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MillimeterIntegrating DV Source Footage into HDV Projects, Part 1
Dec 10, 2007 12:00 PM, By Jan Ozer
Figure 1: Know our pixel aspect ratio. From Digital Anarchy's ReSizer 2 plug-in.
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First, let’s talk resolution and pixel aspect ratio. Typically, you’ll need to know both for your source and target format. Resolution is the simpler of the two, simply the number of pixels in the frame, which is 720x480 for 4:3 DV, 720x480 for 16:9 DV and 1440x1080 for Sony's and Canon's implementations of HDV. (JVC's version of HDV, which we won't be discussing, has a resolution of 1280x720 and an obvious 16:9 aspect ratio.) Intuitively, these numbers look wrong, since 4:3 and 16:9 DV can’t possibly share the same number of pixels, and 1440x1080 obviously doesn’t produce the 16:9 display we love on our widescreen HDV TVs.
Well, actually, they are correct. The difference is the pixel aspect ratio of each of the formats. As you can see in Figure 1, 4:3 D1/DV NTSC has a pixel aspect ratio of .9, which tells the TV (and the video editing software program) to squeeze each horizontal pixel by about 10 percent before display, producing the 4:3 display aspect ratio. D1/DV NTSC Widescreen 16:9 has a pixel aspect ratio of 1.2, which tells the display device or program to expand each horizontal pixel by 20 percent during display.
Finally, HD Anamorphic 1080, which includes HDV, has a pixel aspect ratio of 1.333, which neatly expands the 1440 horizontal pixels to 1920, with 1080 vertical pixels, producing the lovely 16:9 aspect ratio that we all know and love.
Figure 2. If your video looks stretched or smushed in Adobe Premiere Pro, hunt for the Interpret Footage dialog.
Click here for a larger image
You’ll know you have aspect ratio issues if your video looks stretched or smushed on screen. Typically, the easiest way to correct these errors is in the Interpret Footage screen (Premiere Pro, Figure 2) or Item Properties screen (Final Cut Pro), both of which you access by right clicking the video clips in the Project window or timeline.
Otherwise, you’ll have review your Project Settings (Premiere Pro) or Sequence Settings (Final Cut Pro) to see if these are correct. Finally, if the video looks correct in your editor, but the output is hosed, the issue is likely in your final output settings.
