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MillimeterKnow Your Formats, Part 2
Apr 28, 2008 12:00 AM, By Jan Ozer
Panasonic released the AVC-Intra-based Varicam 3700, the AJ-HPX3700, at NAB this month.
The lack of absolutes is also evident in the debates regarding the virtues of Panasonic’s DVCPRO HD and Sony’s XDCAM HD. I thought Panasonic used I-frame only MPEG-2 in its high-definition DVCPRO format, but here’s what a Panasonic white paper had to say:
In essence, DVCPRO HD uses the same compression technology as DV at data rates of up to 100Mbps, according to the same white paper. In contrast, according to Sony’s white paper, XDCAM HD uses long-GOP MPEG-2 at up to 35Mbps. (In February, Sony announced a new implementation of XDCAM HD, which employs 4:2:2 long-GOP MPEG-2 at 50Mbps. This technology makes its debut in the PDW-700 camcorder, available this month.)
Panasonic proponents argue that long-GOP formats can’t deliver the quality of their DCT-based algorithm, and are much less responsive during editing. Shooters drinking the Sony Kool-Aid argue that long-GOP MPEG-2 is so much more efficient than I-frame-only DCT that it delivers the same or better quality at one-third the data rate, and that today’s multicore computers are easily sufficiently powerful to work edit responsively with MPEG-2 (and if you need more speed, use an intermediate format). They also criticize DVCPRO HD for requiring three times the storage space, which is a particular issue for camcorders capturing to solid-state memory.
Who’s right? I dunno; the video produced by both camcorders looks wonderful to me. The point of this newsletter is to define the terms and identify talking points, not pick a winner.
That said, looking back at NAB, it’s tough not to get excited about the AVC-Intra based camcorders that Panasonic showed, with full-raster high-definition recording—1920x1080 pixels for a 1920x1080 display image, and the more efficient AVC codec replacing DCT. It’s also not hard to see the ultimate (although not imminent) demise of HDV, which doesn’t have the resolution, codec, or data rate to compete in the long term.
