Review: Anystream Agility

All that said, Windows Media encoding performance was excellent. Agility correctly assigned keyframes to all six checked scene changes, the first encoder I’ve tested to do so (Apple’s Compressor hit five of six, with several others at four of six). This helps ensure quality in videos with lots of scene changes. The average bitrate of our CBR-encoded file hovered around the 468Kbps target, with the worst spike a short one to 720Kbps during a high-motion skateboard jump scene. This translates to relatively smooth distribution via web or streaming server.

To assess quality directly, I compared frames and real-time playback with video produced by the Windows Media Encoder, which is the gold standard for Windows Media encoding. In terms of frame quality, Agility’s frames were either equal to or slightly better than those produced by the Windows Media Encoder, though the difference was minor, and not really noticeable during real-time playback. Still, since the Windows Media Encoder is theoretically as good as you can get, this was a great result.

H.264 Encoding
You produce H.264 files via Agility’s QuickTime encoder tab, which uses the standard QuickTime configuration screens that most producers already know. Agility also provides presets for the iPod, iPhone, Apple TV, and for MPEG-4 output. Agility proved very well-mannered during encoding, again hitting 100% of the keyframes (though this is hardly unique among H.264 encoders that I’ve tested), and producing a stream within 5% of our target on the first try, which is also nice. For the most part, the data rate hovered around the target, spiking to .94Mbps, compared to .73 for the Adobe Media Encoder and Apple Compressor, and .96Mbps for Grass Valley ProCoder.

There is no gold standard in the H.264 world, so I compared Agility to a range of systems, including Sorenson Squeeze 4.5.7, Grass Valley ProCoder 3, Telestream Episode 4.4.1, Adobe Media Encoder CS3, and Compressor 3.0.2 . All of the encoders performed well during low-motion scenes, but each had an Achilles’ Heel. Agility’s was encoding scenes with challenging backgrounds, like highly saturated reds and fine details.

For example, in a scene shot against wallpaper with a fine pattern, a definite no-no for streaming video. In the Compressor frame, the detail is crisper and more finely preserved, and the back wall is smoother. During real-time playback, the Compressor clip has noticeably less background noise than Agility. On a positive note, Agility maintained quality during high-motion sequences much more effectively than most other tools. Overall, most viewers wouldn’t notice the difference between Agility and other encoding tools without side-by-side comparisons, so the difference is commercially irrelevant.

Flash Encoding
Agility’s Flash encoding controls are basic and include single and 2-pass CBR and VBR, along with data rate, keyframe, and quality controls. Here, I compared encoding quality to that provided by On2 Flix Pro. While Agility held its own in most scenes, it proved noisier in images with compression-unfriendly backgrounds.

Again, these unfavorable results were specific to this scene, with the Agility clip roughly the same as Flix Pro in virtually all other scenes. Even in this one scene, most viewers wouldn’t notice the difference without side-by-side comparisons.

Server Farm Encoding
During the testing process, I wanted to incorporate another computer in my lab in the Agility rendering farm. To accomplish this, I logged into a special Anystream URL, which allowed an Anystream technician to take over my computer, access my network, install the necessary software, and get the encoding farm up and running. While I’m guessing that other vendors offer this type of remote service, it’s the first time I’ve been exposed to it, and it worked exceptionally well.

I also found the system very robust. For example, in one test, I encoded 18 files to four different formats each, adding both bumpers and trailers without a hitch. Overall I produced about 200 files without a crash on either Violet or the HP xw4600 Quad-Core system I included in the rendering farm. While there were failures, all related to incorrect input parameters or other user errors.

I get the feeling that my high-volume test was a walk in the park for the typical Agility system, which usually slaves away in CDNs, TV stations, and similar facilities that produce hundreds of videos a day, day in and day out. The term "industrial-strength" is probably overused, but it’s definitely appropriate when describing Anystream’s Agility Web encoder.