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Médias (1)
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1 000 000 (wav version)
26 septembre 2011, par
Mis à jour : Avril 2013
Langue : English
Type : Audio
Autres articles (103)
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Publier sur MédiaSpip
13 juin 2013Puis-je poster des contenus à partir d’une tablette Ipad ?
Oui, si votre Médiaspip installé est à la version 0.2 ou supérieure. Contacter au besoin l’administrateur de votre MédiaSpip pour le savoir -
Encoding and processing into web-friendly formats
13 avril 2011, parMediaSPIP automatically converts uploaded files to internet-compatible formats.
Video files are encoded in MP4, Ogv and WebM (supported by HTML5) and MP4 (supported by Flash).
Audio files are encoded in MP3 and Ogg (supported by HTML5) and MP3 (supported by Flash).
Where possible, text is analyzed in order to retrieve the data needed for search engine detection, and then exported as a series of image files.
All uploaded files are stored online in their original format, so you can (...) -
Qu’est ce qu’un masque de formulaire
13 juin 2013, parUn masque de formulaire consiste en la personnalisation du formulaire de mise en ligne des médias, rubriques, actualités, éditoriaux et liens vers des sites.
Chaque formulaire de publication d’objet peut donc être personnalisé.
Pour accéder à la personnalisation des champs de formulaires, il est nécessaire d’aller dans l’administration de votre MediaSPIP puis de sélectionner "Configuration des masques de formulaires".
Sélectionnez ensuite le formulaire à modifier en cliquant sur sont type d’objet. (...)
Sur d’autres sites (7075)
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Compressing videos from a smartphone
9 novembre 2016, par fejesjocoI have a Nexus 6p with the stock camera. It’s set to record at 1080p, 30fps. Here’s a 5 second sample (11 MB).
Videos from this phone come out at about 17 Mbps on average. I tried to compress it with ffmpeg with
-c:v libx264 -crf 23 -preset veryslow
, the result comes out at about 5.5 MB, which is about 9 Mbps.I think this bitrate is a bit too much. When I look at torrent file listings, I can see high quality videos at 3 GB in size on average, and if such a movie is 90 minutes long on average, that is about 4-5 Mbps which sounds okay.
I’m wondering, why the big difference ? I can notice that my video is noisy/grainy (which is expected from a phone), and that might reduce compressibility. I tried a few ffmpeg filters, like hqdn3d and atadenoise, but the noise mostly remained (maybe I didn’t play with it enough). Then I figured, the video is also shaky (which is also expected), and that might reduce compressibility too (and even makes temporal noise filtering less effective). I tried to stabilize it with the deshake filter, but that didn’t help either.
I know I could just limit the bandwidth to whatever I like, but there must be a reason why ffmpeg thinks it needs a high bandwidth to maintain a certain quality, and a lower bandwidth would just decrease the quality.
Why do these videos have such a high bitrate ? What’s the best way to compress them more while keeping or even increasing their quality ?
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Use ffmpeg to resize one input's dimension to match another input's dimension
18 novembre 2022, par Hans GDI need to resize one image A to match one dimension of another input B (make height of A match the height of B, for example). I will do this for several pairs of images in a folder, for which I will use a script in the end, but I wanted to know if this particular operation can be done only with
ffmpeg
.

Again, the final script could read the image, find the size and use
scale=-1:height
to accomplish the final goal, but is it posible to make the title's operation only withffmpeg
?

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Create 256 color palette video
2 mars 2020, par rlcabralI already have this working by converting the source video to GIF with :
ffmpeg -y -t 5 source.mp4 -vf fps=10,scale=480:-1,smartblur=ls=-0.5,crop=iw:ih-2:0:0 -hide_banner -loglevel panic output.gif
And then converting the GIF to MP4, like so :
ffmpeg -y animated.gif -hide_banner -pix_fmt yuvj420p -loglevel panic -an -loglevel panic final.mp4
What I want is to convert
source.mp4
directly tofinal.mp4
, and have the same 256 color palette as a normal GIF.I tried merging both commands together, and although it generates a MP4, the result is a 16 bit video, surprisingly smaller than a 8 bit video.
Do I need to generate a palette first with
palettegen
and then re-encode the video with this palette ?