[linux-dvb] [PATCH] cx24116 DVB-S modulation fix

Andreas Oberritter obi at linuxtv.org
Tue Oct 14 23:05:45 CEST 2008


Christophe Thommeret wrote:
> dvbscan initial tuning data files for DVB-S don't have an entry for 
> modulation. So an app like kaffeine simply set modulation to QAM_AUTO.
> Why not QPSK, you ask? Simply because DVB-S standard allows QPSK and 16QAM. 
> Maybe there is not a single 16QAM TP all over the world, but it's still a 
> valid modulation for DVB-S.
> So, we set modulation to QAM_AUTO when it's unknown/unspecified, like in 
> dvbscan files (those being also used by kaffeine). And it works pretty well, 
> just because most dvb-s can only do QPSK and so force modulation to QPSK 
> instead of returning a notsup.
> See this as software QAM_AUTO :)

It simply doesn't make sense to specify QAM_AUTO if dvb_frontend_info.caps
doesn't contain FE_CAN_QAM_AUTO (or FE_CAN_QAM_16 for that matter).

Regards,
Andreas



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