DVL-Digest 712 - Postings: Index (no) DVCAM playback in Sony DH 16:9 --> 4:3 - (2) 720P Seems like you built this IRE Level My personal thoughts on 16:9 - Playing DVCam tape in regular (no) DVCAM playback in Sony DH - "Perry" Albert Elings posted: >Today I ran into a strange problem. The DVCAM tapes (Sony 64 with chip) I got for editing only played at DV speed in my sony DHR-1000 DV recorder. Normally, it plays back DVCAM tapes fine, and when I tried tapes from older projects it still does. But not the new ones, only at the slow DV speed. Anyone has an idea how this is possible, and even better, how to solve this problem?< Not so strange Albert, it happens to me sometimes, although I have never had a DVCam tape that would never play. Sometimes it takes quite a few seconds before it recognises the correct speed. I don't think it is looking for the DVCAM data flag (which would be sensible) but it is just measuring the correct tracking of the recording which can be tricky. DVCam playback on consumer decks/camcorders has always been undocumented by Sony, so it is difficult to say how reliable it is supposed to be. Perry Mitchell Video Facilities http://www.perrybits.co.uk/ 16:9 --> 4:3 - Perry Mitchell Danny: A true dual mode CCD imager has about a 1000 pixels per 'line', but when in 4:3 mode the clock timing is changed so that in effect it only uses the centre 750 pixels. The output of the CCD is an analog signal which is then resampled at the processing clock frequency. Ideally this clock, and the subsequent DV clock, would be high enough to be irrelevant but in practice they become the limiting factor. You may well ask why then the CCD has so many pixels, and the answer is to do with the anti-alias optical filter. Perry Mitchell 16:9 --> 4:3 - "Perry" Danny posted: >I knew there was a reason 16:9 DV didn't do 4:3 gracefully - I'd already explored this before, but forgot. The limitation is not the camera head; the limitation is the signal/data as it is finally recorded to tape. In the absence of downconversion from greater data to less (HD to SD), there is no such thing as aspect ratio conversion without considerable degradation of image quality.< In UK the 16:9 images are typically ARC (Aspect Ratio Converted) to about 14:9 letterbox. In other words the 16:9 image is converted to 4:3 and blown up a little to lose some of the blanking and unfortunately a little of the image sides. This is deemed more acceptable to the viewers en masse. If a good quality ARC is used from somebody like Snell & Wilcox, the result is not too bad. I have done the same job using EditDV and it is a little soft but quite acceptable. I suspect After Effects would have done a better job but since I only needed it for the VHS copy I didn't worry too much. Of course, in PAL we have a little more resolution to play with, and even here I wouldn't want to go out to the full height 4:3. Perry Mitchell Video Facilities http://www.perrybits.co.uk/ 720P Seems like you built this - "Perry" We in Europe all feel a little remote from your discussion, but I'd love to know what poor old Enrico makes of it all! Come on Jan, own up which of your HD machines has a letterboxed NTSC output? :} Perry Mitchell Video Facilities http://www.perrybits.co.uk/ IRE Level - Adam Wilt ...there is a difference in black IRE level between the States and Japan by I don't really understand its function and whether I should be worried about it or not. Could someone please enlighten me on the subject of IRE Level and its implication for dubbing between Japanese NTSC standard decks and US NTSC standard decks. In the USA, we run black levels at 7.5 IRE, unlike the rest of the world. The purpose of this is to ensure a slight separation between the black that's displayed on the TV and the level of the blanked signal during horizontal and vertical retrace. Without this 7.5 IRE separation, early TV sets with poor DC restoration (that is, an inability to hold a constant brightness for a given input level over time) would be likely to show the retracing electron beam as a set of diagonal lines on the picture. With modern sets this is not a problem, and we in the USA could drop "pedestal" or "setup" back to 0 IRE (or 0mV in the PAL world) with impunity, but for all the analog programming with setup physically recorded in the signal and all the 1600 TV stations and innumerable post houses and indie producers set up to use setup (!). Most if not all DV camcorders and VCRs use the Japanese black level of 0 IRE. In DV, as in all digital component systems, setup is only a function of the analog circuitry and is not recorded as part of the digital signal. Digital dubs between two bits of DV equipment are not affected one way or the other. Cheers, Adam Wilt My personal thoughts on 16:9 - - "Perry" Steve: No you won't get a letterbox feed out of the TV, the aspect ratio change is done in the display side. Enrico: Get a good quality Aspect Ratio Converter (ARC). One perfectly good idea is to get a used broadcast DVE box, the early ones go for a song because they don't have all the latest 3D effects, but they will do a perfectly good job of ARC. It will be pretty big, probably composite video, but I bet it will produce a much better image than the output of a DSR-30. A friend of mine went to an auction early this year where one went for less than ! Look out for products from Ampex, Grass Valley, Abekas, and many others. Perry Mitchell Video Facilities http://www.perrybits.co.uk/ Playing DVCam tape in regular - "Perry" Kevin O'Hanlon posted: >I have footage recorded in DVCam which I'm playing on a VX-1000 (which plays only regular DV). I know it runs slow because of the faster tape running speed of DVCam but are there any other quality issues which would affect quality in this recording/playback scenario. I want to capture the DVCam footage to Final Cut Pro. Would it be possible to speed up the footage to compensate for DVCam slower speed and get back to the original running speed. Any thanks for any illumination would be gratefully received.< Kevin, the fact that the tape plays as well as it does is a witness to the ruggedness of the digital format. It is though, in effect, continuously mistracking and will be subject to lots of dropout. The VX1000 is the only Sony DV Camcorder or deck that doesn't play DVCam, so see if you can borrow something else from a friend and you'll be fine. Perry Mitchell Video Facilities http://www.perrybits.co.uk/ (diese posts stammen von der DV-L Mailingliste - THX to Adam Wilt and Perry Mitchell :-) [up] |
 slashCAM  News HD Camcorder database One-on-One Cam comparison About our tests About us |
|
|
