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• FFMPEG : Decode video in h264rgb/libx264rgb error

  9 février 2018, par Furan

  I did a small program to encode raw images in h264rgb codec with ffmpeg.
  I use this codec because I needed to encode lossless rgb images (not possible with the classic h264 codec).

  But now, I have a problem. I’m not able to decode the video generated with ffmpeg. I did a second small program for that, but I get a segfault when I reach the avcodec_decode_video2() function.

  I did all the initialisation correctly. I didn’t forget the avcodec_register_all() and av_init_packet() functions.

  Here is the code for initialisation :

    _c = NULL;
  
    _frame_nb = 0;
  
  
  
    // Register all formats and codecs
  
    #pragma omp critical
  
    {
  
        avcodec_register_all();
  
    }
  
  
  
    _pkt = new AVPacket;
  
    av_init_packet(_pkt);  // a defaut de pouvoir ecrire : pkt = av_packet_alloc();
  
  
  
    if(!_pkt)
  
        exit(1);
  
  
  
      _codec = avcodec_find_encoder_by_name("libx264rgb");
  
  
  
    if (!_codec) {
  
        fprintf(stderr, "codec not found\n");
  
        exit(1);
  
    }
  
  
  
    _c = avcodec_alloc_context3(_codec);
  
    if (!_c) {
  
        fprintf(stderr, "Could not allocate video codec context\n");
  
        exit(1);
  
    }
  
  
  
    _c->debug = true;
  
    _c->pix_fmt =  (AVPixelFormat)AV_PIX_FMT_RGB24;
  
    _c->width = this->_headerCam[this->_currentCam]->iNbCol;
  
    _c->height = this->_headerCam[this->_currentCam]->iNbLine;
  
  
  
    _picture = av_frame_alloc();
  
    if (!_picture) {
  
        fprintf(stderr, "Could not allocate video _picture\n");
  
        exit(1);
  
    }
  
  
  
    _tmp_picture = av_frame_alloc();
  
    if (!_tmp_picture) {
  
        fprintf(stderr, "Could not allocate video _tmp_picture\n");
  
        exit(1);
  
    }
  
  
  
  
  
        _tmp_picture->format = (AVPixelFormat)AV_PIX_FMT_RGB24;
  
        _tmp_picture->width = this->_headerCam[this->_currentCam]->iNbCol;
  
        _tmp_picture->height = this->_headerCam[this->_currentCam]->iNbLine;
  
        _tmp_picture->linesize[0] = this->_headerCam[this->_currentCam]->iNbCol;
  
  
  
    /* open it */
  
    if (avcodec_open2(_c, _codec, NULL) < 0) {
  
        fprintf(stderr, "could not open codec\n");
  
        exit(1);
  
    }

  And the decode function :

          _pkt->data = NULL;    // packet data will be allocated by the encoder
  
          _pkt->size = 0;
  
  
  
          unsigned char * inbuf;
  
          inbuf = (uint8_t*)av_malloc(w*h*3);
  
  
  
          //! read img size
  
          int size_img;
  
          fread(&size_img, sizeof(int), 1, this->_pFile);
  
          _pkt->size = fread(inbuf, 1, size_img, this->_pFile);
  
  
  
          _pkt->data = (unsigned char*)inbuf;
  
  
  
          if(_pkt->size)
  
          {
  
              len = avcodec_decode_video2(_c, _tmp_picture, &got_picture, _pkt);
  
              ...
  
          }

  Any idea ?

• Chiptune Database and API

  14 septembre 2012, par Multimedia Mike — General

  So I set out to create a website that allows people to easily listen to video game music directly through their web browser. I succeeded in that goal. However, I must admit that the project has limited appeal since the web player is delivered via Chrome’s Native Client technology, somewhat limiting its audience. I’m not certain if anyone really expects NaCl to take off in any serious way, but I still have a few other projects in mind.

  I recently realized that, as a side effect of this project, I accidentally created something of significant value to fans of old video games and associated music– a searchable database of chiptune music and metadata. To my knowledge, no one else has endeavored to create such a thing. I figured that I might as well make the database easily accessible with an API and see where it leads.

  To that end, I created 2 API entry points. First, there is the search API located at http://gamemusic.multimedia.cx/api/search/. This can be exercised by ending the URL with a URL-encoded search string, e.g. : http://gamemusic.multimedia.cx/api/search/super+mario. This returns JSON data containing an array of results in decreasing order of relevance. Each result has a game title, database ID, media URL, system type, and an SHA-1 hash. This is the same API that the site’s own search page uses.

  The database ID can be plugged into http://gamemusic.multimedia.cx/api/metadata/ to retrieve the song’s metadata in JSON format. E.g., the ID for Super Mario Bros. 3 on the NES is 161 : http://gamemusic.multimedia.cx/api/metadata/161.

  I recently read an article about sins against true RESTful API principles which led me to believe I’m almost certainly doing this web API stuff wrong. I don’t think it’s a huge deal, though, since I don’t think anyone actually listens to chiptunes any more. But if there are offline chiptune music players that are still in service and actively maintained, perhaps the authors would like to implement this API. It would require some type of HTTP networking library, a JSON parser, the embedded XZ decoder, and some new code to parse through my .gamemusic and .psfarchive formats.

  This database could be a significant value-add to chiptune playback software, and could help people experience classic game music much more easily.

• Revision 122868 : Toujours sur ces vues de saisies fieldset. Champ extra se base sur le ...

  7 mars 2020, par Maïeul Rouquette — Log

  Toujours sur ces vues de saisies fieldset.
  Champ extra se base sur le classe vide pour ne pas afficher les saisies
  sans réponse. Le masquage est en css, contrairement à ce que je pensais
  (suis-je bête !)
  On ajoute donc la classe vide à la vie d’une saisie si l’ensemble de ses
  sous saisies sont vide.
  Permet d’éviter avec champ extra d’avoir un titre de fieldset qui se
  balade sans aucune réponse en dessous.