[mythtv] Network recorder & m3u format,

Laurent ARNAL laurent at clae.net
Fri Dec 31 18:14:10 UTC 2010

Hi Everyone,

Since I wrote the first patch for network recorder (aka freebox recoder) 
somewhere in 2005 (ticket #1458), format of m3u description file for 
channel have undergone significant changes.

I would like to update the network recorder, and more specifically the 
iptvchannelfetcher.cpp, to sync for these changes.

Attach are the last m3u files serve by the original TV box which was use 
for the original patch. There are two main differences with the original 

1/ same channel could be found twice or more in the file, because of 
different channel flavors (High Definition, Standard Definition, etc).

This is the case at the beginning of the files for France 2 Channel, 
which exists in three variants: high definition, standard definition, 
low definition. Such channels have the same channel number: 0,2, but 
different call sign : “France 2 HD”, “France 2”, “France 2 (bas debit)”.

Today, when you scan channel with iptvchannelfetcher.cpp scanner, MythTv 
will only retains last version of the channel, in the file orders, so in 
this case “France 2 (bas debit)”. The idea would be to use a dictionary 
to find matching channel (same channel id), but different channel s 
flavors.  In this case, the channel scanner will only retains the 
shortest callsign (in this case France 2), and will present the others 
variants as different video flux of the same channel. However I don’t 
know how we can multiplex this different URL in Mythtv so they are 
present as only one channel, with choice for the different video streams?

2/ other change are that they could be some options behind the channel 
definition. This is the case for the radio service definitions we find 
at the end of the files.  For a radio definition, you will find a 
channel id as for TV services, a corresponding URL definition, a 
callsign, but also some channel options. Most important are 
“#EXTVLCOPT:audio-track-id=1004” : indicates the default audio track for 
this service. If you take for example service 0,10001 - Europe 1 and 
service 0,10004 - RMC Info, this two service are on the same RTSP url 
but on different audio stream : 1001 & 1004. On Current MythTv, you can 
select a service of this type, but MythTv we always default on the first 
audio stream on the multiplex.

I would appreciate to know if anyone has comments on these changes, and 
if it seems “compatible” with other people using the network recorder, 
before I start to write a patch. I would also appreciate if anyone can 
give me some clue of how to multiplex different URL to a same channel.



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