问题描述
我想使用C ++读取音频(.wav)文件.
I want to read an audio (.wav) file using C++.
到目前为止，我已经阅读了wav文件的标题.我如何循环进入wav文件的数据部分，将其在-1和1之间转换，然后将其写到txt文件中.
So far i have read the header of the wav file. How do i loop into the data part of the wav file convert it between -1 and 1 and then write it out to a txt file.
我已经完成以下操作，但是当我使用MATLAB绘制生成的txt文件时，信号似乎失真了.
i have done the following but when i plot the resulting txt file using MATLAB, the signal seems to be distorted.
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <fstream>
using namespace std;
//double byteToDouble( char firstByte, char secondByte );
// WAVE PCM soundfile format (you can find more in https://ccrma.stanford.edu/courses/422/projects/WaveFormat/ )
typedef struct header_file
{
char chunk_id[4];
int chunk_size;
char format[4];
char subchunk1_id[4];
int subchunk1_size;
short int audio_format;
short int num_channels;
int sample_rate; // sample_rate denotes the sampling rate.
int byte_rate;
short int block_align;
short int bits_per_sample;
char subchunk2_id[4];
int subchunk2_size; // subchunk2_size denotes the number of samples.
//char data; // actual data : Added by tarmizi
} header;
typedef struct header_file* header_p;
int main()
{
ofstream myFile;
myFile.open("mizi.txt");
FILE * infile = fopen("0BF1S1T0.wav","rb"); // Open wave file in read mode
FILE * outfile = fopen("Output.txt","wb"); // Create output ( wave format) file in write mode;
FILE * svFile;
int BUFSIZE = 256; // BUFSIZE can be changed according to the frame size required (eg:512)
int count = 0; // For counting number of frames in wave file.
short int buff16[BUFSIZE]; // short int used for 16 bit as input data format is 16 bit PCM audio
header_p meta = (header_p)malloc(sizeof(header)); // header_p points to a header struct that contains the wave file metadata fields
int nb; // variable storing number of bytes returned
if (infile)
{
fread(meta, 1, sizeof(header), infile);
//fwrite(meta,1, sizeof(*meta), outfile);
cout << "first chunk is :" << sizeof(meta->chunk_id) << " bytes in size" << endl;
cout << "The file is a :" << meta->chunk_id << " format" << endl;
cout << " Size of Header file is "<<sizeof(*meta)<<" bytes" << endl;
cout << " Sampling rate of the input wave file is "<< meta->sample_rate <<" Hz" << endl;
cout << " Number of bits per sample is: "<< meta->bits_per_sample <<"bits" << endl;
cout << " Size of data in the audio is: " << sizeof(meta->subchunk2_size)<< " bytes" << endl;
cout << " The number of channels of the file is "<< meta->num_channels << " channels" << endl;
cout << " The audio format is PCM:"<< meta->audio_format << endl;
//cout << " The size of actual data is "<< sizeof(meta->data) << "bytes" << endl;
while (!feof(infile)) //(nb = fread(buff16,1,BUFSIZE,infile))>0
{
// Reading data in chunks of BUFSIZE
//cout << nb <<endl;
nb = fread(buff16,1,BUFSIZE,infile);
count++;
// Incrementing > of frame
for (int i = 0; i<BUFSIZE; i+=meta->num_channels) // BUFSIZE = 256, meta->num_channels = 1
{
int c = (buff16[i]<<8) | buff16[1+i];
double t = c/32768.0;
myFile << t<< endl;
}
}
cout << " Number of frames in the input wave file are " <<count << endl;
/
return 0;
}
}
有什么主意吗?我认为即时通讯不会循环通过数据并正确转换.在我这里，有人可以帮助显示正确的方法吗?预先感谢...
Any idea ? i think im not looping trough the data and converting properly. Can anyone help show the right way in my case here ? Thanks in advance...
推荐答案
将两个字节组合为一个int的方式始终会产生肯定的结果.为了正确处理符号，您应该将字节组合成短整数而不是整数.
The way you are combining the two bytes into an int is always going to produce a positive result. In order to handle the sign properly you should combine the bytes into a short instead of an int.
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