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• How to remove or attenuate background noise in videos

  20 août 2019, par David

  Tried removing typical background noise (low volume TV, indoor and outdoor air-conditioner/fan) from videos using following code. Didn’t work. Would appreciate advice on how to do this.

  ffmpeg -loglevel warning -y -strict -2 -i IN.mts -af "highpass=f=200, lowpass=f=3000" OUT.mts

  SHORT SAMPLE VIDEOS :

  low volume TV in background :
  https://youtu.be/wOQuKgDeC5A

  Inside air conditioner or fan :
  https://youtu.be/BTDFtH3vksY

  Outside air conditioner :
  https://youtu.be/EeSyKM25Gig

• SDL Audio - Plays only Static Noise

  19 août 2019, par bcpermafrost

  Im having an issue with playing audio.

  Im new to the SDL World of things so im learning from a tutorial.

  http://dranger.com/ffmpeg/tutorial03.html

  As far as audio goes, i have exactly what he put down and didnt get the result he says I should get. In the end of the lesson he specifies that the audio should play normally. However all i get is excessively loud static noise. This leads me to believe that the packets arent being read correctly. However I have no idea how to debug or look for the issue.

  Here is my main loop for parsing the packets :

   while (av_read_frame(pFormatCtx, &packet) >= 0) {
  
  
  
           if (packet.stream_index == videoStream) {
  
               avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
  
  
  
               if (frameFinished){
  
  
  
                   AVPicture pict;
  
  
  
                   pict.data[0] = yPlane;
  
                   pict.data[1] = uPlane;
  
                   pict.data[2] = vPlane;
  
                   pict.linesize[0] = pCodecCtx->width;
  
                   pict.linesize[1] = uvPitch;
  
                   pict.linesize[2] = uvPitch;
  
  
  
                   sws_scale(sws_ctx,
  
                       pFrame->data, pFrame->linesize,
  
                       0, pCodecCtx->height,
  
                       pict.data, pict.linesize);
  
  
  
                   //SDL_UnlockTexture(bmp);
  
  
  
                   SDL_UpdateYUVTexture(bmp, 0, 
  
                       yPlane, pCodecCtx->width, 
  
                       uPlane, uvPitch, 
  
                       vPlane, uvPitch);
  
  
  
  
  
                   SDL_RenderClear(renderer);
  
                   SDL_RenderCopy(renderer, bmp, NULL, NULL);
  
                   SDL_RenderPresent(renderer);
  
  
  
  
  
                   av_free_packet(&packet);
  
  
  
  
  
               }
  
  
  
           }
  
           else if (packet.stream_index == audioStream) { 
  
               packet_queue_put(&audioq, &packet);
  
  
  
           }
  
           else
  
               av_free_packet(&packet);
  
  
  
  
  
  
  
           SDL_PollEvent(&event);
  
  
  
           switch (event.type) {
  
           case SDL_QUIT:
  
               quit = 1;
  
               SDL_DestroyTexture(bmp);
  
               SDL_DestroyRenderer(renderer);
  
               SDL_DestroyWindow(screen);
  
               SDL_Quit();
  
               exit(0);
  
               break;
  
           default:
  
               break;
  
  
  
           }
  
  
  
       }

  this is my initialization of the audio device :

  aCodecCtxOrig = pFormatCtx->streams[audioStream]->codec;
  
      aCodec = avcodec_find_decoder(aCodecCtxOrig->codec_id);
  
      if (!aCodec) {
  
          fprintf(stderr, "Unsupported codec!\n");
  
          return -1;
  
      }
  
  
  
      // Copy context
  
      aCodecCtx = avcodec_alloc_context3(aCodec);
  
      if (avcodec_copy_context(aCodecCtx, aCodecCtxOrig) != 0) {
  
          fprintf(stderr, "Couldn't copy codec context");
  
          return -1; // Error copying codec context
  
      }
  
  
  
  
  
      wanted_spec.freq = aCodecCtx->sample_rate;
  
      wanted_spec.format = AUDIO_U16SYS;
  
      wanted_spec.channels = aCodecCtx->channels;
  
      wanted_spec.silence = 0;
  
      wanted_spec.samples = SDL_AUDIO_BUFFER_SIZE;
  
      wanted_spec.callback = audio_callback;
  
      wanted_spec.userdata = aCodecCtx;
  
  
  
  
  
      if (SDL_OpenAudio( &wanted_spec, &spec) < 0) {
  
          fprintf(stderr, "SDL_OpenAudio: %s\n", SDL_GetError());
  
          return -1;
  
      }
  
  
  
      avcodec_open2(aCodecCtx, aCodec, NULL);
  
  
  
      // audio_st = pFormatCtx->streams[index]
  
      packet_queue_init(&audioq);
  
      SDL_PauseAudio(0);

  The Call back (same as the tutorial) :|

  void audio_callback(void *userdata, Uint8 *stream, int len) {
  
  
  
      AVCodecContext *aCodecCtx = (AVCodecContext *)userdata;
  
      int len1, audio_size;
  
  
  
      static uint8_t audio_buf[(MAX_AUDIO_FRAME_SIZE * 3) / 2];
  
      static unsigned int audio_buf_size = 0;
  
      static unsigned int audio_buf_index = 0;
  
  
  
      while (len > 0) {
  
          if (audio_buf_index >= audio_buf_size) {
  
              /* We have already sent all our data; get more */
  
              audio_size = audio_decode_frame(aCodecCtx, audio_buf, sizeof(audio_buf));
  
              if (audio_size < 0) {
  
                  /* If error, output silence */
  
                  audio_buf_size = 1024; // arbitrary?
  
                  memset(audio_buf, 0, audio_buf_size);
  
              }
  
              else {
  
                  audio_buf_size = audio_size;
  
              }
  
              audio_buf_index = 0;
  
          }
  
          len1 = audio_buf_size - audio_buf_index;
  
          if (len1 > len)
  
              len1 = len;
  
          memcpy(stream, (uint8_t *)audio_buf + audio_buf_index, len1);
  
          len -= len1;
  
          stream += len1;
  
          audio_buf_index += len1;
  
      }
  
  }

• avcodec/ffwavesynth : Fixes invalid shift with pink noise seeking

  10 août 2019, par Michael Niedermayer

  avcodec/ffwavesynth : Fixes invalid shift with pink noise seeking
  Fixes : left shift of negative value -961533698048
  
  Fixes : 16242/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_FFWAVESYNTH_fuzzer-5738550670131200
  Found-by : continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
  
  Reviewed-by : Nicolas George <george@nsup.org>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/ffwavesynth.c