SpeexBits: Bit-stream manipulations

Classes
struct	SpeexBits
Functions
void	speex_bits_init (SpeexBits *bits)
void	speex_bits_init_buffer (SpeexBits *bits, void *buff, int buf_size)
void	speex_bits_set_bit_buffer (SpeexBits *bits, void *buff, int buf_size)
void	speex_bits_destroy (SpeexBits *bits)
void	speex_bits_reset (SpeexBits *bits)
void	speex_bits_rewind (SpeexBits *bits)
void	speex_bits_read_from (SpeexBits *bits, char *bytes, int len)
void	speex_bits_read_whole_bytes (SpeexBits *bits, char *bytes, int len)
int	speex_bits_write (SpeexBits *bits, char *bytes, int max_len)
int	speex_bits_write_whole_bytes (SpeexBits *bits, char *bytes, int max_len)
void	speex_bits_pack (SpeexBits *bits, int data, int nbBits)
int	speex_bits_unpack_signed (SpeexBits *bits, int nbBits)
unsigned int	speex_bits_unpack_unsigned (SpeexBits *bits, int nbBits)
int	speex_bits_nbytes (SpeexBits *bits)
unsigned int	speex_bits_peek_unsigned (SpeexBits *bits, int nbBits)
int	speex_bits_peek (SpeexBits *bits)
void	speex_bits_advance (SpeexBits *bits, int n)
int	speex_bits_remaining (SpeexBits *bits)
void	speex_bits_insert_terminator (SpeexBits *bits)

---

Detailed Description

This is the structure that holds the bit-stream when encoding or decoding with Speex. It allows some manipulations as well.

---

Function Documentation

void speex_bits_advance	(	SpeexBits *	bits,
		int	n
	)

Advances the position of the "bit cursor" in the stream

Parameters:

	bits	Bit-stream to operate on
	n	Number of bits to advance

void speex_bits_destroy

(

SpeexBits *

bits

)

Frees all resources associated to a SpeexBits struct. Right now this does nothing since no resources are allocated, but this could change in the future.

void speex_bits_init

(

SpeexBits *

bits

)

Initializes and allocates resources for a SpeexBits struct

void speex_bits_init_buffer	(	SpeexBits *	bits,
		void *	buff,
		int	buf_size
	)

Initializes SpeexBits struct using a pre-allocated buffer

void speex_bits_insert_terminator

(

SpeexBits *

bits

)

Insert a terminator so that the data can be sent as a packet while auto-detecting the number of frames in each packet

Parameters:

bits

Bit-stream to operate on

int speex_bits_nbytes

(

SpeexBits *

bits

)

Returns the number of bytes in the bit-stream, including the last one even if it is not "full"

Parameters:

bits

Bit-stream to operate on

Returns:

Number of bytes in the stream

void speex_bits_pack	(	SpeexBits *	bits,
		int	data,
		int	nbBits
	)

Append bits to the bit-stream

Parameters:

	bits	Bit-stream to operate on
	data	Value to append as integer
	nbBits	number of bits to consider in "data"

int speex_bits_peek

(

SpeexBits *

bits

)

Get the value of the next bit in the stream, without modifying the "cursor" position

Parameters:

bits

Bit-stream to operate on

Returns:

Value of the bit peeked (one bit only)

unsigned int speex_bits_peek_unsigned	(	SpeexBits *	bits,
		int	nbBits
	)

Same as speex_bits_unpack_unsigned, but without modifying the cursor position

Parameters:

	bits	Bit-stream to operate on
	nbBits	Number of bits to look for

Returns:

Value of the bits peeked, interpreted as unsigned

void speex_bits_read_from	(	SpeexBits *	bits,
		char *	bytes,
		int	len
	)

Initializes the bit-stream from the data in an area of memory

void speex_bits_read_whole_bytes	(	SpeexBits *	bits,
		char *	bytes,
		int	len
	)

Append bytes to the bit-stream

Parameters:

	bits	Bit-stream to operate on
	bytes	pointer to the bytes what will be appended
	len	Number of bytes of append

int speex_bits_remaining

(

SpeexBits *

bits

)

Returns the number of bits remaining to be read in a stream

Parameters:

bits

Bit-stream to operate on

Returns:

Number of bits that can still be read from the stream

void speex_bits_reset

(

SpeexBits *

bits

)

Resets bits to initial value (just after initialization, erasing content)

void speex_bits_rewind

(

SpeexBits *

bits

)

Rewind the bit-stream to the beginning (ready for read) without erasing the content

void speex_bits_set_bit_buffer	(	SpeexBits *	bits,
		void *	buff,
		int	buf_size
	)

Sets the bits in a SpeexBits struct to use data from an existing buffer (for decoding without copying data)

int speex_bits_unpack_signed	(	SpeexBits *	bits,
		int	nbBits
	)

Interpret the next bits in the bit-stream as a signed integer

Parameters:

	bits	Bit-stream to operate on
	nbBits	Number of bits to interpret

Returns:

A signed integer represented by the bits read

unsigned int speex_bits_unpack_unsigned	(	SpeexBits *	bits,
		int	nbBits
	)

Interpret the next bits in the bit-stream as an unsigned integer

Parameters:

	bits	Bit-stream to operate on
	nbBits	Number of bits to interpret

Returns:

An unsigned integer represented by the bits read

int speex_bits_write	(	SpeexBits *	bits,
		char *	bytes,
		int	max_len
	)

Write the content of a bit-stream to an area of memory

Parameters:

	bits	Bit-stream to operate on
	bytes	Memory location where to write the bits
	max_len	Maximum number of bytes to write (i.e. size of the "bytes" buffer)

Returns:

Number of bytes written to the "bytes" buffer

int speex_bits_write_whole_bytes	(	SpeexBits *	bits,
		char *	bytes,
		int	max_len
	)

Like speex_bits_write, but writes only the complete bytes in the stream. Also removes the written bytes from the stream

---