To: DiViT who wrote (45045 ) 9/20/1999 5:09:00 PM From: John Rieman Respond to of 50808
Digital video on tape. Wouldn't it be nice if an encoder would take anything you could feed it? VTRs..............tvbroadcast.com Where's My Bit Bucket? I Want A Picture Recorder That Will Record Anything I Feed It By C. Park Seward (September 17) So, what type of videotape recorder will you buy today? Pretend you are a television station making the transition to digital. You know you don't want to buy an analog VTR. That's a good thing since no manufacturer is promoting analog VTRs today. Why buy analog? You may want to buy one to remain compatible with tapes in the library since you can't dub all those tapes to a new format very easily. Hollywood has an excellent archive medium: film. But do we really expect to playback those original 3/4-inch U-Matic tapes? I hope not. When you get your new digital VTRs, please dub what you want to save. In fact, when you are producing your millennium program (isn't everyone going to produce a century-ending millennium program?), make sure you make a digital dub of all the elements you use in the making of that program. Your grandchildren will thank you for it in 2100. Wouldn't it be nice to buy a bit bucket? A recorder that would record anything you plugged into it? Feed it composite, component, NTSC, PAL and it would take it happily. Tomorrow, feed it HD and it would not miss a beat. Only one company has come close to that holy grail so far with a VTR scheduled for sale next summer. That's Panasonic with its AJ-HD3000 D-5 HD VTR that will also record 525 component digital signals. That's full bandwidth, 10-bit 4:2:2, uncompressed ITU-601 recording and playback, plus full bandwidth, 10-bit 4:2:2, HDTV recording and playback utilizing low compression ratio, 235Mbps I-frame only compression. A single AJ-HD3000 can support multiple high definition video formats including 1080 line progressive, 1080 interlace and 720 progressive, and various frame rates including 60i, 50i, 60p, 25p and 24p. One important point to remember is the Panasonic VTR records the full bandwidth of the HD signal; out to 30 MHz Y channel. The Sony HDCAM VTR rolls the signal off, only recording out to 22.5 MHz To the human eye watching existing monitors, the actual picture sharpness of both decks looks very similar. In fact, I saw a demo last year at the ITS Technical Retreat that showed how a picture could be improved by recording less resolution like the HDCAM. By taking a video picture with noise in it, Sony showed a better image by rolling off the high end. Since noise is the enemy of compression, the full bandwidth image showed blocky artifacts when compressed. By getting rid of the high frequency noise before compression, a better image was shown without noticeable compression artifacts. It's like turning down the treble when listening to a noisy source. It does reduce the noise. It does, however, get rid of some of the picture. If the HDCAM image is good enough for your needs, you may want to take a look at the DVCPRO HD100 VTR. Here, Panasonic uses the same type of trick as Sony. Reduce the bandwidth of the signal before compressing so you don't have to compress as much. You can then fit a HD signal on a 6mm DVCPRO tape. Since I still shoot tape for a living, I'm a fan of the smallest and lightest deck possible. The size of the tape determines the size of the transport. If I have to run-and-gun on a hot summer day, I'll last longer with a lighter camera. The DVCPRO HD100 seems perfect for news. For EFP and commercials, you may want higher performance. Panasonic is also promising upconversion of DVCPRO tape shot today. When you buy a DVCPRO HD deck, it will automatically output HD from a standard resolution tape. Remember, this signal will not be true HD sharpness, it will simply be upconverted. You can do that with any signal but it's nice to have that compatibility built-in the deck. Although Sony has shown backwards compatibility in Digital Betacam decks by playing analog Betacam tapes and Betacam SX by playing analog and digital Betacam, they haven't yet announced the same backward compatibility through HDCAM. I'll give you a possible reason why. Sony was the first out with a new HD machine. It was based on the Digital Betacam transport. They wanted to lower the cost of HD and get a machine and camcorder out to market. They succeeded. Panasonic took a longer time to market and added more features. It will be interesting to see what Sony will do during the next development cycle they have already started. Will the HDCAM II be MPEG based and offer other Betacam format playback? It would be within Sony's capabilities. Do you want uncompressed HD? You may can find some old Sony HDD-1000 VTRs, a HD built from a 1-inch transport. The reel-to-reel machine had eight audio channels and an hour of tape cost $1,000. Philips showed the Voodoo at NAB '99 and again at the recent ITS Forum in NYC, a D-6 VTR with uncompressed HD video and 12 audio channels. You've got to appreciate the performance of these uncompressed HD VTRs. The compressed HDCAM records 140 Mbps, the Panasonic D-5 HD, 288 Mbps. The uncompressed HD signal is 1.5 GBps. Which to buy? Your choice. A station may choose one in-house format. A serious post company will probably have to buy at least one of each.