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
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