On Fri, 14 May 2021, Dominguez Bonini, David wrote:
Hi,
Hi Marton,
Il 2021-05-12 19:18 Marton Balint ha scritto:
On Wed, 12 May 2021, Ubaldo Porcheddu wrote:
Hi Marton,
+ }
+
+ //private data
+ desc_len += 6 + 2;
+ *q++ = 0x5F;
+ *q++ = 4;
+ *q++ = 0x00;
+ *q++ = 0x00;
+ put16(&q, 40);
What are these?
I didn't find any official document about it but this seems to be the
way many national (FR,IT,UK) broadcasters are writing the virtual
channel private data header and the one recognized by many popular tv
on the market.
But this looks like a separate descriptor from the virtual channels
(logical_channel_descriptor).
I think it is better to remove it until it is more clear what it does,
or maybe we add an extra mpegts flag like "nit_lcn_extra" ?
The private data specifier descriptor is needed for the TV to correctly process
the LCN descriptor. When it is needed, you have to include both or none.
Also, in the Scandinavian countries, that use the NORDIG spec, the LCN
descriptor has a different format, though I think the European format may still
be understood.
Specs can be found here for NORDIG :
https://nordig.org/wp-content/uploads/2017/03/NorDig-Unified_ver_2_6.pdf
Specs for the European LCN can be found here, it's the French spec, but the
rest are the same:
https://www.csa.fr/web/index.php/content/download/253685/723620/version/1/file/CSA-Signalling-Profilev3.4.pdf
Specs for the Australian LCN descriptor can be found here:
https://www.freetv.com.au/wp-content/uploads/2019/08/OP-41-LCN-Descriptor-Issue-8-July-2016.pdf
The rules, as far as I know them are:
NORDIG --> Private Data Specifier = 0x00000029, LCN Descriptor Tag = 0x83
(legacy), 0x87 (Nordig version)
United Kingdom --> Private Data Specifier = 0x0000233A, LCN Descriptor Tag =
0x83
Rest of Europe + Most of the World --> Private Data Specifier = 0x00000028,
LCN Descriptor Tag = 0x83
Australia --> _Do_not_include_Private_data_specifier_descriptor_ , LCN
Descriptor Tag = 0x83
My suggestion would be to add an "LCN_mode" parameters, with values: NO_LCN,
Australia,UK,Nordig, etc
Thanks for this, I agree with your suggestion.
It probably also makes sense to split the feature in two patches:
patch 1 adds support the nit flag (I think it is shorter than emit_nit)
without LCN.
patch 2 add support for various lcn modes:
-lcn_mode (none|nordig|nordig_legacy|uk|australia|world).
And this would enable lcn generation in the NIT.
Regards,
Marton
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