DVL-Digest 698 - Postings: Index DV for broadcast?? - (2) Multiple-screens sync'd up? progressive scan real DV time code Sony DCR-PC110E URGENT question DV for broadcast?? - Adam Wilt There's a story going around that when they were designing the case for > DV/DVCAM tape someone who had worked as a videographer said "Can you > imagine being out in the cold with gloves on and trying to stick a label > on one of those mini cassettes. The DVCAM tape cases were made larger. > I don't know if the story is true or not. I heard this at NAB '96 (?) being told by a Panasonic rep as the reason DVCPRO uses the "small" tape instead of the "mini" tape. When the Panny folks went around to the networks talking about making a fully professional DV-based format, they showed people the miniDV tape. One of the muckety-mucks at CBS (or CNN? I don't recall) took one look at it, walked out of the office, and returned carrying a pair of heavy winter gloves. "Here," he said to the Panny people, "put these on. Here's a Sharpie. Now label the cassette!" If the shooter can't hold and label the cassette in a NYC winter, the format wouldn't be practical -- hence the DVCPRO "small" cassette, about twice the size of the miniDV tape. The "standard" DV/DVCAM cassette was always a part of the Blue Book spec and was expected to be the home VCR tape, while the miniDV tape was designed for compact camcorders. Cheers, Adam Wilt DV for broadcast?? - "Perry" Jan Crittenden posted: >What I meant to say is that if the station has chosen a DV format 98% of the time it has been DVCPRO. Sheesh. How embarrassing.< To put this into context, until relatively recently Sony didn't promote DVCAM as a broadcast format, preferring to reserve it for 'Professional' use. This is a Sony euphemism for what used to be called 'Business & Industrial' use. What is interesting is that (certainly in UK) DVCAM and even consumer DV has picked up a fair amount of broadcast use despite this Sony stance. In more recent times Sony and JVC are creating a lot of broadcast interest with the 'DV format' true wide screen cameras (DSR-500 and GY-DV700) that will certainly raise the DV profile a lot. I believe Panasonic are struggling a little to bridge the gap between DVCPRO and consumer DV, and the format differences in PAL make this more difficult. Their decision to market professional DV equipment is very revealing! I also believe the 'real' battles for the News business (which is where most of those DVCPRO units are used) is yet to come with MPEG vs DV, and Tape vs Others. The relatively low cost of DVCPRO mean that it is probably amortised in as little as a year and format decisions can be made in a much shorter timescale than used to be the case. When we have 100% digital broadcasting, which could be as near as 5 years in UK, I would be surprised if tape survives for News. By that time I would also expect to see transmission of pictures back to base via the Internet and thus there will be pressure to minimise data rates; that probably means MPEG. (or at least some form of Inter-frame compression) just my two penn'orth! Perry Mitchell Video Facilities http://www.perrybits.co.uk/ Multiple-screens sync'd up? - Adam Wilt What experiences have you had with doing synchronized playback like this? > > I can imagine queuing several DV VTRs up to the same timecode, then > pressing plan on a remote that starts them all up. I can imagine more > expensive decks with timecode lock/chase capability. Someone even > recommended a computer-based solution. What say ye? If the show is short (around 10 minutes or less) and you don't need frame accuracy, then IR remote-triggered playback from any three DV VTRs or camcorders should work. If it's a longer show, use DSR-20s set for external sync (or 40s? I don't recall if 20s allow external sync). That'll prevent drift as all VTRs will be running in lockstep. Neither solution lends itself to unattended looping playback. For that, you'll need a multi-VTR controller that can stop at the end, rewind and reposition the tapes, and restart them in sync. Again, DSR-20s (40s?) will work. Of course you could move to a multi-stream-capable server like a Pinnacle Thunder, MediaStream, or Omneon VAN. All allow frame accurate, automatable playback of DV25 streams. But they aren't cheap. Using separate computers with 1394 cards is probably not a great idea as most of the 1394 ports I've seen run at widely varying speeds, with none running exactly at 29.97 fps (25 fps PAL). I would expect this setup to lose sync faster than 3 consumer camcorders sync-rolled! Cheers, Adam Wilt progressive scan - Perry Mitchell >Proper progressive scan utilizes all the elements, not half. Why would it use half? The only time you should lose vertical res in a progressive scan is when the manufacturer is "cheating" and really just tossing away a field and duplicating the other.< This argument rather forgets the 'real' world! Most folk don't have access to progressive recording, or except for their computer monitors even a progressive display. A DV camcorder will record interlaced pictures whatever the scan mode, and if they derive from a full vertical bandwidth progressive scan then the resultant 'twitter' will be unwatchable on a standard interlaced display. Anybody that has seen a computer 'desktop' placed on a video monitor will know what a mess this looks. The only current use for such pictures is to get the highest possible resolution for stills or for transfer to movie film. There will of course be progressive broadcast transmissions, and recording systems and displays to match, but we are not there yet. Incidentally, to answer John's exact question, all CCD chips perform a 'progressive scan'. The use of line pairing from the CCD neatly 'converts' to interlaced output and improves sensitivity and noise at the same time. real DV time code - "Perry" >and it does not help at all in keeping the time continuous if you >play forward into the striped area. It just makes the discontinuity >much harder to see. If the tape stretches a tiny bit between stripe >and record, there will be a gap/repetition of the timecode and you >are in the same soup. I couldn't let this one pass since it implies something which doesn't happen! Most DV recorders only have a single pair of heads and therefore only read timecode BEFORE they start recording. After this point there is not only possible tape differences, but simple tolerances of the deck mechanics and tolerances in video frequency that will cause the new recording to slip relative to any striping on the tape. It is an indication of DV's ability to play mistracking tape that the join at the 'out point' plays without a serious loss of pictures. Simple housekeeping, or (if you have to) tape striping, will ensure that timecode is sequential on the various 'takes' on a tape. Simple tape logging will ensure that the discontinuity doesn't get used as part of a wanted clip and therefore allow unattended Batch Capture. Perry Mitchell Video Facilities http://www.perrybits.co.uk/ Sony DCR-PC110E - "Perry" Lawrence Ho: The Sony DCR-PC110E is actually 3 cameras in one: 1)Stills camera recording to Memory Stick 2)MPEG movie camera recording to Memory Stick 3)DV movie camera recording to tape To interface all the options to your computer via a cable interconnect (as opposed to playing the Memory Stick in a reader) you need to connect to the computer via USB for the Memory Stick options, and via Firewire (iLink) for the DV options. Many Sony Vaio computers come with software called DVGate which allows DV capture, simple assembly, and record back to camera via the iLink connection. If you want to install a more 'serious' DV edit application then you may need to de-install DVGate. I haven't seen the Vaio model you mention, but you would need to check that this model's system can sustain the required data transfer rates to ensure no dropped frames for either capture or record. Perry Mitchell Video Facilities http://www.perrybits.co.uk/ URGENT question - Adam Wilt Remember back awhile when we are talking about CCD capture resolution -- > here are 3 questions:... I covered these in detail in the past few months of DV Magazine. These are reposted to the web (with a month or two of delay) at http://www.dv.com/howto/technicaldifficulties.html, with the most current at http://www.dv.com/magazine/2000/0900/wilt0900.html. The articles "Lookin' Sharp", "Chip Shots", and "Fields and Frames..." (and the next in the series, not yet on the web: "...Frames and Fields") should answer most of your questions. Cheers, AJW (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 |
|
|
