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  • Les autorisations surchargées par les plugins

    27 avril 2010, par

    Mediaspip core
    autoriser_auteur_modifier() afin que les visiteurs soient capables de modifier leurs informations sur la page d’auteurs

  • Encoding and processing into web-friendly formats

    13 avril 2011, par

    MediaSPIP 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 (...)

  • Création définitive du canal

    12 mars 2010, par

    Lorsque votre demande est validée, vous pouvez alors procéder à la création proprement dite du canal. Chaque canal est un site à part entière placé sous votre responsabilité. Les administrateurs de la plateforme n’y ont aucun accès.
    A la validation, vous recevez un email vous invitant donc à créer votre canal.
    Pour ce faire il vous suffit de vous rendre à son adresse, dans notre exemple "http://votre_sous_domaine.mediaspip.net".
    A ce moment là un mot de passe vous est demandé, il vous suffit d’y (...)

Sur d’autres sites (10847)

  • image -> video -> image not lossless using avconv

    15 décembre 2015, par nrob

    I’m trying to test the amount of information lost with some different video codecs. I’ve got a python script which uses PyPNG to write a series of 8 bit RGB images. I then encode it using avconv, for instance

    avconv -r 1 -i ../frames/data%03d.png -c:v ffv1 -qscale:v 0 -r 1

    outffv1.avi

    I then decode this back into pngs like so

    avconv -r 1 -i outffv1.avi -r 1 ./outffv1/frame%03d.png

    But when I compare the images before and after the video compression, they are different (mean absolute error of 15%). The thing that is confusing me is that this is true (give or take) independent of the codec.

    For instance, I get similar answers for libtheora for a range of qscale values.

    The png encoding i.e. write to png, and immediately load back in without and video compression step, is lossless.

  • ffmpeg reverts audio volume even after removing the audio track

    7 avril 2023, par DniweTamp

    I tried making a simple batch file that separates and normalizes audio track, and merges it with the reencoded video track afterwards, but whenever I try to add the edited audio track back the volume just goes back to the original level.

    


    It happens specifically when I try to add the audio back to video, the volume level stays normalized if I reencode said audio to .aac or .ogg files, but when I try to add it to the video, even using -c:a copy, the volume just reverts to the original level

    


    Below is an image that shows the volume levels of audio tracks

    


    I detach audio, normalize it (result is top track), add it back to the video, and it becomes what's on the bottom (which is also the same volume as the original video's audio)
Normalized and quiet volume levels

    


    Here's the contents of my batch file, expected result was a reencoded video, with normalized audio

    


    I tried removing audio track with both -an and -map 0 -map -0:a, same result

    


    I can confirm that the normalize program does its job correctly, by checking volume levels in audacity

    


    ffmpeg -i %1 -y temp.wav
normalize.exe temp.wav
ffmpeg -i %1 -c:v libx264 -map 0 -map -0:a -profile:v main -pix_fmt yuv420p -movflags +faststart -preset medium -crf 22 -map_metadata -1 -y video.temp.mp4
ffmpeg -i %1 -i temp.wav -c:v copy -y video.h264.mp4
del temp.wav
del video.temp.mp4


    


    Edit : and here's the video file I tried this on.

    


  • What does 'dash' option in ffmpeg command do ?

    29 janvier 2020, par Hyldrean

    What is the effect or meaning of the -dash option in a ffmpeg command (extracting a track for DASH streaming) ? E.g this one :

    ffmpeg -i in.video -vn -acodec libvorbis -ab 128k -dash 1 audio.webm

    I can’t find anything about it in the ffmpeg documentation.

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