Testing the New Windows Media Encoding Profiles

At least in the short term, you're going to have to roll up your sleeves to access, test, and use these new settings. Note that Ben Waggoner discussed these options in his tutorial "Using Windows Media Registry Keys"Another resource is the WMV9 PowerToy shown in Figure 2, which is available here. Designed by Alex Zambelli, who works on Microsoft's Windows Media team, this is essentially a GUI for making the requisite registry settings. Also on that site are more links to the new command-line script and accompanying documentation.

Figure 2 (below). Alex Zambelli of Microsoft’s Windows Media team designed this WMV9 PowerToy, which is essentially a GUI for making the requisite registry settings.

Figure 2

A quick glance at the PowerToy reveals an impressive number of well-organized options, plus some helpful presets on the top left. The problem I faced in writing this article was how to efficient identify the settings that would deliver optimum quality.

To accomplish this, I asked Waggoner to prepare a command-line script that he felt would optimize quality over a six-minute test file I had prepared for two codec studies that I had produced for StreamingMedia.com in 2006. As part of these studies, I had supplied the test file to Microsoft (as well as Apple, On2, and other included companies), so Waggoner was familiar with the content. He was also in the process of encoding multiple hours of footage for Microsoft's Silverlight announcement, and obviously very familiar with the encoding options. Fortunately, Waggoner was kind of enough to agree to prepare the batch files which I used as described below.

With batch files in hand, here were the specific questions I set out to answer.
1. Do the version 11 releases of the WMV 9 codec improve quality over the older versions. In essence, should you upgrade your encoding stations to the new codec (if you haven't already)?
2.If you upgrade to the new codec, should you encode using the Advanced Profile?
3.Would the options accessed via the command-line script improve the quality of the WMV files over a file produced using the default parameters? In essence, should you spend the time to learn and use these options?
4.Does encoding with the command line options improve Microsoft's performance vis a vis Flash and Apple's H.264 codec? In essence, does quality improve sufficiently that you should consider switching to WMV if you're not currently a user?
5.What techniques can you use to optimize the quality of your Windows Media files?

Should You Upgrade to the New Windows Media Video 9 Codec?
Here I compared a file I produced using Sorenson Squeeze back in January 2006, before installing the codec updates, with one I encoded using the same tool after installing the updates. To be specific, the codec version used in the original test clip was, and the Version 11 code was 11.0.5721.5145. (To derive this information, I analyzed the files in WMSnoop, from Sliq Media Technologies.)

In all tests reported here, I compared clips encoded at 640x480x30 fps, at a combined data rate of 500Kbps, with 468Kbps allocated to video, 32 Kbps to audio. Except where indicated, I encoded all files until they matched the target data rate within 5% using 2-pass constant bit rate encoding. To match the procedure used in the codec study, I encoded this test clip from the original DV source, while I encoded all other files from an intermediate file produced in Adobe After Effects using Algolith's AlgoSuite plug-in for scaling and deinterlacing (see sidebar, "How We Tested").

In comparing the files, I noticed two main differences. First, in some high-motion sequences, the new codec was slightly less blocky than the older (Figure 3). Second, in scenes with poorly designed backgrounds that displayed banding and similar compression artifacts, the new codec seemed less noisy. I saw no scenes where the older codec outperformed the newer codec. Don't expect the difference to be life-changing, but if you haven't upgraded already, you probably should now.

Figure 3 (below).In some high-motion sequences, the new codec was slightly less blocky than the older one.

Figure 3

Note that files producing using the updated Windows Media Video 9 Main Profile codec should play on both Macs and PCs with no codec update. However, if you use the new Windows Media Audio 10 Professional audio codec, your customers will require an update, so be careful there. If forcing your viewers to download updates before viewing your new files is a concern, you probably should update a computer other than your main encoding station to produce some test files to cycle into your distribution system.

Main vs. Advanced Profile
Once you update your codecs, you can produce files using either the Main Profile or Advanced Profile, either within the Windows Media Encoder or using the command line script. Unless you're currently producing via a command-line process or using the Windows Media Encoder, you'll probably have to change your workflow to produce files using the Advanced Profile. In addition, all target viewers-both PC and Mac-will have to upgrade their players to view the files. Is it worth it?

To test this, I compared two sets of files. The first were two files produced using the Windows Media Encoder, one using the Main Profile, the other using the Advanced Profile. Then I tweaked Waggoner's command line script, which originally produced files using the Advanced Profile, to produce a file using the Main Profile.

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