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Autres articles (73)

  • Contribute to documentation

    13 avril 2011

    Documentation is vital to the development of improved technical capabilities.
    MediaSPIP welcomes documentation by users as well as developers - including : critique of existing features and functions articles contributed by developers, administrators, content producers and editors screenshots to illustrate the above translations of existing documentation into other languages
    To contribute, register to the project users’ mailing (...)

  • MediaSPIP en mode privé (Intranet)

    17 septembre 2013, par

    À partir de la version 0.3, un canal de MediaSPIP peut devenir privé, bloqué à toute personne non identifiée grâce au plugin "Intranet/extranet".
    Le plugin Intranet/extranet, lorsqu’il est activé, permet de bloquer l’accès au canal à tout visiteur non identifié, l’empêchant d’accéder au contenu en le redirigeant systématiquement vers le formulaire d’identification.
    Ce système peut être particulièrement utile pour certaines utilisations comme : Atelier de travail avec des enfants dont le contenu ne doit pas (...)

  • Multilang : améliorer l’interface pour les blocs multilingues

    18 février 2011, par

    Multilang est un plugin supplémentaire qui n’est pas activé par défaut lors de l’initialisation de MediaSPIP.
    Après son activation, une préconfiguration est mise en place automatiquement par MediaSPIP init permettant à la nouvelle fonctionnalité d’être automatiquement opérationnelle. Il n’est donc pas obligatoire de passer par une étape de configuration pour cela.

Sur d’autres sites (10128)

  • When compressing a set of images with libx264, why does frame rate affect final output size ?

    3 avril 2018, par jd20

    I’m using ffmpeg to encode a set of images as a short timelapse video, using libx264 codec. My first attempt, I encoded it at 30 FPS, using :

    ffmpeg -r 30 -pattern_type glob -i "*.jpg" -vcodec libx264 -crf 30 -pix_fmt yuv420p output.mp4

    With 60 frames, that gives me a 163 KB file that’s 2 seconds long. Then I realized I needed it to be slower, so I re-ran the same command, but changed -r to 2. Now I have a file that’s 30 seconds long, but the size jumped to 891 KB ! The video quality looks perceptually the same.

    How do I encode at a slower frame rate, without the final file size ballooning ?

    Notes : Some theories I had, and things I checked. First, to make sure ffmpeg wasn’t duplicating frames in the longer verison, I check the I/P/B counts. The 30 FPS file had :

    [libx264 @ 0x7f9b26001c00] frame I:1     Avg QP:30.67  size: 44649
    
[libx264 @ 0x7f9b26001c00] frame P:15    Avg QP:31.19  size:  5471
    
[libx264 @ 0x7f9b26001c00] frame B:44    Avg QP:31.45  size:   767

    The 2 FPS file had :

    [libx264 @ 0x7fcd32842200] frame I:1     Avg QP:21.29  size: 90138
    
[libx264 @ 0x7fcd32842200] frame P:15    Avg QP:22.48  size: 33686
    
[libx264 @ 0x7fcd32842200] frame B:44    Avg QP:26.29  size:  6674

    So, the I/P/B counts are identical, but the QP is much lower for the 2 FPS file. To offset, I tried increasing -crf for the 2 FPS file, to get about the same target size, but that just gave me a very blurry video (had to go to crf=40). I tried messing with -minrate, -maxrate, -bt, none helped. I’m guessing there is some x264 codec setting which is frame rate dependent, but I’m at a loss trying to figure out which one (from what I understand, constant bitrate is affected by frame rate but CRF should not be, but maybe I’m misunderstanding it.

  • When compressing a set of images with libx264, why does frame rate affect final output size ?

    3 avril 2018, par jd20

    I’m using ffmpeg to encode a set of images as a short timelapse video, using libx264 codec. My first attempt, I encoded it at 30 FPS, using :

    ffmpeg -r 30 -pattern_type glob -i "*.jpg" -vcodec libx264 -crf 30 -pix_fmt yuv420p output.mp4

    With 60 frames, that gives me a 163 KB file that’s 2 seconds long. Then I realized I needed it to be slower, so I re-ran the same command, but changed -r to 2. Now I have a file that’s 30 seconds long, but the size jumped to 891 KB ! The video quality looks perceptually the same.

    How do I encode at a slower frame rate, without the final file size ballooning ?

    Notes : Some theories I had, and things I checked. First, to make sure ffmpeg wasn’t duplicating frames in the longer verison, I check the I/P/B counts. The 30 FPS file had :

    [libx264 @ 0x7f9b26001c00] frame I:1     Avg QP:30.67  size: 44649
    
[libx264 @ 0x7f9b26001c00] frame P:15    Avg QP:31.19  size:  5471
    
[libx264 @ 0x7f9b26001c00] frame B:44    Avg QP:31.45  size:   767

    The 2 FPS file had :

    [libx264 @ 0x7fcd32842200] frame I:1     Avg QP:21.29  size: 90138
    
[libx264 @ 0x7fcd32842200] frame P:15    Avg QP:22.48  size: 33686
    
[libx264 @ 0x7fcd32842200] frame B:44    Avg QP:26.29  size:  6674

    So, the I/P/B counts are identical, but the QP is much lower for the 2 FPS file. To offset, I tried increasing -crf for the 2 FPS file, to get about the same target size, but that just gave me a very blurry video (had to go to crf=40). I tried messing with -minrate, -maxrate, -bt, none helped. I’m guessing there is some x264 codec setting which is frame rate dependent, but I’m at a loss trying to figure out which one (from what I understand, constant bitrate is affected by frame rate but CRF should not be, but maybe I’m misunderstanding it.

  • Anomalie #4189 (Fermé) : extraire_multi mélange un /li /ul final avec le de langue ajouté p...

    8 mars 2021, par cedric -

    intégré par https://git.spip.net/spip/spip/commit/2731ba05209cf61588923a5cd8cc4442cad6878e alea jacta est

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