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MillimeterTest Drive: Affordable HD Formats, Part 2
Sep 22, 2008 12:00 PM, By Jan Ozer
Figure 1. Comparing frames from the encoded files with a frame from the original.
Click here for a larger image
Of course, I don’t get paid to postulate, I get paid to test and prove or disprove my theories. So here’s what I did. I dusted off my Canon Digital Rebel SLR camera, which shoots an 8-megapixel image. I then shot my standard resolution chart, DSC Labs' ChromaDuMonde, in raw mode. Then I imported the image into Adobe Photoshop, cropped and scaled the image down to 1920x1080, imported the frame into Adobe Premiere Pro, and produced a 10-second video, saving it using a lossless codec.
Next, I loaded the file into Rhozet Carbon Coder and rendered the file out into four different targets: AVCHD at 1440x1080i (14Mbps) and 1920x1080i (24Mbps); HDV at 1080i (25Mbps); and DVCPRO HD at 1280x1080 (100Mbps). Then I grabbed screens from each file and compared the quality (see Figure 1).
At the risk of sounding hyperbolic, I was shocked at how little difference I saw between the formats. Essentially, DVCPRO HD discarded 33 percent of the horizontal pixels during encoding, and then it was able to reconstitute the frames during decompression with just a hair less detail than full-resolution AVCHD. You’ll have to view the full-resolution image to see and believe it, but the difference between any of the formats was virtually imperceptible.
So scratch storage resolution as a source of format differentiation, and let’s turn to comparing the effectiveness of the compression technique used by the respective formats. Here, while the single frame of the ChromaDuMonde chart performed admirably for the resolution tests, I needed a source for the compression-related tests.
