'Jukka Aho' wrote, in part:
| But let me help: what Richard means is that, in common everyday speech
| people tend to call 625-line / 50 Hz formats (and their digital
| equivalents, such as 720×576) "PAL" and 525-line / 59.94 Hz formats (and
| their digital equivalents, such as 720×480) "NTSC" - regardless of
| whether the colors are actually encoded as PAL or NTSC.
_____
Thanks for explaining Richard's explanations.
Just two among many quibbles:
RBG is neither fish nor fowl nor NTSC nor PAL nor SECAM, it is unencoded.
Since nonlinear video editing is done on digital systems (else it could not
be nonlinear), it is done with monitors that display the digital, unencoded
signals, sometimes with multiple windows. The 'professional' encoded video
monitor is a valuable quality check, but not sufficient for engineering
purposes.
Phil Weldon
| Phil Weldon wrote:
|
| >> I guess that depends on how you define "NTSC" and "PAL".
| >> Most people define it as the dimension of the frame in pixels,
| >> and the frame rate (and the interlaced fields). You can be sure
| >> that people who try to mix NTSC and PAL very quickly discover
| >> that they are quite real, whether in analog or in digital form.
|
| > NTSC and PAL and SECAM are defined as SMPTE (<
http://www.smpte.org>
| > ) defines them.
|
| ITU-R BT.470 would be more authoritative at least for PAL and SECAM than
| anything SMPTE says.
|
| But let me help: what Richard means is that, in common everyday speech
| people tend to call 625-line / 50 Hz formats (and their digital
| equivalents, such as 720×576) "PAL" and 525-line / 59.94 Hz formats (and
| their digital equivalents, such as 720×480) "NTSC" - regardless of
| whether the colors are actually encoded as PAL or NTSC.
|
| That's inaccurate, sloppy usage, of course (and there are some
| PAL-N/PAL-M countries where this implied "PAL = 625/50/576, NTSC =
| 525/59.94/480" relationship doesn't even hold true), but those are still
| the name tags that people most commonly attach to these formats. Why?
| Because "PAL" and "NTSC" are usually more convenient and more compact
| for this kind of use than the other available alternatives. The message
| usually gets through by using "PAL" or "NTSC" even though the
| terminology is a bit off. You may not like it and I don't like it
| either, but it's impossible to get people stop using these terms
| sloppily. (Hardware manufacturers and software houses use them in a
| sloppy way, too.)
|
| >> NTSC and PAL are not even processed the same in digital
| >> form. For example, in DV (the most widely-used digital video
| >> codec), NTSC is sampled 4:1:1 (Y,U,V) while PAL is
| >> sampled 4:2:0
http://en.wikipedia.org/wiki/4:2:0
|
| > What makes you think that the signal from the sensors of a digital
| > camcorder is encoded in NTSC or PAL before recording? If you have a
| > COMPOSITE, analog signal output it may be NTSC or PAL, but not if the
| > output is a digital signal.
|
| He doesn't think that. He just uses the acronyms "PAL" and "NTSC" as
| name tags for 625/50 and 525/59.94 Hz formats, as described above.
|
| >> Actually, people who are motivated to do quality video editing
| >> never use computer monitors for qualitative evaluation of TV
| >> pictures. You just cannot display a proper television picture on
| >> a computer monitor. Mainly because of the very great difference
| >> in gamma transfer curve, and also because of differences in
| >> colorimetry. A good television monitor likely costs more than
| >> your whole computer system (or maybe 2x or 3x more).
|
| > People who are motivated to do quality video editing use digital
| > signals, and produce a digital recording.
|
| Yes, but up until the last couple of years they have monitored the
| results on a professional-grade, color-calibrated, 15 kHz analog
| CRT-based video monitor - such as one of these:
|
| <
http://www.expandore.com/product/Sony/Monitor/ind
| ex.htm#PROFESSIONAL%20VIDEO%20MONITORS>
|
| Professional production has moved or is in the process of moving to HD,
| and people are buying flat panels instead of CRT-based sets - but we
| were not discussing HD here.
|
| As long as the majority of tv sets are still SD and CRT-based, and as
| long as we're still shooting and processing standard-definition
| interlaced video, professional-grade CRT-based 15 kHz video monitor is
| the way to go. Flat panels can't show interlaced signals the way
| CRT-based sets do (simply because panels don't update the picture by
| scanning), and their color rendition is different. Things are about to
| change in the next couple of years as more and more people are replacing
| their CRT-based sets with TFT panels and as we're starting to get
| HD-based consumer video formats, but we're not there yet.
|
| > Which brings up the question, what do you mean by a good televison
| > monitor? Certainly in editing on a non-linear system a NTSC or PAL
| > analog monitor is not appropriate.
|
| What do you mean by "analog" monitor? For example, all CRT-based
| VGA-monitors are "analog" by definition.
|
| The pro-grade 15 kHz analog video monitors used for video editing
| typically have component (Y'PbPr) or RGB inputs, or, in some cases, SDI.
|
| As long as analog PAL, SECAM, and NTSC transmissions are still on air
| (or on the cable), people should also check that their video stays
| within the legal broadcast levels. This can be done without visual aids,
| but it still doesn't hurt to check how the pictures will actually look
| when encoded to true composite PAL or NTSC. The old analog systems have
| their limitations with allowed color saturation or workable adjacent
| colors. These sort of checks and practices will of course become
| obsolete when the analog transmissions are turned off for good, but
| they're not quite obsolete yet.
|
| > Of course you can display a proper television picture on a
| > computer monitor.
|
| For starters, many TFT panels have severe issues with their black level
| (the backlight is shining through) and a limited color bit depth, which
| causes banding on color ranges. Then there's the viewing angle issue:
| colors will look different depending on the angle from which you look at
| them. Some monitors will also clip black and white levels. Then you have
| the problem of not being able to assess whatever flickery problems
| interlaced scanning might cause to certain types of pictures when
| displayed on a regular CRT-based tv set. The list goes on and on; gamma
| is but one of the problems.
|
| Of course, many many many video processing programs don't even _allow_
| you to adjust anything to a given specification, or two programs may
| display the same video with different colors/luminance range (the
| 16...235 vs. 0...255 luminance range issue.) Regular color calibration
| generally doesn't even apply to video overlays. What is more, when
| watching your interlaced videos on a computer screen, you often get to
| see only half of the motion since many video players (and NLE apps with
| preview functions) don't even _try_ to display the video on
| field-by-field basis. If you don't monitor on a CRT-based interlaced
| video monitor, you might have something as trivial as the field order
| wrong without realizing it, which will make the video look horrible when
| it is played back on a regular CRT-based tv set.
|
| > I'd say a little cross-fertilization is a Good Thing.
| > alt.com.hardware.overclocking, [...]
|
| Followups have been set to go back to rec.video.desktop only.
|
| --
| znark
|
