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speex的语音处理模块要使用独立于 speex codec库的libspeexdsp 库。
这个分离的库是在1.2版本后实现;
它这库包括了: 预处理,回声消除,jitter buffer 和重采样模块;
在Unix/Linux环境下,使用 -lspeexdsp -lm 来编译和链接。
和libspeex一样,库libspeexdsp的库函数都是可重入函数。
但它不是线程安全的,所以在多个线程中使用同一个实例时,必须加个线程安全锁。
NOTE:
所谓就是允许被的函数。
函数的递归调用是 指当一个函数正被调用尚未返回时,又直接或间接调用函数本身。
一般的函数不能做到这样,只有重入函数才允许递归调用.
$ tar -zxvf
$ cd speexdsp-1.2rc3
$./configure --prefix=/data/speexdsp-1.2rc3-install/ --enable-static --disable-shared --with-pic
$ make && make install
预处理模块需要添加头文件:
#include <speex/speex_preprocess.h>
创建实例:
SpeexPreprocessState *preprocess_state = speex_preprocess_state_init(frame_size,sampling_rate);
参数: frame_size , 建议设置成编码器相同的值。
对于每一个输入帧,调用处理的函数:
speex_preprocess_run(preprocess_state, audio_frame);
参数: audio_frame , 即是输入,也是输出。
在某些场景下,有些降噪的数据并不想输出,可以下面的API:
它会更新处理器内部的状态,但不会将降噪后的数据输出,这样可以节省一些计算量:
speex_preprocess_estimate_update(preprocess_state, audio_frame);
使用下面API来改变进行预处理器的状态设置,更多的参数见下面的一节:
speex_preprocess_ctl(preprocess_state, request, ptr);
实例销毁 :
speex_preprocess_state_destroy(preprocess_state);
3.1 Preprocessor options
As with the codec, the preprocessor also has options that can be controlled using an ioctl()-like call. The available options are:
SPEEX_PREPROCESS_SET_DENOISE Turns denoising on(1) or off(2) (spx_int32_t)
SPEEX_PREPROCESS_GET_DENOISE Get denoising status (spx_int32_t)
SPEEX_PREPROCESS_SET_AGC Turns automatic gain control (AGC) on(1) or off(2) (spx_int32_t)
SPEEX_PREPROCESS_GET_AGC Get AGC status (spx_int32_t)
SPEEX_PREPROCESS_SET_VAD Turns voice activity detector (VAD) on(1) or off(2) (spx_int32_t)
SPEEX_PREPROCESS_GET_VAD Get VAD status (spx_int32_t)
SPEEX_PREPROCESS_SET_AGC_LEVEL
SPEEX_PREPROCESS_GET_AGC_LEVEL
SPEEX_PREPROCESS_SET_DEREVERB Turns reverberation removal on(1) or off(2) (spx_int32_t)
SPEEX_PREPROCESS_GET_DEREVERB Get reverberation removal status (spx_int32_t)
SPEEX_PREPROCESS_SET_DEREVERB_LEVEL Not working yet, do not use
SPEEX_PREPROCESS_GET_DEREVERB_LEVEL Not working yet, do not use
SPEEX_PREPROCESS_SET_DEREVERB_DECAY Not working yet, do not use
SPEEX_PREPROCESS_GET_DEREVERB_DECAY Not working yet, do not use
SPEEX_PREPROCESS_SET_PROB_START
SPEEX_PREPROCESS_GET_PROB_START
SPEEX_PREPROCESS_SET_PROB_CONTINUE
SPEEX_PREPROCESS_GET_PROB_CONTINUE
SPEEX_PREPROCESS_SET_NOISE_SUPPRESS Setmaximumattenuation of the noise in dB (negativespx_int32_t)
SPEEX_PREPROCESS_GET_NOISE_SUPPRESS Getmaximumattenuation of the noise in dB (negativespx_int32_t)
SPEEX_PREPROCESS_SET_ECHO_SUPPRESS Setmaximumattenuation of the residual echo in dB (negative spx_int32_t)
SPEEX_PREPROCESS_GET_ECHO_SUPPRESS Setmaximumattenuation of the residual echo in dB (negativespx_int32_t)
SPEEX_PREPROCESS_SET_ECHO_SUPPRESS_ACTIVE Set maximum attenuation of the echo in dB when near
end is active (negative spx_int32_t)
SPEEX_PREPROCESS_GET_ECHO_SUPPRESS_ACTIVE Set maximum attenuation of the echo in dB when near
end is active (negative spx_int32_t)
SPEEX_PREPROCESS_SET_ECHO_STATE Set the associated echo canceller for residual echo suppression (pointer
or NULL for no residual echo suppression)
SPEEX_PREPROCESS_GET_ECHO_STATE Get the associated echo canceller (pointer)
C语言实现的音频降噪代码如下。
代码中采样率、音频帧大小需要根据实际情况设置,
HEADLEN是WAV格式的文件头,占44个字节,这44个字节是不需要处理的,不然文件头会损坏,
导致得到的结果无法播放。
如果是PCM数据,则没有这个头,直接输入指定长度的数据就行;
noiseSuppress的值可以控制减除的噪声强度,负值越小,噪声去除的强度越大,
同时会造成原声的失真,需要作出权衡。
#include#include #include #include #include #include #define HEADLEN 44#define SAMPLE_RATE (48000) #define SAMPLES_PER_FRAME (1024)#define FRAME_SIZE (SAMPLES_PER_FRAME * 1000/ SAMPLE_RATE)#define FRAME_BYTES (SAMPLES_PER_FRAME)int main(){ size_t n = 0; FILE *inFile, *outFile; fopen_s(&inFile, "./audio/input01L.wav", "rb"); fopen_s(&outFile, "./audio/output01L.wav", "wb"); char *headBuf = (char*)malloc(HEADLEN); char *dataBuf = (char*)malloc(FRAME_BYTES * 2 ); memset(headBuf, 0, HEADLEN); memset(dataBuf, 0, FRAME_BYTES); assert(headBuf != NULL); assert(dataBuf != NULL); SpeexPreprocessState *state = speex_preprocess_state_init(1024, SAMPLE_RATE); int denoise = 1; int noiseSuppress = -25; speex_preprocess_ctl(state, SPEEX_PREPROCESS_SET_DENOISE, &denoise); speex_preprocess_ctl(state, SPEEX_PREPROCESS_SET_NOISE_SUPPRESS, &noiseSuppress); int i; i = 0; speex_preprocess_ctl(state, SPEEX_PREPROCESS_SET_AGC, &i); i = 80000; speex_preprocess_ctl(state, SPEEX_PREPROCESS_SET_AGC_LEVEL, &i); i = 0; speex_preprocess_ctl(state, SPEEX_PREPROCESS_SET_DEREVERB, &i); float f = 0; speex_preprocess_ctl(state, SPEEX_PREPROCESS_SET_DEREVERB_DECAY, &f); f = 0; speex_preprocess_ctl(state, SPEEX_PREPROCESS_SET_DEREVERB_LEVEL, &f); //静音检测,效果一般 /* int vad = 1; int vadProbStart = 80; int vadProbContinue = 65; speex_preprocess_ctl(state, SPEEX_PREPROCESS_SET_VAD, &vad); speex_preprocess_ctl(state, SPEEX_PREPROCESS_SET_PROB_START, &vadProbStart); speex_preprocess_ctl(state, SPEEX_PREPROCESS_SET_PROB_CONTINUE, &vadProbContinue); */ bool flag = true; while (1) { if (flag == true) { flag = false; n = fread(headBuf, 1, HEADLEN, inFile); if (n == 0) break; fwrite(headBuf, 1, HEADLEN, outFile); } else { n = fread(dataBuf, 1, SAMPLES_PER_FRAME, inFile); if (n == 0) break; speex_preprocess_run(state, (spx_int16_t*)(dataBuf)); fwrite(dataBuf, 1, SAMPLES_PER_FRAME, outFile); } } free(headBuf); free(dataBuf); fclose(inFile); fclose(outFile); speex_preprocess_state_destroy(state); return 0;}
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