Why the Tegra 2 sucks at video decoding

Recently several new Tegra 2 based Android tablets have been release by major manufacturers, such as the Motorola Xoom or the Eee pad transformer. Most of those manufacturers are claiming that their tablets have good multimedia capabilities and are proudly promising 1080P video decoding thanks to mojo from the Nvidia Tegra 2 chip. And in a way it makes sense: the Nvidia chipsets and video cards for PC are probably the best at decoding high definition H264 video. Most people purchasing these tablets to play high resolution video will probably be disappointed though because when you look at the specifications of the Tegra 2 platform you will notice that unlike its PC cousins the chip is unable to decode most 1080p H264 videos.

The issue is that there are actually several flavors of H264 videos. You have the Main profile that is relatively easy to decode and is used for things like Youtube and digital camera recordings. The Tegra 2 will have no problem with these. The other kind are the High profiles (yes there are several) that allow a much better compression vs quality ratio. This is used for most videos that you can actually download from the internet: Podcasts, fansubs, bittorent etc... There we have a problem: the Tegra 2 is incapable of decoding these videos in HD. What this means is that unless you are only using the video capabilities of your Tegra 2 tablet to watch Youtube, you will have to stick to lover definitions or transcode videos on your PC before watching them on the tablet, which defeats the point of having a tablet in the first place.

What is disturbing is that Nvidia "PC" chipsets such as the ION are perfectly capable of decoding High profile 1080p H264 video and that consumers purchasing Tegra 2 based tablets will likely expect the same level of functionality. It is only the next version of the Tegra chip (codenamed Kal-el) that will be able to decode HD video in a way similar to Nvidia ION chipsets a point that Nvidia should be much clearer about. If you want a tablet to watch HD, either purchase one with another chip or wait for Kal-el.