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#1
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Were there problems editing with dropframe timecode?
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#2
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Drop frame doesn't work too badly on short programmes, as all editing software has been designed to cope with its peculiarities. Generating it in the long term requires all sorts of corrections as there is no simple relationship between clock time and dropframe TC.
It's all due to a decision made at the start of NTSC colour, long before TC was invented. The relationship beween colour SC and sound carrier had to be set to minimise certain crossmodulation problems. It was felt that moving the sound carrier by 0.1% would upset too many existing receivers so they moved H, V and SC frequencies instead. We've been living with the consequences ever since TC was invented. |
#3
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Changing the H & V frequencies slightly to 15734.26 and 59.94 and reducing the color subcarrier to 3.579545 MHZ resolved the problem for the B&W sets, although it was never a problem for the new color sets. Much Later, this change proved to be the undoing of videotape editing, special effects, standards conversion, and digital video. Life in the engineering department would have been so much easier if they'd left it alone. Cliff Last edited by cbenham; 08-18-2012 at 05:40 PM. Reason: clarity |
#4
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More on Hi-Vision experiment
http://www.bbc.com/news/technology-19370582 Article says UK HD is 25 FpS With 8mhz channels they should have followed EBU with 50p FpS Especially since they have 12.5% more bandwidth than Continent --and 25% more Bw than US channel (which can do 720 @ 60p ) As 25 FpS is really poor motion sampling rate |
#5
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Otto Schade did research in which the raster was reduced in size. With a fine beam, it showed that the target was capable of finer resolution.
In pickup tubes, it is necessary to have the beam wide enough to produce complete discharge of the target in one field (not one frame). Otherwise, there is an inverse raster of unread charge remaining on the target. The next scan will then produce a coarse moire' or flicker as it scans slightly out of register with the original scan. This can occur for either interlace or progressive. Of course, for interlace, the beam must be twice as wide as for progressive with the same number of total lines per frame. In old recordings, you can sometimes see this flicker in areas where the beam focus was too good. A similar effect could occur on kinescope recordings when they were rebroadcast, but there the moire' was more often a higher frequency swirly line pattern because the rescan had a much worse match to the original scan than the two fields in a camera. In CCD pickups, it was found that using every other line of elements for interlaced scanning resulted in far too much vertical resolution, producing excessive interline flicker in interlaced CRT displays. Therefore, rows were combined (with a coefficient that was adjustable to set the vertical peaking in high-end gear). This was the equivalent of the wide scanning beam in tube pickups. |
Audiokarma |
#6
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More on "PsF", now being used more widely for 30fps!
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#7
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I hadn't realised that PsF was proliferating. I know about 24pSF which is used to dress up progressive film material to look like interlace. Now they're doing it for 25, 29.97 and 30Hz.
I though that we were trying to abolish interlace but it's a hardy weed. |
#8
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I think this is welcome news given the ubiquity 1080/60i, with even ABC switching to this after a decade of 720p - and maybe this is why: They now have more confidence for artifact-free images now that PsF can be originated from new generation cameras? (It's all done in the camera)
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#9
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It is sad that 720p has had such a bad rap since it is capable of conveying higher resolution video than 1080i. Most of the problem stems from poor image rescaling in not only consumer equipment but also broadcast equipment. The point is that if the broadcast chain is properly set up so that production video is oversampled (1080p) and properly rescaled to 720p for delivery and then properly rescaled to 1080p for display, the image will knock the socks off 1080i. Interlace is archaic and it cannot be further condoned. And the temporal refresh rate has been ignored too long: it must be higher than 30 frames per second. And where did you hear that ABC was departing from 720p? It doesn't make sense ABC going from a higher overall resolution of 720p down to 1080i? Unless it is to overcome the poor engineering practises of many current broadcasters. Last edited by Penthode; 12-14-2012 at 09:57 AM. |
#10
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ABC in a few areas are in fact in 1080i now. For example, in Boston it's 1080i now, and has been for the past couple years.
In my area, it's reported as 720p, but I'll need to double check to see what I'm actually receiving. |
Audiokarma |
#11
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The important thing to remember is that today's commercialization of video media is through multi-platform delivery. This means the content must at some point be rescaled to another format. Interlace is totally irrelevant and is detrimental to the new world of multi-platform delivery. |
#12
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Not sure what latest ABC policy is re-720 but my set indicates local affiliate has switched to 1080.
They must think 1080 looks better for local news & commercials or it could be expedient for equipment standardization. But since 1080i/60 PsF = 1080/30p (not bad) (no intra-frame motion smear) I think 720/60p is in trouble |
#13
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But it is now late in the game. The broadcasters are now, after many years, entrenched in their formats. Only ABC affiliates are rescaling at emission. I think broadcasters will mostly remain as they are until the next big change to 1080p and beyond. |
#14
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And deriving 60p from same imaging chips (which would also send 30 PsF for 1080 - we hope) |
#15
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Just noticed this feature of latest studio camera:
"Newly developed 2/3-inch progressive CCD Newly developed LSI (16bits A/D) 3G transmission 1080/60p/50p, 1080i/720p and all Psf signal format" http://pro.sony.com/bbsc/ssr/cat-bro...duct-HDC2000W/ Cool, Psf, definitely the way to go Sony! Last edited by NewVista; 04-20-2014 at 09:58 AM. |
Audiokarma |
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