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[Data Service Decoder]


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Functions

void vbi_unref_page (vbi_page *pg)
int vbi_is_cached (vbi_decoder *, int pgno, int subno)
int vbi_cache_hi_subno (vbi_decoder *vbi, int pgno)
vbi_bool vbi_fetch_cc_page (vbi_decoder *vbi, vbi_page *pg, vbi_pgno pgno, vbi_bool reset)
vbi_bool vbi_fetch_vt_page (vbi_decoder *vbi, vbi_page *pg, vbi_pgno pgno, vbi_subno subno, vbi_wst_level max_level, int display_rows, vbi_bool navigation)
int vbi_page_title (vbi_decoder *vbi, int pgno, int subno, char *buf)

Function Documentation

void vbi_unref_page vbi_page pg  ) 
 

Parameters:
pg Previously fetched vbi_page.
A vbi_page fetched from cache with vbi_fetch_vt_page() or vbi_fetch_cc_page() may reference other resource in cache which are locked after fetching. When done processing the page, you must call this function to unlock all the resources associated with this vbi_page.

int vbi_is_cached vbi_decoder *  vbi,
int  pgno,
int  subno
 

Parameters:
vbi 
pgno 
subno 

Deprecated:
At the moment pages can only be added to the cache but not removed unless the decoder is reset. That will change, making the result volatile in a multithreaded environment.
Returns:

int vbi_cache_hi_subno vbi_decoder *  vbi,
int  pgno
 

Parameters:
vbi 
pgno 
Deprecated:
Rationale same as vbi_is_cached().
Returns:

vbi_bool vbi_fetch_cc_page vbi_decoder *  vbi,
vbi_page pg,
vbi_pgno  pgno,
vbi_bool  reset
 

Parameters:
vbi Initialized vbi decoding context.
pg Place to store the formatted page.
pgno Page number 1 ... 8 of the page to fetch, see vbi_pgno.
reset TRUE resets the vbi_page dirty fields in cache after fetching. Pass FALSE only if you plan to call this function again to update other displays.
Fetches a Closed Caption page designated by pgno from the cache, formats and stores it in pg. CC pages are transmitted basically in two modes: at once and character by character ("roll-up" mode). Either way you get a snapshot of the page as it should appear on screen at present. With vbi_event_handler_add() you can request a VBI_EVENT_CAPTION event to be notified about pending changes (in case of "roll-up" mode that is with each new word received) and the vbi_page->dirty fields will mark the lines actually in need of updates, to speed up rendering.

Although safe to do, this function is not supposed to be called from an event handler, since rendering may block decoding for extended periods of time.

Returns:
FALSE if some error occured.

vbi_bool vbi_fetch_vt_page vbi_decoder *  vbi,
vbi_page pg,
vbi_pgno  pgno,
vbi_subno  subno,
vbi_wst_level  max_level,
int  display_rows,
vbi_bool  navigation
 

Parameters:
vbi Initialized vbi_decoder context.
pg Place to store the formatted page.
pgno Page number of the page to fetch, see vbi_pgno.
subno Subpage number to fetch (optional VBI_ANY_SUBNO).
max_level Format the page at this Teletext implementation level.
display_rows Number of rows to format, between 1 ... 25.
navigation Analyse the page and add navigation links, including TOP and FLOF.
Fetches a Teletext page designated by pgno and subno from the cache, formats and stores it in pg. Formatting is limited to row 0 ... display_rows - 1 inclusive. The really useful values are 1 (format header only) or 25 (everything). Likewise navigation can be used to save unnecessary formatting time.

Although safe to do, this function is not supposed to be called from an event handler since rendering may block decoding for extended periods of time.

Returns:
FALSE if the page is not cached or could not be formatted for other reasons, for instance is a data page not intended for display. Level 2.5/3.5 pages which could not be formatted e. g. due to referencing data pages not in cache are formatted at a lower level.

int vbi_page_title vbi_decoder *  vbi,
int  pgno,
int  subno,
char *  buf
 

Parameters:
vbi Initialized vbi decoding context.
pgno Page number, see vbi_pgno.
subno Subpage number.
buf Place to store the title, Latin-1 format, at least 41 characters including the terminating zero.
Given a Teletext page number this function tries to deduce a page title for bookmarks or other purposes, mainly from navigation data. (XXX TODO: FLOF)

Returns:
TRUE if a title has been found.


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