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• Using ffmpeg to display a static image if an RTMP input source is missing

  19 mars 2016, par iameli

  Here is what I would like ffmpeg to output :

  • If I am streaming from my iPhone to my RTMP server, ffmpeg should output the live video from my iPhone.
  • If not, ffmpeg should output a blank red screen.

  Here’s what I have so far. It sort of works.

  ffmpeg \
  
    -f lavfi \
  
    -re \
  
    -i 'color=s=320x240:r=30:c=red' \
  
    -thread_queue_size 512 \
  
    -i 'rtmp://localhost/stream/iphone' \
  
    -c:v libx264 \
  
    -f flv \
  
    -filter_complex "\
  
      [1:v]scale=320:240[stream]; \
  
      [0:v][stream]overlay=0:0:eof_action=pass[output] \
  
    "\
  
    -map '[output]' \
  
    -tune zerolatency \
  
    'rtmp://localhost/stream/output'

  What happens : it boots up and starts streaming my iPhone’s output no problem. When I disconnect, it hangs for a long time, perhaps 20 seconds. Then it starts outputting red, okay. But then if I reconnect my phone, it doesn’t resume. It’s still red. Two questions :

  • Is there a way to configure the buffering so that it starts outputting red as soon as it stops getting data from the RTMP stream ?
  • Is there a way to have it auto-retry, so after the RTMP stream returns, it will switch back ?

  Full verbose output, if that’s helpful. I’m using the latest git version of ffmpeg as of 2016-03-18 on Ubuntu Wily. The RTMP server is nginx-rtmp.

• OpenGLES glReadPixels exc_bad_access

  29 novembre 2011, par Yanny

  I'm trying to create video from images using OpenGLES and ffmpeg, but on iPad(4.3) I have a crash on glReadPixels

  -(NSData *) glToUIImage {
  
  
  
      int numberOfComponents = NUMBER_OF_COMPONENTS; //4
  
      int width = PICTURE_WIDTH; 
  
      int height = PICTURE_HEIGHT;
  
  
  
      NSInteger myDataLength = width * height * numberOfComponents;   
  
  
  
      NSMutableData * buffer= [NSMutableData dataWithLength :myDataLength];    
  
  
  
      [self checkForGLError]; 
  
  
  
      GLenum type = NUMBER_OF_COMPONENTS == 3 ? GL_RGB : GL_RGBA; //RGBA
  
      glReadPixels(0, 0, width, height, type, GL_UNSIGNED_BYTE, [buffer mutableBytes]);   //EXC_BAD_ACCESS here
  
  
  
      return buffer; 
  
  }

  It is working on iPhone 4 (4.3) and iPod Touch, but have problems on iPhone 3G(3.0) and iPad(4.3). Can you help me with this issue ?

  Also on iPhone 3G(3.0) and iPad(4.3) I have problems with Video - first 5-20 video frames have trash. Maybe issue with optimization ? Or architecture ?

• Treating a video stream as playback with pausing

  21 janvier 2020, par kealist

  I am working on an application that streams multiple h264 video streams to a video wall. I am using libav/ffmpeg libs to stream multiple video files at once from inside the application. The application will control playback speed, seeking, pausing, resuming, stopping, and the video wall will only be receiving udp streams.

  I want to implement streaming such that if the videos are paused, the same frame is sent continually so that it looks as if it is a video window in a paused state.

  How can i insert copies of the same h264 frame into the stream so that it does not mess up sending of later frames ?

  My code is almost an exact port of transcoding.c from ffmpeg.exe. Planning on retaining a copy of the last frame/packet, and when paused to send this. Is this likely to function properly, or should I approach this a different way.

  while (true)
  
  {
  
      if (paused) {
  
          // USE LAST PACKET
  
      }
  
      else 
  
      {
  
          if ((ret = ffmpeg.av_read_frame(ifmt_ctx, &packet)) < 0)
  
              break;
  
      }
  
      stream_index = packet.stream_index;
  
  
  
      type = ifmt_ctx->streams[packet.stream_index]->codec->codec_type;
  
      Console.WriteLine("Demuxer gave frame of stream_index " + stream_index);
  
      if (filter_ctx[stream_index].filter_graph != null)
  
      {
  
          Console.WriteLine("Going to reencode&filter the frame\n");
  
          frame = ffmpeg.av_frame_alloc();
  
          if (frame == null)
  
          {
  
              ret = ffmpeg.AVERROR(ffmpeg.ENOMEM);
  
              break;
  
          }
  
  
  
          packet.dts = ffmpeg.av_rescale_q_rnd(packet.dts,
  
                  ifmt_ctx->streams[stream_index]->time_base,
  
                  ifmt_ctx->streams[stream_index]->codec->time_base,
  
                  AVRounding.AV_ROUND_NEAR_INF | AVRounding.AV_ROUND_PASS_MINMAX);
  
          packet.pts = ffmpeg.av_rescale_q_rnd(packet.pts,
  
                  ifmt_ctx->streams[stream_index]->time_base,
  
                  ifmt_ctx->streams[stream_index]->codec->time_base,
  
                  AVRounding.AV_ROUND_NEAR_INF | AVRounding.AV_ROUND_PASS_MINMAX);
  
  
  
  
  
  
  
          if (type == AVMediaType.AVMEDIA_TYPE_VIDEO)
  
          {
  
  
  
              ret = ffmpeg.avcodec_decode_video2(stream_ctx[packet.stream_index].dec_ctx, frame,
  
                  &got_frame, &packet); 
  
  
  
          }
  
          else
  
          {
  
              ret = ffmpeg.avcodec_decode_audio4(stream_ctx[packet.stream_index].dec_ctx, frame,
  
                  &got_frame, &packet);
  
          }
  
          if (ret < 0)
  
          {
  
              ffmpeg.av_frame_free(&frame);
  
              Console.WriteLine("Decoding failed\n");
  
              break;
  
          }
  
          if (got_frame != 0)
  
          {
  
              frame->pts = ffmpeg.av_frame_get_best_effort_timestamp(frame);
  
              ret = filter_encode_write_frame(frame, (uint)stream_index);
  
              // SAVE LAST FRAME/PACKET HERE
  
              ffmpeg.av_frame_free(&frame);
  
              if (ret < 0)
  
                  goto end;
  
          }
  
          else
  
          {
  
              ffmpeg.av_frame_free(&frame);
  
          }
  
      }
  
      else
  
      {
  
          /* remux this frame without reencoding */
  
          packet.dts = ffmpeg.av_rescale_q_rnd(packet.dts,
  
                  ifmt_ctx->streams[stream_index]->time_base,
  
                  ofmt_ctx->streams[stream_index]->time_base,
  
                  AVRounding.AV_ROUND_NEAR_INF | AVRounding.AV_ROUND_PASS_MINMAX);
  
          packet.pts = ffmpeg.av_rescale_q_rnd(packet.pts,
  
                  ifmt_ctx->streams[stream_index]->time_base,
  
                  ofmt_ctx->streams[stream_index]->time_base,
  
                  AVRounding.AV_ROUND_NEAR_INF | AVRounding.AV_ROUND_PASS_MINMAX);
  
          ret = ffmpeg.av_interleaved_write_frame(ofmt_ctx, &packet);
  
          if (ret < 0)
  
              goto end;
  
      }
  
      ffmpeg.av_free_packet(&packet);
  
  }