On Thu, Apr 2, 2009 at 10:30 PM, Steven Toth <stoth@xxxxxxxxxxx> wrote: > 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 > -- > To unsubscribe from this list: send the line "unsubscribe linux-media" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > You means because union DVB-T and GB20600, there's a need to get/set frame body size? Frame body is always 3780 symbols in GB20600, only frame header is changeable. Frame header , A.K.A guard interval, is filled with Pseudo-random Number(PN). So there are three defined frame header modes: PN420, 420 symbols, 420 / (420 + 3780) = 1/10 guard interval PN595, 595 symbols, 595 / (595 + 3780) = 0.136 guard interval PN945, 945 symbols, 945 / (945 + 3780) = 1/5 guard interval Also, new TRANSMISSION_MODE (C=1 and C=3780) need to be added besides 2K and 8K mode. Cheers, David -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
