audio custom filter documentation?

[mhfowler]

I am trying to write my own custom audio filter.

I am looking at audio_fadein as an example, but I am having trouble understanding the expected type of (t) the input variable.

Could anyone explain what the expected type of t is? Or where in the moviepy code I can look to see what libraries this t comes from or is used by? Thank you for any help, it is greatly appreciated.

@audio_video_fx
def audio_fadein(clip, duration):
    """ Return an audio (or video) clip that is first mute, then the
        sound arrives progressively over ``duration`` seconds. """

    def fading(gf,t):
        gft = gf(t)

        if np.isscalar(t):
            factor = min(1.0 * t / duration, 1)
            factor = np.array([factor,factor])
        else:
            factor = np.minimum(1.0 * t / duration, 1)
            factor = np.vstack([factor,factor]).T
        return factor * gft
    return clip.fl(fading, keep_duration = True)

[Zulko]

t represents the time in second since the beginning of the clip. gf(t) is a function that represents the sound signal, for a given t it returns either a single value (for mono sound ) a pair [left, right](for stereo sound).

If you give me more infos on what you are trying to do I could help, but maybe it's better to ask the question on stackoverflow or reddit/moviepy and use Github just for issue tracking.

[mhfowler]

Hi zulko, thanks for responding!

I ended up figuring it out -- I was just thrown off by the fact that the t values I was getting were actually an array of 2000 equidistant values. Once I realized that all of these values were time in seconds since the beginning of the clip then I was able to achieve the effect I wanted without a problem.

I also asked and answered this question on stack overflow here: http://stackoverflow.com/questions/35441672/how-do-you-make-a-custom-audio-filter-using-moviepy/35515807#35515807 but feel free to add more detail or corrections.

Have really been enjoying using moviepy. Thanks for the awesome work!