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  • Configuration spécifique d’Apache

    4 février 2011, par

    Modules spécifiques
    Pour la configuration d’Apache, il est conseillé d’activer certains modules non spécifiques à MediaSPIP, mais permettant d’améliorer les performances : mod_deflate et mod_headers pour compresser automatiquement via Apache les pages. Cf ce tutoriel ; mode_expires pour gérer correctement l’expiration des hits. Cf ce tutoriel ;
    Il est également conseillé d’ajouter la prise en charge par apache du mime-type pour les fichiers WebM comme indiqué dans ce tutoriel.
    Création d’un (...)

  • HTML5 audio and video support

    13 avril 2011, par

    MediaSPIP uses HTML5 video and audio tags to play multimedia files, taking advantage of the latest W3C innovations supported by modern browsers.
    The MediaSPIP player used has been created specifically for MediaSPIP and can be easily adapted to fit in with a specific theme.
    For older browsers the Flowplayer flash fallback is used.
    MediaSPIP allows for media playback on major mobile platforms with the above (...)

  • Use, discuss, criticize

    13 avril 2011, par

    Talk to people directly involved in MediaSPIP’s development, or to people around you who could use MediaSPIP to share, enhance or develop their creative projects.
    The bigger the community, the more MediaSPIP’s potential will be explored and the faster the software will evolve.
    A discussion list is available for all exchanges between users.

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  • Multimedia Exploration Journal : The Past Doesn’t Die

    12 juillet 2011, par Multimedia Mike — Game Hacking

    New haul of games, new (old) multimedia formats.

    Lords of Midnight
    Check out the box copy scan for Lords of Midnight in MobyGames. In particular, I’d like to call your attention to this little blurb :



    Ahem, "Journey through an immense world — the equivalent of 8 CD-ROMs." Yet, when I procured the game, it only came on a single CD-ROM. It’s definitely a CD-ROM (says so on the disc) and, coming from 1995, certainly predates the earliest DVD-ROMs (which can easily store 8 CD-ROMs on a disc). Thus, I wanted to jump in a see if they were using some phenomenal compression in order to squeeze so much info into 600 or so megabytes.

    I was surprised to see the contents of the disc clocking in at just under 40 megabytes. An intro movie and an outro movie account for 75% of that. Format ? None other than that curious ASCII anomaly, ARMovie/RPL with Escape 122 codec data.

    Cyclemania



    Cyclemania is one of those FMV backdrop action games, but with a motorcycle theme. I had a good feeling I would find some odd multimedia artifacts here and the game didn’t disappoint. The videos are apparently handled using 3-4 discrete files per animation. I’ve documented my cursory guesses and linked some samples at the new MultimediaWiki page.

    Interplay ACMP
    This is unrelated to this particular acquistion, but I was contacted today about audio files harvested from the 1993 DOS game Star Trek : Judgment Rites. The files begin with the ASCII signature "Interplay ACMP Data". This reminds me of Interplay MVE files which begin with the similar string "Interplay MVE File". My theory is that these files use the ACOMP compression format, though I’m still trying to make it fit.

    Wiki and samples are available as usual if you’d like to add your own research.

  • Convert mp3 to AAC with mpeg-2 container (FFMPEG)

    18 mars 2016, par jsurf

    I’m trying to convert an mp3 audio file to an AAC file with FFMPEG, and I need the audio to be wrapped in an MPEG-2 container.
    The resulting AAC file needs to be AAC-LC (Low Complexity), 1-channel, CBR mode, 44100 sample rate, and 48kb/s bitrate, so I use this command :

    ffmpeg -y -i input.mp3 -ar 44100 -ab 48k -acodec libfdk_aac -ac 1 output.aac

    But when I examine the ADTS headers, the audio file is always being wrapped in an MPEG-4 container. I have tried all the codecs listed here but I still end up with an mpeg-4 container wrapped around the audio : http://trac.ffmpeg.org/wiki/AACEncodingGuide.

    Here are the headers I get when examining the AAC output file :

    mpeg_type : ’MPEG4’,
    profile : 2,
    profile_name : ’AAC LC’,
    sample_freq : 44100,
    channel_config : 1,
    channels : 1,
    frame_length : 139,
    buffer_fullness : 157,
    number_of_frames : 1,
    frames_per_sec : 43.06640625

    Any ideas as to why ffmpeg wraps an mp4 container around the audio ? Can I get around this somehow ? Are there any other encoders I can try aside from FFMPEG ? I was giving FAAC encoder a shot and it gives me the proper encoding and ADTS headers, but alas it does not support mp3, only WAV.

  • Setting qscale programmatically when using MPEG4 encoder ( for constant quality / VBR)

    14 février 2019, par Dennis

    i implemented the possibility to encode various self-rendered video-frames with MPEG4 codec and create an .mp4 video file. This works fine. Now i want to add the possibility to define a quality slider (0-100%) to parameterize a factor for constant quality (VBR). I don’t know how to do that.

    I found out that -qscale seems to do what i want, so i looked in ffmpeg_opt.c what happens there and tried the same :

    config.codecContext->flags |= AV_CODEC_FLAG_QSCALE;
    
config.codecContext->global_quality = FF_QP2LAMBDA * QualityLvl;

    with :

    • "config.codecContext" being the code context
    • "FF_QP2LAMBDA" being 118
    • "QualityLvl" is the "factor for constant quality" (has to be an int between 1 and 31 according to this :
      https://trac.ffmpeg.org/wiki/Encode/MPEG-4)

    The problem is, that it actually doesn’t matter if "QualityLvl" is 1,2 or 30 it always results in the same file size and a visually same(?) video file. I would have expected file size and quality differences ?!

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