DVL-Digest 784 - Postings: Index DV software codecs - (2) OT Weekend rambles OT PAL-NTSC-PAL Panasonic DV cams DV software codecs - "Perry" Walt posted: >You may have missed the first part of this thread. The discussion started with the practicality of adding a filter to a clip and rendering it out to a new clip. Next replace the old clip with the new one. Now add another filter and render a new clip and so on. I was suggesting that you apply all of your processing and just go through one render stage to eliminate any unnecessary passes through the codecs. No matter how many filters you apply this should minimize the loss to the point that a lossless editing system would not make a great difference since the starting point was DV25.< An interesting supposition that gets to the very heart of what happens with digital compression. The answer lies with what you do with the filter. If you take away information (e.g. blurring, noise reduction) then the compression is likely to be near transparent. If you add information (e.g. sharpening, increasing contrast) then there is likely to be more artefacts. Never the less, it MUST be beneficial to limit the number of codec passes to a minimum since there has never been one that ADDS wanted information! It is also true that the production process often calls for multi passes, and in my experience a good DV codec design will allow this with minimal extra signs of degradation. If a producer asked me to modify a final copy (eg reduce chroma level) then I wouldn't think twice about running it through an extra pass. I used to edit with BetacamSP, where for broadcast work 6 generations was common for the transmission copy and it was looking a little ragged. 10 or more generations were not unusual and it would look very worse for wear. In comparison, the extra losses with DV codec generations are very minimal. Digital Betacam (2:1 compression) can add hundreds of codec passes with no sign of extra losses at all. The best analogy I can think of is a grass mower. Digital compression lops off most of the information loss in the first pass, just like the mower lops the grass. Provided the grass doesn't grow, then any subsequent mower passes don't take off any more. Perry Mitchell Video Consultant http://www.perrybits.co.uk DV software codecs - "Perry" There are some familiar misconceptions arising, the truth is: Uncompressed video files are much quicker to process but obviously take longer to get on/off the hard drive and through the system. Realtime play of un-compressed video therefore still needs SCSI RAID arrays but a pretty ordinary processor. Realtime DV playing on the computer screen needs a very fast processor but these days most any IDE drive will cope. Swings and roundabouts! Perry Mitchell Video Consultant http://www.perrybits.co.uk OT Weekend rambles OT - "Perry" Kevin Marks: >>I started doing editing in a mobile truck with an Ampex 2inch machine. >>We once got stuck in snow for 4 days, but fortunately it was in a pub >>car park!!! >Yeah yeah, I edited 2-inch with a razor blade and iron filings to see >the sync pulses. >This is a bit like Mary Kenny's 'I entered the UK as a barefoot >immigrant from Ireland...' - she took of her shoes and stockings >before getting off the boat so that in later days she'd be able to >truthfully say exactly that. Quite the opposite Kevin! When I started editing, an Ampex VR2000 was worth about a in modern money. It occupied a whole air conditioned truck and we as operators were very proud of them. We did cut editing(it used a special guillotine, not a razor blade) because that was the only way then of doing any editing. I finished my BBC career doing location drama with big budget casts and crews ultimately relying on me pressing the right button! Truth was it was pretty mundane work, but then I expect brain surgery is too most of the time! It resembled a description I once heard of flying airliners - 10 hours of shear boredom surrounded by 10 seconds of near panic! I remember sitting next to a suited business gent chatting in BA Club Class, and telling him what I did and earned. He spluttered into his G&T that it was ridiculous that I got more than the Prime Minister!! Perry Mitchell Video Consultant http://www.perrybits.co.uk PAL-NTSC-PAL - "Perry" How could I ignore a chap with a fine name like Don Mitchell! I was going to offer him a special deal, but then I thought what the hell, I'll offer everybody on the list a special deal! If you post me a PAL tape, either DV, DVCAM, VHS, S-VHS, 8mm, Hi-8 or any sort of Betacam, then I will transfer it to NTSC DV (or DVCAM) for inc tape and return shipping. Only restriction is miniDV record tape for this price, but I'll extend it to cover longer programs and multiple reels pro rata. Broadcast-quality standards conversion and pro decks all round. Contact me off list for more details if you're interested or want to haggle. Perry Mitchell Video Consultant http://www.perrybits.co.uk Panasonic DV cams - "Perry" Dexter: Whatever they do with their 'own' DVCPRO format, DV is an 'open' published format and Panasonic would fit any products within the specification: In NTSC, DV records Y,U,V to a 4:1:1 color space. In PAL, DV records Y,U,V to a 4:2:0 color space. DVCPRO records Y,U,V to a 4:1:1 color space for both standards. Perry Mitchell Video Consultant 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 |
|
|
