer(FrameCount);
if(NULL == buffer_p)
{
perror("fopen failed in main");
ret = -1;
goto error1;
}
/*Fill the buffer*/
ret = generate_dual_sawtooth( frequency1,
amplitude1,
frequency2,
amplitude2,
SAMPLE_RATE,
FrameCount,
buffer_p);
if(ret < 0)
{
fprintf(stderr, "generate_dual_sawtooth failed in main\n");
ret = -1;
goto error2;
}
/*Write the wav file header*/
ret = write_PCM16_stereo_header(file_p,
SAMPLE_RATE,
FrameCount);
if(ret < 0)
{
perror("write_PCM16_stereo_header failed in main");
ret = -1;
goto error2;
}
/*Write the data out to file*/
written = write_PCM16wav_data( file_p,
FrameCount,
buffer_p);
if(written < FrameCount)
{
perror("write_PCM16wav_data failed in main");
ret = -1;
goto error2;
}
/*Free and close everything*/
error2:
free(buffer_p);
error1:
fclose(file_p);
error0:
return ret;
}