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@@ -0,0 +1,108 @@ +This program is free software; you can redistribute it and/or modify it under +the terms of the GNU General Public License as published by the Free Software +Foundation; either version 2 of the License, or (at your option) any later +version. See the file COPYING for more information. + +Description: + +TV-Anytime is the name given to a set of technologies which aim to simplify the +process of recording and replaying broadcast content. The standards are +published by ETSI and are available without cost from www.etsi.org. The main +standard is ETSI TS 102 323. + +In the UK a subset of the TV-Anytime specification is broadcast on the DTV +service under the trade name "FreeView Plus". This plugin is written for the UK +version but should work with the full specification (untested). + +TV-Anytime data is contained in Content Reference Identifiers (CRIDs). The +syntax of a CRID is described in RFC 4078; it is a URI-compliant string of the +form: + + crid://<DNS name>/<data> + +in which <DNS name> is a registered internet domain name (RFC 1034) and <data> +is a free-format string. The <DNS Name> section relates to the content provider +(TV channel or company), and the <data> section to the programme. + +CRIDs are transmitted in the EIT as Content Identifier Descriptors, with +descriptor ID 0x76. To save bandwith only the <data> section is sent, the <DNS +Name> part is taken from the Default Authority Descriptor in the SDT, and the +crid:// is assumed. + +A programme may have up to three CRIDs in its EPG entry. One identifies the +specific item of content which is being broadcast, while another identifies a +series of programmes which this item belongs to. The third type includes the +CRIDs of 'suggested' events which the viewer might be interested in. In FreeView +Plus these CRIDs have crid_type values 0x31 0x32 and 0x33 respectively +(TV-Anytime uses values 0x01 - 0x03). + +To give an example, the programme "Torchwood" broadcast on channel BBC2 at 21:00 +on 2008-01-16 had item CRID '54BXLC' and series CRID 'KCJ00C'. When the same +programme was repeated the following day on channel BBC3, the item CRID remained +the same but the series CRID was 'KCJ12C'. Meanwhile the episode broadcast on +BBC2 one week later on 2008-01-24 had CRID '54BXLD' but the same series as the +previous week. Hence it is possible for a PVR to record an entire series by +using the series CRID, or to find an alternative broadcast for an individual +item if there is a clash with another recording. + +Operation: + +The use of the 'Accurate Recording' feature is described in README-vps. + +The plugin runs every 24 hours at a time set by the '-u' parameter (default +03:00). It captures CRID data for a time (10 minutes) then: + +- Checks for new manually-created timers and adds series links for them. + +- Checks each series link to see if any new events have been added to the EPG in + the same series. If so then timers are added for them. + +- Checks for timer clashes and suggests possible alternative recording times. + +- Checks that the event being recorded by each timer is the same as when the + timer was set (ie that the EPG has not changed in the meantime) + +- Flags any split events (eg a long programme with a news sumary in the middle). + At present a manual check is needed that all perts of the programme are set to + be recorded. + +The plugin logs its activity through the VDR syslog. + +The plugin has an SVDRP interface which is mainly used for debugging, but could +be used to interface with other applications. The commands are: + +LSTL Print the series links list + +LSTS Print the 'suggested' events list + +LSTY Print the CRIDs for each event + +LSTZ Print the Default Authority data for each channel + +STOP Start and stop CRID data capture +STRT + +UPDT Trigger an update of the series links. + +Points to remember: + +- Not all channels on UK Freeview have CRIDs in the EPG. Some radio channels + have item CRIDs but none have series CRIDs. + +- Different programme providers have different ideas of what constitutes a + 'series'. + +- The timer creation process is very simplistic; it doesn't check for timer + clashes, and selects the first physical entry in the EPG (which may not be + the prime broadcast of the programme). + +- A series link is created for every timer whether you want one or not. + +- This plugin has not been tested with multiple tuner cards or with mixed DVB-T + and DVB-S setups. + +- The 'suggested' events list may contain duplicates and may have CRIDs which + do not appear in the events list. + +Although I use this software on my VDR installation, this is Alpha-quality code +- USE AT YOUR OWN RISK!! |