Recherche avancée

Sur d’autres sites (4228)

• 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;
  
      }
  
  }

• FFMPEG audio plays faster then video after conversion

  14 septembre 2019, par Yevhen Nalisnyi

  I have code which geting raw videos from one folder and adding intro and outro videos individually to each of them. There is only one issue. After convertion audio plays faster then video. What should I change or apply ?

  ---

  ffmpeg -i intro.mp4 -r 30 -c:v libx264 -c:a libmp3lame -crf 22 -preset ultrafast -c:a libmp3lame intro-converted.mp4
  
  ffmpeg -i outro.mp4 -r 30 -c:v libx264 -c:a libmp3lame -crf 22 -preset ultrafast -c:a libmp3lame outro-converted.mp4
  
  cd input
  
  for %%f in (*.mp4) do (
  
  echo %%f
  
  ffmpeg -i %%f -i ..\overlay.png -filter_complex "[1:v]scale=320:-1,format=rgba,colorchannelmixer=aa=1[fg];[0][fg]overlay=950:645:enable='between(t,0,240)'" -r 30 -pix_fmt yuv420p -c:v libx264 -preset ultrafast -crf 22  -c:a libmp3lame ..\temp-%%f
  
  echo file '..\intro-converted.mp4' > ..\list.txt
  
  echo file '..\temp-%%f' >> ..\list.txt
  
  echo file '..\outro-converted.mp4' >> ..\list.txt
  
  ffmpeg -f concat -safe 0 -i ..\list.txt -r 30 -pix_fmt yuv420p -c:v libx264 -preset ultrafast -crf 22  -c:a libmp3lame ..\output\%%f
  
  del ..\temp-%%f
  
  )
  
  cd ..

• Timelimit plays for twice the duration [on hold]

  26 septembre 2019, par the_new_james

  I am using the following command to stream to a test an endpoint :

  ffmpeg -loglevel debug -f lavfi -re -i testsrc=size=hd720:rate=30 
  
         -f lavfi -re -i anoisesrc 
  
         -vf "drawtext=fontfile=\'/Library/Fonts/Arial.ttf\': text=\'Local time %{localtime\: %Y\/%m\/%d %H.%M.%S} (%{n})\': x=50: y=50: fontsize=48: fontcolor=white: box=1: boxcolor=0x00000099" 
  
         -pix_fmt yuv420p -c:v libx264 -b:v 1000k -g 30 -profile:v baseline -preset veryfast 
  
         -c:a libfdk_aac -b:a 96k -timelimit 60 -f flv $RTMP_OUTPUT/$NAME

  Because I’m adding this command to my automation, I would like to protect it from running indefinitely in case something goes wrong with my script (I start the ffmpeg job in a background process that is detached from the script). Therefore, I added the flag -timelimit 60, that, according to the documentation, the job should exit after duration seconds.

  I can see that the command is being parsed correctly

  Reading option '-timelimit' ... matched as option 'timelimit' (set max runtime in seconds) with argument '60'.
  
  ...
  
  Finished splitting the commandline.
  
  ...
  
  Applying option timelimit (set max runtime in seconds) with argument 60.
  
  ...

  Here’s an example output

  

  The issue is that I noticed that the stream runs for longer than the specified time. After a couple of tests, I noticed that it is running for double the time, which got me thinking if it is taking the number of frames (assuming 2-second frames).

  Can someone clarify the timelimit option, please ? And the possible causes for running longer than specified.

  PS : I’m using ffmpeg version 4.1.4 on a MAC OS Mojave (10.14.6)