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In VLC for Android, i discovered an option to preserve the pitch during faster-than-normal playback:

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The "requires a fast device" obviously implies that faster playback is more performant when the pitch is changed too. Why is that so?

What i've tried: Before posting this question i did some shallow research through Google. According to Wikipedia, there are several methods for faster playback of audio, the "simplest" one (Resampling) changes the pitch.

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up vote 3 down vote accepted

When your PC "plays" a single datum of sound, the end result of the digital to analog process is that a speaker is caused to move by a certain amount. If this process happens faster for a given amount of data, and nothing else is done, the frequency will then be higher. Faster vibration = higher frequency.

To keep the frequency the same for a given speed, the output waveform must be modified (I think the process is called FFT) instead of just straight being played, and this is computationally expensive.

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