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  • Gestion des droits de création et d’édition des objets

    8 février 2011, par

    Par défaut, beaucoup de fonctionnalités sont limitées aux administrateurs mais restent configurables indépendamment pour modifier leur statut minimal d’utilisation notamment : la rédaction de contenus sur le site modifiables dans la gestion des templates de formulaires ; l’ajout de notes aux articles ; l’ajout de légendes et d’annotations sur les images ;

  • Supporting all media types

    13 avril 2011, par

    Unlike most software and media-sharing platforms, MediaSPIP aims to manage as many different media types as possible. The following are just a few examples from an ever-expanding list of supported formats : images : png, gif, jpg, bmp and more audio : MP3, Ogg, Wav and more video : AVI, MP4, OGV, mpg, mov, wmv and more text, code and other data : OpenOffice, Microsoft Office (Word, PowerPoint, Excel), web (html, CSS), LaTeX, Google Earth and (...)

  • Keeping control of your media in your hands

    13 avril 2011, par

    The vocabulary used on this site and around MediaSPIP in general, aims to avoid reference to Web 2.0 and the companies that profit from media-sharing.
    While using MediaSPIP, you are invited to avoid using words like "Brand", "Cloud" and "Market".
    MediaSPIP is designed to facilitate the sharing of creative media online, while allowing authors to retain complete control of their work.
    MediaSPIP aims to be accessible to as many people as possible and development is based on expanding the (...)

Sur d’autres sites (9053)

  • Difference between DirectShowSource() and FFmpegSource2() in AviSynth

    29 mars 2024, par MarianD

    For non .avi A/V sources (as .mp3, .mp4, etc.) there are (at least) 2 possibilities for reading those media files in AviSynth (in Windows) :

    



      

    • The built-in media filter DirectShowSource(), using Microsoft's DirectShow media architecture.

      • 


    • The AviSynth Plugin FFmpegSource2() alias FFMS2() using FFmpeg and nothing else.

      • 


    



    What are advantages and disadvantages of them ?
    
Which is more reliable, frame / sample accurate, etc.?

    


  • What is the difference between different fadein/fadeout curves in ffmpeg ?

    16 août 2018, par siods333333

    Here is the list of possible curves for afade and acrossfade filters from here https://ffmpeg.org/ffmpeg-filters.html#afade-1

    tri
    
    select triangular, linear slope (default) 
    

    
qsin
    
    select quarter of sine wave 
    

    
hsin
    
    select half of sine wave 
    

    
esin
    
    select exponential sine wave 
    

    
log
    
    select logarithmic 
    

    
ipar
    
    select inverted parabola 
    

    
qua
    
    select quadratic 
    

    
cub
    
    select cubic 
    

    
squ
    
    select square root 
    

    
cbr
    
    select cubic root 
    

    
par
    
    select parabola 
    

    
exp
    
    select exponential 
    

    
iqsin
    
    select inverted quarter of sine wave 
    

    
ihsin
    
    select inverted half of sine wave 
    

    
dese
    
    select double-exponential seat 
    

    
desi
    
    select double-exponential sigmoid

    Here is the code for them, from libavfilter/af_afade.c :

    switch (curve) {
    
case QSIN:
    
    gain = sin(gain * M_PI / 2.0);
    
    break;
    
case IQSIN:
    
    /* 0.6... = 2 / M_PI */
    
    gain = 0.6366197723675814 * asin(gain);
    
    break;
    
case ESIN:
    
    gain = 1.0 - cos(M_PI / 4.0 * (CUBE(2.0*gain - 1) + 1));
    
    break;
    
case HSIN:
    
    gain = (1.0 - cos(gain * M_PI)) / 2.0;
    
    break;
    
case IHSIN:
    
    /* 0.3... = 1 / M_PI */
    
    gain = 0.3183098861837907 * acos(1 - 2 * gain);
    
    break;
    
case EXP:
    
    /* -11.5... = 5*ln(0.1) */
    
    gain = exp(-11.512925464970227 * (1 - gain));
    
    break;
    
case LOG:
    
    gain = av_clipd(1 + 0.2 * log10(gain), 0, 1.0);
    
    break;
    
case PAR:
    
    gain = 1 - sqrt(1 - gain);
    
    break;
    
case IPAR:
    
    gain = (1 - (1 - gain) * (1 - gain));
    
    break;
    
case QUA:
    
    gain *= gain;
    
    break;
    
case CUB:
    
    gain = CUBE(gain);
    
    break;
    
case SQU:
    
    gain = sqrt(gain);
    
    break;
    
case CBR:
    
    gain = cbrt(gain);
    
    break;
    
case DESE:
    
    gain = gain <= 0.5 ? cbrt(2 * gain) / 2: 1 - cbrt(2 * (1 - gain)) / 2;
    
    break;
    
case DESI:
    
    gain = gain <= 0.5 ? CUBE(2 * gain) / 2: 1 - CUBE(2 * (1 - gain)) / 2;
    
    break;
    
}

    How do they look like ? How do they sound like ? Which one is recommended for fadein+fadeout and crossfade ? Personally I’m just trying to avoid audio clicks, maybe crossfade is a bit of an overkill here.

    Related link : http://manual.audacityteam.org/man/fade_and_crossfade.html . Not sure how audacity names translate into ffmpeg names though.

  • What's the difference with crf and qp in ffmpeg ?

    12 novembre 2024, par Nova

    I read https://trac.ffmpeg.org/wiki/Encode/H.264 about h264 encoding and discovered qp.

    


    Q1 : What are the differences with crf and qp ?
    
Q2 : Is it better to use qp over crf overall, or is it only if for using qp 0 for best lossless ?
    
Q3 : Does qp have a known sensible setting if it's preferred ? So far, I know crf has the default value of 23 while 18 is a sensible preferred increase in quality, although I don't understand why 18 wouldn't be default if better sensible lossless.
    
Q4 : Would changing either of them cause incompatibility with non-ffmpeg players or just qp ?

    


    I'm converting from webm to mp4.

    


    I was going to test crf 23 and 18 and pick which is best but I can't seem to find any concrete information on this comparison or about qp.

    


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