Extended Data Service (XDS) demultiplexer
[Low Level Decoding]

Separating XDS data from a Closed Caption stream (EIA 608). More...

Data Structures
struct	vbi_xds_packet
	XDS Packet. A pointer to this structure is passed to the XDS demux callback. More...
Defines
#define	VBI_XDS_MAX_CLASSES   (VBI_XDS_CLASS_UNDEFINED + 1)
#define	VBI_XDS_MAX_SUBCLASSES   (0x18)
Typedefs
typedef unsigned int	vbi_xds_subclass
	Generic XDS subclass. You must cast to the appropriate subclass type depending on the XDS class.
typedef struct _vbi_xds_demux	vbi_xds_demux
	XDS demultiplexer.
typedef vbi_bool	vbi_xds_demux_cb (vbi_xds_demux *xd, const vbi_xds_packet *xp, void *user_data)
Enumerations
enum	vbi_xds_class {   VBI_XDS_CLASS_CURRENT = 0x00,   VBI_XDS_CLASS_FUTURE,   VBI_XDS_CLASS_CHANNEL,   VBI_XDS_CLASS_MISC,   VBI_XDS_CLASS_PUBLIC_SERVICE,   VBI_XDS_CLASS_RESERVED,   VBI_XDS_CLASS_UNDEFINED }
	XDS packet class. XDS data is transmitted in packets. Each packet belongs to one of seven classes.
enum	vbi_xds_subclass_program {   VBI_XDS_PROGRAM_ID = 0x01,   VBI_XDS_PROGRAM_LENGTH,   VBI_XDS_PROGRAM_NAME,   VBI_XDS_PROGRAM_TYPE,   VBI_XDS_PROGRAM_RATING,   VBI_XDS_PROGRAM_AUDIO_SERVICES,   VBI_XDS_PROGRAM_CAPTION_SERVICES,   VBI_XDS_PROGRAM_CGMS,   VBI_XDS_PROGRAM_ASPECT_RATIO,   VBI_XDS_PROGRAM_DATA = 0x0C,   VBI_XDS_PROGRAM_MISC_DATA,   VBI_XDS_PROGRAM_DESCRIPTION_BEGIN = 0x10,   VBI_XDS_PROGRAM_DESCRIPTION_END = 0x18 }
	VBI_XDS_CLASS_CURRENT and VBI_XDS_CLASS_FUTURE subclass. More...
enum	vbi_xds_subclass_channel {   VBI_XDS_CHANNEL_NAME = 0x01,   VBI_XDS_CHANNEL_CALL_LETTERS,   VBI_XDS_CHANNEL_TAPE_DELAY,   VBI_XDS_CHANNEL_TSID }
	VBI_XDS_CLASS_CHANNEL subclass. More...
enum	vbi_xds_subclass_misc {   VBI_XDS_TIME_OF_DAY = 0x01,   VBI_XDS_IMPULSE_CAPTURE_ID,   VBI_XDS_SUPPLEMENTAL_DATA_LOCATION,   VBI_XDS_LOCAL_TIME_ZONE,   VBI_XDS_OUT_OF_BAND_CHANNEL = 0x40,   VBI_XDS_CHANNEL_MAP_POINTER,   VBI_XDS_CHANNEL_MAP_HEADER,   VBI_XDS_CHANNEL_MAP }
	VBI_XDS_CLASS_MISC subclass. More...
enum	vbi_xds_subclass_public_service {   VBI_XDS_WEATHER_BULLETIN = 0x01,   VBI_XDS_WEATHER_MESSAGE }
	VBI_XDS_CLASS_PUBLIC_SERVICE subclass. More...
Functions
void	vbi_xds_demux_reset (vbi_xds_demux *xd)
vbi_bool	vbi_xds_demux_feed (vbi_xds_demux *xd, const uint8_t buffer[2])
vbi_bool	vbi_xds_demux_feed_frame (vbi_xds_demux *xd, const vbi_sliced *sliced, unsigned int n_lines)
void	vbi_xds_demux_delete (vbi_xds_demux *xd)
vbi_xds_demux *	vbi_xds_demux_new (vbi_xds_demux_cb *callback, void *user_data) _vbi_alloc

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Detailed Description

Separating XDS data from a Closed Caption stream (EIA 608).

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Typedef Documentation

typedef struct _vbi_xds_demux vbi_xds_demux

XDS demultiplexer.

The contents of this structure are private. Call vbi_xds_demux_new() to allocate a XDS demultiplexer.

typedef vbi_bool vbi_xds_demux_cb(vbi_xds_demux *xd, const vbi_xds_packet *xp, void *user_data)

Parameters:

	xd	XDS demultiplexer context allocated with vbi_xds_demux_new().
	user_data	User data pointer given to vbi_xds_demux_new().
	xp	Pointer to the received XDS data packet.

The XDS demux calls a function of this type when an XDS packet has been completely received, all bytes have correct parity and the packet checksum is correct. Other packets are discarded.

Returns:

FALSE on error, will be returned by vbi_xds_demux_feed().

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Enumeration Type Documentation

enum vbi_xds_subclass_program

VBI_XDS_CLASS_CURRENT and VBI_XDS_CLASS_FUTURE subclass.

Enumerator:

VBI_XDS_PROGRAM_DATA	Since: 0.2.17
VBI_XDS_PROGRAM_MISC_DATA	Since: 0.2.17

enum vbi_xds_subclass_channel

VBI_XDS_CLASS_CHANNEL subclass.

Enumerator:

VBI_XDS_CHANNEL_TSID

Since: 0.2.17

enum vbi_xds_subclass_misc

VBI_XDS_CLASS_MISC subclass.

Enumerator:

VBI_XDS_OUT_OF_BAND_CHANNEL	Since: 0.2.17
VBI_XDS_CHANNEL_MAP_POINTER	Since: 0.2.17
VBI_XDS_CHANNEL_MAP_HEADER	Since: 0.2.17
VBI_XDS_CHANNEL_MAP	Since: 0.2.17

enum vbi_xds_subclass_public_service

VBI_XDS_CLASS_PUBLIC_SERVICE subclass.

Since:

0.2.17

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Function Documentation

void vbi_xds_demux_reset

(

vbi_xds_demux *

xd

)

Parameters:

xd

XDS demultiplexer context allocated with vbi_xds_demux_new().

Resets the XDS demux, useful for example after a channel change.

Since:

0.2.16

vbi_bool vbi_xds_demux_feed	(	vbi_xds_demux *	xd,
		const uint8_t	buffer[2]
	)

Parameters:

	xd	XDS demultiplexer context allocated with vbi_xds_demux_new().
	buffer	Closed Caption character pair, as in struct vbi_sliced.

This function takes two successive bytes of a raw Closed Caption stream, filters out XDS data and calls the output function given to vbi_xds_demux_new() when a new packet is complete.

You should feed only data from NTSC line 284.

Returns:

FALSE if the buffer contained parity errors.

Since:

0.2.16

vbi_bool vbi_xds_demux_feed_frame	(	vbi_xds_demux *	xd,
		const vbi_sliced *	sliced,
		unsigned int	n_lines
	)

Parameters:

	xd	XDS demultiplexer context allocated with vbi_xds_demux_new().
	sliced	Sliced VBI data.
	n_lines	Number of lines in the sliced array.

This function works like vbi_xds_demux_feed() but operates on sliced VBI data and filters out VBI_SLICED_CAPTION_525 on NTSC line 284.

Returns:

FALSE if any of the Caption lines contained parity errors.

Since:

0.2.26

void vbi_xds_demux_delete

(

vbi_xds_demux *

xd

)

Parameters:

xd

XDS demultiplexer context allocated with vbi_xds_demux_new(), can be NULL.

Frees all resources associated with xd.

Since:

0.2.16

vbi_xds_demux* vbi_xds_demux_new	(	vbi_xds_demux_cb *	callback,
		void *	user_data
	)

Parameters:

	callback	Function to be called by vbi_xds_demux_feed() when a new packet is available.
	user_data	User pointer passed through to callback function.

Allocates a new Extended Data Service (EIA 608) demultiplexer.

Returns:

Pointer to newly allocated XDS demux context which must be freed with vbi_xds_demux_delete() when done. NULL on failure (out of memory).

Since:

0.2.16