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• Adding HEVC reference decoder to ffmpeg framework

  4 mars 2014, par Zax

  I have a tweaked HM reference code of HEVC Decoder based on my requirements. I also know that FFMPEG version 2.1 onwards supports HEVC. But its a necessity for me to integrate my modified HM code.

  Hence I have gone through the post :

  http://wiki.multimedia.cx/index.php?title=FFmpeg_codec_howto

  According to this post, I need to define some functions that are needed to add a new decoder support to FFMPEG framework.

  The structure is : typedef struct AVCodec

  I have defined a structure as shown below :

  AVCodec HMHEVC_decoder =
  
  {
  
      .name           = "hmhevc",
  
      .type           = AVMEDIA_TYPE_VIDEO,
  
      .id             = AV_CODEC_ID_HMHEVC,
  
  
  
      .init           = hmhevc_decode_init,
  
      .close          = hmhevc_decode_close,
  
      .decode         = hmhevc_decode_frame,
  
  };

  However, looking at the other examples, I feel I have to add another variable like :

      .priv_data_size = sizeof(HEVCContext),

  But the problem is that I don't have any such context. So in case I don't define this, what are the things that FFMPEG framework wont provide my decoder ?

  Also is definition of this private data context compulsary ?

  What are the other fields that have to be compulsorily defined ?

  My main intention is that FFPLAY should be able to play the decoded frame.

• Input seeking for frame at specified timestamp with Py-AV

  9 décembre 2019, par neonScarecrow

  I have a project already using Py-AV and am trying to replicate a specific ffmpeg command. The goal is to get a frame roughly around the specified timestamp.

  Here’s the ffmpeg commmand :
  https://trac.ffmpeg.org/wiki/Seeking

  ffmpeg -ss 14 -i https://some_url.mp4 -frames:v 1 frame_at_14_seconds.jpg

  Here’s my code :

      #return one frame around 14 seconds into the movie
  
      target_sec = 14 
  
      container = av.open('https://some_url.mp4', 'r')
  
      container.streams.video[0].thread_type = 'AUTO'
  
      video_stream = next(s for s in container.streams if s.type == 'video')
  
      time_base = float(video_stream.time_base)
  
      target_timestamp = int(target_sec / time_base) + video_stream.start_time
  
      video_stream.seek(target_timestamp)
  
      for frame in container.decode(video_stream):
  
          frame.to_image().save('frame_at_14_seconds.jpg')
  
          break

  Additionally, I have found any documentation about this, but does anyone know if either command (ffmpeg/av.open) is downloading the entire file to a tmp file behind the scenes. I’m looking for a less memory-intensive way to read a frame for every second in an up to 60 second video.

• Evolution #4841 (Fermé) : Z-index de la modale

  2 juillet 2021

  Bonjour,

  Le ticket https://git.spip.net/spip-contrib-extensions/crayons/issues/9 montre qu’il peut y avoir 2 cas d’usage d’une modale-box et des crayons :

  1. un crayon qui appelle une modale (comportement qui fonctionne depuis des années avec le plugin Insérer Modèles)
  2. une modale qui contient un crayon

  C’est ce 2e cas qui provoqué ce commit https://git.spip.net/spip-contrib-extensions/crayons/commit/f1c7f89a115eda2bc166ce50a76c5b1e9d01a3a7
  Commit qui casse le premier cas

  Proposition de piste de solution : est-ce qu’il serait possible à la modale box de s’adapter automagiquement et d’avoir un z-index dynamique qui serait égal au z-index actuel maximum de la page + 1 ?

  La question du z-index max d’une page a plein de réponses : https://www.google.com/search?q=javascript+get+highestindex+on+page

  • https://awik.io/make-sure-element-highest-z-index/
  • https://www.willmaster.com/blog/javascript/z-index-range.php
  • https://www.sitepoint.com/jquery-find-highest-z-index-page/
  • https://blog.frankmtaylor.com/2019/05/16/whats-the-highest-z-index-on-a-page-and-other-css-property-problems/ (la plus complexe, mais la mieux expliquée)