Float
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
