DVL-Digest 873 - Postings: Index DV Raptor Codec DVCAM vs miniDV Quicktime (was Apple looking for speed?) DV Raptor Codec - Adam Wilt So I'd appreciate hearing from anyone who's been > working with this codec. Any assessment of it would be > appreciated; the more specific the better. The Canopus software codec is one of the two best codecs I've found on the PC platform, tied with Matrox. In 5-generation tests it holds more detail, more accurately, with less artifacting, than any other codec I've seen other than Matrox (software, PC) and QT 4.1.3/5.X (Mac only). There are some minor differences between it and Matrox and QT, but it's been a few months since I did the tests and I don't have the test results handy at the moment. And as my tests were done with Premiere in RGB mode (Canopus runs in YUV mode in RaptorEdit; don't know what Avid is going) some of the minor differences might be due to YUV/RGB conversions. Cheers, Adam Wilt DVCAM vs miniDV - Adam Wilt I had already looked at this pdf. There is only mention of the 15 micron > track size, I found no published specs describing head size anywhere. I have had multiple Sony engineers tell me that the current DVCAM head *is* 15 microns, and Perry has the photomicrographs to prove it. > With DV the track size in SP is 10 microns and in LP it is 6.7 microns. > This leads me to believe that the same head produces a different tack > size due to the speed of the tape, because in LP a dv tape travels slower. That's correct: there's a 33% overlap of one track with the next in LP mode (as I believe the is recording DV Sp with a DVCAM head). However, as has been mentioned before, azimuth differences between the two heads prevents significant crosstalk between the signals, and playback recovery is excellent. > If the theory that hacking a DV camera into DVCAM records a skinny 66% > track there should be a very significant increase in data errors and > drop outs. This has not been the case in my tests. As long as the CNR (carrier to noise ratio) is well above the level where ones are mistaken for zeros and vice versa you will not see any appreciable change -- the so-called "cliff effect" of the sudden onset of errors in digital recording. If anything the DV-width track on a DVCAM pitch would perform as well as or slightly better than DV-width heads recording DV (same track width gives same susceptibility to minor dropout "hits"; wider track pitch slightly increases tolerances for tracking). All the DV formats have CNRs well above the level where the cliff effect sets in so a very considerable drop in signal level is required before errors creep in to any noticeable degree. Cheers, Adam Wilt Quicktime (was Apple looking for speed?) - Adam Wilt Um... Kevin, what OSes other than Apple's and WinTel does Apple > provide or license a QT decored or encoder for? It's a published standard anyone can licence and write to. At Omneon we are using QT as the fundamental file format for our video servers, with DV, D-7, DV50, MPEG-2, HDCAM, and uncompressed media, and it's running on our multiprocessor StrongARM / i960 embedded systems. In our case we're using hardware codecs and just had to write QT wrappers around them, but our files are readable and displayable by PC and Mac versions of QT as long as they have codecs for the media contained therein (easy with DV, not so common yet with HDCAM!). Cheers, Adam Wilt (diese posts stammen von der DV-L Mailingliste - THX to Adam Wilt and Perry Mitchell :-) [up] |
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