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• ffplay : how does it calculate the fps for playback ?

  21 octobre 2020, par Daniel

  I'm trying to playback a live media (h264) which is produced by a hardware encoder.

  


  The actual desired FPS on the encoder is set to 20, and when checking the logs of the encoder it prints "FPS statistics" every minute :

  


  2020-10-21 17:26:54.787 [  info] video_stream_thread(),video chn 0, fps: 19.989270
2020-10-21 17:27:54.836 [  info] video_stream_thread(),video chn 0, fps: 19.989270
2020-10-21 17:28:54.837 [  info] video_stream_thread(),video chn 0, fps: 20.005924
2020-10-21 17:29:54.837 [  info] video_stream_thread(),video chn 0, fps: 19.989270
2020-10-21 17:30:54.888 [  info] video_stream_thread(),video chn 0, fps: 19.989274
2020-10-21 17:31:54.918 [  info] video_stream_thread(),video chn 0, fps: 19.989264


  


  You can see it's varying, but not too much around 20.

  


  Question1 : Is this normal ? Or it should be exactly 20 every time ? To avoid confusion : I'd like to know if by the standard of H264, can this be accepted as a valid stream or this violates some
rule ?

  


  I'm trying to playback this stream with ffplay :

  


  $ ffplay rtsp://this_stream
Input #0, rtsp, from 'xyz'
  Metadata:
    title           : 
    comment         : substream
  Duration: N/A, start: 0.040000, bitrate: N/A
    Stream #0:0: Video: h264 (Constrained Baseline), yuv420p(progressive), 640x360, 25 fps, 25 tbr, 90k tbn, 180k tbc


  


  The thing is that ffplay thinks this is a stream with 25fps. And it also plays 25 frames each sec, causing the stream to stall and buffer in every few seconds.

  


  I believe the fps is calculated by some pts/dts values in the stream itself, and it's not hardcoded. Am I wrong here ?

  


  If I'm not wrong, why does ffplay thinks this stream runs at 25fps, whereas it only runs at (around) 20 ?

  


• Revision 6723e34224 : Merge "fix permissions on cpplint.py (0644->0755)" into experimental

  4 mai 2013, par James Zern

  Merge "fix permissions on cpplint.py (0644->0755)" into experimental

• "File doesn't exist" - streamio FFMPEG on screenshot after create method

  3 mai 2013, par dodgerogers747

  I have videos being directly uploaded to S3 using Amazon's CORS configuration. Videos are uploaded via a dedicated S3 form, once they have been uploaded successfully the URL of the video is appended to the @video.file hidden_field via javascript and then the video saves.

  I can't get this after_save method to work which takes a screenshot of the video and saves it to S3 via carrierwave after the video has been saved as a rails object. ( It was previously working using a carrierwave video upload instance )

  It errors out withErrno::ENOENT - No such file or directory - the file 'http://bucket-name.s3.amazonaws.com/uploads/video/file/secure-random-hex/video_name.m4v' does not exist: I have tried running this method as a class method to call it from the console but it always comes back with the same error, even though the video exists.

  My bucket is set to public, read and write. How come it doesn't think the file exists ?

  If anyone needs more code just shout, thanks in advance.

  application trace

  Started POST "/videos" for 127.0.0.1 at 2013-05-03 10:48:07 -0700
  
  Processing by VideosController#create as JS
  
    Parameters: {"utf8"=>"✓", "authenticity_token"=>"MAHxrVcmPDtVIMfDWZBwL0YnzaAaAe1PTGip5M4OVoY=", "video"=>{"user_id"=>"5", "file"=>"http://bucket-name.s3.amazonaws.com/uploads/video/file/secure-random-hex/video.m4v"}}
  
    User Load (0.3ms)  SELECT `users`.* FROM `users` WHERE `users`.`id` = 5 LIMIT 1
  
     (0.1ms)  BEGIN
  
    SQL (20.5ms)  INSERT INTO `videos` (`created_at`, `file`, `question_id`, `screenshot`, `updated_at`, `user_id`) VALUES ('2013-05-03 17:48:07', 'http://teebox-network.s3.amazonaws.com/uploads/video/file/secure-random-hex/video.m4v', NULL, NULL, '2013-05-03 17:48:07', 5)
  
     (44.0ms)  ROLLBACK
  
  Completed 500 Internal Server Error in 71ms
  
  
  
  Errno::ENOENT - No such file or directory - the file 'http://teebox-network.s3.amazonaws.com/uploads/video/file/secure-random-hex/video.m4v' does not exist:
  
    (gem) streamio-ffmpeg-0.9.0/lib/ffmpeg/movie.rb:10:in `initialize'
  
    app/models/video.rb:25:in `new'
  
    app/models/video.rb:25:in `take_screenshot'

  video.rb

    attr_accessible :user_id, :question_id, :file, :screenshot
  
    belongs_to :question
  
    belongs_to :user
  
  
  
    default_scope order('created_at DESC')
  
  
  
    after_create :take_screenshot
  
  
  
    mount_uploader :screenshot, ImageUploader
  
  
  
    validates_presence_of :user_id, :file
  
  
  
    def take_screenshot
  
      FFMPEG.ffmpeg_binary = '/opt/local/bin/ffmpeg'
  
      movie = FFMPEG::Movie.new("#{self.file}")
  
      self.screenshot = movie.screenshot("#{Rails.root}/public/uploads/tmp/screenshots/#{File.basename(self.file)}.jpg", seek_time: 2 )
  
      self.save!
  
    end

  videos/_form.html.erb

  <form action="http://bucket-name.s3.amazonaws.com" data-remote="true" class="direct-upload" enctype="multipart/form-data" method="post">
  
    <input type="hidden" />
  
    <input type="hidden" value="ACCESS_KEY" />
  
    <input type="hidden" value="public-read" />
  
    <input type="hidden" />
  
    <input type="hidden" />
  
    <input type="hidden" value="201" />
  
    <input type="file" />
  
  </form>
  
  
  
  &lt;%= form_for @video, html: { multipart: true, id: "new_video" }, remote: true do |f| %>
  
          &lt;% if @video.errors.any? %>
  
      <div>
  
      <h2>&lt;%= pluralize(@video.errors.count, "error") %> prohibited this post from being saved:</h2>
  
  
  
    <ul>
  
      &lt;% @video.errors.full_messages.each do |msg| %>
  
          <li>&lt;%= msg %></li>
  
          &lt;% end %>
  
      </ul>
  
      </div>
  
  &lt;% end %>
  
  
  
      &lt;%= f.hidden_field :user_id, value: current_user.id %>
  
      &lt;%= f.hidden_field :file %><br />
  
  
  
      &lt;% end %>

  ImageUploader

  class ImageUploader < CarrierWave::Uploader::Base
  
  
  
    include CarrierWave::RMagick
  
  
  
     include Sprockets::Helpers::RailsHelper
  
     include Sprockets::Helpers::IsolatedHelper
  
  
  
    storage :fog
  
  
  
    before :store, :remember_cache_id
  
    after :store, :delete_tmp_dir
  
  
  
      def cache_dir
  
        Rails.root.join('public/uploads/tmp/') 
  
      end
  
  
  
      def remember_cache_id(new_file)
  
        @cache_id_was = cache_id
  
      end
  
  
  
      def delete_tmp_dir(new_file)
  
        if @cache_id_was.present? && @cache_id_was =~ /\A[\d]{8}\-[\d]{4}\-[\d]+\-[\d]{4}\z/
  
          FileUtils.rm_rf(File.join(root, cache_dir, @cache_id_was))
  
        end
  
      end
  
  
  
    process resize_and_pad: [306, 150, '#000']
  
  
  
    def store_dir
  
      "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
  
    end
  
  
  
    def extension_white_list
  
      %w(jpg)
  
      # %w(ogg ogv 3gp mp4 m4v webm mov)
  
    end