ResampleAudio - Revision history

Reel.Deal: add link to avs+ documentation

2022-09-18T04:39:09Z

add link to avs+ documentation

Raffriff42: spellcheck

2016-02-27T18:10:13Z

spellcheck

Raffriff42: one more touch-up

2016-02-27T14:13:00Z

one more touch-up

Raffriff42: remove unclear section on fractional resampling

2016-02-27T01:12:25Z

remove unclear section on fractional resampling

Raffriff42: correction in 4% speed up example

2016-02-17T08:17:06Z

correction in 4% speed up example

Raffriff42: formatting, links, phrasing

2016-02-15T06:21:29Z

formatting, links, phrasing

Raffriff42: added category

2015-11-08T15:30:14Z

added category

Admin: 1 revision

2013-05-09T15:02:25Z

1 revision

Wilbert at 20:05, 29 March 2006

2006-03-29T20:05:04Z

New page

{{Template:FuncDef|ResampleAudio(clip, int new_rate_numerator [, int new_rate_denominator])}}

ResampleAudio performs a high-quality change of audio sample rate.
The conversion is skipped if the samplerate is already at the given rate.

When using fractional resampling the output audio samplerate is given by :

int(new_rate_numerator / new_rate_denominator + 0.5)

However the internally the resampling factor used is :

new_rate_numerator / (new_rate_denominator * old_sample_rate)

This causes the audio duration to vary slightly (which is generally what is desired).

Starting from v2.53 ResampleAudio accepts any number of channels.
Starting from v2.56 ResampleAudio process float samples directly. Support fractional resampling.

# Resamples audio to 48 kHz:
source = AviSource("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()
ResampleAudio(Ar*FramerateNumerator()*Nfr_den, FramerateDenominator()*Nfr_num)
AssumeSampleRate(Ar)
AssumeFPS(Nfr_num, Nfr_den, False)

For exact resampling the intermediate samplerate needs to be 42293.706293 which if rounded to 42294 would causes about 30ms per hour variation.

'''Changes:'''
{| border="1"
|-
| v2.56
| Added new_sample_rate=float.
|}

[[Category:Internal filters]]

@@ Line 1: / Line 1: @@
 <div style="max-width:62em" >
 High-quality change of audio sample rate.
 * Accepts any number of channels.

@@ Line 4: / Line 4: @@
 * The conversion is skipped if the sample rate is already at the given rate.
 * Supports ''fractional'' resampling (where {{FuncArg|new_rate_denominator}} ≠ 1).
-* Note, internal rounding may affect [[Clip_properties|AudioDuration]] slighly &ndash; see [[#Examples|example]] below.
+* Note, internal rounding may affect [[Clip_properties|AudioDuration]] slightly &ndash; see [[#Examples|example]] below.
 </div>

@@ Line 13: / Line 13: @@
 |ResampleAudio(clip ''clip'', ''int new_rate_numerator'' [, int ''new_rate_denominator'' ] )
 }}
 :{{Par2|new_rate_numerator|int|}}

@@ Line 3: / Line 3: @@
 * Accepts any number of channels.
 * The conversion is skipped if the sample rate is already at the given rate.
-* Supports ''fractional'' resampling (where {{FuncArg|new_rate_denominator}} != 1).
+* Supports ''fractional'' resampling (where {{FuncArg|new_rate_denominator}} ≠ 1).
 </div>
@@ Line 14: / Line 15: @@
 :{{Par2|new_rate_numerator|int|}}
-::Set new sample rate, or if {{FuncArg|new_rate_denominator}} != 1, set the numerator.
+::Set the numerator for the new sample rate.
 :{{Par2|new_rate_denominator|int|1}}
 ::Set the denominator for the new sample rate. Default 1.
 </div>

@@ Line 47: / Line 47: @@
   ''# final sample rate:''
   [[AssumeSampleRate]](Ar)
-  [[AssumeFPS]](Nfr_num, Nfr_den, False)
+  [[AssumeFPS]](Nfr_num, Nfr_den, false)
 </div>
 <div style="max-width:62em" >
-In the example above, the ''intermediate sample rate'' needs to be
+In the example above, the intermediate sample rate needs to be
-:(44100 * 24000 / 1001) / (25 * 1) = 42293.706294
+:<tt>([[Clip_properties|AudioRate]]*[[Clip_properties|FramerateNumerator]]*Nfr_den=1)/([[Clip_properties|FramerateDenominator]]*Nfr_num=25)</tt>
 but because audio sample rates are always integers, 42293.706294 must be rounded to 42294, <br>
 which results in a time slippage of about 30ms per hour.
 </div>

@@ Line 1: / Line 1: @@
-{{Template:FuncDef|ResampleAudio(clip, int new_rate_numerator [, int new_rate_denominator])}}
+<div style="max-width:62em" >
-When using fractional resampling the output audio samplerate is given by :
+== Syntax and Parameters ==
- int(new_rate_numerator / new_rate_denominator + 0.5)
+:{{Par2|new_rate_numerator|int|}}
-However the internally the resampling factor used is :
+:{{Par2|new_rate_denominator|int|1}}
-This causes the audio duration to vary slightly (which is generally what is desired).
+When using fractional resampling (where {{FuncArg|new_rate_denominator}} != 1) the output audio sample rate is given by :
-Starting from v2.53 ResampleAudio accepts any number of channels.
+However internally the resampling factor used is :
-Starting from v2.56 ResampleAudio process float samples directly. Support fractional resampling.
+:{{FuncArg|new_rate_numerator}} / ({{FuncArg|new_rate_denominator}} * [[Clip_properties|AudioRate]])
- # Resamples audio to 48 kHz:
+This causes the audio duration to vary slightly (which is generally what is desired).{{Clarify}}
- source = AviSource("c:\audio.wav")
+</div>
- return ResampleAudio(source, 48000)
-  # Exact 4% speed up for PAL telecine:
+== Examples ==
   Nfr_num = 25
   Nfr_den = 1
-  AviSource("C:\Film.avi") # 23.976 fps, 44100Hz
+  [[AviSource]]("C:\Film.avi") # 23.976 fps, 44100Hz
-  Ar = Audiorate()
+  Ar = [[Clip_properties|AudioRate]]
-  ResampleAudio(Ar*FramerateNumerator()*Nfr_den, FramerateDenominator()*Nfr_num)
+ ''# intermediate sample rate:''
-  AssumeSampleRate(Ar)
+  ResampleAudio(Ar*[[Clip_properties|FramerateNumerator]]*Nfr_den, [[Clip_properties|FramerateDenominator]]*Nfr_num)
-  AssumeFPS(Nfr_num, Nfr_den, False)
+  ''# final sample rate:''
-'''Changes:'''
+== Changes ==
 {| border="1"
 |-

← Older revision		Revision as of 15:30, 8 November 2015
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	[[Category:Internal filters]]		[[Category:Internal filters]]
		+	[[Category:Audio_filters]]