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

DUBOST Brice dubost at crans.ens-cachan.fr
Tue Feb 14 19:58:11 CET 2006


Mauro Borghi wrote:
> 
> 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.

Hello

Try to tune the card and look at the output of "scan -a -c card_number"

You'll get a stream analysis (PAT and PMT decode)

Regards

-- 
Brice

http://mumudvb.braice.net



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