[linux-dvb] DVB-T devices supporting hierarchical mode?
patrick.boettcher at desy.de
Wed Feb 15 14:53:18 CET 2006
On Wed, 15 Feb 2006, Johannes Stezenbach wrote:
>> The Twinhan box has a MT352 inside and the controlling is done inside the
>> FX2 USB firmware. As hierarchical transmission has significant drawbacks
>> when used and no one (not even Twinhan :) ) expected that to be used
>> anywhere, they don't have it implemented. Ie. there is no way to give this
>> information to the firmware.
> It seems to me that a parameter is missing in the Linux DVB API
> to select between the high/low priority stream. If I understand
> it correctly the hierarchy mode just modifies the modulation scheme,
> and you still need a seperate knob to select which TS (high or low)
> the frontend should output. Can someone confirm this?
I think the hierarchy-field contains actually two values:
If hierarchy is used and what is the values for alpha. Or what does
1,2 and 4 mean?
If that is the case: I think we don't need to change: HIERARCHY_NONE could
mean get the high priority stream and HIERARCHY_1 and the others: get lp
stream with an appropriate alpha.
If my understanding is correct and we agree on a change of the API, IMHO,
it would be better like this.
Dividing the HIERARCHY_NONE _1, _2 and _4 in two different tuning
one field for: SELECT_HP, SELECT_LP
one field for: ALPHA_1, ALPHA_2, ALPHA_4
Afaik: by default in a non-hierarchical transmission the alpha is always 1
(that is where it clashes with HIERARCHY_NONE, I remember once having
difficulties with that).
What do you think?
Mail: patrick.boettcher at desy.de
More information about the linux-dvb