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• QSharedMemory in Real-Time process

  21 novembre 2016, par Seungsoo Kim

  I’m trying to use QSharedMemory Class to share video data between two processes.

  So I tried like following method, but it has problem in simultaneous access of two processes.

  Two process crashes when they access sequentially to same memory name(key) "SharedMemory".

  I locked them while they’re used, but also it doesn’t work well.

  How can i avoid this crash ??

  1. Writing to SharedMemory - data type is and this function called by callback.

     QBuffer buffer;
     
     buffer.open(QBuffer::ReadWrite);
     
     QDataStream out(&buffer);
     
     
     
     QByteArray outArray = QByteArray::fromRawData(reinterpret_cast<const>(data), strlen(reinterpret_cast<const>(data)));
     
     out &lt;&lt; width &lt;&lt; height &lt;&lt; step &lt;&lt; cameraId &lt;&lt; strlen(reinterpret_cast<const>(data));
     
     out.writeRawData(outArray.data(), outArray.size());
     
     
     
     int size = buffer.size();
     
     
     
     sharedMemory.setKey("SharedMemory");
     
     
     
     if (!sharedMemory.isAttached()) {
     
         printf("Cannot attach to shared memory to update!\n");
     
     }
     
     if (!sharedMemory.create(size))
     
     {
     
         printf("failed to allocate memory\n");
     
     }
     
     sharedMemory.lock();
     
     char *to = (char*)sharedMemory.data();
     
     const char *from = buffer.data().data();
     
     memcpy(to, from,qMin(sharedMemory.size(),size));
     
     sharedMemory.unlock();
     
     </const></const></const>

  2. Using data in SharedMemory. - this function is called by QThread, interval 100ms

     QSharedMemory sharedMemory("SharedMemory");
     
     sharedMemory.lock();
     
     if (!sharedMemory.attach()) {
     
         printf("failed to attach to memory\n");
     
         return;
     
     }
     
     
     
     QBuffer buffer;
     
     QDataStream in(&buffer);
     
     
     
     sharedMemory.create(1920 * 1080);
     
     buffer.setData((char*)sharedMemory.constData(), sharedMemory.size());
     
     buffer.open(QBuffer::ReadOnly);
     
     sharedMemory.unlock();
     
     sharedMemory.detach();
     
     
     
     int r_width = 0;    
     
     int r_height = 0;
     
     int r_cameraId = 0;
     
     int r_step = 0;
     
     int r_strlen = 0;
     
     in >> r_width >> r_height >> r_step >> r_cameraId >> r_strlen;
     
     
     
     char* receive = new char[r_strlen];
     
     in.readRawData(receive, r_strlen);
     
     //unsigned char* r_receive = new unsigned char[r_strlen];
     
     //r_receive = (unsigned char*)receive;
     
     
     
     QPixmap backBuffer = QPixmap::fromImage(QImage((unsigned char*)receive, r_width, r_height, r_step, QImage::Format::Format_RGB888));
     
     ui.label->setPixmap(backBuffer.scaled(ui.label->size(), Qt::KeepAspectRatio));
     
     ui.label->show();

  please share your idea ! thank you !

• How to extract frames at 30 fps using FFMPEG APIs on Android ?

  8 septembre 2016, par Amber Beriwal

  We are working on a project that consumes FFMPEG library for video frame extraction on Android platform.

  On Windows, we have observed :

  • Using CLI, ffmpeg is capable of extracting frames at 30 fps using command ffmpeg -i input.flv -vf fps=1 out%d.png.
  • Using Xuggler, we are able to extract frames at 30 fps.
  • Using FFMPEG APIs directly in code, we are getting frames at 30 fps.

  But when we use FFMPEG APIs directly on Android (See Hardware Details), we are getting following results :

  • 720p video (1280 x 720) - 16 fps (approx. 60 ms/frame)
  • 1080p video (1920 x 1080) - 7 fps (approx. 140 ms/frame)

  We haven’t tested Xuggler/CLI on Android yet.

  Ideally, we should be able to get the data in constant time (approx. 30 ms/frame).

  How can we get 30 fps on Android ?

  Code being used on Android :

  if (avformat_open_input(&pFormatCtx, pcVideoFile, NULL, NULL)) {
  
      iError = -1;  //Couldn't open file
  
  }
  
  
  
  if (!iError) {
  
      //Retrieve stream information
  
      if (avformat_find_stream_info(pFormatCtx, NULL) < 0)
  
          iError = -2; //Couldn't find stream information
  
  }
  
  
  
  //Find the first video stream
  
  if (!iError) {
  
  
  
      for (i = 0; i < pFormatCtx->nb_streams; i++) {
  
          if (AVMEDIA_TYPE_VIDEO
  
                  == pFormatCtx->streams[i]->codec->codec_type) {
  
              iFramesInVideo = pFormatCtx->streams[i]->nb_index_entries;
  
              duration = pFormatCtx->streams[i]->duration;
  
              begin = pFormatCtx->streams[i]->start_time;
  
              time_base = (pFormatCtx->streams[i]->time_base.num * 1.0f)
  
                      / pFormatCtx->streams[i]->time_base.den;
  
  
  
              pCodecCtx = avcodec_alloc_context3(NULL);
  
              if (!pCodecCtx) {
  
                  iError = -6;
  
                  break;
  
              }
  
  
  
              AVCodecParameters params = { 0 };
  
              iReturn = avcodec_parameters_from_context(&params,
  
                      pFormatCtx->streams[i]->codec);
  
              if (iReturn < 0) {
  
                  iError = -7;
  
                  break;
  
              }
  
  
  
              iReturn = avcodec_parameters_to_context(pCodecCtx, &params);
  
              if (iReturn < 0) {
  
                  iError = -7;
  
                  break;
  
              }
  
  
  
              //pCodecCtx = pFormatCtx->streams[i]->codec;
  
  
  
              iVideoStreamIndex = i;
  
              break;
  
          }
  
      }
  
  }
  
  
  
  if (!iError) {
  
      if (iVideoStreamIndex == -1) {
  
          iError = -3; // Didn't find a video stream
  
      }
  
  }
  
  
  
  if (!iError) {
  
      // Find the decoder for the video stream
  
      pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
  
      if (pCodec == NULL) {
  
          iError = -4;
  
      }
  
  }
  
  
  
  if (!iError) {
  
      // Open codec
  
      if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0)
  
          iError = -5;
  
  }
  
  
  
  if (!iError) {
  
      iNumBytes = av_image_get_buffer_size(AV_PIX_FMT_RGB24, pCodecCtx->width,
  
              pCodecCtx->height, 1);
  
  
  
      // initialize SWS context for software scaling
  
      sws_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height,
  
              pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height,
  
              AV_PIX_FMT_RGB24,
  
              SWS_BILINEAR,
  
              NULL,
  
              NULL,
  
              NULL);
  
      if (!sws_ctx) {
  
          iError = -7;
  
      }
  
  }
  
  clock_gettime(CLOCK_MONOTONIC_RAW, &end);
  
  delta_us = (end.tv_sec - start.tv_sec) * 1000000
  
          + (end.tv_nsec - start.tv_nsec) / 1000;
  
  start = end;
  
  //LOGI("Starting_Frame_Extraction: %lld", delta_us);
  
  if (!iError) {
  
      while (av_read_frame(pFormatCtx, &packet) == 0) {
  
          // Is this a packet from the video stream?
  
          if (packet.stream_index == iVideoStreamIndex) {
  
              pFrame = av_frame_alloc();
  
              if (NULL == pFrame) {
  
                  iError = -8;
  
                  break;
  
              }
  
  
  
              // Decode video frame
  
              avcodec_decode_video2(pCodecCtx, pFrame, &iFrameFinished,
  
                      &packet);
  
              if (iFrameFinished) {
  
                  //OUR CODE
  
              }
  
              av_frame_free(&pFrame);
  
              pFrame = NULL;
  
          }
  
          av_packet_unref(&packet);
  
      }
  
  }

• Facebook Reels Upload always failing

  21 juin, par Evrard A.

  I'm trying to upload Reels through Facebook Graph API. The video is created with the following ffmpeg command.

  


  cmd = [
            'ffmpeg',
            '-i', video_path,
            '-i', voice_path,
            '-i', music_path,

            '-filter_complex',
            '[1:a]loudnorm=I=-16:LRA=11:TP=-1.5,adelay=0|0[a1];' +
            '[2:a]volume=0.2,afade=t=in:ss=0:d=0.02,afade=t=out:st=28:d=0.03[a2];' +
            '[a1][a2]amix=inputs=2:duration=first:dropout_transition=0[aout]',

            '-map', '0:v:0',
            '-map', '[aout]',

            '-vf',
             f"subtitles='{str(ass_path)}',format=yuv420p,scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2,setsar=1",  # Incrustation des sous-titres

            '-r', '30',
            '-g', '60',
            '-keyint_min', '60',
            '-sc_threshold', '0',
            '-x264opts', 'no-scenecut',

            '-c:v', 'libx264',
            '-profile:v', 'baseline',
            '-level', '4.1',
            '-pix_fmt', 'yuv420p',
            '-color_range', 'tv',
            '-colorspace', 'bt709',

            '-b:v', '9500k',
            '-maxrate', '9500k',
            '-bufsize', '19000k',

            '-c:a', 'aac',
            '-b:a', '192k',
            '-ac', '2',
            '-ar', '48000',

            '-movflags', '+faststart',
            '-video_track_timescale', '15360',
            '-max_muxing_queue_size', '9999',

            '-y', self.output_video_path if self.output_video_path else f'{parts[0]}.subtitled.{parts[1]}'
        ]

        subprocess.run(cmd, check=True)


  


  Here is the class method I use to publish :

  


    import requests, os,  time
  from datetime import datetime, timedelta
  from moviepy.editor import VideoFileClip
   
  def post_reel(
      self,
      page_id: str,
      page_access_token: str,
      video_file_path: str,
      video_description: str,
      tags: list = None, # type: ignore
      publish_now: bool = True
  ):
      def extract_first_frame(video_path: str, output_image_path: str, time_in_seconds: float = 1):
          """
          Extrait une frame à time_in_seconds et la sauvegarde comme miniature.
          """
          try:
              clip = VideoFileClip(video_path)
              clip.save_frame(output_image_path, t=time_in_seconds)
              print(f"[THUMBNAIL] Frame at {time_in_seconds}s saved to {output_image_path}")
              return output_image_path
          except Exception as e:
              print(f"[ERROR] Could not extract thumbnail: {str(e)}")
              return None

      def wait_for_video_ready(video_id, page_access_token, timeout=300, poll_interval=10):
          """
          Attends que la vidéo soit complètement traitée et publiée.
          """
          status_url = f"{self.BASE_API_URL}/{video_id}"
          params = {
              "access_token": page_access_token,
              "fields": "status"
          }

          start = time.time()
          while time.time() - start < timeout:
              try:
                  r = requests.get(url=status_url, params=params)
                  r.raise_for_status()
                  status = r.json().get("status", {})
                  processing = status.get("processing_phase", {}).get("status")
                  publishing = status.get("publishing_phase", {}).get("status")
                  video_status = status.get("video_status")

                  print(f"[WAIT] video_status={video_status}, processing={processing}, publishing={publishing}")

                  if processing == "complete" and publishing == "complete":
                      print("[READY] Reel processed and published")
                      return True
                  elif processing == "error":
                     print(r.json())

              except Exception as e:
                  print(f"[ERROR] during polling: {e}")

              time.sleep(poll_interval)

          print("[TIMEOUT] Video did not finish processing in time.")
          return False

      try:
          # Step 1: Initialize upload
          init_url = f"{self.BASE_API_URL}/{page_id}/video_reels"
          init_params = {"upload_phase": "start"}
          init_payload = {'access_token': page_access_token}

          r = requests.post(url=init_url, data=init_payload, params=init_params)
          r.raise_for_status()
          response = r.json()
          video_id = response["video_id"]
          upload_url = response["upload_url"]
          print(f"[INIT OK] Video ID: {video_id}")

          # Step 2: Upload video
          file_size = os.path.getsize(video_file_path)
          headers = {
              'Authorization': f"OAuth {page_access_token}",
              'offset': "0",
              'file_size': str(file_size),
          }

          with open(video_file_path, 'rb') as f:
              files = {'source': f}
              r = requests.post(url=upload_url, data=files, headers=headers)
              r.raise_for_status()
              upload_response = r.json()

          if not upload_response.get("success"):
              print("[ERROR] Upload failed.")
              return None
          print(f"[UPLOAD OK]")

          # Step 3: Check video status
          status_check_url = f'{self.BASE_API_URL}/{video_id}'
          check_params = {
              "access_token": page_access_token,
              "fields": "status"
          }
          r = requests.get(url=status_check_url, params=check_params)
          r.raise_for_status()
          print(f"[STATUS CHECK] {r.json()}")

          # Step 4: Finalize video
          finalize_params = {
              "video_id": video_id,
              "upload_phase": "finish",
              "published": "true",
              "access_token": page_access_token,
              "video_state": "PUBLISHED" if publish_now else "SCHEDULED",
              "title": video_description,
              "description": video_description
          }

          if not publish_now:
              finalize_params["scheduled_publish_time"] = int((datetime.now() + timedelta(days=1)).timestamp())

          if tags:
              finalize_params["tags"] = ",".join(tags)

          r = requests.post(url=init_url, params=finalize_params, headers=headers)
          r.raise_for_status()
          finalize_response = r.json()
          post_id = finalize_response.get("post_id")
          print(f"[FINALIZE OK] Post ID: {post_id}")
          
          # WAIT UNTIL PUBLISHED
          if not wait_for_video_ready(video_id, page_access_token):
              print("[ERROR] Reel processing timeout or failure")
              return None
          
          # Step 5: Extract and upload thumbnail
          thumbnail_path = f"temp_thumb_{video_id}.jpg"
          if extract_first_frame(video_file_path, thumbnail_path):
              thumb_url = f"{self.BASE_API_URL}/{video_id}/thumbnails"
              with open(thumbnail_path, 'rb') as img:
                  files = {'source': img}
                  thumb_payload = {'access_token': page_access_token}
                  r = requests.post(url=thumb_url, files=files, data=thumb_payload)
                  r.raise_for_status()
                  print("[THUMBNAIL UPLOADED]")
              # Clean up temp file
              os.remove(thumbnail_path)
              print("[THUMBNAIL CLEANED UP]")

          return post_id

      except Exception as e:
          print(f"[ERROR] {str(e)}")
          return None


  


  Here are the logs I get :

  


  

  • [INIT OK] Video ID: 1020853163558419

  


  • [UPLOAD OK]

  


  • [STATUS CHECK]

  


  


  {
  "status": {
    "video_status": "upload_complete",
    "uploading_phase": {
      "status": "complete",
      "bytes_transferred": 37780189
    },
    "processing_phase": {
      "status": "not_started"
    },
    "publishing_phase": {
      "status": "not_started"
    },
    "copyright_check_status": {
      "status": "in_progress"
    }
  },
  "id": "1020853163558419"
}


  


  

  • [FINALIZE OK] Post ID: 122162302376476425

  


  • [WAIT] video_status=upload_complete, processing=not_started, publishing=not_started

  


  • [WAIT] video_status=error, processing=error, publishing=not_started

  


  


  {
  "status": {
    "video_status": "error",
    "uploading_phase": {
      "status": "complete",
      "bytes_transferred": 37780189
    },
    "processing_phase": {
      "status": "error",
      "errors": [
        {
          "code": 1363008,
          "message": "Video Creation failed, please try again."
        }
      ]
    },
    "publishing_phase": {
      "status": "not_started"
    },
    "copyright_check_status": {
      "status": "in_progress"
    }
  },
  "id": "1020853163558419"
}


  


  It seems the error code 1363008 is related to the video properties format but even after following Facebook Reels video format recommandations, I can't make it work.

  


  Can you help me with this please ?

  


  I failed getting usefull help with ChatGPT 😅, and thanks in advance for anyone who answers or comments my question.