9. Performance

In order to test the quality of the recordings and different styles of compression, I recorded seven minutes of the final round of the U.S. Open in 1080i high def. Then I compressed it in several of the available file formats offered by BTV. High definition files inevitably lose some of their detail when they are re-encoded into WMV-HD and DivX-HD formats. However, unless a direct comparison is being made, the differences are not very noticeable and the smaller file size is worth the sacrifice in quality.

Figures 11 - 13 were all encoded from the same OTA HD recording. The quality differences are much more pronounced when you click the image to view the full sized picture (Regarding the images with mismatched resolutions: It's important to keep in mind that the lower resolution has been stretched to match the higher resolution for the purposes of this comparison and the loss in quality will be more evident).

Figure 11: Original full quality HD screen capture (click image to enlarge)

In order to give you an idea about how the compressed files compare with the original high-definition video, I encoded with both DivX-HD and a WMV-HD at their highest settings and split the picture with the original HD file (I needed to stretch both of the compressed files from 1280x720 to 1920x1088 to match the resolution of the original file in order to keep the image intact).

In both comparisons, look at the pattern of the grass on the green, and the text on the scoreboard for clues to see the differences in quality of the files. To my eye, the WMV-HD high-quality format result in Figure 12 is very impressive!

Figure 12: WMV / HD comparison (click image to enlarge)

Figure 13 shows the DivX-HD encoding in its highest quality mode. Again, keep an eye on the scoreboard and the smudgy grass on the green. The highest-quality DivX file is not quite as nice looking as the WMV against the original high-definition file.

Figure 13: Divx / HD comparison (click image to enlarge)

But comparing the encode time and resulting file size of the WMV-HD and DivX-HD files might make it easier to choose an encoding format. The same seven minutes of HD video took 82 minutes to encode to a 378 MB WMV-HD high-quality file, but only 16 minutes to be compressed to a DivX-HD 199 MB file. So when you consider the five-fold reduction in encode time and roughly half the file size, you might change your mind as to which format you prefer!

There are several other compression options available within BTV, including standard-definition TV and portable video player formats. I also tested ShowSqueeze compressed files on both a pocket PC and an iRiver Portable Media Center and was pleased with the quality and file size with both.