At 5:34 PM -0700 10/14/04, Eory Frank-p22212 wrote: >What do you mean a "COFDM transport stream" or an "ATSC transport >stream"? Both ATSC and DVB-T use MPEG-2 transport streams. Even with >a non-8-VSB modulation scheme, the transport parser, video decoder, >audio decoder, PSIP processor, etc. would see the same 188 byte >MPEG-2 TS packets that they see now from an 8-VSB demod. You're >getting hung up on differences between ATSC & DVB-T regarding what >goes into those TS packets, and I'm saying those contents wouldn't >have to change just because the modulation was (hypothetically) >changed. A "COFDM ATSC" system could still be ATSC in every respect, >except for the modulation. > >But of course this is all water under the bridge. The decision was >made and so we move on and make the best of it. But that doesn't >mean we can't look back and speculate about how things might have >been different if it had gone the other way. > >The real irony is that two of the reasons COFDM was rejected by >ACATS were (a) it was believed it was still in the R&D stage, not >yet ready for deployment; and (b) it was believed that the large FFT >sizes would require too much silicon to make a cost-effective >solution. Considering the earlier and still much larger volume >shipments of DVB-T receivers relative to ATSC receivers, and >considering the dramatically smaller silicon area & power of DVB-T >demods vs. ATSC demods, points (a) & (b) above turned out to be 180 >degrees out of phase with reality. Franks accurate analysis of the differences between COFDM and 8-VSB based systems brings to mind another bit of DTV history. leading up to the decision to implement the ATSC standard, the computer industry and many others (including myself) filed comments with the FCC stating that the best approach to the decision would be to mandate AS LITTLE AS POSSIBLE. We advanced the idea that the FCC need only do two things to create a more open system: 1. Choose a modulation standard; 2. Choose a packet-bbased transport standard with headers/descriptors to identify the content of the packets. The FCC did pay attention, as this approach was being promoted by the computer industry in the last minute talks that led to the FCC decision to drop table 3 from the standard. Alas, the FCC did not know how easily the ATSC and the CE vendors walked around the table 3 issue. As a result, we still cannot send a legitimate ITU-R.BT601 raster to an ATSC receiver (i.e. 720 x 480). Fortunately, the cable guys did not place the same constraints on the MPEG-2 implementation, so cable ready receivers must deal with a range of formats that are not ATSC compliant. All of this would be irrelevant if vendors simply included a fully conformant MPEG-2 decoder, which could care less about formats. Regards Craig ---------------------------------------------------------------------- You can UNSUBSCRIBE from the OpenDTV list in two ways: - Using the UNSUBSCRIBE command in your user configuration settings at FreeLists.org - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word unsubscribe in the subject line.