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Autres articles (19)

  • 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 (...)

  • 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 (...)

  • Les vidéos

    21 avril 2011, par

    Comme les documents de type "audio", Mediaspip affiche dans la mesure du possible les vidéos grâce à la balise html5 .
    Un des inconvénients de cette balise est qu’elle n’est pas reconnue correctement par certains navigateurs (Internet Explorer pour ne pas le nommer) et que chaque navigateur ne gère en natif que certains formats de vidéos.
    Son avantage principal quant à lui est de bénéficier de la prise en charge native de vidéos dans les navigateur et donc de se passer de l’utilisation de Flash et (...)

Sur d’autres sites (3347)

  • Changing volume halfway through video using FFmpeg ?

    10 avril 2019, par Essem

    I’m trying to use the fluent-ffmpeg NPM module in an application to decrease the volume of the audio in the first half of a video, then increase the volume when it reaches the midway point. I’ve wrote this code to try to do that :

    const ffmpeg = require("fluent-ffmpeg");
    

    
ffmpeg("test.mp4")
    
 .audioFilters("volume=enable='between(t,0,t/2)':volume='0.25'", "volume=enable='between(t,t/2,t)':volume='1'")
    
 .save("output.mp4");

    However, whenever I run this code, the volume levels of output.mp4 are exactly the same as test.mp4. What do I do ?

  • Is it possible to change volume with no reencode with ffmpeg ?

    30 juin 2023, par John Smith

    I just had this question because I used the following command with ffmpeg :

    



    ffmpeg -i input.wav -filter:a "volume=0.2" output.wav


    



    Following the documentation here : https://trac.ffmpeg.org/wiki/AudioVolume

    



    However, when I created the new file, the output was half the size of the input and the bitrate of the audio track was reduced as well.

    



    So my questions are :

    



      

    1. Is the bitrate supposed to decrease with decreasing and increasing volume like so ?

      2. 


    2. Is it possible to change volume without reencoding with ffmpeg ?

      3. 


    


  • Why do the results of my "ffmpeg -ss -to" split have audio but no video ?

    10 avril 2018, par BenKnght

    I am trying to split clips into short intervals (that I am reading in from a csv) using ffmpeg. The commands that I’m using look like this :

    ffmpeg -i filename.mp4 -ss 00:00:00.030000 -to 00:00:02.030000   
    
-pix_fmt yuv420p -c copy new_filename.mp4

    This successfully splits the parent mp4 into many smaller mp4s, but the smaller files lose some or all of their video. Most of them end up being just audio. Some have video - but only for about half of the clip (the rest is black). The audio is always there. Any ideas why this might be happening ?

    A couple notes : I’m using ffmpeg 3.0.2. Also, I am creating this command as a Python list and running it with the following call

    subprocess.run(cmd, stderr=subprocess.STDOUT)

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