ResampleAudio
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Revision as of 08:21, 15 February 2016 by Raffriff42 (Talk | contribs)
High-quality change of audio sample rate.
- Accepts any number of channels.
- The conversion is skipped if the sample rate is already at the given rate.
- Supports fractional resampling (where new_rate_denominator != 1).
Syntax and Parameters
ResampleAudio(clip clip, int new_rate_numerator [, int new_rate_denominator ] )
- int new_rate_numerator =
- Set new sample rate, or if new_rate_denominator != 1, set the numerator.
- int new_rate_denominator = 1
- Set the denominator for the new sample rate. Default 1.
When using fractional resampling (where new_rate_denominator != 1) the output audio sample rate is given by :
- int(new_rate_numerator / new_rate_denominator + 0.5)
However internally the resampling factor used is :
- new_rate_numerator / (new_rate_denominator * AudioRate)
This causes the audio duration to vary slightly (which is generally what is desired).[clarification needed]
Examples
- Resample audio to 48 kHz:
source = WavSource("c:\audio.wav") return ResampleAudio(source, 48000)
- Exact 4% speed up for PAL telecine:
Nfr_num = 25 Nfr_den = 1 AviSource("C:\Film.avi") # 23.976 fps, 44100Hz Ar = AudioRate # intermediate sample rate: ResampleAudio(Ar*FramerateNumerator*Nfr_den, FramerateDenominator*Nfr_num) # final sample rate: AssumeSampleRate(Ar) AssumeFPS(Nfr_num, Nfr_den, False)
In the example above, the intermediate sample rate needs to be
- (44100 * 24000 / 1001) / (25 * 1) = 42293.706294
but because audio sample rates are always integers, 42293.706294 must be rounded to 42294,
which results in a time slippage of about 30ms per hour.
Changes
v2.56 | Added new_sample_rate=float. |