Float: Difference between revisions
From Avisynth wiki
Jump to navigationJump to search
No edit summary |
Raffriff42 (talk | contribs) Float audio range notes |
||
| (7 intermediate revisions by 2 users not shown) | |||
| Line 1: | Line 1: | ||
Float (or fully IEEE floating point with single precision) is one of the samples | ''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]]. | |||
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: | ||
[ 1 Sign Bit | 8 Bit Exponent | 23 Bit Mantissa ] | <code>[ 1 Sign Bit | 8 Bit Exponent | 23 Bit Mantissa ]</code> | ||
* 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 | * 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]. | |||
Examples: | Examples: | ||
| Line 24: | Line 43: | ||
and | and | ||
0xBF800000 = 10111111100000000000000000000000 | 0xBF800000 = 10111111100000000000000000000000 | ||
Sign Bit Exp 1.Mantissa | Sign Bit Exp 1.Mantissa | ||
| Line 33: | Line 52: | ||
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 | ||
source: [http://www.opferman.net/Text/ieee.txt] | 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] | |||
[[Category:Glossary]] | [[Category:Glossary]] | ||
Latest revision as of 22:25, 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
