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• Why codecs x264/x265 ignores pts and dts of input frame ?

  1er mars 2018, par Iceman

  I’m trying to encode images from a webcam with libx265 (libx264 tried earlier) ...
  The webcam can not shoot with stable FPS because of the different amount of light entering the matrix and, as a result, different delays. Therefore, I count the fps and dts of the incoming frame and set these values for the corresponding parameters of the x265_image object, and init the encoder fpsNum with 1000 and fpsDenom with 1 (for millisecond timebase).
  The problem is that the encoder ignores pts and dts of input image and encodes at 1000 fps ! The same trick with timebase produces smooth record with libvpx. Why it does not work with x264/x265 codecs ?

  Here is parameters initialization :

  ...
  
      error = (x265_param_default_preset(param, "fast", "zerolatency") != 0);
  
      if(!error){
  
          param->sourceWidth = width;
  
          param->sourceHeight = height;
  
          param->frameNumThreads = 1;
  
          param->fpsNum = 1000;
  
          param->fpsDenom =  1;
  
          // Intra refres:
  
          param->keyframeMax = 15;
  
          param->intraRefine = 1;
  
          // Rate control:
  
          param->rc.rateControlMode = X265_RC_CQP;
  
          param->rc.rfConstant = 12;
  
          param->rc.rfConstantMax = 48;
  
          // For streaming:
  
          param->bRepeatHeaders = 1;
  
          param->bAnnexB = 1;
  
          encoder = x265_encoder_open(param);
  
          ...
  
      }
  
  ...

  Here is frame adding function :

  bool hevc::Push(unsigned char *data){
  
      if(!error){
  
          std::lock_guard lock(m_framestack);
  
          if( timer > 0){
  
              framestack.back()->dts = clock() - timer;
  
              timer+= framestack.back()->dts;
  
          }
  
          else{timer = clock();}
  
          x265_picture *picture = x265_picture_alloc();
  
          if( picture){
  
              x265_picture_init(param, picture);
  
              picture->height = param->sourceHeight;
  
              picture->stride[0] = param->sourceWidth;
  
              picture->stride[1] = picture->stride[2] = picture->stride[0] / 2;
  
              picture->planes[0] = new char[  luma_size];
  
              picture->planes[1] = new char[chroma_size];
  
              picture->planes[2] = new char[chroma_size];
  
  
  
              colorspaces::BGRtoI420(param->sourceWidth, param->sourceHeight, data, (byte*)picture->planes[0], (byte*)picture->planes[1], (byte*)picture->planes[2]);
  
              picture->pts = picture->dts = 0;
  
              framestack.emplace_back(picture);
  
          }
  
          else{error = true;}
  
      }
  
      return !error;
  
  }

  Global PTS is increasing right after x265_encoder_encode call :
  pts+= pic_in->dts; and sets as a pts of new image from framestack queue when it comes to encoder.

  Can the x265/x264 codecs encode at variable fps ? How to configure it if yes ?

• Can ffmpeg write metadata encoder when transcoding alac/flac to aac audio file ?

  11 juin 2022, par David I

  I have a collection of alac and flac files from Bandcamp and an ffmpeg instance compiled with libfdk_aac https://trac.ffmpeg.org/wiki/CompilationGuide/Centos#libfdk_aac and am trying to convert these to lossy audio aac files for non-critical listening.

  


  With ffmpeg -i Liholesie\ -\ Shamanic\ Twilight\ -\ 09\ Gray\ Wings.m4a -c:a libfdk_aac -vbr 4 -c:v copy 09_Gray_wings_vbr4.m4a an expected aac .m4a audio file is produced, album art included, works well. There's one slight detail missing :

  


  During the ffmpeg conversion process ffmpeg says :

  


  Output #0, ipod, to '09_Gray_wings_vbr4.m4a':
  Metadata:
    major_brand     : M4A 
    minor_version   : 512
    compatible_brands: M4A isomiso2
    title           : Gray Wings
    artist          : Liholesie
    album_artist    : Liholesie
    album           : Shamanic Twilight
    comment         : Visit https://liholesie.bandcamp.com
    date            : 2021
    track           : 9
    encoder         : Lavf59.24.100
  Stream #0:0: Video: mjpeg (Baseline), yuvj444p(pc, bt470bg/unknown/unknown), 700x700 [SAR 72:72 DAR 1:1], q=2-31, 90k tbr, 90k tbn (attached pic)
  Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, s16 (default)
    Metadata:
      handler_name    : SoundHandler
      vendor_id       : [0][0][0][0]
      encoder         : Lavc59.33.100 libfdk_aac 
..




  


  and the file produced looks like that when ffprobed except that the Metadata : encoder field is missing :

  


  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '09_Gray_wings_vbr4.m4a':
  Metadata:
    major_brand     : M4A 
    minor_version   : 512
    compatible_brands: M4A isomiso2
    title           : Gray Wings
    artist          : Liholesie
    album_artist    : Liholesie
    album           : Shamanic Twilight
    date            : 2021
    encoder         : Lavf59.24.100
    comment         : Visit https://liholesie.bandcamp.com
    track           : 9
  Duration: 00:06:57.78, start: 0.000000, bitrate: 155 kb/s
  Stream #0:0[0x2](und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 152 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
      vendor_id       : [0][0][0][0]
  Stream #0:1[0x0]: Video: mjpeg (Baseline), yuvj444p(pc, bt470bg/unknown/unknown), 700x700 [SAR 72:72 DAR 1:1], 90k tbr, 90k tbn (attached pic)


  


  Is there a way to write the encoder field in the Metadata section when transcoding (or is "encoder" not supported for aac m4a ? That would be weird since ffmpeg says what it says when specifying output during transcoding) .

  


  Any hints on how to write a self-defined text to said tag during transcoding are also welcome.

  


• Anomalie #4706 (Nouveau) : safehtml vire des trucs légitimes

  29 mars 2021, par RastaPopoulos ♥

  Il semblerait que safehtml fasse quelque peu de la merde : ça vire des attributs totalement légitimes, par ex des data-truc où on met ce qu’on veut.
  En 3.2 ou 3.3, à corriger dans les deux.

  Par exemple le plugin Intl qui a une fonction d’affichage des montants, utilise le mot "montant" dans des attributs (logique vu que c’est tout l’objet du plugin).

  J’ai bien testé avec juste charger_fonction(’safehtml’, ’inc’) de ce plugin.

  <span class="CodeRay"><span class="local-variable">$safehtml</span>(<span class="string"><span class="delimiter">'</span><span class="content"><span class="montant" data-montant-nombre="100" data-montant-devise="EUR"></span><span class="delimiter">'</span></span>)
  </span></span>
  Télécharger

  Au retour ya plus que :
  

  <span class="CodeRay"><span class="tag">span> <span class="attribute-name">class</span>=<span class="string"><span class="delimiter">"</span><span class="content">montant</span><span class="delimiter">"</span></span> 
  
  </span></span>

  Et du coup ça affiche l’emoji danger avec le code visible, par exemple dans des affichages du plugin Bank, mais pas que, dès qu’on passe ce HTML à une chaine de langue un truc comme ça.