From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.kapsi.fi ([217.30.184.167]:51209 "EHLO mail.kapsi.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753624Ab3ACUkI (ORCPT ); Thu, 3 Jan 2013 15:40:08 -0500 Message-ID: <50E5EC7E.4020508@iki.fi> Date: Thu, 03 Jan 2013 22:39:26 +0200 From: Antti Palosaari MIME-Version: 1.0 To: Mauro Carvalho Chehab CC: Manu Abraham , Devin Heitmueller , Linux Media Mailing List , Klaus Schmidinger Subject: Re: [PATCH RFCv3] dvb: Add DVBv5 properties for quality parameters References: <1356739006-22111-1-git-send-email-mchehab@redhat.com> <20130101130041.52dee65f@redhat.com> <50E5A515.4050500@iki.fi> <20130103172735.0aa1db6d@redhat.com> <20130103175359.5fc157eb@redhat.com> In-Reply-To: <20130103175359.5fc157eb@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-media-owner@vger.kernel.org List-ID: On 01/03/2013 09:53 PM, Mauro Carvalho Chehab wrote: > Em Fri, 4 Jan 2013 01:02:02 +0530 > Manu Abraham escreveu: > >> On Fri, Jan 4, 2013 at 12:57 AM, Mauro Carvalho Chehab >> wrote: >>> Em Fri, 4 Jan 2013 00:39:25 +0530 >>> Manu Abraham escreveu: >>> >>>> Hi Antti, >>>> >>>> On Thu, Jan 3, 2013 at 9:04 PM, Antti Palosaari wrote: >>>>> On 01/01/2013 06:48 PM, Manu Abraham wrote: >>>>>> >>>>>> On Tue, Jan 1, 2013 at 8:30 PM, Mauro Carvalho Chehab >>>>>> wrote: >>>>>> >>>>>>> [RFCv4] dvb: Add DVBv5 properties for quality parameters >>>>>>> >>>>>>> The DVBv3 quality parameters are limited on several ways: >>>>>>> - Doesn't provide any way to indicate the used measure; >>>>>>> - Userspace need to guess how to calculate the measure; >>>>>>> - Only a limited set of stats are supported; >>>>>>> - Doesn't provide QoS measure for the OFDM TPS/TMCC >>>>>>> carriers, used to detect the network parameters for >>>>>>> DVB-T/ISDB-T; >>>>>>> - Can't be called in a way to require them to be filled >>>>>>> all at once (atomic reads from the hardware), with may >>>>>>> cause troubles on interpreting them on userspace; >>>>>>> - On some OFDM delivery systems, the carriers can be >>>>>>> independently modulated, having different properties. >>>>>>> Currently, there's no way to report per-layer stats; >>>>>> >>>>>> >>>>>> per layer stats is a mythical bird, nothing of that sort does exist. If >>>>>> some >>>>>> driver states that it is simply due to lack of knowledge at the coding >>>>>> side. >>>>>> >>>>>> ISDB-T uses hierarchial modulation, just like DVB-S2 or DVB-T2 >>>>> >>>>> >>>>> Manu, you confused now two concept (which are aimed to resolve same real >>>>> life problem) - hierarchical coding and multiple transport stream. Both are >>>>> quite similar on lower level of radio channel, but differs on upper levels. >>>>> >>>>> Hierarchical is a little bit weird baby as it remuxes those lower lever >>>>> radio channels (called layers in case of ISDB-T) to one single mux! >>>> >>>> That is not really correct. There is one single OFDM channel, the layers >>>> are processed via hierarchial separation. Stuffing exists, to maintain >>>> constant rate. >>>> >>>> http://farm9.staticflickr.com/8077/8343296328_e1e375b519_b_d.jpg >>>> >>>> When rate is constant within the same channel.. >>>> (The only case what I can think parameters could be different with a >>>> constant rate, >>>> is that stuffing frames are unaccounted for. Most likely a bug ?) >>> >>> What did you smoke? That picture has nothing to do with ISDB! >>> >> >> ARIB STD – B31 >> Version 1.6-E2 >> －17－ >> Fig. 3-2 shows the basic configuration of the channel coding. >> >> It just shows, you understand crap. > > That is the picture you need to look, not the random one you picked. > It clearly shows there that, after the hierarchical coding done by > the "Division of TS into hierarchical levels", the TS packets are > split into 3 independent channels, each with its own convolutional > coding, carrier modulation, etc. > > This picture shows how each program is split at the FDM sub-carriers: > http://en.wikipedia.org/wiki/File:ISDB-T_CH_Seg_Prog_allocation.jpg.svg > > There, LD programs are at segment 0 (S0). HD programs use 12 segments > and SD programs use 4 segments. > > As each segment group has a different spectrum (as they're using FDM), > and are modulated with different encoding schemas (modulation type, FEC, > etc), they have different QoS measures. > > Segment 0 (the one at the center of the spectrum) is less sensitive to > inter-channel interference. That's why it is used for LD programs. > > > Cheers, > Mauro > Manu, here is manual of the professional ISDB-T signal analyzer. Look especially BER measurement picture from "Slide 10". I think you don't bother to say Anritsu MS8901A ISDB-T Digital Broadcast Signal Analyzer, which street price is $20,000, does not know how to measure ISDB-T statistics.... http://downloadfiles.anritsu.com/Files/en-US/Product-Introductions/Product-Introduction/MS8901A_EL1100.pdf Antti -- http://palosaari.fi/