Data Structures
struct	_bitstream
	Declaration of the bitstream data structure. More...

Typedefs
typedef enum _bitstream_error	BITSTREAM_ERROR
	Bitstream error codes. More...

typedef uint32_t	BITWORD
	Data type of the internal bitstream buffer.

typedef uint_fast8_t	BITCOUNT
	Number of bits in the bitsteam buffer.

typedef struct _bitstream	BITSTREAM
	Declaration of the bitstream data structure. More...

Enumerations
enum	_bitstream_error { BITSTREAM_ERROR_OKAY = 0, BITSTREAM_ERROR_UNDERFLOW, BITSTREAM_ERROR_OVERFLOW, BITSTREAM_ERROR_BADTAG }
	Bitstream error codes. More...

Functions
CODEC_ERROR	InitBitstream (BITSTREAM *bitstream)
	Initialize a bitstream data structure. More...

CODEC_ERROR	AttachBitstream (struct _bitstream bitstream, struct _stream stream)
	Attach a bitstream to a byte stream. More...

CODEC_ERROR	ReleaseBitstream (BITSTREAM *stream)
	Detach a bitstream from a byte stream. More...

BITWORD	GetBits (BITSTREAM *stream, BITCOUNT count)

BITWORD	GetBuffer (BITSTREAM *stream)

CODEC_ERROR	PutBits (BITSTREAM *stream, BITWORD bits, BITCOUNT count)
	Write the specified number of bits to the bitstream.

CODEC_ERROR	PutBuffer (BITSTREAM *stream)
	Write the internal bitstream buffer to a byte stream. More...

CODEC_ERROR	PutLong (BITSTREAM *stream, BITWORD longword)
	Write a longword (32 bits) to the stream.

CODEC_ERROR	RewindBitstream (BITSTREAM *bitstream)
	Reset the bitstream. More...

CODEC_ERROR	BitstreamCodecError (BITSTREAM *bitstream)
	Convert a bitstream error code into a codec error code. More...

CODEC_ERROR	SkipPayload (BITSTREAM *bitstream, int chunk_size)

size_t	GetBitstreamPosition (BITSTREAM *stream)
	Get the current position in the byte stream. More...

CODEC_ERROR	AlignBitsByte (BITSTREAM *bitstream)
	Align the bitstream to a byte boundary. More...

CODEC_ERROR	AlignBitsWord (BITSTREAM *bitstream)
	Align the bitstream to the next word boundary. More...

BITWORD	AddBits (BITSTREAM *stream, BITWORD bits, BITCOUNT count)

CODEC_ERROR	FlushBitstream (BITSTREAM *bitstream)
	Write any bits in the buffer to the byte stream.

uint32_t	PopSampleOffsetStack (BITSTREAM *bitstream)
	Pop the top value from the sample offset stack.

CODEC_ERROR	PutByteArray (BITSTREAM bitstream, const uint8_t block, size_t size)
	Write a block of bytes into the bitstream.

Detailed Description

Declaration of the bitstream data structure.

Typedef Documentation

◆ BITSTREAM

typedef struct _bitstream BITSTREAM

Declaration of the bitstream data structure.

The bitstream uses a byte stream to read bytes from a file or a buffer in memory. This isolates that bitstream module from the type of byte stream.

◆ BITSTREAM_ERROR

typedef enum _bitstream_error BITSTREAM_ERROR

Bitstream error codes.

The bitstream contains its own enumeration of error codes since this module may be used in other applications.

Enumeration Type Documentation

◆ _bitstream_error

enum _bitstream_error

Bitstream error codes.

The bitstream contains its own enumeration of error codes since this module may be used in other applications.

Enumerator
BITSTREAM_ERROR_OKAY	No error.
BITSTREAM_ERROR_UNDERFLOW	No unread bits remaining in the bitstream.
BITSTREAM_ERROR_OVERFLOW	No more bits can be written to the bitstream.
BITSTREAM_ERROR_BADTAG	Unexpected tag found in the bitstream.

Function Documentation

◆ AlignBitsByte()

CODEC_ERROR AlignBitsByte ( BITSTREAM * bitstream )

Align the bitstream to a byte boundary.

Enough bits are written to the bitstream to align the bitstream to the next byte.

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◆ AlignBitsWord()

CODEC_ERROR AlignBitsWord ( BITSTREAM * bitstream )

Align the bitstream to the next word boundary.

Enough bits are written to the bitstream to align the bitstream to the next word.

◆ AttachBitstream()

CODEC_ERROR AttachBitstream	(	struct _bitstream *	bitstream,
		struct _stream *	stream
	)

Attach a bitstream to a byte stream.

It is permitted for the byte stream to be NULL, in which case the bitstream will not be able to replenish its internal buffer, but the consequences are undefined.

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◆ BitstreamCodecError()

CODEC_ERROR BitstreamCodecError ( BITSTREAM * bitstream )

Convert a bitstream error code into a codec error code.

The bitstream and byte stream modules might be used in other applications and have their own errors codes. This routine embeds a bitstream error code into a codec error code. The bitstream error code is carried in the low bits of the codec error code.

Todo:: Eliminate separate error codes for bitstreams?

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◆ GetBitstreamPosition()

size_t GetBitstreamPosition ( BITSTREAM * bitstream )

Get the current position in the byte stream.

The current position in the byte stream associated with the bitstream is returned. The intent is to allow the bitstream (and the associated byte stream) to be restored to the saved position.

Todo:: Need to record the state of the bitstream buffer and bit count so that the entire bitstream state can be restored.

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◆ InitBitstream()

CODEC_ERROR InitBitstream ( BITSTREAM * bitstream )

Initialize a bitstream data structure.

This routine is the constructor for the bitstream data type.

The sample offset stack is used to mark the offset to a position in the bitstream for computing the size field of sample chunks.

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◆ PutBuffer()

CODEC_ERROR PutBuffer ( BITSTREAM * bitstream )

Write the internal bitstream buffer to a byte stream.

Todo:: Need to modify this routine to return an error code if it cannot write to the byte stream associated with the bitstream.

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◆ ReleaseBitstream()

CODEC_ERROR ReleaseBitstream ( BITSTREAM * bitstream )

Detach a bitstream from a byte stream.

Any resources allocated by the bitstream are released without deallocating the bitstream data structure itself. The byte stream associated with the bitstream is not closed by this routine. The byte stream must be closed, if and when appropriate, by the caller.

◆ RewindBitstream()

CODEC_ERROR RewindBitstream ( BITSTREAM * bitstream )

Reset the bitstream.

This routine resets the bitstream to the beginning of the byte stream that has been attached to the bitstream. The byte stream is also reset.

If the byte stream could not be reset, then the internal bitstream state is not reset.

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Data Structures

Typedefs

Enumerations

Functions

Detailed Description

Typedef Documentation

◆ BITSTREAM

◆ BITSTREAM_ERROR

Enumeration Type Documentation

◆ _bitstream_error

Function Documentation

◆ AlignBitsByte()

◆ AlignBitsWord()

◆ AttachBitstream()

◆ BitstreamCodecError()

◆ GetBitstreamPosition()

◆ InitBitstream()

◆ PutBuffer()

◆ ReleaseBitstream()

◆ RewindBitstream()