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Compare encoding methods

The A/B Compare mode helps you achieve the desired balance between file size and perceived video (and audio) quality. By using this feature, you can simultaneously compare the visual results of different profile settings applied to your videos and compare the final estimated file sizes of your videos, depending on the profile settings that you apply. By providing quick test renders of your media, A/B Compare encourages experimentation and helps you quickly decide on the ideal encoding method.

A/B Compare divides your video into two separate streams. Microsoft Expression Encoder displays the streams in one of four different modes: split screen, bands, side by side, or difference, with each segment or side representing a separate stream. You can choose and then use an encoding profile to match one of the streams. When you complete the encoding, you use the dual screen mode to visually compare one version of the stream with another.

Comparing video using split-screen mode, with the split positioned vertically

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Comparing video using bands mode, with the split positioned vertically

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Comparing video using side-by-side mode

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Comparing video using difference mode

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In split-screen mode, you can split the video either horizontally or vertically. The viewer pane displays the split video with a yellow line bisecting the frame. You can drag this yellow line to compare different-sized regions, or to directly compare the effect of two encoding methods on one subject in the image.

Bands mode is similar to split-screen mode, but has more than one divider. By placing the pointer over the divider and dragging the divider to the left or right, you can increase or decrease the number of divisions displayed in the video. You can also display the divisions either horizontally or vertically.

In side-by-side mode, the viewer displays full-screen images of your two streams.

Difference mode is similar to side-by-side mode, but shows the difference in grayscale. You can invert the color of the difference area by double-clicking the area. Difference mode displays the difference in quality as a contrast between black and white. For example, if you have two streams of the same quality, the difference will appear as black. If you have one stream that is the original, and another stream that is a much lower quality, the difference between the two encodings will appear as white on a black background.

When you play back your video, the viewer simultaneously plays back both streams of video, in sync, to allow for the most precise comparison. The video loops during playback. If there is any audio in your file, Expression Encoder plays back the encoded version.

To choose the video to compare, and to choose the compare mode, you use a combination of three menus, all located under the transport controls.

To compare different encoding methods, you first perform the test encodings, and then choose the versions to compare from the first two lists. For example, if you set the lists as they are in the previous graphic, on the left side of the Compare viewer, you will see the original, unencoded video, and, on the right side, you will see the encoded version which uses the first encoding profile that you chose. As designated in the third list, you see these two streams in split-screen mode. You can perform any number of successive test encodings and then subsequently compare any of the previous encodings with each other.

Another tool you can use in your comparison is the Total Bitrate and Estimated File Size values in the Profile category (Settings panel). As you choose encoded versions from the second list, these values change to show you the corresponding figures for your encoded version so that you can compare those parameters too.

If your mouse has a mouse wheel, you can also use the mouse to zoom in and out of the video. Click in the video and rotate the mouse wheel to zoom in and out. The position of the mouse determines the center of the zoom.

For longer videos, a scroll bar appears at the bottom of the video. You can use the mouse to scroll forward and back through the video by dragging the mouse.

To use A/B Compare to visually compare encoding methods

  1. In the Media Content panel, select the video that you want to use as a source.

  2. In the area underneath the transport controls, click the A/B Compare mode button, or, on the View menu, click A/B Compare.

  3. The compare view uses split-screen mode, with a vertical split. Double-click the yellow line to toggle it from vertical to horizontal. To view your video by using another mode, select the mode from the Compare Mode list.

  4. In the Profile category, select a profile from the Video or Audio lists.

  5. In the Viewer pane, click the section that reads "Click here to build preview" or, in the area underneath the transport controls, click the Build Preview button. By default, Expression Encoder encodes only a 3-second segment of your video. To encode a longer duration, or a different segment, drag the white bars in the Timeline.

  6. To compare more encoding methods, repeat steps 4 and 5. Use the first two menus underneath the transport controls to compare all the versions of your video.

  7. To clear the version list, in either of the two version lists, click Clear Versions.

  8. To exit A/B Compare mode, click Exit A/B compare mode.

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