Testing the New Windows Media Encoding Profiles
In the first set—those encoded via the Windows Media Encoder—I saw very little, if any, benefit, to the Advanced Profile over the Main Profile. Given the potential production hassle and required codec upgrade, I would not automatically choose the Advanced Profile when using the Windows Media Encoder.
Interestingly, with comparable files produced via the command line encoder, the Advanced Profile was noticeably better in many sequences. That's because, according to Waggoner, one of the critical options-DQuant mode, which helps limit blockiness on smooth or gradient backgrounds-works better in AP mode than in MP. For this reason, it appears that if you're going to tweak, you should use the AP codec.
Will Tweaking the Settings Deliver Improved Quality?
Preliminaries aside, let's get to where the rubber meets the road. Specifically, did Waggoner's batch file deliver improved quality over a file produced by the Windows Media Encoder? Here, I compared the files encoded using Waggoner's script to those produced by the Windows Media Encoder using the Windows Media Video 9 Advanced Profile codec.
The results were mostly very good, but there were some concerns. Starting with the positive, in low motion clips, background noise is often the most annoying artifact, especially if the background contains large, uncluttered spaces. This is shown in Figure 4, with the file produced by the Windows Media Encoder codec on the left, and the command-line file on the right.
Figure 4 (below).The file produced by Windows Media Encoder is on the left, and the command-line file is on the right. You’ll see that the command-line file produced better results.
As you can see, the wall and floor on the right are more homogenous, and the improvement are much more noticeable during real-time playback. In general, in low-motion sequences with spacious, uncluttered backgrounds, the tweaks contained in Waggoner's command-line script worked amazingly well. In most other instances of low- to even mid-motion, the script also produced less overall blockiness in the image.
On the other hand, when the going got particularly rough, quality could drop well below that provided by the default encoding profile. For example, on the right in Figure 5, the man is blocky and terribly distorted, while on the left, using the Windows Media Encoder, the man is reasonably smooth.
Figure 5 (below).The command-line encode (right) didn’t work as well as the Windows Media Encoder (left) in high-motion, cluttered-background sequences.
To a degree, this performance disparity makes perfect sense. Intuitively, we understand that there are certain encoding tweaks, like extending the search for interframe redundancies, that take more time but improve quality across the board. In contrast, other parameters may improve certain types of videos at the expense of another. For example, inserting additional I-Frames may improve high-motion videos but degrade low-motion videos.
What these results suggest is that if your video is relatively homogenous, like talking head training videos, or even primarily high-motion, like sports videos, you can derive parameters that improve quality across the board, and customization is well worth exploring. On the other hand, if your video is a mix of low and high motion, default settings may be the best option.
I didn't spend a lot of time analyzing the customizable parameters available for the new codecs, but some were obvious (like noise reduction) and some fairly opaque with technical definitions that don't suggest usage scenarios. Hopefully, between upcoming application support and additional guidance from Microsoft, these parameters will be tied to specific types of footage and specific problems.
For now, however, you're on your own. While I believe there is "gold in them thar hills" for Windows Media producers, you'll have to find it and mine it all by yourself. To help get you started, in the online version of this article, you can download the batch file used in these tests. Between that and the documentation available on the CitizenInsomniac site, you should be able to get a running start.
Let's summarize before going forward. The key points so far are as follows:
1. You should definitely obtain the latest WMV codecs for production.
2. There's little qualitative reason for using the Advanced Profile unless you intend to customize your encoding parameters, whether video command-line encoding or changing the Windows Registry.
3. Customizing your encoding parameters can produce substantially higher quality, but there probably isn't any one-size-fits-all script.