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• Evolution #4417 : Augmenter la longueur du mot de passe demandé pour créer un nouvel auteur

  24 décembre 2019, par cy_altern -

  complémentairement, pour compliquer le "brut force" des mots de passes, il y aurait l’utilisation d’un algorithme de hashage de type Argon2 (cf https://fr.wikipedia.org/wiki/Argon2) qui est conçu pour imposer un coût mémoire.
  Voir https://github.com/p-h-c/phc-winner-argon2 pour les implémentations disponibles de Argon2 (PHP > 7.2 et JavaScript OK)

• What's the simplest way of installing ffmpeg on my server (on a Mac) ?

  13 octobre 2011, par Nick

  I am looking to install ffmpeg on my server to enable audio files uploaded to a website to be converted to MP3. I understand that I need to install ffmpeg and ffmpeg-php, but I am not sure how to do this. I am wondering what the simplest way of doing this would be on my Mac. Would I need to use Terminal and learn command line methods, or is there a simpler way ? I have checked with my host that I have SSH access.

• FFmpeg - generate x264 CBR video transport stream with C-API

  6 juillet 2020, par ZeroDefect

  Using various posts sprinkled around the Internet, including this one here on SO, I've been able to understand how to use the FFmpeg cli to generate a CBR video bitrate using the x264 codec (wrapped in an MPEG-2 transport stream). Note : I'm concerned with the video bitrate - nothing else.

  


  ffmpeg -i cbr_test_file_input.mp4 -c:v libx264 -pix_fmt yuv420p -b:v 6000000 -preset fast -tune film -g 25 -x264-params vbv-maxrate=6000:vbv-bufsize=6000:force-cfr=1:nal-hrd=cbr -flags +ildct+ilme x264_cbr_test_output.ts


  


  However, I'm trying to approach this from an FFmpeg C-API point of view. I'm having issues. I've knocked together some code to try do something very similar to what is being done in the FFmpeg CLI. I can generate a transport stream of what I think should be CBR, but the profile of the video bitrate is very different from what I thought was the FFmpeg cli equivalent :

  


  The initialisation of the AVCodecContext looks something like :

  


        av_dict_set(&amp;pDict, "preset", "faster", 0);&#xA;      av_dict_set(&amp;pDict, "tune", "film", 0);&#xA;      av_dict_set_int(&amp;pDict, "rc-lookahead", 25, 0);&#xA;&#xA;      pCdcCtxOut->width = pCdcCtxIn->width;&#xA;      pCdcCtxOut->height = pCdcCtxIn->height;&#xA;      pCdcCtxOut->pix_fmt = AV_PIX_FMT_YUV420P;&#xA;      pCdcCtxOut->gop_size = 25;&#xA;&#xA;      // Going for 6Mbit/s&#xA;      pCdcCtxOut->bit_rate = 6000000;&#xA;      //pCdcCtxOut->rc_min_rate = pCdcCtxOut->bit_rate;&#xA;      pCdcCtxOut->rc_max_rate = pCdcCtxOut->bit_rate;&#xA;      pCdcCtxOut->rc_buffer_size = pCdcCtxOut->bit_rate;&#xA;      pCdcCtxOut->rc_initial_buffer_occupancy = static_cast<int>((pCdcCtxOut->bit_rate * 9) / 10);&#xA;&#xA;      std::string strParams = "vbv-maxrate="&#xA;                              &#x2B; std::to_string(pCdcCtxOut->bit_rate / 1000)&#xA;                              &#x2B; ":vbv-bufsize="&#xA;                              &#x2B; std::to_string(pCdcCtxOut->bit_rate / 1000)&#xA;                              &#x2B; ":force-cfr=1:nal-hrd=cbr";&#xA;&#xA;      av_dict_set(&amp;pDict, "x264-params", strParams.c_str(), 0);&#xA;&#xA;      pCdcCtxOut->field_order = AV_FIELD_TT;&#xA;      pCdcCtxOut->flags = (AV_CODEC_FLAG_INTERLACED_DCT | AV_CODEC_FLAG_INTERLACED_ME | AV_CODEC_FLAG_CLOSED_GOP);&#xA;&#xA;      // WARN: Make some assumptions here!&#xA;      pCdcCtxOut->time_base = AVRational{1,25};&#xA;      pCdcCtxOut->framerate = AVRational{25,1};&#xA;      pCdcCtxOut->sample_aspect_ratio = AVRational{64,45};&#xA;</int>

  


  The output graphs appear very different :

  


  

  


  Above is the FFmpeg CLI output - video bitrate holds fairly steady.

  


  

  


  Above is the output of my sample application - some significant dips in the video bitrate.

  


  I've taken this a step further and created a git repo consisting of :

  


  

  • Code of sample application

  


  • Test input file (.mp4)

  


  • Outputs (.ts file) of tests

  


  • Graphs of output bitrates.