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• How can I mux (or encapsulate) H.264 RTP output into a container using FFMPEG ?

  7 octobre 2013, par Grad

  I am working on the effects of network losses in video transmission. In order to simulate the network losses I use a simple program which drops random RTP packets from the output of H.264 RTP encoding.

  I use Joint Model (JM) 14.2 in order to encode the video. However, I don't use AnnexB format as my output, instead I choose the output as RTP packets. The JM output is generated as RTP packets with RTP headers and payload as a sequence. After that, some of RTP packets are dropped by using a simple program. Then, I can decode the output bitstream by using also JM and it's error concealment methods.

  The main purpose of this process is to evaluate the differences created by network losses on the human video quality perception. In order to measure the perceived quality, the shown video must be in its decoded form (i.e. full resolution) or it can be decodable at the receiver side. The RTP packets created by the JM Encoder cannot be decoded without the JM software installed. However, with the proper header (or container) most video players are able to decode the bitstream. So, the my goal in this question is to encapsulate my encoded RTP packet bitstream in a common container such as AVI or MP4 to have my content decodable at the receiver computer.

  The format of the encoded bitstream in RTP packetized form is as follows :

       ----------------------------------------------------------------------
  
       | RTP Header #1 | RTP Payload #1 | RTP Header #2 | RTP Payload #2 |...
  
       ----------------------------------------------------------------------

  In order to find the video quality, I want to make a subjective test with these bitstreams. I can make these test by using the full resolution data decoded by myself whereas it's very inconvenient to crowdsource this subjective test with GBs of video data on the Internet. So, I want to mux these bitstreams into a container (i.e. AVI) by using FFMPEG. I have tried to decode these bitstreams with FFMPEG and FFPLAY ; however, both of them didn't work. I also tried the following command and it didn't work, either.

      ffmpeg - f h264 -i  -vcodec copy -r 25 out.avi

  Which format or muxer should I use ? Do I need to convert these files to any other format ?

• ffmpegthumbnailer error with carrierwave-video-thumbnailer

  30 janvier 2014, par scientiffic

  I am getting the error "No such file or directory" when I try to run ffmpegthumbnailer using the carrierwave-video-thumbnailer gem.

  I confirmed that ffmpegthumbnailer is working correctly on my computer since I can generate a thumbnail image from a video straight from the command line.

  From my logs, it looks like my app thinks that it has generated a thumbnail image. However, when I look in the directory, there is no file tmpfile.png, and my app fails with the error.

  Has anyone successfully used the carrierewave-video-thumbnailer gem to create thumbnails, and if so, what am I doing wrong ? Alternatively, if there is some way I can just run ffmpegthumbnailer within my model, I could do that too.

  Here are my logs :

  Running....ffmpegthumbnailer -i /Users/.../Website/public/uploads/tmp/1380315873-21590-2814/thumb_Untitled.mov -o /Users/.../Website/public/uploads/tmp/1380315873-21590-2814/tmpfile.png -c png -q 10 -s 192 -f
  
  Success!
  
  Errno::ENOENT: No such file or directory - (/Users/.../Website/public/uploads/tmp/1380315873-21590-2814/tmpfile.png, /Users/.../Website/public/uploads/tmp/1380315873-21590-2814/thumb_Untitled.mov)

  video_path_uploader.rb

  class VideoPathUploader < CarrierWave::Uploader::Base
  
    include CarrierWave::Video
  
    include CarrierWave::Video::Thumbnailer
  
  
  
    process encode_video: [:mp4]
  
  
  
    # Include RMagick or MiniMagick support:
  
    # include CarrierWave::RMagick
  
    include CarrierWave::MiniMagick
  
  
  
    # Choose what kind of storage to use for this uploader:
  
    # storage :file
  
    storage :fog
  
  
  
    # Override the directory where uploaded files will be stored.
  
    # This is a sensible default for uploaders that are meant to be mounted:
  
    def store_dir
  
      "#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
  
    end
  
  
  
     version :thumb do
  
        process thumbnail: [{format: 'png', quality: 10, size: 192, strip: true, logger: Rails.logger}]
  
        def full_filename for_file
  
          png_name for_file, version_name
  
        end
  
    end
  
  
  
      def png_name for_file, version_name
  
        %Q{#{version_name}_#{for_file.chomp(File.extname(for_file))}.png}
  
      end
  
  
  
  end

  Video.rb

  class Video < ActiveRecord::Base
  
    # maybe we should add a title attribute to the video?
  
    attr_accessible :position, :project_id, :step_id, :image_id, :saved, :embed_url, :thumbnail_url, :video_path
  
    mount_uploader :video_path, VideoPathUploader
  
  ...
  
  end

• Get rtsp error when connection is corrupted ?

  9 septembre 2013, par vominhtien961476

  I using ffmpeg libavformat to record RTSP stream from the Panasonic Camera. I can get both audio and video stream frome that everything is fine until there is a corruption between server and camera.

  • the "av_read_frame" function did not return anything I think it has been waiting to received frame from camera however, it cannot due to corrupted connection. I expected that this function should complete its task and return error (connection failure or something like that) but it did not and stuck forever.
  • the same problem with "avformat_open_input" function when the connection is corrupted. Therefore, the left functions cannot be processed

  Anyone can explain to me what the problem's here and what wrong with my code. How can I avoid the deadlock for this case.

  (Enviroment : Win 7, VS 2010, FFMPEG : 20130227-git-5d2f2c7, LAN network)

      int main(int argc, char** argv)
  
  {
  
  
  
      AVFormatContext* context = avformat_alloc_context();
  
      int video_stream_index;
  
  
  
      av_register_all();
  
      avcodec_register_all();
  
      avformat_network_init();
  
  
  
      //open rtsp
  
      if(avformat_open_input(&context, "rtsp://username:12345/192.168.1.253:554/mpeg4/640x480",NULL,NULL) != 0)
  
      {
  
          return EXIT_FAILURE;
  
      }
  
  
  
      if(avformat_find_stream_info(context,NULL) < 0)
  
      {
  
          return EXIT_FAILURE;
  
      } 
  
      AVPacket packet;
  
      av_init_packet(&packet);
  
      //start reading packets from stream and write them to file
  
  
  
      while(av_read_frame(context,&packet))
  
      {
  
         //Store packet here
  
      }
  
      av_free_packet(&packet);
  
      return (EXIT_SUCCESS);
  
  }