[linux-dvb] DVB-T devices supporting hierarchical mode?

Mauro Borghi mauro.borghi at TILAB.COM
Tue Feb 14 18:48:44 CET 2006


Hello all,
first of all a brief intro :-)

For the first time here in Torino, RAI (Italy's public television 
broadcaster) is broadcasting an experimental DVB-T channel, featuring in 
high definition the Olympic Winter Games.

They are exploiting *hierarchical* modulation, in order to accomodate 
-in the same radio channel- both a DVB-H test stream and this HDTV stream.
The low bitrate DVB-H stream is the "high priority" stream, while the 
HDTV stream (H.264/AVC) is the "low priority" one.

 From the information I got from devices supporting hierarchical mode, 
tuning data are as following:

RAIHD:538000000:INVERSION_OFF:BANDWIDTH_8_MHZ:\
  FEC_1_2:FEC_3_4:QAM_64:TRANSMISSION_MODE_8K:\
  GUARD_INTERVAL_1_8:HIERARCHY_2:x:x:x

[intro end]

Do you know about LinuxDVB-supported devices which are known to support 
hierarchical modulation?
Is it meant to be sufficient setting HIERARCHY_2 in the struct passed to 
the frontend device when tuning, in order to select the LOW priority stream?

 From the tests I did with a Twinhan 7045 USB2 clone (from digicom), the 
device seems to always lock on the HIGH priority stream, no matter what 
params are passed!

Ciao,
Mauro.

PS: unfortunately, even if I could correctly tune the HD stream, it 
would be encrypted (Irdeto CAS)... :-(
However, I'm curious about additional info I could get from stream analysis.



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