The Cobra Engine

One of the most anticipated feature of the All-in-Wonder 9700 Pro is its Cobra MPEG-2 engine, described on page four of our All-in-Wonder 9700 Pro preview. To briefly recap, the Cobra engine gives the R300 core in the All-in-Wonder 9700 Pro the ability to not only do hardware MPEG-2 decoding (for video playback) but also hardware MPEG-2 encoding (for video encoding). This makes the All -in-Wonder 9700 Pro the only TV tuner video card to offer some form of hardware encode, which can result in lower CPU utilization during MPEG-2 encoding processes. ATI claims that the Cobra engine can shift 10% to 20% of the MPEG-2 encode process into hardware, meaning that your CPU does not have to do as much work when encoding a file.

To test how the Cobra MPEG-2 engine aided in encoding of video, we compared the CPU utilization of the All-in-Wonder 9700 Pro in a variety of MPEG-2 encoding scenarios to the CPU utilization of the older All-in-Wonder 8500DV (without hardware MPEG-2 encode). For both cards we used Multimedia Center 8.0 (described later) with VideoSoap turned off (also described later in this review). The table below illustrates what we found.

AIW 9700 Pro (% CPU utilization)
AIW 8500 DV (% CPU utilization)
MPEG-2 (10M Bit/s max, 8M Bit/s target, 224K Bit/s audio)
MPEG-2 (8M Bit/s max, 6M Bit/s target, 224K Bit/s audio)
MPEG-2 (3M Bit/s max, 2M Bit/s target, 224K Bit/s audio)
MPEG-2 (2M Bit/s max, 1M Bit/s target, 224K Bit/s audio)

According to our tests, the Cobra MPEG-2 engine is working as advertised. On average, CPU utilization went down by 2.65% when using the hardware MPEG-2 encode functionality provided by the All-in-Wonder 9700 Pro. Remember, the Cobra engine is only able to offload about 10-20% of the total MPEG-2 encode process to hardware, so this 2.65% decrease in CPU utilization represents at maximum 20% off the total encoding process. We suspect that the amount of MPEG-2 encode functions being offloaded from the CPU to the video card are closer to the 10% mark than the 20% mark. This is because a 2.65% decrease in CPU utilization with hardware encoding suggests that MPEG-2 encoding process took a total of 26.5% of our CPU utilization. This is approximately what we observed, as CPU utilization hovered around 20-30% while watching TV and not encoding any video and jumped up to the numbers above when recording live TV to MPEG-2 format.

As you may have noticed, the system that we tested the All-in-Wonder 9700 Pro on is a fairly high-end one. The amount that the Cobra MPEG-2 engine will help during MPEG-2 encoding should go up by a reasonable amount on slower machines since the CPU will be doing comparatively more work. For example, if you were running a machine where MPEG-2 encoding takes up 85% of your CPU power, expect the hardware based encoding offered by the Cobra engine to reduce CPU utilization by approximately 4% or so.

Although the amount of CPU savings that the Cobra engine results in does not seem exceptional, the savings do have benefits other than just make it easier to multitask while encoding video. The cycles freed by the use of hardware MPEG-2 encoding also give the All-in-Wonder 9700 Pro the ability to apply filtering methods to a video stream while encoding. This feature is called VideoSoap.

Index VideoSoap
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