Float

From Avisynth wiki
(Difference between revisions)
Jump to: navigation, search
(link did not exist anymore)
(Float audio range notes)
 
(3 intermediate revisions by 2 users not shown)
Line 1: Line 1:
''This page is about the ''Float ''audio format''. ''For the variable type, see [[Script_variables]]''. ''For the'' <code>Float()</code> ''function, go to [[Internal_functions#Float]]''
+
''This page is about the ''Float ''audio format.'' <br>
 +
:''For the variable type, see [[Script_variables]].'' <br>
 +
:''For the'' <code>Float()</code> ''function, go to [[Internal_functions#Float]].'' <br>
 +
:''For the {{Deep_color}} format, go to [[Float_(color_format)]]''
  
  
 
'''Float''' (or fully IEEE floating point with single precision) is one of the [[ConvertAudio|AviSynth audio sample formats]].  
 
'''Float''' (or fully IEEE floating point with single precision) is one of the [[ConvertAudio|AviSynth audio sample formats]].  
  
The samples of this type have values between -1.00000 (= 0xBF800000) and 1.000000 (= 0x3F800000).
+
The samples of this type have normal values between -1.0 (= 0xBF800000) and +1.0 (= 0x3F800000). Values outside this range are usable as long as the audio remains in Float format, but will create audio clipping if [[ConvertAudio|converted]] to an integer format: 8, 16, 24 or 32 integer bits. For safety, you can call [[Normalize]] before converting from Float to Integer.
 +
 
 +
ColorBarsHD ## audio format = Float; range -1.0 - +1.0
 +
Amplify(1000.0) ## range -1000.0 - +1000.0
 +
Amplify(0.001) ## range -1.0 - +1.0
 +
## output: unchanged
 +
 
 +
ColorBarsHD ## audio format = Float; range -1.0 - +1.0
 +
Amplify(1000.0) ## range -1000.0 - +1000.0
 +
ConvertAudioTo16bit ## convert to Integer; severe clipping
 +
Amplify(0.001) ## still clipping
 +
 
  
 
The value of such a IEEE-754 number is computed as: sign * 2^exponent * 1.mantissa, using the following scheme:
 
The value of such a IEEE-754 number is computed as: sign * 2^exponent * 1.mantissa, using the following scheme:
Line 12: Line 26:
 
* The sign bit is 1 (negative) or 0 (positive).
 
* The sign bit is 1 (negative) or 0 (positive).
 
* The exponent runs from -127 (00000000) to 0 (0111111) to 128 (11111111).  
 
* The exponent runs from -127 (00000000) to 0 (0111111) to 128 (11111111).  
* The mantissa m1m2m3 ... means m1/2 + m2/4 + m3/8 + ... in decimal. Sometimes people denote "1.m1m2m3..." as the mantissa (like is done in the converter above).
+
* The mantissa m1m2m3 ... means m1/2 + m2/4 + m3/8 + ... in decimal. Sometimes people denote "1.m1m2m3..." as the mantissa (like is done in the converter below).
  
 
For an on-line converter between decimal numbers and IEEE 754 floating point, see [http://www.h-schmidt.net/FloatConverter/IEEE754.html here].
 
For an on-line converter between decimal numbers and IEEE 754 floating point, see [http://www.h-schmidt.net/FloatConverter/IEEE754.html here].
Line 37: Line 51:
 
   
 
   
 
  Sign bit is negative, exponent = 0, 1.mantissa = 1, so the number is -1.0
 
  Sign bit is negative, exponent = 0, 1.mantissa = 1, so the number is -1.0
 +
 +
and
 +
 +
0x800000 = 01001011000000000000000000000000
 +
 +
Sign Bit      Exp      1.Mantissa
 +
0          10010110  00000000000000000000000
 +
 +
150 - 127 = 23    1.0 bitshift 23 places
 +
 +
Sign bit is positive, exponent = 23, 1.mantissa = 1, so the number is 8388608
  
 
source: [https://web.archive.org/web/20120728135435/http://www.opferman.net/Text/ieee.txt opferman.net]
 
source: [https://web.archive.org/web/20120728135435/http://www.opferman.net/Text/ieee.txt opferman.net]
  
 
[[Category:Glossary]]
 
[[Category:Glossary]]

Latest revision as of 21:25, 28 October 2019

This page is about the Float audio format.

For the variable type, see Script_variables.
For the Float() function, go to Internal_functions#Float.
For the Deep Color format, go to Float_(color_format)


Float (or fully IEEE floating point with single precision) is one of the AviSynth audio sample formats.

The samples of this type have normal values between -1.0 (= 0xBF800000) and +1.0 (= 0x3F800000). Values outside this range are usable as long as the audio remains in Float format, but will create audio clipping if converted to an integer format: 8, 16, 24 or 32 integer bits. For safety, you can call Normalize before converting from Float to Integer.

ColorBarsHD ## audio format = Float; range -1.0 - +1.0
Amplify(1000.0) ## range -1000.0 - +1000.0
Amplify(0.001) ## range -1.0 - +1.0
## output: unchanged
ColorBarsHD ## audio format = Float; range -1.0 - +1.0
Amplify(1000.0) ## range -1000.0 - +1000.0
ConvertAudioTo16bit ## convert to Integer; severe clipping
Amplify(0.001) ## still clipping


The value of such a IEEE-754 number is computed as: sign * 2^exponent * 1.mantissa, using the following scheme:

[ 1 Sign Bit | 8 Bit Exponent | 23 Bit Mantissa ]

  • The sign bit is 1 (negative) or 0 (positive).
  • The exponent runs from -127 (00000000) to 0 (0111111) to 128 (11111111).
  • The mantissa m1m2m3 ... means m1/2 + m2/4 + m3/8 + ... in decimal. Sometimes people denote "1.m1m2m3..." as the mantissa (like is done in the converter below).

For an on-line converter between decimal numbers and IEEE 754 floating point, see here.

Examples:

0x3F800000 = 00111111100000000000000000000000 (binary, see [1])

Sign Bit      Exp       1.Mantissa
0          01111111  00000000000000000000000

127 - 127 = 0     1.0 bitshift 0 places

Sign bit is positive, exponent = 0, 1.mantissa = 1, so the number is +1.0

and

0xBF800000 = 10111111100000000000000000000000

Sign Bit      Exp       1.Mantissa
1          01111111  00000000000000000000000

127 - 127 = 0     1.0 bitshift 0 places

Sign bit is negative, exponent = 0, 1.mantissa = 1, so the number is -1.0

and

0x800000 = 01001011000000000000000000000000

Sign Bit      Exp       1.Mantissa
0          10010110  00000000000000000000000

150 - 127 = 23     1.0 bitshift 23 places

Sign bit is positive, exponent = 23, 1.mantissa = 1, so the number is 8388608

source: opferman.net

Personal tools