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  • Keeping control of your media in your hands

    13 avril 2011, par

    The vocabulary used on this site and around MediaSPIP in general, aims to avoid reference to Web 2.0 and the companies that profit from media-sharing.
    While using MediaSPIP, you are invited to avoid using words like "Brand", "Cloud" and "Market".
    MediaSPIP is designed to facilitate the sharing of creative media online, while allowing authors to retain complete control of their work.
    MediaSPIP aims to be accessible to as many people as possible and development is based on expanding the (...)

  • Encodage et transformation en formats lisibles sur Internet

    10 avril 2011

    MediaSPIP transforme et ré-encode les documents mis en ligne afin de les rendre lisibles sur Internet et automatiquement utilisables sans intervention du créateur de contenu.
    Les vidéos sont automatiquement encodées dans les formats supportés par HTML5 : MP4, Ogv et WebM. La version "MP4" est également utilisée pour le lecteur flash de secours nécessaire aux anciens navigateurs.
    Les documents audios sont également ré-encodés dans les deux formats utilisables par HTML5 :MP3 et Ogg. La version "MP3" (...)

  • Automated installation script of MediaSPIP

    25 avril 2011, par

    To overcome the difficulties mainly due to the installation of server side software dependencies, an "all-in-one" installation script written in bash was created to facilitate this step on a server with a compatible Linux distribution.
    You must have access to your server via SSH and a root account to use it, which will install the dependencies. Contact your provider if you do not have that.
    The documentation of the use of this installation script is available here.
    The code of this (...)

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  • ffmpeg : Apply a time-based expr to control intensity of lowpass, highpass, aphaser, or aecho [closed]

    17 mai 2024, par Wes Modes

    I am procedurally constructing complexFilters for ffmpeg via fluent-ffmpeg. My fluent-ffmpeg complex filters look like :

    


    {
   "filter": "volume",
   "options": {
       "volume": "min(1, max(0, ((cos(PI * t * 1 / 13) * 1 + cos(PI * t * 1 / 7) * 0.5 + cos(PI * t * 1 / 3) * 0.25) +
-0.5 ) * 0.75 * -1 + 0.5))",
       "eval": "frame"
    },
    "inputs": "track_1_output",
    "outputs": "track_1_adjusted"
},


    


    Note that I am using an expression to determine the volume dynamically.

    


    Here I'm testing on the command line, to understand the mysteries of lightly-documented ffmpeg filters. I'm fading in and out two sources, intertwined in the output. Now I want to apply lowpass, highpass, aphaser, and/or aecho to the transitions using a time-based expr.

    


    I've already succeeded using the volume filter to fade the sources in and out (Note that the sine has reversed polarity for the second volume filter) :

    


    # working fade in/out
ffmpeg -i knox.mp3 -i static.mp3 -filter_complex \
"[0:a] \
    volume = 'min(1, max(0, 0.5 + 0.5 * cos(PI * t / 5)))': eval=frame \
    [a0]; \
[1:a] \
    volume = 'min(1, max(0, 0.5 - 0.5 * cos(PI * t / 5)))': eval=frame \
    [a1]; \
[a0][a1]
    amix = inputs=2: duration=shortest" \
-c:a libmp3lame -q:a 2 output.mp3


    


    ffmpeg -filters says that lowpass has time-based support :

    


      T.. = Timeline support
 TSC lowpass           A->A       Apply a low-pass filter with 3dB point frequency.


    


    How can I similarly apply these other filters to source1 using a time-bassed expr ? I was unsuccessful in figuring out lowpass and highpass :

    


    # applying a lowpass filter
ffmpeg -i knox.mp3 -i static.mp3 -filter_complex \
"[0:a] \
    volume = 'min(1, max(0, 0.5 + 0.5 * cos(PI * t / 5)))': eval=frame, \
    lowpass=f=3000: mix='0.5 + 0.5 * cos(PI * t / 5)' \
    [a0]; \
[1:a] \
    volume = 'min(1, max(0, 0.5 - 0.5 * cos(PI * t / 5)))': eval=frame \
    [a1]; \
[a0][a1]
    amix = inputs=2: duration=shortest" \
-c:a libmp3lame -q:a 2 output.mp3


    


    With the resultant error :

    


    [Parsed_lowpass_1 @ 0x7f9a72005c00] [Eval @ 0x7ff7bec423d8] Undefined constant or missing '(' in 't/5)'
[Parsed_lowpass_1 @ 0x7f9a72005c00] Unable to parse option value "0.5 + 0.5 * cos(PI * t / 5)"
Error applying option 'mix' to filter 'lowpass': Invalid argument


    


    What complicated fffmpeg faerie magic is needed to make some of the filters other than volume controlled by a time-based expr ?

    


  • Revision f1781e86b7 : Refactoring of rate control - part 1 Moves all rate control variables to a sepa

    6 novembre 2013, par Deb Mukherjee

    Changed Paths :
     Modify /vp9/encoder/vp9_firstpass.c


     Modify /vp9/encoder/vp9_mbgraph.c


     Modify /vp9/encoder/vp9_onyx_if.c


     Modify /vp9/encoder/vp9_onyx_int.h


     Modify /vp9/encoder/vp9_ratectrl.c


     Modify /vp9/encoder/vp9_ratectrl.h


     Modify /vp9/encoder/vp9_temporal_filter.c



    Refactoring of rate control - part 1

    Moves all rate control variables to a separate structure,
    removes some currently unused variables,
    moves some rate control functions to vp9_ratectrl.c,
    and splits the encode_frame_to_data_rate function.

    Change-Id : I4ed54c24764b3b6de2dd676484f01473724ab52b

  • Revision 0aae100076 : Reuse inter prediction result in real-time speed 6 In real-time speed 6, no par

    20 juin 2014, par Yunqing Wang

    Changed Paths :
     Modify /vp9/encoder/vp9_encodeframe.c


     Modify /vp9/encoder/vp9_pickmode.c


     Modify /vp9/encoder/vp9_pickmode.h


     Modify /vp9/encoder/vp9_speed_features.c


     Modify /vp9/encoder/vp9_speed_features.h



    Reuse inter prediction result in real-time speed 6

    In real-time speed 6, no partition search is done. The inter
    prediction results got from picking mode can be reused in the
    following encoding process. A speed feature reuse_inter_pred_sby
    is added to only enable the resue in speed 6.

    This patch doesn’t change encoding result. RTC set tests showed
    that the encoding speed gain is 2% - 5%.

    Change-Id : I3884780f64ef95dd8be10562926542528713b92c

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