前幾天無意間看到一個專案rnnoise。

專案地址: https://github.com/xiph/rnnoise

基於RNN的音訊降噪演算法。

採用的是 GRU/LSTM 模型。

閱讀下訓練程式碼，可惜的是作者沒有提供資料訓練集。

不過基本可以斷定他採用的資料集裡，肯定有urbansound8k。

urbansound8k 資料集地址:

https://serv.cusp.nyu.edu/projects/urbansounddataset/urbansound8k.html

也可以考慮採用用作者訓練的模型來構建資料集的做法，不過即費事，也麻煩。

經過實測，降噪效果很不錯，特別是在背景噪聲比較嚴重的情況下。

不過作者僅僅提供 pcm 的程式碼示例，並且還只支援48K取樣率，

( 明顯是為了相容其另一個 專案  opus)

在很多應用場景下，這很不方便。

儘管稍微有點麻煩，但是事在人為，花了點時間，稍作修改。

具體修改如下：

1.支援wav格式

 採用dr_wav(https://github.com/mackron/dr_libs/blob/master/dr_wav.h )

2.支援全部取樣率

取樣率的處理問題，採用簡單粗暴法，

詳情請移步博主另一篇小文《簡潔明瞭的插值音訊重取樣演算法例子 (附完整C程式碼)

3.增加CMake檔案

4.增加測試用 示例音訊sample.wav 

取自(https://github.com/orctom/rnnoise-java)

貼上完整示例程式碼 ：

/* Copyright (c) 2017 Mozilla */
/*
   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions
   are met:

   - Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.

   - Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
   CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#include <stdio.h>
#include "rnnoise.h"
#include <stdlib.h>
#include <stdint.h>

#define DR_WAV_IMPLEMENTATION

#include "dr_wav.h"


void wavWrite_int16(char *filename, int16_t *buffer, int sampleRate, uint32_t totalSampleCount) {
    drwav_data_format format;
    format.container = drwav_container_riff;
    format.format = DR_WAVE_FORMAT_PCM;
    format.channels = 1;
    format.sampleRate = (drwav_uint32) 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);
        if (samplesWritten != totalSampleCount) {
            fprintf(stderr, "ERROR\n");
            exit(1);
        }
    }
}

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) {
        fprintf(stderr, "ERROR\n");
        exit(1);
    }
    if (channels != 1) {
        drwav_free(buffer);
        buffer = NULL;
        *sampleRate = 0;
        *totalSampleCount = 0;
    }
    return buffer;
}

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';
    }
}

void resampleData(const int16_t *sourceData, int32_t sampleRate, uint32_t srcSize, int16_t *destinationData,
                  int32_t newSampleRate) {
    if (sampleRate == newSampleRate) {
        memcpy(destinationData, sourceData, srcSize * sizeof(int16_t));
        return;
    }
    uint32_t last_pos = srcSize - 1;
    uint32_t dstSize = (uint32_t) (srcSize * ((float) newSampleRate / sampleRate));
    for (uint32_t idx = 0; idx < dstSize; idx++) {
        float index = ((float) idx * sampleRate) / (newSampleRate);
        uint32_t p1 = (uint32_t) index;
        float coef = index - p1;
        uint32_t p2 = (p1 == last_pos) ? last_pos : p1 + 1;
        destinationData[idx] = (int16_t) ((1.0f - coef) * sourceData[p1] + coef * sourceData[p2]);
    }
}

void denoise_proc(int16_t *buffer, uint32_t buffen_len) {
    const int frame_size = 480;
    DenoiseState *st;
    st = rnnoise_create();
    int16_t patch_buffer[frame_size];
    if (st != NULL) {
        uint32_t frames = buffen_len / frame_size;
        uint32_t lastFrame = buffen_len % frame_size;
        for (int i = 0; i < frames; ++i) {
            rnnoise_process_frame(st, buffer, buffer);
            buffer += frame_size;
        }
        if (lastFrame != 0) {
            memset(patch_buffer, 0, frame_size * sizeof(int16_t));
            memcpy(patch_buffer, buffer, lastFrame * sizeof(int16_t));
            rnnoise_process_frame(st, patch_buffer, patch_buffer);
            memcpy(buffer, patch_buffer, lastFrame * sizeof(int16_t));
        }
    }
    rnnoise_destroy(st);
}

void rnnDeNoise(char *in_file, char *out_file) {
    uint32_t in_sampleRate = 0;
    uint64_t in_size = 0;
    int16_t *data_in = wavRead_int16(in_file, &in_sampleRate, &in_size);
    uint32_t out_sampleRate = 48000;
    uint32_t out_size = (uint32_t) (in_size * ((float) out_sampleRate / in_sampleRate));
    int16_t *data_out = (int16_t *) malloc(out_size * sizeof(int16_t));
    if (data_in != NULL && data_out != NULL) {
        resampleData(data_in, in_sampleRate, (uint32_t) in_size, data_out, out_sampleRate);
        denoise_proc(data_out, out_size);
        resampleData(data_out, out_sampleRate, (uint32_t) out_size, data_in, in_sampleRate);
        wavWrite_int16(out_file, data_in, in_sampleRate, (uint32_t) in_size);
        free(data_in);
        free(data_out);
    } else {
        if (data_in) free(data_in);
        if (data_out) free(data_out);
    }
}


int main(int argc, char **argv) {
    printf("Audio Noise Reduction\n");
    printf("blog:http://cpuimage.cnblogs.com/\n");
    printf("e-mail:
 
[email protected]\n");
    if (argc < 2)
        return -1;

    char *in_file = argv[1];
    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);
    rnnDeNoise(in_file, out_file);
    printf("press any key to exit.\n");
    getchar();
    return 0;
}

不多寫註釋，直接看程式碼吧。

 專案地址：https://github.com/cpuimage/rnnoise

示例具體流程為：

載入wav(拖放wav檔案到可執行檔案上)->重取樣降噪->儲存wav

若有其他相關問題或者需求也可以郵件聯絡俺探討。

郵箱地址是: 
[email protected]