babe ruthless wrote:
I've got a CD recorder and am going to acquire a video capture card for my PC as part of a plan to convert my recorded TV show collection to digital format. So, if everything goes wrong with these DVDs, I can always use the equipment to make VCDs out of them like you said.
Heh... well... don't go down the route my uncle did, unless your recordings aren't great quality. He got a cheap USB plug-in thing that basically sits as a box between the composite source (in this case, his camcorder, for playing back home movie hi-8 tapes) and the port. I suspect it's USB v1
... the software is awful for one thing, but that's not the major problem, as the picture quality is diabolical :p.... he's trying to make DVDs with it from source material that's pushing SVHS quality (so should look damn good, though not DV quality) and it looks like some of my dodgy VCDs that have come from people wielding ancient VHS-C recorders in an after-hours cinema (...and then transferred to disc using similarly old computers and internal cards).
babe ruthless wrote:On a separate note, I can tell when something's been originally recorded in PAL50, too - particularly TV reports from Brazilian correspondents in Europe and elsewhere. I don't know quite how to describe the images, perhaps they look a bit hazy when compared to locally-recorded ones.
What would you describe the overall watchability of those recordings as, though? Assuming your TV stations have all up-to-date equipment, that's about as good as you could expect a UK DVD to look on your television (top-notch transcoding) unless both the DVD player and the TV switch into 50hz mode.
(( I suspect the haziness comes from having to do a real-time 20% reduction on the number of lines - hard to smooth the "gaps" without causing at least a little blurriness - and, if it's motion-hazy, from over-smoothing the 5-times-a-sec gaps where an extra frame is shoved in. ))
babe ruthless wrote:
As for NTSC, I don't know why, but NTSC-encoded video and DVD pictures show their line stucture very clearly even on small-screen TVs (like my bedroom's 38cm) when compared to PAL-M output. I wonder why, when both systems appear to have the same line structure.
I've found NTSC to be clearly more "liney" than PAL too... well, and PAL60 more so than 50, too
... probably due to the lower number of lines, but then I would have expected the "beam" to have been set wider in order to cope. After all I rarely see *any* gap between lines with a pal TV signal.
Heck... actually...... I dont know. it may depend on other circumstances. I have PAL50 playstation games (eg, GT2*) that can look similar to this. It's a bit puzzling.
It's a known thing with NTSC however - it's why many console emulators (almost exclusively originating from USA or Japan) include a "simulate scanlines" display option
babe ruthless wrote:Still, many thanks for your help - I can see you're as keen on video technology as you are on VW Polos!
Hehe, I was into all this nonsense (even if on a very basic level) before I could even drive, let alone before I made the final coin flip on what first car my 700 hard earned pounds would be wasted on
When I had the time for it (i.e. at university when i should have been studying rather than scoring 2 grades below prediction) I could have talked your ears off even worse O_O
rooboy wrote:
all this is down to the framerate, where Pal-m and NTSC are both 30fps, it is just down to the colour system (NTSC uses one tube for all it's colour, pal uses three: red, green, blue to put it in it's simplest form) so it is relatively easy to convert.
Without wishing to be rude, rooboy.... "um, come again"?
1. your sentence appears to change subject halfway though - you say it's to do with the framerate and in the same breath change to saying its because of the colour guns.
2. ntsc gets three colours out of one gun? That's a neat trick. please show me how that works. (or conversely: my PAL tv has three tubes? i'm sure i would have noticed by now...) ... and what of the multi-standard TVs, or that awesome (albeit 13 inch) Phillips monitor that came with my Atari in 1989, which could do PAL and NTSC full colour hook ups direct out of the box without need to change tubes - and a few other computer specific standards besides. The tube and projection gun in TVs are pretty much standard worldwide (though the dot-mask may change to adapt to different numbers of lines - if it's not a Trinitron), on single-standard sets the limitation comes with A/ the timing circuits controlling the electromagnets deflecting the triple X-ray beams, B/ the decoder filter circuits which separate out the different information channels (audio, black and white, colour hue and strength) and recombine them in ways the "raw" projection circuits can understand.
I think maybe you've got the connection standards mixed up with the actual TV circuitry. For a quick reference, there are a small number of main ones, and they can actually be applied to either PAL or NTSC...
(beleive it or not the next section is a complete rewrite of what I originally put, half asleep yesterday evening, and about half the length)
RF (radio frequency) - what you get out of an aerial, VHS player, old-style cable decoder. Not very good quality, as all four picture components (black & white, colour hue and strength, synch), audio, are combined on the one signal and then modulated into a radio wave for transmission (competing for space with at least 5 others locally) - whether through the air, or in a wire between your boxes. It's quite amazing that you can get the quality that you do from aerials on modern TVs, with the challenge they are up against!
Composite video - a step up, as it is just the video components are mixed together without audio, and without conversion to radio waves. Gives good enough quality most of the time, with minimal clutter, which is why you see it's little yellow round socket on pretty much everything these days. It can still suffer from dodgy colour accuracy, some smearing and distortion effects e.g. where there's purple bordering green, or a fine chequerboard pattern, but it's usually not a problem unless you're mad about quality or using a lot of 'hard' computer graphics.
Both of the above are used equally across PAL and NTSC, and also show the biggest variation. The composite signal itself has a certain base frequency, for better transmission and easier synch. PAL is somewhere around 4.2 - 4.5mhz (roughly translating to that many pixels of colour information per second and at least twice as much B/W clarity), and the official NTSC specs say 3.5 to 4.2mhz - you can see that at essentially the same line frequency, the NTSC transmissions will have less horizontal clarity, and many stations record and even transmit at lower frequencies than this as the airwaves are more cramped (lower freq = fit more channels in) and the regulations looser. In addition NTSC settled on cheaper AM-type colour encoding (hard to automatically 'tune' the colour, susceptible to interference), whereas PAL uses more robust FM encoding and doesn't normally need a colour 'control' (compare AM radio to FM..)
RF encoding compounds this, as PAL tends to be on UHF bands (low Ghz) allowing a clearer picture over a short distance, whereas NTSC also uses VHF (high hundreds Mhz) for greater range at the cost of clarity. Much like medium wave vs long wave radio.
Higher quality standards include
* S-Video, a rather odd american invention that has spread to europe. Small circular socket with 4 pins, splits the video signal into Black & White with synch, and Colour hue/saturation (well, to be technical - "red" and "blue" components. Don't ask me how THAT works). As it's also a non-broadcast standard, the frequency is fixed at the highest level. May seem like a kooky idea but it works very well, virtually eliminating most of the problems seen with Composite, with almost monitor-like clarity, and only needs a slightly thicker cable rather than several thin ones or a chunky SCART... so much so that component outputs are often not bothered with even on comparitively high-end NTSC kit. Still, the colour resolution is only half of that of the black and white (not a problem with anything except computer/console outputs - DVD has only a half-rez colour clarity itself due to the MPG standard).
* Component video. In NTSC regions this tends to be Y-Cr-Cb (an extension of SVideo, but using separate lines for both colour components - usually three composite-style cables) or Y-U-V (using hue/saturation not red/blue), making for a very short and simple circuit path inside the TV; socket, to picture adjustment (working *directly* on those signals), to RGB decoder, to tube. With PAL, it's often RGB (particularly with consoles and cable smartboxes), utilising the 21 pin SCART standard socket to split off even the synch onto separate wires whilst keeping picture and stereo sound inside one (thick) cable (also capable of composite and s-video!), meaning that theoretically the picture can go straight from 'source' to the colour guns in the tube without encountering any more circuits, for exquisite monitor-class clarity. As it is, it still has to go through the brightness/etc chip, but that is all. Some NTSC equipment also uses RGB (usually through a similar method to Y-Cr-Cb) but it's generally 50" sets and projectors - specialised and highly expensive stuff.
(Really, all three are just variations on the same thing, just moving some conversion stages from one side of the cable to the other).
The colour clarity with these methods is unsurpassed, being 1:1 with the black and white detail. Also the actual base resolution is higher - i've had a sharp and fully usable 720 pixel wide display from an RGB TV-out card, vs about a 560 maximum from composite (where even VGA is a bit blurry). I tried pushing it up to 800, which may have been better but for the actual screen not having a sharp enough physical dot-mask in the tube!
So what I think you're thinking of is - to make a massive assumption....
Composite/RF, maybe SVideo if you didnt realise it was split, for the american TV sets.
Component RGB for the european ones.
rooboy wrote:European Pal and SECAM (yet another system used in france, some of their ex-terrirtories and some middle east countries)
As an aside; my understanding of SECAM is that is essentially the same as PAL, it just handles the colour encoding in a weird way, much like an Amiga in HAL mode. Instead of a pixel having an 'absolute' colour, it instead is described as how different it is from the previous one
Which must make for a lot of fun effects in bad weather!
(most PAL tvs and videos are now SECAM compatible, and vice versa, as they've had a lot more cross exposure to one another)
rooboy wrote:
The blurring occurs because they have to stretch the frame and merge part of it with the next one (the easiest way). We don't really have that problem as we have no choice but to do it properly as it would look stupid.
Yep.... even better, to blur the first one of the frame pair that's being doubled with the preceding frame, and the second with the suceeding one. So maybe three or four of every six/seven frames will be "mashed". Of course them being interlaced makes it easier and more complex at the same time - an effect which is hijacked to great effect by NTSC stations for showing films.
("We" being where, and doing things "properly" how?
... sorry I dont know where you are!)
rooboy wrote:
There is another problem that every single 25fps film dvd will suffer from though. movies are shot at 24fps, so to save money, all the studios do for these markets is speed up the frame rate by one. It is not enough to notice any difference in the pace of the film, but it means that films are roughly 4 minute shorter than in the cinema.
I don't suppose it's a money saving move - it just gives the best quality possible in the easiest fashion. Even if it were more expensive it'd be the preferred method. As it happens it's almost free - it's a piece of cake to tweak the fine speed adjuster on a cine projector so that it will run the film one fps faster - and facing into a TV camera, makes a "telecine" projector. Really, would you notice that a film was 4% faster than it was last time you saw it, unless you had perfect pitch, a stopwatch, or were sitting in the cinema with a portable Televideo? Truth is you probably would never have noticed had you not been told. The difference is (naturally) 1 minute in every 25, and approx one semitone in sound (going up from a white C key to a black C# on a piano), very difficult to tell. I'll take that over a jumpy NTSC telecine'd pic or a hazy, needlessly transcoded PAL version any day.
(plus it means I can fit an 83 minute kids' film onto an 80 minute VCD without having to pull any fancy tricks
)
rooboy wrote:
With 30fps markets they cannot do this as it would be noticable being 1/5 faster than before so it has to be formatted, athough most dvd players with a switchable tv output (pal/ntsc) can hande this.
Yep, instead, you have another, different thing also confusingly called Telecine. In the case of NTSC, it involves lengthening every other frame by half to bring a 24fps picture up to 30fps (the interlacing being finally useful for something - producing a natural blend effect over what was originally a full-frame non interlaced pic).... technically "3-2 Telecine" as one frame runs for 3 interlace "fields", then the next only runs for 2, alternating the field order 6 times a second. Again, it works very well on still scenes, but produces a constant, very small but noticable "jerk" on fast motion, slightly alleviated by only being a half-frame of jigginess at a time. It used to be the case that this was always hard-coded onto the video tape or in the TV transmission, but with DVD, there's the option for the picture to be recorded "progressively" in pure 24fps for the benefit of those with the ability to play it back, with the player doing the telecine in hardware. This happens with too few films, unfortunately, and often a dodgy 30fps hard coded one gets directly transcoded to 25fps PAL without going through the essential Reverse Telecine stage back to 24fps. This is where pain occurs (especially on freeze frame) both picture wise and in confusing the MPG encoder..
(also, it's just a touch more complicated than that - the NTSC standard is actually 29.97fps, or exactly 99.9% of 30fps, for reasons lost to history. So you have to alter the timing of the projector *anyway* by 0.1%, or find some way of hiding the 'dropped' frame you get every 33 seconds without it causing an even more noticable jump)
(* hm, i wonder if the half frame thing gets used for 25-to-30 conversions as well... Something like 3-2-3-2-2 instead of 3-2-3-2..)
In summary, i really like living in a 25fps country when things go right. Though the ultimate would of course be to live in america - so I could get very soon an HD Blue-ray disc player, doing a pure 24.000 frames per second progressive picture, with a 72hz scan rate on a 50" screen
What was the question again?
(yay for posts that get written over the course of about 15 hours with looooong breaks... i fell asleep at the keys)
, very high speed play as player searches for a "properly encoded" part.... etc etc. On my own player, I had to do odd things like making an SVCD (full SV resolution) using vanilla VCD encoding, attempting a max quality "KVCD" (528 horizontal rez SVCD - yep...), very bonkers bit-rates, etc.... all the same, they happened, and are examples of what a confused DVD chipset can do.