与《》为姊妹篇。
为了便于学习C++音频处理并研究音频算法，
俺写了一个适合初学者学习的小小框架。
麻雀虽小五脏俱全，仅仅考虑单通道处理。
采用Decoder and Encoder:dr_wav
https://github.com/mackron/dr_libs/blob/master/dr_wav.h
关于wav格式的解析移步至:
http://soundfile.sapp.org/doc/WaveFormat/
个人习惯，采用int16的处理方式，也可以通过简单的修改，改为float类型。
wav音频样本可以从维基百科上(https://en.wikipedia.org/wiki/WAV)下载。
注:少数wav格式不支持
| Format | Bitrate () | 1 minute () | Sample |
|---|---|---|---|
| 11,025 Hz 16 bit PCM | 176.4 | 1292 | |
| 8,000 Hz 16 bit PCM | 128 | 938 | |
| 11,025 Hz 8 bit PCM | 88.2 | 646 | |
| 11,025 Hz | 88.2 | 646 | |
| 8,000 Hz 8 bit PCM | 64 | 469 | |
| 8,000 Hz µ-Law | 64 | 469 | |
| 11,025 Hz 4 bit | 44.1 | 323 | |
| 8,000 Hz 4 bit ADPCM | 32 | 234 | |
| 11,025 Hz GSM 06.10 | 18 | 132 | |
| 8,000 Hz MP3 16 kbit/s | 16 | 117 | |
| 8,000 Hz GSM 06.10 | 13 | 103 | |
| 8,000 Hz SBC 12 kbit/s | 12 | 88 | |
| 8,000 Hz | 9 | 66 | |
| 8,000 Hz MP3 8 kbit/s | 8 | 60 | |
| 8,000 Hz Lernout & Hauspie | 4.8 | 35 |
附带处理耗时计算,示例演示了一个简单的将音频前面一半静音处理,并简单注释了一下部分逻辑。
完整代码:
#include#include #include #include #include //采用https://github.com/mackron/dr_libs/blob/master/dr_wav.h 解码#define DR_WAV_IMPLEMENTATION#include "dr_wav.h"auto const epoch = clock();static double now(){ return (clock() - epoch);};template static double bench(const FN &fn){ auto took = -now(); return (fn(), took + now()) / 1000;}//写wav文件void wavWrite_int16(char* filename, int16_t* buffer, int sampleRate, uint32_t totalSampleCount) { drwav_data_format format; format.container = drwav_container_riff; // <-- drwav_container_riff = normal WAV files, drwav_container_w64 = Sony Wave64. format.format = DR_WAVE_FORMAT_PCM; // <-- Any of the DR_WAVE_FORMAT_* codes. format.channels = 1; format.sampleRate = sampleRate; format.bitsPerSample = 16; drwav* pWav = drwav_open_file_write(filename, &format); if (pWav) { drwav_uint64 samplesWritten = drwav_write(pWav, totalSampleCount, buffer); drwav_uninit(pWav); } }//读取wav文件int16_t* wavRead_int16(char* filename, uint32_t* sampleRate, uint64_t *totalSampleCount) { unsigned int channels; int16_t* buffer = drwav_open_and_read_file_s16(filename, &channels, sampleRate, totalSampleCount); if (buffer == NULL) { printf("读取wav文件失败."); } //仅仅处理单通道音频 if (channels != 1) { drwav_free(buffer); buffer = NULL; *sampleRate = 0; *totalSampleCount = 0; } return buffer;}//分割路径函数void splitpath(const char* path, char* drv, char* dir, char* name, char* ext){ const char* end; const char* p; const char* s; if (path[0] && path[1] == ':') { if (drv) { *drv++ = *path++; *drv++ = *path++; *drv = '\0'; } } else if (drv) *drv = '\0'; for (end = path; *end && *end != ':';) end++; for (p = end; p > path && *--p != '\\' && *p != '/';) if (*p == '.') { end = p; break; } if (ext) for (s = end; (*ext = *s++);) ext++; for (p = end; p > path;) if (*--p == '\\' || *p == '/') { p++; break; } if (name) { for (s = p; s < end;) *name++ = *s++; *name = '\0'; } if (dir) { for (s = path; s < p;) *dir++ = *s++; *dir = '\0'; }}int main(int argc, char* argv[]){ std::cout << "Audio Processing " << std::endl; std::cout << "博客:http://cpuimage.cnblogs.com/" << std::endl; std::cout << "支持解析单通道wav格式." << std::endl; if (argc < 2) return -1; char* in_file = argv[1]; //音频采样率 uint32_t sampleRate = 0; //总音频采样数 uint64_t totalSampleCount = 0; int16_t* wavBuffer = NULL; double nLoadTime = bench([&] { wavBuffer = wavRead_int16(in_file, &sampleRate, &totalSampleCount); }); std::cout << " 加载耗时: " << int(nLoadTime * 1000) << " 毫秒" << std::endl; //如果加载成功 if (wavBuffer != NULL) { //将前面一般进行静音处理，直接置零即可 for (uint64_t i = 0; i < totalSampleCount / 2; i++) { wavBuffer[i] = 0; } } //保存结果 double nSaveTime = bench([&] { char drive[3]; char dir[256]; char fname[256]; char ext[256]; char out_file[1024]; splitpath(in_file, drive, dir, fname, ext); sprintf(out_file, "%s%s%s_out%s", drive, dir, fname, ext); wavWrite_int16(out_file, wavBuffer, sampleRate, totalSampleCount); }); std::cout << " 保存耗时: " << int(nSaveTime * 1000) << " 毫秒" << std::endl; if (wavBuffer) { free(wavBuffer); } getchar(); std::cout << "按任意键退出程序 \n" << std::endl; return 0;}
示例具体流程为：
加载wav(拖放wav文件到可执行文件上)->简单静音处理->保存wav
并对 加载，保存 这2个环节都进行了耗时计算并输出。
若有其他相关问题或者需求也可以邮件联系俺探讨。
邮箱地址是:
gaozhihan@vip.qq.com
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