bsdec.h File Reference

#include <stdint.h>

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Classes
struct	BsdecProf
struct	BsdecResult

Enumerations
enum	BsdecError {   BSDEC_OK = 0 , BSDEC_SHORT , BSDEC_NOT_BS , BSDEC_BAD_VERSION ,   BSDEC_OUTPUT_TOO_SMALL , BSDEC_TRUNCATED , BSDEC_OVERLONG }

Functions
uint32_t	bsdecRlHalfwords (const void *in, uint32_t inBytes)
	How many run-level halfwords a frame decodes to.
struct BsdecResult	bsdecFrame (const void *in, uint32_t inBytes, uint16_t *out, uint32_t outHalfwords)
	Decode one BS frame into MDEC run-level halfwords.

Enumeration Type Documentation

BsdecError

enum BsdecError

Enumerator
BSDEC_OK
BSDEC_SHORT
BSDEC_NOT_BS
BSDEC_BAD_VERSION
BSDEC_OUTPUT_TOO_SMALL
BSDEC_TRUNCATED
BSDEC_OVERLONG

Function Documentation

bsdecFrame()

struct BsdecResult bsdecFrame	(	const void *	in,
		uint32_t	inBytes,
		uint16_t *	out,
		uint32_t	outHalfwords
	)

Decode one BS frame into MDEC run-level halfwords.

in must be halfword aligned - the bit reader walks the payload in halfword pairs - and in practice it is, since a frame arrives in sector payloads. out needs bsdecRlHalfwords(in, inBytes) entries.

The output is always a complete frame of exactly that many halfwords whenever bsdecUsable() holds, whatever the bitstream did: a partially decoded block is discarded, a short bitstream is padded with end-of-block markers, and a bitstream carrying more than its header declares is cut at the declared length. That is deliberate - a video decoder that refuses a damaged frame outright drops a frame where it could have shown most of one.

bsdecRlHalfwords()

uint32_t bsdecRlHalfwords	(	const void *	in,
		uint32_t	inBytes
	)

How many run-level halfwords a frame decodes to.

Read straight out of the header, so it costs two bytes and can be called before every decode. This is the size out must have. Returns 0 if the buffer is too short to hold a header.