Modules | |
BCD arithmetic for Teletext page numbers | |
Page cache | |
Events | |
Exporting formatted Teletext and Closed Caption pages | |
Formatted text page | |
Typedefs | |
typedef int | vbi_pgno |
typedef int | vbi_subno |
Enumerations | |
enum | vbi_page_type |
Page classification. More... | |
enum | vbi_wst_level { VBI_WST_LEVEL_1, VBI_WST_LEVEL_1p5, VBI_WST_LEVEL_2p5, VBI_WST_LEVEL_3p5 } |
Teletext implementation level. More... | |
Functions | |
vbi_decoder * | vbi_decoder_new (void) |
Allocate a new data service decoder instance. | |
void | vbi_decoder_delete (vbi_decoder *vbi) |
Delete a data service decoder instance. | |
void | vbi_decode (vbi_decoder *vbi, vbi_sliced *sliced, int lines, double time) |
Main function of the data service decoder. | |
void | vbi_channel_switched (vbi_decoder *vbi, vbi_nuid nuid) |
vbi_page_type | vbi_classify_page (vbi_decoder *vbi, vbi_pgno pgno, vbi_subno *subno, char **language) |
void | vbi_teletext_set_default_region (vbi_decoder *vbi, int default_region) |
void | vbi_teletext_set_level (vbi_decoder *vbi, int level) |
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Teletext or Closed Caption page number. For Teletext pages this is a bcd number in range 0x100 ... 0x8FF. Page numbers containing digits 0xA to 0xF are reserved for various system purposes, these pages are not intended for display. Closed Caption page numbers between 1 ... 8 correspond to the four Caption and Text channels:
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This is the subpage number only applicable to Teletext pages, a BCD number in range 0x00 ... 0x99. On special 'clock' pages (for example listing the current time in different time zones) it can assume values between 0x0000 ... 0x2359 expressing local time. These are not actually subpages. |
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Page classification. See vbi_classify_page(). |
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Allocate a new data service decoder instance.
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Delete a data service decoder instance.
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Main function of the data service decoder.
timestamp shall advance by 1/30 to 1/25 seconds whenever calling this function. Failure to do so will be interpreted as frame dropping, which starts a resynchronization cycle, eventually a channel switch may be assumed which resets even more decoder state. So even if a frame did not contain any useful data this function must be called, with lines set to zero.
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The decoder attempts to detect channel switches automatically, but this is not 100 % reliable, especially without receiving and decoding Teletext or VPS which frequently transmit network identifiers. Note the reset is not executed until the next frame is about to be decoded, so you may still receive "old" events after calling this. You may also receive blank events (e. g. unknown network, unknown aspect ratio) revoking a previously sent event, until new information becomes available. |
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For Closed Caption pages (pgno 1 ... 8) subno will always be zero, language set or For Teletext pages (pgno 0x100 ... 0x8FF) subno returns the highest subpage number used. Note this number can be larger (but not smaller) than the number of subpages actually received and cached. Still there is no guarantee the advertised subpages will ever appear or stay in cache.
language currently returns the language of subtitle pages, Other page types are:
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