Recherche avancée

Médias (1)

Mot : - Tags -/biomaping

Autres articles (58)

  • 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 (...)

  • Ajouter notes et légendes aux images

    7 février 2011, par

    Pour pouvoir ajouter notes et légendes aux images, la première étape est d’installer le plugin "Légendes".
    Une fois le plugin activé, vous pouvez le configurer dans l’espace de configuration afin de modifier les droits de création / modification et de suppression des notes. Par défaut seuls les administrateurs du site peuvent ajouter des notes aux images.
    Modification lors de l’ajout d’un média
    Lors de l’ajout d’un média de type "image" un nouveau bouton apparait au dessus de la prévisualisation (...)

  • 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 (...)

Sur d’autres sites (9519)

  • What determine number of cpu core usage of filter select=gt(scene,0.1) ?

    15 décembre 2022, par kocoten1992

    I've notice that when using filter gt(scene,0.1), for example :

    


    ffmpeg -i big_buck_bunny.mkv -filter:v "select='gt(scene,0.1)',showinfo" -f null -

    


    Depends on the video, number of cpu cores usage varies extremely (sometimes it 3 cores usage - other time 12 cores usage in different video).

    


    Would like to ask what determine that logic ?

    


    I try to read ffmpeg source code but not familiar with it, a general explanation would be enough, but much appreciate if you point out the line/directory determine that logic in https://github.com/FFmpeg/FFmpeg.

    


    (Also not asking how to reduce cpu usage, interested in the logic determine that).

    


  • How does MPG determine its default audio track ?

    1er octobre 2022, par codedread

    I have some mpg files that I transcoded from DVDs I bought a long time ago (maybe 20 years ago). ffprobe :

    


    Input #0, mpeg, from 'da-orig.mpg':
  Duration: 00:06:59.44, start: 0.044100, bitrate: 6354 kb/s
  Stream #0:0[0x1e0]: Video: mpeg2video (Main), yuv420p(tv, progressive), 720x480 [SAR 8:9 DAR 4:3], Closed Captions, 31 fps, 59.94 tbr, 90k tbn
    Side data:
      cpb: bitrate max/min/avg: 7500000/0/0 buffer size: 1835008 vbv_delay: N/A
  Stream #0:1[0x85]: Audio: ac3, 48000 Hz, stereo, fltp, 192 kb/s
  Stream #0:2[0x83]: Audio: ac3, 48000 Hz, stereo, fltp, 192 kb/s
  Stream #0:3[0x81]: Audio: ac3, 48000 Hz, mono, fltp, 192 kb/s
  Stream #0:4[0x80]: Audio: ac3, 48000 Hz, mono, fltp, 192 kb/s


    


    This shows there are 4 audio streams. When I play this file in VLC / QuickTime it seems that Audio Track 4 is the default. I'd like to understand how this is chosen. Is it something within the mpg container format or are players choosing the stream that has the lowest id (0x80) ?

    


    More background, when I try to turn this into a mp4 file with the following command :

    


    ffmpeg -i da-orig.mpg -c copy -map 0 da-copy.mp4

    


    I get roughly the same size file, but the default audio track is stream #0:1[0x85].

    


    What I want is an equivalent mp4 file (so the same audio track chosen).

    


  • avcodec/vorbisdec : don't use a flag to determine if frames have been output

    8 septembre 2022, par Jyrki Vesterinen
    avcodec/vorbisdec : don't use a flag to determine if frames have been output

    If a developer using FFmpeg libraries seeks into an earlier position and calls
    
avcodec_flush_buffers() afterwards as recommended, the Vorbis decoder will drop
    
the next frame, since buffer flushing clears the first_frame flag. As a result,
    
the audio samples the calling code receives may be ahead of the requested seek
    
position, which is unacceptable in some use cases such as playing a looping
    
sound effect.
    

    This commit records the presentation timestamp of the first frame and
    
determines after that if the new frame is the first frame (possible after
    
seeking to the start) by comparing its pts to the stored pts.
    • [DH] libavcodec/vorbisdec.c

Navigation