README


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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 (registration required).

In the UK a subset of the TV-Anytime specification is broadcast on the DTV service 
under the trade name "FreeView Plus". This patch is written for the UK version but
should work with the full specification.

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 two CRIDs in its EPG entry. One identifies the specific 
item of content which is being broadcast, while the other identifies a series of
programmes which this item belongs to. In FreeView Plus these CRIDs have crid_type
values 0x31 and 0x32 respectively (TV-Anytime uses values 0x01 and 0x02).

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.