Teletext PFC packet demultiplexer
[Low Level Decoding]

Functions to decode data transmissions in Teletext Page Function Clear packets (EN 300 708 section 4). More...

Data Structures
struct	vbi_pfc_block
	One block of data returned by vbi_pfc_demux_cb(). More...
Typedefs
typedef _vbi_pfc_demux	vbi_pfc_demux
	PFC demultiplexer context.
typedef vbi_bool	vbi_pfc_demux_cb (vbi_pfc_demux *dx, void *user_data, const vbi_pfc_block *block)
Functions
void	vbi_pfc_demux_reset (vbi_pfc_demux *dx) _vbi_nonnull((1))
vbi_bool	vbi_pfc_demux_feed (vbi_pfc_demux *dx, const uint8_t buffer[42])
vbi_bool	vbi_pfc_demux_feed_frame (vbi_pfc_demux *dx, const vbi_sliced *sliced, unsigned int n_lines)
void	vbi_pfc_demux_delete (vbi_pfc_demux *dx)
vbi_pfc_demux *	vbi_pfc_demux_new (vbi_pgno pgno, unsigned int stream, vbi_pfc_demux_cb *callback, void *user_data)

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Detailed Description

Functions to decode data transmissions in Teletext Page Function Clear packets (EN 300 708 section 4).

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Typedef Documentation

typedef struct _vbi_pfc_demux vbi_pfc_demux

PFC demultiplexer context. The contents of this structure are private. Call vbi_pfc_demux_new() to allocate a PFC demultiplexer context.

typedef vbi_bool vbi_pfc_demux_cb(vbi_pfc_demux *dx, void *user_data, const vbi_pfc_block *block)

Parameters: dx  PFC demultiplexer context returned by vbi_pfx_demux_new() and given to vbi_pfc_demux_feed(). user_data  User pointer given to vbi_pfc_demux_new(). block  Structure describing the received data block. Function called by vbi_pfc_demux_feed() when a new data block is available. Returns: FALSE on error, will be returned by vbi_pfc_demux_feed(). Bug: vbi_pfc_demux_feed() returns the user_data pointer as second parameter the block pointer as third parameter, but prior to version 0.2.26 this function incorrectly defined block as second and user_data as third parameter.

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Function Documentation

void vbi_pfc_demux_reset (  vbi_pfc_demux *  dx  )

Parameters: dx  PFC demultiplexer context allocated with vbi_pfc_demux_new(). Resets the PFC demux context, useful for example after a channel change.

vbi_bool vbi_pfc_demux_feed (  vbi_pfc_demux *  dx, const uint8_t  buffer[42] )

Parameters: dx  PFC demultiplexer context allocated with vbi_pfc_demux_new(). buffer  Teletext packet (last 42 bytes, i. e. without clock run-in and framing code), as in struct vbi_sliced. This function takes a raw stream of Teletext packets, filters out the page and stream requested with vbi_pfc_demux_new() and assembles the data transmitted in this page in a buffer. When a data block is complete it calls the output function given to vbi_pfc_demux_new(). Returns: FALSE if the packet contained incorrectable errors.

vbi_bool vbi_pfc_demux_feed_frame (  vbi_pfc_demux *  dx, const vbi_sliced *  sliced, unsigned int  n_lines )

Parameters: dx  PFC demultiplexer context allocated with vbi_pfc_demux_new(). sliced  Sliced VBI data. n_lines  Number of lines in the sliced array. This function works like vbi_pfc_demux_feed() but operates on sliced VBI data and filters out VBI_SLICED_TELETEXT_B_625. Returns: FALSE if any Teletext lines contained incorrectable errors. Since: 0.2.26

void vbi_pfc_demux_delete (  vbi_pfc_demux *  dx  )

Parameters: dx  PFC demultiplexer context allocated with vbi_pfc_demux_new(), can be NULL. Frees all resources associated with dx.

vbi_pfc_demux* vbi_pfc_demux_new (  vbi_pgno  pgno, unsigned int  stream, vbi_pfc_demux_cb *  callback, void *  user_data )

Parameters: pgno  Page to take PFC data from. stream  PFC stream to be demultiplexed. callback  Function to be called by vbi_pfc_demux_feed() when a new data block is available. user_data  User pointer passed through to cb function. Allocates a new Page Function Clear (ETS 300 708 section 4) demultiplexer. Returns: Pointer to newly allocated PFC demux context which must be freed with vbi_pfc_demux_delete() when done. NULL on failure (out of memory).

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