[mythtv] BIG DVB PATCH V3.5 - Logical Channel Numbers

[Tim Davies]

John,

Not that I know *anything* about the Europe/UK LCNs, but to paraphrase some
pertinent parts of the Australian spec (yawn!):

- The LCN is found in the second descriptor loop of the NIT with tag 0x83.
I think it is a reserved id, but that's good isn't it?  Reserved for Aussie
LCNs ;-)

- Unlike Europe, Australia uses non contiguous LCNs and three digit LCNs.
Are we using 10 bits, and you guys use 8 bits?

- There are some rules about what to do with a service that doesn't have an
LCN.  This bit of the code might need to be un-Australianised.  I haven't
yet seen a service here without an LCN anyway...  

- European standards say that services with the same original_network_id /
service_id shall have the same LCN.  That way, regional variants of a
service can have the same LCN.  Not so here!  In Australia the service is
uniquely identified by original_network_id / transport_stream_id /
service_id.  There are several networks (approx ten?) in Oz with unique
original_network_ids.  Each transmitter has its own network_id, it seems.

Not that most of it really matters too much.  I tried to write the patch so
that if you get the 0x83 descriptor, it populates the LCN data without
stomping on another descriptor's code that can also populate it.  Assuming
of course, any other LCN descriptor just populates a service_id to LCN
mapping.

It only falls down if the 0x83 descriptor is used for something else
somewhere.


Tim.


-----Original Message-----
From: mythtv-dev-bounces at mythtv.org [mailto:mythtv-dev-bounces at mythtv.org]
On Behalf Of John Pullan
Sent: Sunday, 9 January 2005 10:11 PM
To: Development of mythtv
Subject: Re: [mythtv] BIG DVB PATCH V3.5 - Logical Channel Numbers

Tim,

On Sun, 2005-01-09 at 07:44 +0800, Tim Davies wrote:

> Here is a patch to read the logical channel numbers in the channel
> scan.  It works in Australia at least.

> Much better than using the ServiceID J
> 

Is 0x83 a standard descriptor ? I only ask because I was under the
impression that it was a reserved one. If it isn't a standard can you
let us know what network ids it's present on.

The UK is using same system, and we are working on doing something with
logical channels, but we obviously need to make sure we don't break the
rest of the world.

Thanks
-- 
John Pullan <jmp at tarantella.com>