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MillimeterTest Drive: Affordable HD Formats, Part 2
Sep 22, 2008 12:00 PM, By Jan Ozer
Figure 3. Comparing the formats in interlaced mode.
Click here for a larger image
As before, I used presets in Carbon Coder to produce the four files in the three formats, then loaded them into Premiere Pro for snapshots. After testing about four different clips, the nickel dropped, and I reached the rather obvious conclusion that all three formats at the format specific data rates were very artifact-resistant; otherwise, the vendors wouldn’t have used them.
To put this quality in a bit of perspective, at 24Mbps and 1920x1080 resolution, AVCHD devotes about .385 bits of data per pixel. By comparison, a 720p streaming file encoded with the same H.264 codec might have a data rate of 2Mbps, which is .0723 bits per pixel. This is a long way of saying that not only are the compression technologies used in these formats very advanced, the data rates are very generous compared to other common uses. That’s why these cameras produce such stunning (and affordable) HD quality.
The clip that showed the most obvious quality difference was an underwater clip shot by Kenneth Corben. Here, after zooming each clip to 300 percent and comparing them side-by-side, HDV showed the most macro-blocks and mosquitoes surrounding the moving objects, but these really wasn’t obvious at full frame playback. DVCPRO HD was the most block-resistant of the three formats, showing the least artifacts.
Figure 4. The Red One’s depth of field makes compression a snap.
Click here for a larger image
Along the way, I also noted that the depth-of-field performance of the Red One should make it a dream for shooting for streaming. For example, Figure 4 shows the milk girls clip that I downloaded from the Red website. Even at 5Mbps, about 20 percent the data rate of AVCHD, the clip was virtually artifact free because so little of the image was in focus. Now that I know that the workflow isn’t horrendous, it might be time to start begging for a Red camera for testing for this purpose.
Anyway, back to our format comparison. By this point, I had reached the conclusion that DVCPRO HD offered slightly higher quality than AVCHD and HDV, though at four times the data rate, it obviously comes with its own set of storage related issues. Still, this conclusion helped shift the focus to a two-horse race between full resolution AVCHD and HDV.
