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  • Submit bugs and patches

    13 avril 2011

    Unfortunately a software is never perfect.
    If you think you have found a bug, report it using our ticket system. Please to help us to fix it by providing the following information : the browser you are using, including the exact version as precise an explanation as possible of the problem if possible, the steps taken resulting in the problem a link to the site / page in question
    If you think you have solved the bug, fill in a ticket and attach to it a corrective patch.
    You may also (...)

  • D’autres logiciels intéressants

    12 avril 2011, par

    On ne revendique pas d’être les seuls à faire ce que l’on fait ... et on ne revendique surtout pas d’être les meilleurs non plus ... Ce que l’on fait, on essaie juste de le faire bien, et de mieux en mieux...
    La liste suivante correspond à des logiciels qui tendent peu ou prou à faire comme MediaSPIP ou que MediaSPIP tente peu ou prou à faire pareil, peu importe ...
    On ne les connais pas, on ne les a pas essayé, mais vous pouvez peut être y jeter un coup d’oeil.
    Videopress
    Site Internet : (...)

  • 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 (9047)

  • vaapi_encode : Pass framerate parameters to driver

    29 novembre 2016, par Mark Thompson
    vaapi_encode : Pass framerate parameters to driver

    Only do this when building for a recent VAAPI version - initial
    
driver implementations were confused about the interpretation of the
    
framerate field, but hopefully this will be consistent everywhere
    
once 0.40.0 is released.
    

    (cherry picked from commit ff35aa8ca4069bf1543adeec4c28e51e4a012eee)
    • [DH] libavcodec/vaapi_encode.c
    • [DH] libavcodec/vaapi_encode.h

  • ffmpeg : Downmixing 5.1 to stereo with phase invert

    1er novembre 2022, par anti-hero

    I'd like to use ffmpeg and Dolby Logic Pro II formula to downmix a 5.1 song to stereo :

    


    


    Lt = L + (–3 dB × C) – (–1.2 dB × Ls) – (–6.2 dB × Rs)

    


    Rt = R + (–3 dB × C) + (–6.2 dB × Ls) + (–1.2 dB × Rs)

    


    


    I came up with this long and probably redundant bash script :

    


    # L channel
ffmpeg -i "$filename" -map_channel 0.1.0 -c:a pcm_f32le L.wav
ffmpeg -i "$filename" -map_channel 0.1.2 -filter:a "volume=-3dB" -c:a pcm_f32le C.wav
ffmpeg -i "$filename" -map_channel 0.1.4 -af "volume=-1.2dB" -c:a pcm_f32le Ls.wav
ffmpeg -i "$filename" -map_channel 0.1.5 -af "volume=-6.2dB" -c:a pcm_f32le Rs.wav
ffmpeg -i Ls.wav -af "aeval=-val(0)" -c:a pcm_f32le Lsi.wav
ffmpeg -i Rs.wav -af "aeval=-val(0)" -c:a pcm_f32le Rsi.wav
ffmpeg -i L.wav -i C.wav -i Lsi.wav -i Rsi.wav -filter_complex "amix=inputs=4" -c:a pcm_f32le L_final.wav
rm L.wav Ls.wav Rs.wav Lsi.wav Rsi.wav

# R channel
ffmpeg -i "$filename" -map_channel 0.1.1 -c:a pcm_f32le R.wav
ffmpeg -i "$filename" -map_channel 0.1.4 -filter:a "volume=-6.2dB" -c:a pcm_f32le Ls.wav
ffmpeg -i "$filename" -map_channel 0.1.5 -filter:a "volume=-1.2dB" -c:a pcm_f32le Rs.wav
ffmpeg -i R.wav -i C.wav -i Ls.wav -i Rs.wav -filter_complex "amix=inputs=4" -c:a pcm_f32le R_final.wav
rm R.wav C.wav Ls.wav Rs.wav

# Mix
ffmpeg -i L_final.wav -i R_final.wav -filter_complex "[0:0][1:0] amerge=inputs=2" -c:a pcm_f32le "${filename%.*}_dm.wav"
rm L_final.wav R_final.wav


    


    Would this work ? And is there a simpler way to do this ?

    


    update : I also wrote Python code for the 90 degree phase shift version.

    


    import scipy, os, numpy as np

os.system(f'ffmpeg -i "{filename}" -c:a pcm_f32le temp.wav')
sample_rate, waves = scipy.io.wavfile.read("temp.wav")
os.remove("temp.wav")

L, R, C, LFE, LS, RS = waves.T

LS_shifted = -np.imag(scipy.signal.hilbert(LS))
RS_shifted = np.imag(scipy.signal.hilbert(RS))
L_out = L + 0.708 * C - 0.871 * LS_shifted - 0.49 * RS_shifted
R_out = R + 0.708 * C + 0.49 * LS_shifted + 0.871 * RS_shifted

scipy.io.wavfile.write("out.wav", sample_rate, np.vstack((L_out, R_out)).T)


    


    Hope someone finds this useful ! (and that someone verifies it's correct)

    


  • avcodec/libopus : support disabling phase inversion.

    5 février 2018, par Menno
    avcodec/libopus : support disabling phase inversion.

    Signed-off-by : Menno <mrdegier@gmail.com>
    
Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
    • [DH] doc/encoders.texi
    • [DH] libavcodec/libopusdec.c
    • [DH] libavcodec/libopusenc.c

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