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• MPEG DASH : frame seeking

  13 août 2014, par bisc8

  TL ;DR : Is it possible to achieve frame seeking using DASH ? How ?

  I’m using ffmpeg to create non-multiplexed content :

  ffmpeg -y -an -codec:v libx264 -profile:v baseline output_video.mp4 -i video.mp4
  
  ffmpeg -y -vn -codec:a libvo_aacenc -ac 1 -ar 44100 output_audio.mp4 -i video.mp4

  Then I’m using mp4box to create DASH content :

  mp4box -dash 10000 -frag 1000 -rap -dash-profile live -segment-name mp4-live-$RepresentationID$-$Number$ -out manifest.mpd output_video.mp4 output_audio.mp4

  Finally I open the generated content with Chrome, using dash.js. Everything works fine except that I can’t do frame seek. I keep on adding (1/frame_rate) seconds to the current time but nothing happens, the frame only changes after 10 seconds.

  I suppose this has to do with the video’s key interval. However, I am able to do frame seek after the ffmpeg part, so I guess I’m missing something in the mp4box command.

  Is it possible to achieve frame seeking using DASH or am I missing something ?

  Thanks in advance.

• Anomalie #4506 : Supprimer les CSS inline des modèles de documents

  9 juin 2020

  Trouvé une astuce qui fonctionne très bien sur ce bon vieux stackoverflow : https://stackoverflow.com/a/11652170

  <span class="CodeRay"><span class="class">.spip_documents</span> { <span class="key">display</span>: <span class="value">table</span>; }
  <span class="class">.spip_doc_legende</span> { <span class="key">display</span>: <span class="value">table-caption</span>; <span class="key">caption-side</span>: <span class="value">bottom</span>; }
  </span>
  Télécharger

  Ça donne le même résultat purement en CSS : la légende ne dépassera jamais l’image en largeur.
  Donc facile à surcharger pour adapter les styles à son site (si on veut la légende en haut, sur les côtés, etc.).
  Enfin, c’est si mon postulat sur la présence du style inline est correct, à confirmer ^^

  Le markup pour rappel :
  

  <span class="CodeRay">
  
  <span class="tag">span> <span class="attribute-name">class</span>=<span class="string"><span class="delimiter">"</span><span class="content">spip_documents</span><span class="delimiter">"</span></span><span class="tag">></span>
  
      <span class="tag">span> <span class="attribute-name">src</span>=<span class="string"><span class="delimiter">"</span><span class="content">image.png</span><span class="delimiter">"</span></span> <span class="attribute-name">class</span>=<span class="string"><span class="delimiter">"</span><span class="content">spip_doc</span><span class="delimiter">"</span></span> <span class="attribute-name">width</span>=<span class="string"><span class="delimiter">"</span><span class="content">500</span><span class="delimiter">"</span></span> <span class="attribute-name">height</span>=<span class="string"><span class="delimiter">"</span><span class="content">400</span><span class="delimiter">"</span></span><span class="tag">></span>
  
      <span class="tag">span> <span class="attribute-name">class</span>=<span class="string"><span class="delimiter">"</span><span class="content">spip_doc_legende</span><span class="delimiter">"</span></span><span class="tag">></span>
  
          <span class="tag">span> <span class="attribute-name">class</span>=<span class="string"><span class="delimiter">"</span><span class="content">spip_doc_titre</span><span class="delimiter">"</span></span><span class="tag">></span>Lorem ipsum<span class="tag"></span>
  
          <span class="tag">span> <span class="attribute-name">class</span>=<span class="string"><span class="delimiter">"</span><span class="content">spip_doc_descriptif</span><span class="delimiter">"</span></span><span class="tag">></span>
  
              Nobis laudantium eum voluptatibus. Illum iure rem nulla quos et ipsum optio sapiente. Quis placeat cum quod animi. Reprehenderit laudantium laudantium repellendus libero qui iure
  
          <span class="tag"></span>
  
      <span class="tag"></span>
  
  <span class="tag"></span>
  
  </span></span></span></span></span></span>

• ffmpeg : memory not freed on multi-threaded decoding

  31 mai 2020, par toby_e

  I am developing a video player based on the ffmpeg libraries and have run into a rather strange memory increase or failure to decrease memory when unloading a video file. My code is based on various examples of demuxing, decoding and scaling video and audio frames - but with the excecption that i have put each of these steps into seperate threads to avoid waiting for time-consuming calls. Everything works perfectly, but Visual Studio shows that Process Memory does not decrease when i call the various avclose and avfree calls. My Windows task manager confirms these memory increases that continue into the gigabyes !

  



  My player is roughly made up by two clases with the following calls to the ffmpeg libraries :

  



  —

  



  READER :

  



  Open (on main thread) : avformat_open_input(), avformat_find_stream_info()

  



  Read (on seperate thread) : av_read_frame()

  



  Close (on main thrad) : avformat_close_input()

  



  DECODER :

  



  Open (on main thread) : avcodec_find_decoder(), avcodec_alloc_context3(), avcodec_parameters_to_context(), avcodec_open2()

  



  Decode (on seperate thread) : avcodec_send_packet(), avcodec_receive_frame()

  



  Close (on main thread) : avcodec_free_context()

  



  —

  



  Is threre any issues with opening/closing on the main thread and reading/deconding on other threads ?