Craig wrote: > provide 120 lines of color resolution, which is the spec > cited for NTSC (but not for all colors because of the 0.5 MHz > bandpass for Q). It may have had a bit more resolution internally, > but the outputs are base band are limited by the NTSC specification. As a practical matter: consumer grade NTSC TV sets limit both color carriers to 0.5 MHz bandwidth. This feature, while degrading color performance, saved the cost of adding a second post demodulator delay line to compensate for unequal filter delays. This design was possibly changed in recent analog tuners but I don't know if that is the case..... My point is: any composite color signal applied to an analog NTSC set through the tuner or composite video connector will be degraded to 0.5 MHz bandwidth. > -----Original Message----- > From: opendtv-bounce@xxxxxxxxxxxxx > [mailto:opendtv-bounce@xxxxxxxxxxxxx]On Behalf Of Craig Birkmaier > Sent: Wednesday, July 09, 2008 5:41 AM > To: opendtv@xxxxxxxxxxxxx > Subject: [opendtv] Re: Digital vs. Analog Quality > > > At 1:56 PM -0400 7/8/08, Cliff Benham wrote: > >Craig Birkmaier wrote: > >...baseband NTSC could be > >>far better than transmitted NTSC. True for the luminance, but not > >>true for the color difference signals. > > > >I think there are several examples of wideband color difference > >signals being used in NTSC. As far back as the late 1970s, baseband > >NTSC has been capable of 120 lines of chroma resolution. This > >includes Laserdisk and later in the early 1980s, analog component > >recording formats, notably Betacam. > > Neither of these are valid examples. > > Laserdisc is an analog format with extended frequency response for > the luminance component - in the range of 4.9 to 5.4 MHz. Laserdis > uses the same subcarrier based system for the carriage of the color > components. I found one reference that suggests that the internal > recorded bandwidth for the subcarrier signal is 1.5 MHz, qwhich could > allow for improved color recording in the Q channel. The system is > said to provide 120 lines of color resolution, which is the spec > cited for NTSC (but not for all colors because of the 0.5 MHz > bandpass for Q). It may have had a bit more resolution internally, > but the outputs are baseband are limited by the NTSC specification. > > see: http://home.online.no/~espen-b/ld/ > > > Betacam is an analog component format with R-Y and B-Y sampled at > half the bandwidth for the luminance channel - i.e. 4:2:2. It > provided a HUGE improvement over composite video recording formats > for several reasons: > > 1. NO mixing of the color and luma components as with > subcarrier-based systems. The color components are completely > recoverable without the problems of separating luma and subcarrier > via comb filtering techniques. > > 2. The R-Y and B-Y color difference signals are sampled at 1/2 the > bandwidth of the luminance signal This is more than double the color > information in NTSC (about 8x the bandwidth of the NTSC Q component. > > Alas, when a Betacam machine encodes the analog component signals > into a baseband NTSC output, the color signals are bandpass limited > to NTSC specs. The good news is that the color difference signals are > "oversampled" relative to NTSC and can be recovered accurately - thus > the composite output is MUCH cleaner than for any heterodyne color > recording system. > > The BREAKTHRU with Betacam was the availability of analog component > outputs, which could be used to feed an analog component video mixer > that did not suffer from the limitations of composite video > processing. I am reasonably knowledgeable about this, having built a > prototype analog component mixer for Sony for the 1983 NAB. This was > followed by an RGB 1600 series mixer, which both Sony and Grass > Valley used at NAB in 1984 - This was the year we had two Eiodophor > projectors displaying analog component video on huge screens above > the NAB booth. It was also the year that we introduce the Model 100. > After building the 1600 series mixer using RGB processing we realized > that these were the wrong components to process - it was difficult to > get three mixers to track in a perfectly linear fashion - any > non-linearities showed up as shifts in the luminance level. So when > we built the first commercial analog component switcher - the Model > 100 CV - we change the components to Y, R-Y, B-Y. This allowed for > excellent linearity in the luminance component - any tracking errors > were shifted to the color difference components and were far less > noticeable. > > I might add that there were a number of improved NTSC encoders and > NTSC enhancements developed in the same time frame as Betacam. > Central Dynamics developed an excellent NTSC encoder that carefully > limited the energy from the subcarrier in three dimensional space so > that it did not overlap with the energy from the luminance signal. > This allowed decoders to produce improved color components largely > free from the luma/cross color issues in most NTSC decoders. > > And Yve Farudja came up with several excellent NTSC enhancements with > significantly improved performance, but the world was more interested > in moving to HD. > > >[Betacam]"provides a crisp, true broadcast quality product with 300 > >lines of horizontal luma resolution, and 120 lines chroma resolution > >(versus ~30 for Betamax/VHS)." > >http://en.wikipedia.org/wiki/Betacam > > Luma - 300 lines, which is better than the 240 line (typical) from NTSC > > Chroma- 120 lines - this is the same as NTSC, but is misleading, as > only certain colors actually have this resolution. Any color based on > the ! component has far less resolution > > Betamax/VHS - really poor color performance due to heterodyne color > recording - FAR LESS color information and far more color distortion > than a clean NTSC baseband signal. > > 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. > > > > ---------------------------------------------------------------------- > 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. > > ---------------------------------------------------------------------- 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.