DVL-Digest 888 - Postings: Index - (2) Ghost in the machine True 16:9 DV - (2) DV or DVCAM? - "Perry" Ton posted: >I maybe wrong but I've always thought that the cassette size of the DVCPro line was different from DV/DVCAM.< The original DVC format proposals had 3 cassette sizes, let's call them 1,2,3. DV and DVCAM chose to use 1&3, DVCPRO chose to use 2&3. Decks that take more than one size move the hub carriers to fit, the actual reel sprocket is the same for all cassette sizes. It is relatively easy to accommodate 3 sizes if you can already accommodate 2. Nearly all pro decks now take all 3 sizes. Perry Mitchell Video Consultant http://www.perrybits.co.uk Ghost in the machine - "Perry" Christopher J. Bell asked about ghosts! If you shoot your 'ghost' against a dark background and then use After Effects 'transfer modes' then you will get precise control over the look. A simple way though, since you are locking off the shot, is to simply mix your ghost shot in situ with the empty room (you can use a still frame) until you get a suitable transparent effect. Then do a simple wipe between this mix and the other actor shot, with a soft edge to hide any slight lighting differences. Be careful of shadows and be prepared to make a custom wipe shape (i.e. a matte) if it doesn't split nicely. Perry Mitchell Video Consultant http://www.perrybits.co.uk True 16:9 DV - "Perry" Jeff Greenberg: CCD chips are actually analog devices (although with digital spatial sampling). The output is thus sampled in an A/D converter where the 'squashing' effectively occurs. There is thus no direct correlation between the number of pixels and the DV samples per line. The DV 16:9 mode could happily be supplied with a CCD with 720 rectangular pixels per line, but they are currently all dual mode so 960 is a minimum pro rata to allow full res 4:3. In practice more is better to allow for the losses in the optical anti-alias filter. Perry Mitchell Video Consultant http://www.perrybits.co.uk True 16:9 DV - "Perry" Jeff asked: >So exactly how is 16:9 info stored in the DV format? Or is there some kind of interpolation that is performed by the codecs to properly represent the 16:9 frame? How exactly, when using DV, is the 16:9 squished...< Normal 4:3 DV is 'squished' in PAL; 720 pixels in the DV code need to be stretched to 768 'square pixels' on the analog screen. This is done automatically in the D/A process. 16:9 just increases the squish so that the 720 pixels need to be stretched to 1024 'pixels'. The data is in fact not squished at all if it is read at the same rate as it was written, the 4:3 squishing is just an allusion to a relative square pixel model that doesn't exist. It only really means something when you take a square pixel digital file produced in say Photoshop and then transcode it to DV. Then you need to interpolate. 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] |
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