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• Transcode to virtual device/memory in VLC

  27 septembre 2013, par Atrotygma

  I have a unicast h264 stream from a video transmitter. Now, I would like to view the stream in a web browser using HTML5s tag. For this, I have to transcode it first via VLC to theora/ogg and then streaming it out as a HTTP stream. This works fine for 1 client, but since HTTP streaming isn't multicast, I have the fear that my server will break down really quick because VLC will transcode the input stream for every additional client request.

  For this reason, I'd like to write the transcoded stream in something like a 'virtual device' or memory or any other form of temporary storage (but dear god, NO files, I don't want to destroy my hard disk). Then, I would like to grab the transcoded stream with a secondary VLC instance and stream it via HTTP, so that in the end, I have to transcode it only once for all clients.

  In steps :

  1. [DONE] Grab H.264 unicast stream from transmitter via RTSP
  2. VLC instance 1 transcodes it to theora/ogg and writes it to a temporary memory
  3. VLC instance 2 reads from the memory and streams it via HTTP
  4. [DONE] Browser requests HTTP stream via HTTP live Streaming (html5 video).

  Is this possible in any way ?

• 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

• avfilter/vf_rotate : use vsub for output plane height calculation

  29 septembre 2013, par Paul B Mahol

  avfilter/vf_rotate : use vsub for output plane height calculation
  Output plane height used horizontal instead of vertical subsampling.
  
  This is just cosmetic change as filter does not support formats where
  
  vertical subsampling does not match horizontal one.
  Signed-off-by : Paul B Mahol <onemda@gmail.com>
  

  • [DH] libavfilter/vf_rotate.c