#sound #codec #immersive #bub #oao

floaout

Floaout encoding and decoding library

2 unstable releases

0.2.0 Aug 30, 2021
0.1.0 Feb 7, 2020

#34 in Audio

MIT/Apache

1MB
5K SLoC

Floaout

Floaout is the next-generation audio format.

Bubble File Format Specification

Metadata

Name Type (Bytes) Description
Spec Version u8 (1) Version of Bubble File Format Specification.
Bubble ID u128 (16) Bubble ID of this file. The value is 0 if the Bubble is undefined.
Bubble Version u16 (2) Version of Bubble
Frames u64 (8) Number of frames
First Head Absolute Frame u64 (8) First Head Absolute Frame
Samples Per Sec f64 (8) Samples per sec
LpcmKind u8 (1) LpcmKind
BubSampleKind u8 (1) BubSampleKind
Name Size u8 (1) Name Size (0~255)
Name String Name (UTF-8)
CRC-32K/4.2 u32 (4) Max length at Hamming Distance 4 is 2147483615 (bits). And max length at Hamming Distance 6 is 6167 (bits).

LpcmKind

Variant Description Value (Type)
F32LE f32 Little Endian 0 (u8)
F64LE f64 Little Endian 1 (u8)

BubSampleKind

Variant Description Value
Lpcm Lpcm 0
Expr Expr 1

CRC

Algorithm::<u32> {
    endian: Endian::Little,
    poly: 0x93a409eb, // CRC-32K/4.2
    init: 0xffffffff,
    refin: true,
    refout: true,
    xorout: 0xffffffff,
    residue: 0x76e908ce,
}

Each Sample

| Bubble Sample | | BubbleSample |

Bubble Sample

Name Type (Bytes) Description
Functions size u16 (1) Functions size
Bubble's X coordinate Sum Bubble's X coordinate (X_0)
Space char (1) ' '
Bubble's Y coordinate Sum Bubble's Y coordinate (Y_0)
Space char (1) ' '
Bubble's Z coordinate Sum Bubble's Z coordinate (Z_0)
Space char (1) ' '
Domain OrOrExpr
Space char (1) ' '
Volume Sum
Space or Empty char (1) ' ' if there is another
Foot Relative Frame u64 (8) Number of frames at the end of function.
Next Head Relative Frame Option<u64> (8) Number of frames at the start of the next function. None if 0.
Sample Data Sample Data
CRC-32K/4.2 u32 (4) After every foot frames. From the previous CRC.

Sample Data

Lpcm

Name Type (Bytes) Description
Sample f32 or f64 (4 or 8) depends on LpcmKind

Expr

Name Type (Bytes) Description
Expr Size u16 (2) Expr Size
Expr Sum Expr

Keywords

Variables

Keyword Description
X Speaker's absolute X coordinate
Y Speaker's absolute Y coordinate
Z Speaker's absolute Z coordinate
x x = X - X_0 (X_0 is Bubble's absolute X coordinate). Speaker's relative X coordinate.
y y = Y - Y_0 (Y_0 is Bubble's absolute Y coordinate). Speaker's relative Y coordinate.
z z = Z - Z_0 (Z_0 is Bubble's absolute Z coordinate). Speaker's relative Z coordinate.
N Absolute frame n. Number of frames starting from the file. (as f64)
n Relative frame n. Number of frames starting from the function.(as f64)
F Frames (as f64)
S Samples per sec
Constants
Keyword Description
E Euler's number
PI Pi

Functions

Keyword Description
sin Sine
cos Cosine
tan Tangent
ln The natural logarithm of the number.
lg The base 2 logarithm of the number.

Others

Keyword Description
b b???????? f64

Punctuation

Symbol Name
+ Plus
- Minus
* Star
/ Slash
&& AndAnd
== EqEq
!= Ne
> Gt
< Lt
>= Ge
<= Le

Delimiters

Symbol Name
Space
, Comma
( ) Parentheses

Syntax

// BubFns
BubFns = BubFn ZeroOrMoreBubFns / f
ZeroOrMoreBubFns = SpaceAndBubFn ZeroOrMoreBubFns / ()

SpaceAndBubFn = Space BubFn / f

// BubFn
// BubFn = Sum Space Sum Space Sum Space OrOrExpr Space Sum
BubFn = SumAndSpace BubFn1 / f
BubFn1 = SumAndSpace BubFn2 / f
BubFn2 = SumAndSpace BubFn3 / f
BubFn3 = OrOrExprAndSpace BubFn4 / f
BubFn4 = Sum () / f

SumAndSpace = Sum Space / f
OrOrExprAndSpace = OrOrExpr Space / f

// OrOr Expr
OrOrExpr = AndAndExpr OrOrExpr1 / AndAndExpr
OrOrExpr1 = OrOr OrOrExpr / f

OrOr = "||" () / f

// AndAnd Expr
AndAndExpr = ComparisonExpr AndAndExpr1 / ComparisonExpr
AndAndExpr1 = AndAnd AndAndExpr / f

AndAnd = "&&" () / f

// Comparison Expr
ComparisonExpr = Sum ComparisonExpr1 / f
ComparisonExpr1 = Comparison Sum / f

Comparison = EqEq () / Comparison1
Comparison1 = Ne () / Comparison2
Comparison2 = Ge () / Comparison3
Comparison3 = Le () / Comparison4
Comparison4 = Gt () / Comparison5
Comparison5 = Lt () / f

EqEq = "==" () / f
Ne = "!=" () / f
Ge = ">=" () / f
Le = "<=" () / f
Gt = '>' () / f
Lt = '<' () / f

// Sum
Sum = Term ZeroOrMorePlusOrMinusAndTerms / f
ZeroOrMorePlusOrMinusAndTerms = PlusOrMinusAndTerm ZeroOrMorePlusOrMinusAndTerms / ()
PlusOrMinusAndTerm = PlusOrMinus Term / f

// Term
Term = Factor ZeroOrMoreStarOrSlashAndFactors / f
ZeroOrMoreStarOrSlashAndFactors = StarOrSlashAndFactor ZeroOrMoreStarOrSlashAndFactors / ()
StarOrSlashAndFactor = StarOrSlash Factor / f

// Factor
Factor = PlusOrMinus Factor / Power

// Power
Power = Atom PowerAndFactor / Atom
PowerAndFactor = '^' Factor / f

// Atom
Atom = ExprInParentheses () / Atom1
Atom1 = FloatLiteral () / Atom2
Atom2 = IntegerLiteral () / Atom3
Atom3 = Function () / Atom4
Atom4 = Variable () / Atom5
Atom5 = Constant () / f

// Variable
Variable = UppercaseX () / Variable1
Variable1 = UppercaseY () / Variable2
Variable2 = UppercaseZ () / Variable3
Variable3 = LowercaseX () / Variable4
Variable4 = LowercaseY () / Variable5
Variable5 = LowercaseZ () / Variable6
Variable6 = UppercaseN () / Variable7
Variable7 = LowercaseN () / Variable8
Variable8 = UppercaseF () / Variable9
Variable9 = UppercaseS () / f

UppercaseX = 'X' () / f
UppercaseY = 'Y' () / f
UppercaseZ = 'Z' () / f
LowercaseX = 'x' () / f
LowercaseY = 'y' () / f
LowercaseZ = 'z' () / f
UppercaseN = 'N' () / f
LowercaseN = 'n' () / f
UppercaseF = 'F' () / f
UppercaseS = 'S' () / f

// Constant
Constant = E () / Constant1
Constant1 = Pi () / f

E = 'E' () / f
Pi = "PI" () / f

// Function
Function = Sine () / Function1
Function1 = Cosine () / Function2
Function2 = Tangent () / Function3
Function3 = Ln () / Function4
Function4 = Lg () / f

Sine = "sin" Factor / f
Cosine = "cos" Factor / f
Tangent = "tan" Factor / f
Ln = "ln" Factor / f
Lg = "lg" Factor / f

// Delimiters
ExprInParentheses = '(' ExprAndClose / f
ExprAndClose = Sum ')' / f

// Integer
IntegerLiteral = DecLiteral () / f

// Float
FloatLiteral = DecLiteral PointAndDecLiteral / BytesF64Literal
PointAndDecLiteral = '.' DecLiteral / f

BytesF64Literal = 'b' ???????? / f

// Dec
DecLiteral = DecDigit ZeroOrMoreDecDigits / f
ZeroOrMoreDecDigits = DecDigit ZeroOrMoreDecDigits / ()

DecDigit = '0' () / DecDigit1
DecDigit1 = '1' () / DecDigit2
DecDigit2 = '2' () / DecDigit3
DecDigit3 = '3' () / DecDigit4
DecDigit4 = '4' () / DecDigit5
DecDigit5 = '5' () / DecDigit6
DecDigit6 = '6' () / DecDigit7
DecDigit7 = '7' () / DecDigit8
DecDigit8 = '8' () / '9'

// Others
PlusOrMinus = Plus () / PlusOrMinus1
PlusOrMinus1 = Minus () / f
Plus = '+' () / f
Minus = '-' () / f

StarOrSlash = Star () / StarOrSlash1
StarOrSlash1 = Slash () / f
Star = '*' () / f
Slash = '/' () / f

Space = ' ' () / f

Floaout File Format Specification

Metadata

Name Type (Bytes) Description
Spec Version u8 (1) Version of Floaout File Format Specification.
Floaout ID u128 (16) Floaout ID of this file. The value is 0 if the song is undefined.
Floaout Version u16 (2) Version of Floaout
Bubbles u16 (2) Number of Bubbles
Frames u64 (8) Number of frames
Samples Per Sec f64 (8) Samples per sec
LpcmKind u8 (1) LpcmKind
Title Size u8 (1) Title Size (0~255)
Title String Title (UTF-8)
Artist Size u8 (1) Artist Size (0~255)
Artist String Artist (UTF-8)
CRC-32K/4.2 u32 (4) Max length at Hamming Distance 4 is 2147483615 (bits). And max length at Hamming Distance 6 is 6167 (bits).

Each Bubble

Bubble Files will be 'i.bub' (i = 0, ... , Bubbles - 1)

Name Type (Bytes) Description
Name Size u8 (1) Name Size (0~255)
File Name String Bubble File Name without ".bub" (UTF-8)
Bubble Starting Frames u16 (2) Number of Bubble Starting Frames
Bubble Starting Frame u64 (8) Bubble Starting Frame
... ... ...
Bubble Starting Frame u64 (8) Bubble Starting Frame
CRC-32K/4.2 u32 (4) From the previous CRC.

TODO

  • Use generic type in Color and Space.
  • Add read_bub_fns_block in BubFrameReader
  • error handling
  • Clarify whether #[derive(Order)] is needed
  • Add Position field in BubfnsInterpreter
  • Check file is supported version or not
  • Parallel computing
  • Add Functions like pow, sinh, ...

Dependencies