NTSC versus PAL
in [Repair]
|
From: stratus46 on 2 Apr 2010 00:13 On Apr 1, 7:04 am, "Geoffrey S. Mendelson" <g...(a)cable.mendelson.com> wrote: > Meat Plow wrote: > > What about PAL and NTSC videos, DVD/BluRay? When did they die? > > Technically video tapes are not NTSC or PAL. They have separate tracks > for luminance and chroma. The recorders all stripped them apart before > recording them and put them back together when playing them. > > There is no technical reason not to build a video player with a digital > output, which digitzes the signals and presents them as an digital data > stream, with out actual NTSC nor PAL encoding. The field/frame rate would > be the same as the source material, but that's not the same thing. > > The same with DVD's and BluRay. The data is encoded using MPEG compression, > which has separate information for luminance and chroma. It can be rebuilt > as red-green-blue pixels without ever going through NTSC or PAL. > > As reg-green-blue cameras become more common, I expect that there will be > an eventual shift to rgb encoded data, but that's a long way off. > > Geoff. > > -- > Geoffrey S. Mendelson, Jerusalem, Israel g...(a)mendelson.com N3OWJ/4X1GM > New word I coined 12/13/09, "Sub-Wikipedia" adj, describing knowledge or > understanding, as in he has a sub-wikipedia understanding of the situation. > i.e possessing less facts or information than can be found in the Wikipedia. Not so fast there. 2" quadruplex invented by Ampex in 1956 was a composite recorder that records the composite signal as analog FM with no processing at all. It was replaced by SMPTE C 1" helical recorders which also recorded the composite analog FM signal with no processing. Sony Betacam was the first recorder that used separate luma/chroma channels analog FM. This is a little problem when supplied with a composite input as the luma and chroma has to be separated but when mounted directly on a camera where the luma and chroma originate it's very good. D1 digital is a component format with 13.5 MHz luma sampling and 6.75 MHz chroma channels with no data compression on 19 mm tape. Commonly called 4:2:2. Digital Betacam is the same sample rate as D1 on a 1/2" tape with 3-1 data compression. This is one of the most common formats. D-2 digital invented by Ampex for commercial play is a composite digital machine sampled at 14.3MHz aka 4x subcarrier on 19mm (3/4") tape. The Sony D-2 machines were much more successful. Panasonic D-3 digital is 4x subcarrier composite digital on 1/2" tape. Ampex DCT on 19mm tape is a component digital 4:2:2 machine with 2-1 compression. So, PAL / NTSC refers to the subcarrier encoding so composite machines are indeed PAL or NTSC while component machines are not. They are however referred to as 525 or 625. And yes, all those formats are still in daily use, the 1" and 2" primarily for dubbing to modern formats - often digital Beta. HD machines have options to record all 3 channels at full bandwidth. This becomes important when compositing images using blue screen or green screen. G²
From: Sylvia Else on 2 Apr 2010 00:40 On 2/04/2010 12:45 PM, Arfa Daily wrote: > <snip> >> >> This issue is confused by two factors -- the differences between European >> and American distribution systems, and their studio standards. >> >> If the transmission network has constant group delay, the hue setting >> should >> be set 'n forget, and never need to be changed. The American system had >> good >> group-delay characteristics -- the European did not. So switching channels >> could require twisting the hue knob. But that's not all there is to it. >> >> Non-linear group delay changes the colors in a way that cannot be >> corrected >> simply by adjusting the hue control. All the colors cannot be "correct" at >> the same time. The advantage of PAL is that these color errors "flip" with >> the phase, and are complementary -- the eye "averages" them to the correct >> color. > > I don't think that is actually true. I think you'll find that was the intent. However, if the phase error is too great, the eye averaging doesn't work so well, hence the introduction of the delay line. At which point you wonder why bother sending two colour signals in quadrature if you're just going to average them with the next scan line anyway. SECAM avoids that complexity by just going straight to the delay line. I lived in Paris for 18 months. If there's a quality difference between a SECAM and PAL picture, it was far from obvious. Sylvia.
From: Phil Allison on 2 Apr 2010 01:08 <stratus46(a)yahoo.com > In * REALITY * the NTSC broadcast signal is massively compromised in > comparison to a PAL signal. PAL has plenty wrong with it and is 'massively compromised' the same ways as NTSC. ** More INSANE CRAPOLOGY !!!!!!!!!! Editing in composite PAL ..... ** More fuckwit, OFF TOPIC CRAPOLOGY !! See the words " broadcast signal " - fuckhead ??? Even know what it means ??? ...... Phil
From: Dave Plowman (News) on 2 Apr 2010 03:41 In article <b0011216-745f-45f6-a48d-c55ae3db26a7(a)b33g2000yqc.googlegroups.com>, <stratus46(a)yahoo.com> wrote: > PAL has plenty wrong with it and is 'massively compromised' the same > ways as NTSC. Editing in composite PAL is twice as crappy as NTSC > because of the 8 field PAL vs 4 field NTSC color frame sequences. Of > course nobody's done that kind of editing in many years since the > change to digital component in the '90s. Company I worked for in the UK were using component recording (Panasonic MII - high band like Beta SP) in the early '80s, and low band component was around for quite some time before that. Although didn't meet UK broadcast spec for most things, unlike high band. Within a couple of years it was the main format with 1" relegated to archive use. Next change was to DigiBeta. -- *Give me ambiguity or give me something else. Dave Plowman dave(a)davenoise.co.uk London SW To e-mail, change noise into sound.
From: William Sommerwerck on 2 Apr 2010 06:21
>> If the transmission network has constant group delay, the >> hue setting should be set 'n forget, and never need to be >> changed. The American system had good group-delay >> characteristics -- the European did not. So switching channels >> could require twisting the hue knob. But that's not all there is to it. >> Non-linear group delay changes the colors in a way that >> cannot be corrected simply by adjusting the hue control. >> All the colors cannot be "correct" at the same time. The >> advantage of PAL is that these color errors "flip" with >> the phase, and are complementary -- the eye "averages" >> them to the correct color. > I don't think that is actually true. It's been a lot of years since > I studied PAL decoding at college, but as far as I recall, the > averaging is done totally electronically, courtesy of the PAL > delay line. This is a glass block delay line of one scan-line > period, so if you run a direct and a delayed path side by side > in the chrominance channel, and then sum the outputs of both, > you arrive at an electronically averaged result of two sequential > lines, with any phase errors balanced to zero. This has nil effect > on the overall colour saturation, as this is controlled by a) the > ACC circuit, and b) the user saturation control. The averaging can be done electronically, but there is also some visual averaging. I'm not sure you can remove the phase distortion without reducing the saturation -- all the stuff I've read on PAL says otherwise -- but I won't press the issue because I haven't thought it through carefully. |