Streaming Media - December 2007/January 2008 - (Page 70) express yourself Figure 7. Your A/B Compare views At a complexity setting of zero, the file took 39 seconds to encode, which jumped to 3:40 at a setting of five. When I compared the files, I definitely noticed better quality on the clip encoded at a setting of five. Unless you’re timeconstrained, you should consider running all encoding runs at a complexity setting of five. Figure 8. Here I’m converting 16:9 video into a 4:3 display and overlaying the Streaming Media logo over local banjo legend Stevie Barr, interviewed at the fabulous Rex Theater. A/B Compare Then it struck me: Rather than encoding separate files, why not try Expression Encoder’s A/B Compare to perform the same analysis? This mode is shown in Figure 6, with the key controls shown atop the Media Content Panel and on the player timeline and scrubber controls. The theory is simple—you want to compare multiple encoding parameters before finalizing encoding parameters. So you choose your first set of parameters, then enter A/B Compare Mode by clicking the eponymous button. Then you drag the green markers in the timeline panel to the frames you’d like to compare, and click the Build Preview button, which is grayed in Figure 6 because I’m currently previewing. After performing this action once, you have two items to compare: the original file and the encoded file, which has limited utility. However, if you change any encoding parameter, the Build Preview button becomes active, and you can click it to create another alternative to compare. Figure 7 shows the display alternatives. You can display the two videos sideby-side, as shown in Figure 6, or in a split screen view that works similarly to Apple’s Compressor. You choose which encoding alternative to display in each window (or on which side in the split screen display) with the A and B drop-down lists shown in Figure 7. How do you keep track of which alternative is which? The encoding properties for the encoding run shown on the right (in the B list box) appear in 70 STREAMING MEDIA December 2007/January 2008 Figure 9. Expression Encoder’s Metadata panel
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