# Float

From Avisynth wiki

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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]] |

## Revision as of 16:58, 3 April 2016

*This page is about the *Float *audio format*. *For the variable type, see Script_variables*. *For the* `Float()`

*function, go to Internal_functions#Float*

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

The samples of this type have values between -1.00000 (= 0xBF800000) and 1.000000 (= 0x3F800000).

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