usb摄像头加live555建立rtspserver

使用vlc来播放rtsp的结果

1、采集usb摄像头

在我的其他文章中可以找到如何使用ffmpeg使用dshow采集usb摄像头，我们也可以直接使用dshow。也可以参考以下代码。

   int CameraCapture::initialise()
   {
      fState = 0;

      if (fCamDesc == NULL) {
         wprintf("camera description pointer not set!");
         return -1;
      }

      if (fCamDesc->name[0] == '\0') {
         wprintf("camera name is empty!");
         return -1;
      }

      int ret = 0;

      char str_tmp[128];
      str_tmp[127] = 0;

      AVDictionary* opt = nullptr;
      AVDictionaryEntry* dict_entry = nullptr;
      AVInputFormat *inFrmt = nullptr;

      // Initialize FFmpeg environment
      avdevice_register_all();
      av_log_set_level(AV_LOG_ERROR);
      if (fDecCtx != nullptr) {
         avcodec_free_context(&fDecCtx);
         fDecCtx = nullptr;
      }

      if (fInputCtx != nullptr) {
         avformat_close_input(&fInputCtx);
         fInputCtx = nullptr;
      }

      if (fFrameOut != nullptr) {
         if (fFrameOut->data[0] != nullptr) {
            av_freep(fFrameOut->data[0]);
         }
         av_frame_free(&fFrameOut);
         fFrameOut = nullptr;
      }

      fInputCtx = avformat_alloc_context();

      inFrmt = av_find_input_format("dshow");

      //video size
      ret = snprintf(str_tmp, 127, "video_size=%dx%d;pixel_format=%s;framerate=%g;",
         fCamDesc->width, fCamDesc->height, (fCamDesc->pixel_format).c_str(),
         fCamDesc->frame_rate);

      av_dict_parse_string(&opt, str_tmp, "=", ";", 0);

      if (fCamDesc->device_num > 0) {
         ret += av_dict_set(&opt, "video_device_number", int2str(fCamDesc->device_num).c_str(), 0);
      }
      if (!fCamDesc->pin_name.empty()) {
         av_dict_set(&opt, "video_pin_name", fCamDesc->pin_name.c_str(), 0);
      }

      if (fCamDesc->rtbuffsize > 102400) { //ignore a small rtbuffsize
         av_dict_set(&opt, "rtbufsize", byte2str(fCamDesc->rtbuffsize).c_str(), 0);
      }


      snprintf(str_tmp, 127, "video=%s", fCamDesc->name.c_str());

      if (ret = avformat_open_input(&fInputCtx, str_tmp, inFrmt, &opt) != 0) {
         //exception
         av_dict_free(&opt);
         av_strerror(ret, str_tmp, 127);
         eprintf("open video input '%s' failed! err = %s", fCamDesc->name.c_str(), str_tmp);
         return -1;
      }

      if (opt != nullptr) {
         iprintf("the following options are not used:");
         dict_entry = nullptr;
         while (dict_entry = av_dict_get(opt, "", dict_entry, AV_DICT_IGNORE_SUFFIX)) {
            fprintf(stdout, "  '%s' = '%s'\n", dict_entry->key, dict_entry->value);
         }
         av_dict_free(&opt);
      }

      if (avformat_find_stream_info(fInputCtx, nullptr) name.c_str());
         return -1;
      }

      //print out the video stream information
      iprintf("video stream from '%s': ", fCamDesc->name.c_str());
      av_dump_format(fInputCtx, 0, fInputCtx->url, 0);

      fOutStreamNum     = -1;
      AVStream*  stream = nullptr;
      for (unsigned int i = 0; i nb_streams; i++) {
         if (fInputCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
            fOutStreamNum = i;
            stream = fInputCtx->streams[i];
         }
      }

      if (fOutStreamNum == -1 || stream == nullptr) {
         //exception
         eprintf("no video stream found in '%s'!\n", fCamDesc->name.c_str());
         return -1;
      }

      AVCodecParameters  *codec_param = stream->codecpar;

      fBitrate = codec_param->bit_rate;

      fDelayClock = (int)((double)(CLOCKS_PER_SEC) * (double)(stream->avg_frame_rate.den) / (double)(stream->avg_frame_rate.num));

      AVCodec* decoder = avcodec_find_decoder(codec_param->codec_id);
      if (decoder == nullptr) {
         eprintf("cannot find decoder for '%s'!", avcodec_get_name(codec_param->codec_id));
         return -1;
      }

      fDecCtx = avcodec_alloc_context3(decoder);

      avcodec_parameters_to_context(fDecCtx, codec_param);

      av_log_set_level(AV_LOG_FATAL);
      if (avcodec_open2(fDecCtx, decoder, nullptr) width, fDecCtx->height, fDecCtx->pix_fmt,
         fDecCtx->width, fDecCtx->height, AV_PIX_FMT_NV12, SWS_BICUBIC, nullptr, nullptr, nullptr);

      fFrameOut = av_frame_alloc();
      if (fFrameOut == nullptr) {
         eprintf("allocating output frame failed!");
         return -1;
      }
      fFrameOut->width = fDecCtx->width;
      fFrameOut->height = fDecCtx->height;
      fFrameOut->format = AV_PIX_FMT_NV12;
      fDataOutSz = av_image_get_buffer_size(AV_PIX_FMT_NV12, fFrameOut->width,
         fFrameOut->height, MEM_ALIGN);
      ret = av_frame_get_buffer(fFrameOut, MEM_ALIGN);
      if (ret set_PPS_NAL(fH264Encoder->PPS_NAL(), fH264Encoder->PPS_NAL_size());
         sub->set_SPS_NAL(fH264Encoder->SPS_NAL(), fH264Encoder->SPS_NAL_size());
         if (fH264Encoder->h264_bit_rate() > 102400) {
            sub->set_bit_rate(fH264Encoder->h264_bit_rate());
         }
         else {
            sub->set_bit_rate(static_cast(fH264Encoder->pict_width() * fH264Encoder->pict_height() * fH264Encoder->frame_rate() / 20));
         }
         
         sms->addSubsession(sub);
         rtspServer->addServerMediaSession(sms);

         char* url = rtspServer->rtspURL(sms);
         *env taskScheduler().doEventLoop(&fQuit); // does not return

         Medium::close(rtspServer);
         Medium::close(inputDevice);
      }

      env->reclaim();
      delete scheduler;
   };
}