Compressor and QuickTime: About the displayed frame size of MPEG-2 video
Last Modified: October 04, 2008
Article: TA23436
Old Article: 302075
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Products Affected
Final Cut Pro, Final Cut Pro 5.X, QuickTime, DVD Studio Pro 4.0, Final Cut Studio, DVD Studio Pro, Compressor
The frame size you see reported for MPEG-2 video may not be accurate in all applications.
QuickTime has the ability to play back MPEG-2 content using the QuickTime MPEG-2 Playback Component, which is available as an add-on to QuickTime Player. This component is included with Apple DVD Studio Pro, Final Cut Pro, Motion, and Final Cut Studio.
Please note that the frame size reported by the MPEG-2 Playback Component represents the displayed size of the MPEG-2 video—not the actual pixels that comprise the video. This is due to the MPEG-2 format's use of non-square pixels.
The QuickTime MPEG-2 Playback Component displays MPEG-2 content in the correct geometrical proportions (4:3). For example, an NTSC MPEG-2 file for DVD-Video is commonly 720 pixels wide and 480 pixels tall. However, 720 x 480 is not equivalent to a 4:3 ratio. This is normal. In DVD playback, the software adjusts the geometry of the MPEG-2 video, scaling the image to the correct proportions.
The QuickTime MPEG-2 Playback Component will display a 720 x 480 MPEG-2 video as 640 x 480 to present the correct proportions. QuickTime Player (and some other applications that use QuickTime to display video) will report that the video is 640 x 480, but the actual pixel dimensions are still 720 x 480, conforming to the MPEG-2 specification for DVD-Video.
Similarly, PAL MPEG-2 video is displayed in the correct 4:3 aspect at a 720 x 540-pixel resolution, although the actual non-square pixels that comprise the video are really 720 x 576.
DVD Studio Pro (included with Final Cut Studio and available separately) can validate an MPEG-2 video file and reveal its actual dimensions. QuickTime Player, Final Cut Pro, and Compressor should not be used to validate an MPEG-2 video's frame size.
This document will be updated as more information becomes available.
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