DVL-Digest 1506 - Postings: Index - (6) What are the true DV specs? - "Perry Mitchell" From: Vidiot Perry posted: >It is truly a miscommunication. I am not saying that the recorder provides >any active digital blanking, I AM saying that the recorder should never >record more than approx 712 active pixels from a NTSC-legal analog source. >Your first example simply proves that: >1) Fox are using a digitally generated test frame >2) It was created by somebody who doesn't understand what is happening! >(witness 4:3 markers) >3) Neither your receiver or the DSR-20/11 have any analog blanking and can >thus receive/record/play illegal width NTSC signals. Now you really have me confused. I wish I would have looked at the analog output of the receiver when the 4:3 test pattern was being used. But I had to get ready to record a feed on a different transponder. OK, let's reword this a little. Each video line, be it NTSC or PAL, has a horizontal sync pulse. We'll use the leading edge of that pulse as our reference starting point. After the end, or trailing edge, of the pulse, we have the back porch, which contain the color burst signal. A little bit after that starts setup (for NTSC). According to the spec, from sync start, to setp is 9.4 usec (+/- 0.1). Then we have the video, until we hit the front porch, which is 1.5 usec before sync (+/- 0.1). Total time, about 10.9 usec (+/- 0.2). Of the 63.6 usec line, that leaves 52.7 usec containing video that has setup. Are you saying that that the 712 pixel sampling is only of that 52.7 usec and the remaining 8 pixels are sample before and after that area (or about 4 pixels before and 4 pixels after)? I'm saying that all 720 pixels are sampling the 52,7 usec, as shown by the 20th Century Fox 4:3 test pattern, since all 720 pixels had live video. I wish I had a book that had the NTSC spec in it, with the DV sampling spec rules, i.e., at what point in time after the start of the horizontal sync pulse the first pixel is sampled and at what point in time the 720th pixel is sampled. It would be so much easier for this discussion if I had a copy of that. Does it exist somewhere? Would it be in the service manual for the DSR-20? (diese posts stammen von der DV-L Mailingliste - THX to Adam Wilt and Perry Mitchell :-) [up] |
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