Re: API for China DTV standard

[Steven Toth <stoth@linuxtv.org>]

David Wong wrote:
> I would like to initiate a discussion of v4l-dvb API proposal for China DTV.
> 
> Some of you may heard about China DTV standard as DMB-T/H, it is not
> totally correctly.
> China standard GB20600-2006 is indeed a union of DMB-TH(multi-carrier)
> and ADTB-T(single carrier).
> 
> For API inclusion, I just read the standard document for GB20600. I am
> not very good in that electronics area,
> but I gather the following information of parameters, hope I don't
> miss anything:
> 
> Number of Carriers:  C=1, C=3780
> Constellations: 4QAM, 4QAM-NR, 16QAM, 32QAM, 64QAM
> FEC(LDPC): rate = 0.4,  rate = 0.6, rate = 0.8
> Frame body size: always 3780 symbols
> Frame header size:  420 symbols (1/10 guard interval), 595 symbols
> (0.136 guard interval), 945 symbols (1/5 guard interval)
> Time domain symbol interleave: M=240(B=52), M=720(B=52)
> 
> Despite "C=1" and "interleave", I don't know if DVB has such
> interleave, I see a chance to extend the current FE_OFDM structure (in
> dvb_frontend_parameters).
> Or should we create a new structure, like the separation of FE_ATSC
> and FE_OFDM?

No new structures are required. The existing user facing structures are fine.

The S2API will need new properties/types for Constellations, frame header size 
symbol interleave etc.

I suggest:

1) Identify new #defines EG. M_240_52, M_720_52
2) Identify new property types EG. GET/SET_FRAME_BODY_SIZE
3) Update the dvb-core property_cache so dvb-core has a place to store these values.
4) Update dvb-core so that it can interpret you GET/SET_FRAME_BOSY_SIZE and 
other messages.

No user API changes required.

- Steve