一、获取麦克风设备

#include <stdio.h>
#include <dshow.h>
#include <string>
#include <Windows.h>
#include <comutil.h>#pragma comment(lib, "Strmiids.lib")
#pragma comment(lib, "comsuppw.lib")#define MAX_FRIENDLY_NAME_LENGTH    128int GetAudioInputDevice(char* device)
{HRESULT hr;// 初始化COMhr = CoInitializeEx(NULL, COINIT_APARTMENTTHREADED);if (FAILED(hr)){return -1;}// 创建系统设备枚举器实例ICreateDevEnum *pSysDevEnum = NULL;hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL, CLSCTX_INPROC_SERVER, IID_ICreateDevEnum, (void **)&pSysDevEnum);if (FAILED(hr)){CoUninitialize();return -1;}// 获取设备类枚举器IEnumMoniker *pEnumCat = NULL;hr = pSysDevEnum->CreateClassEnumerator(CLSID_AudioInputDeviceCategory, &pEnumCat, 0);if (hr == S_OK){// 枚举设备名称IMoniker *pMoniker = NULL;ULONG cFetched;int i = 0;while (pEnumCat->Next(1, &pMoniker, &cFetched) == S_OK){IPropertyBag *pPropBag;hr = pMoniker->BindToStorage(NULL, NULL, IID_IPropertyBag, (void **)&pPropBag);if (SUCCEEDED(hr)){// 获取设备友好名VARIANT varName;VariantInit(&varName);hr = pPropBag->Read(L"FriendlyName", &varName, NULL);if (SUCCEEDED(hr)){StringCchCopy(device, MAX_FRIENDLY_NAME_LENGTH, _com_util::ConvertBSTRToString(varName.bstrVal));}VariantClear(&varName);pPropBag->Release();break;}pMoniker->Release();} // End for WhilepEnumCat->Release();}pSysDevEnum->Release();CoUninitialize();return 0;
}

// ANSI转UTF-8，后面初始化解码时使用

std::string AnsiToUTF8( const std::string& strIn, std::string& strOut )
{WCHAR* strSrc    = NULL;TCHAR* szRes    = NULL;int len = MultiByteToWideChar(CP_ACP, 0, (LPCSTR)strIn.c_str(), -1, NULL,0);unsigned short* wszUtf8 = new unsigned short[len+1];memset(wszUtf8, 0, len * 2 + 2);MultiByteToWideChar(CP_ACP, 0, (LPCSTR)strIn.c_str(), -1, (LPWSTR)wszUtf8, len);len = WideCharToMultiByte(CP_UTF8, 0, (LPCWSTR)wszUtf8, -1, NULL, 0, NULL, NULL);char* szUtf8 = new char[len + 1];memset(szUtf8, 0, len + 1);WideCharToMultiByte (CP_UTF8, 0, (LPCWSTR)wszUtf8, -1, szUtf8, len, NULL,NULL);strOut = szUtf8;delete[] szUtf8;delete[] wszUtf8;return strOut;
}

二、抓取音频并转为G711

1、结构体定义   

typedef struct  
{AVCodecContext        *pEncCodecCtx;AVFrame                *pEncFrame;uint8_t                *pEncFrameBuf;int                    iAudioIndex;AVFormatContext        *pDecFmtCtx;AVCodecContext        *pDecCodecCtx;AVPacket            *pDecPacket;AVFrame                *pDecFrame;int                    src_chl_layout;int                    dst_chl_layout;int                    src_sample_rate;int                    dst_sample_rate;int                    frameSize;AVAudioFifo*        audiofifo;struct SwrContext    *swr_ctx;int                    src_nb_samples;int                    dst_nb_samples;int                    max_dst_nb_samples;int                    dst_nb_channels;int                    dst_linesize;uint8_t                **dst_data;audio_data_call_back    cb;void*                    usr;
}ST_FFAUDIO;static ST_FFAUDIO s_st_ff;static int s_ichannel = 1;        //通道数
static int s_sample = 8000;    //采样率
static int s_type = 0;               //类型 A - U

2、ffmpeg初始化 

avformat_network_init();
avdevice_register_all();

3、初始化编码器

static int init_enc(int ichannel)
{AVCodec *pCodec;int size=0;AVCodecID codec_id = AV_CODEC_ID_PCM_ALAW;   //G711Aif (s_type == 1){codec_id = AV_CODEC_ID_PCM_MULAW;  //G711U}pCodec = avcodec_find_encoder(codec_id);if (!pCodec) {return -1;}s_st_ff.pEncCodecCtx = avcodec_alloc_context3(pCodec);if (!s_st_ff.pEncCodecCtx) {return -1;}s_st_ff.pEncCodecCtx->codec_id = codec_id;s_st_ff.pEncCodecCtx->codec_type = AVMEDIA_TYPE_AUDIO;s_st_ff.pEncCodecCtx->sample_fmt = AV_SAMPLE_FMT_S16;s_st_ff.pEncCodecCtx->sample_rate= s_sample;//44100;s_st_ff.pEncCodecCtx->channel_layout= ichannel==1 ? AV_CH_LAYOUT_MONO : AV_CH_LAYOUT_STEREO;s_st_ff.pEncCodecCtx->channels = av_get_channel_layout_nb_channels(s_st_ff.pEncCodecCtx->channel_layout);s_st_ff.pEncCodecCtx->bit_rate = 64000;  if (avcodec_open2(s_st_ff.pEncCodecCtx, pCodec, NULL) < 0) {return -1;}s_st_ff.pEncCodecCtx->frame_size = s_st_ff.frameSize;    //s_st_ff.pEncCodecCtx->sample_rate / 2;s_st_ff.pEncFrame = av_frame_alloc();s_st_ff.pEncFrame->nb_samples= s_st_ff.pEncCodecCtx->frame_size;s_st_ff.pEncFrame->format= s_st_ff.pEncCodecCtx->sample_fmt;size = av_samples_get_buffer_size(NULL, s_st_ff.pEncCodecCtx->channels,s_st_ff.pEncCodecCtx->frame_size,s_st_ff.pEncCodecCtx->sample_fmt, 1);s_st_ff.pEncFrameBuf = (uint8_t *)av_malloc(size);avcodec_fill_audio_frame(s_st_ff.pEncFrame, s_st_ff.pEncCodecCtx->channels, s_st_ff.pEncCodecCtx->sample_fmt,(const uint8_t*)s_st_ff.pEncFrameBuf, size, 1);s_st_ff.audiofifo = av_audio_fifo_alloc(AV_SAMPLE_FMT_S16, s_ichannel, 1);return 0;
}

4、初始化解码器

static int init_decode(const char* dev, int ichannel)
{s_st_ff.pDecFmtCtx = avformat_alloc_context();AVDictionary* options = NULL;av_dict_set(&options, "list_devices", "true", 0);AVInputFormat *iformat = av_find_input_format("dshow");char _dev[128] = {0};   GetAudioInputDevice(_dev);log_msg_ex("dev : %s", _dev);std::string device_name = "audio=";device_name += std::string(_dev);std::string strOut;const char* utf8 = AnsiToUTF8(device_name, strOut).c_str();AVDictionary* tmp = NULL;av_dict_set_int(&tmp, "sample_rate", (long)44100, 0);     //我的设备不支持8000,先采44100在重采样成8000av_dict_set_int(&tmp, "sample_size", (long)16, 0);av_dict_set_int(&tmp, "channels", (long)ichannel, 0);//av_dict_set_int(&tmp, "audio_buffer_size", (long)40, 0);  //buffer大小是以采样率44100计算的,设置了采样率也无效int ret2 = avformat_open_input(&s_st_ff.pDecFmtCtx, strOut.c_str(), iformat, &tmp);if (ret2 != 0){return -1;}if(avformat_find_stream_info(s_st_ff.pDecFmtCtx,NULL)<0)  { return -1;  }  int ret;AVCodec         *pCodec;for(int i=0; i<s_st_ff.pDecFmtCtx->nb_streams; i++)   {if(s_st_ff.pDecFmtCtx->streams[i]->codecpar->codec_type==AVMEDIA_TYPE_AUDIO)  {  pCodec = avcodec_find_decoder(s_st_ff.pDecFmtCtx->streams[i]->codecpar->codec_id);if (pCodec == nullptr){printf("Codec not found.（没有找到解码器）\n");return -1;}//从视频流中拷贝参数到codecCtxs_st_ff.pDecCodecCtx = avcodec_alloc_context3(pCodec);if ((ret = avcodec_parameters_to_context(s_st_ff.pDecCodecCtx, s_st_ff.pDecFmtCtx->streams[i]->codecpar)) < 0){return -1;}s_st_ff.iAudioIndex=i;  break;  }  if(s_st_ff.iAudioIndex==-1)  { return -1;  }}if(avcodec_open2(s_st_ff.pDecCodecCtx, pCodec,NULL)<0)  { return -1;  } s_st_ff.pDecFrame=av_frame_alloc();  if(NULL==s_st_ff.pDecFrame)  { return -1;  }  return 0;
}

5、初始化转码

int init_swr(int ichannel)
{int ret = 0;s_st_ff.swr_ctx = swr_alloc();if (!s_st_ff.swr_ctx) {fprintf(stderr, "Could not allocate resampler context\n");return -1;}/* set options */av_opt_set_int(s_st_ff.swr_ctx, "in_channel_layout",     ichannel==1 ? AV_CH_LAYOUT_MONO : AV_CH_LAYOUT_STEREO, 0);av_opt_set_int(s_st_ff.swr_ctx, "in_sample_rate",       44100, 0);av_opt_set_sample_fmt(s_st_ff.swr_ctx, "in_sample_fmt", AV_SAMPLE_FMT_S16, 0);av_opt_set_int(s_st_ff.swr_ctx, "out_channel_layout",    ichannel==1 ? AV_CH_LAYOUT_MONO : AV_CH_LAYOUT_STEREO, 0);av_opt_set_int(s_st_ff.swr_ctx, "out_sample_rate",       s_sample, 0);av_opt_set_sample_fmt(s_st_ff.swr_ctx, "out_sample_fmt", AV_SAMPLE_FMT_S16, 0);/* initialize the resampling context */if ((ret = swr_init(s_st_ff.swr_ctx)) < 0) {fprintf(stderr, "Failed to initialize the resampling context\n");return -1;}s_st_ff.src_nb_samples = 22050;s_st_ff.max_dst_nb_samples = s_st_ff.dst_nb_samples =av_rescale_rnd(s_st_ff.src_nb_samples, s_sample, 44100, AV_ROUND_UP);s_st_ff.dst_nb_channels = av_get_channel_layout_nb_channels(ichannel==1 ? AV_CH_LAYOUT_MONO : AV_CH_LAYOUT_STEREO);ret = av_samples_alloc_array_and_samples(&s_st_ff.dst_data, &s_st_ff.dst_linesize, s_st_ff.dst_nb_channels,s_st_ff.dst_nb_samples, AV_SAMPLE_FMT_S16, 0);if (ret < 0) {fprintf(stderr, "Could not allocate destination samples\n");return -1;}return 0;
}

6、抓取线程

FILE *fp_pcm;
FILE *fp_711;
FILE *fp_swr;
void* __stdcall thread_cap(void* arg)
{int frameCnt=100;AVPacket pkt;int i = 0;int ret;uint64_t tss = 0;uint ts = 0;while(s_istart){  //log_msg_ex("run  %d", s_istart);MSG   msg;while( PeekMessage( &msg, NULL, 0, 0, PM_REMOVE ) ){TranslateMessage( &msg );DispatchMessage( &msg );}uint64_t ts_start = gettime();if(av_read_frame(s_st_ff.pDecFmtCtx, s_st_ff.pDecPacket)>=0){  if(s_st_ff.pDecPacket->stream_index==s_st_ff.iAudioIndex){ret = avcodec_send_packet(s_st_ff.pDecCodecCtx, s_st_ff.pDecPacket);if(ret < 0){  printf("avcodec_send_packet Error.\n");  return NULL;  }  ret = avcodec_receive_frame(s_st_ff.pDecCodecCtx, s_st_ff.pDecFrame);if(ret < 0){  printf("avcodec_receive_frame Error.\n");  return NULL;  }  uint8_t * pcmBuffer = s_st_ff.pDecFrame->data[0];int pcmSize = av_samples_get_buffer_size(NULL, s_st_ff.pDecCodecCtx->channels, s_st_ff.pDecFrame->nb_samples, s_st_ff.pDecCodecCtx->sample_fmt, 1);if (pcmSize <= 0){printf("pcmSize <= 0");continue;}
#if OUTPUT_PCM    fwrite(pcmBuffer,1,pcmSize,fp_pcm);    //Y                   
#endif                       //重采样              int swr_len = 0;int fifo_size = swr_get_out_samples(s_st_ff.swr_ctx, 0);swr_len = swr_convert(s_st_ff.swr_ctx, s_st_ff.dst_data, s_st_ff.dst_nb_samples, (const uint8_t **)s_st_ff.pDecFrame->data, s_st_ff.src_nb_samples);if (swr_len < 0) {printf("Error while converting\n");break;}int dst_bufsize = av_samples_get_buffer_size(&s_st_ff.dst_linesize, s_st_ff.dst_nb_channels,swr_len, AV_SAMPLE_FMT_S16, 1);if (dst_bufsize < 0) {log_msg_ex("Could not get sample buffer size\n");break;}
#if OUTPUT_PCM    fwrite(s_st_ff.dst_data[0], 1, dst_bufsize, fp_swr);
#endif               av_audio_fifo_realloc(s_st_ff.audiofifo, av_audio_fifo_size(s_st_ff.audiofifo) + s_st_ff.dst_nb_samples);av_audio_fifo_write(s_st_ff.audiofifo, (void **)s_st_ff.dst_data, s_st_ff.dst_nb_samples);while(av_audio_fifo_size(s_st_ff.audiofifo) >= s_st_ff.frameSize){//encode g711aint frame_size = FFMIN(av_audio_fifo_size(s_st_ff.audiofifo), s_st_ff.frameSize);tss+=frame_size;AVFrame* output_frame = NULL;output_frame = av_frame_alloc();output_frame->nb_samples = frame_size;output_frame->channel_layout = AV_CH_LAYOUT_MONO;output_frame->format = AV_SAMPLE_FMT_S16;output_frame->sample_rate = s_sample;output_frame->pts = tss;av_frame_get_buffer(output_frame, 0);av_audio_fifo_read(s_st_ff.audiofifo, (void **)output_frame->data, frame_size);av_init_packet(&pkt);pkt.data = NULL;    // packet data will be allocated by the encoderpkt.size = 0;//s_st_ff.pEncFrame->pts = i++;ret = avcodec_send_frame(s_st_ff.pEncCodecCtx, output_frame);    //s_st_ff.pEncFrameret = avcodec_receive_packet(s_st_ff.pEncCodecCtx, &pkt);if (ret < 0) {printf("Error encoding frame\n");return NULL;}#if OUTPUT_G711fwrite(pkt.data, 1, pkt.size, fp_711);#endifts += s_st_ff.frameSize;//printf("Succeed to encode size:%5d   pts:%I64d   ts:%u\n", pkt.size, pkt.pts, ts);if (s_st_ff.cb){s_st_ff.cb(pkt.data, pkt.size, ts, s_st_ff.usr);}av_packet_unref(&pkt);if (!s_istart){break;}}}  av_packet_unref(s_st_ff.pDecPacket);  }  }  printf("thread quit");return NULL;
}

参考链接：

https://blog.csdn.net/wer85121430/article/details/79672813

https://blog.csdn.net/leixiaohua1020