For MPEG-2 playback tests we ran The Matrix DVD, a personal favourite of mine on each system with hardware acceleration enabled to check for smoothness of playback as well as CPU usage during the test. The result was with 30 minutes of playback and the CPU utilization is the average.
Here both platforms are able to handle MPEG-2 playback using the same amount of CPU usage. It seems like MPEG-2 is no longer hard for a CPU to work with.
Playback for MPEG-4 was again done with the Matrix, only encoded down to an MPEG-4 DivX 6.8 codec. 30 minutes was the time run. Smoothness of playback, audio sync and CPU usage are the keys here once again.
MPEG-4 playback was less intense on the AMD CPU in both instances here. AMD really has more power to play with on its CPU.
HD 720p Playback
This is the big one for the platforms. We downloaded a random 720p video to test out using Media Player 11. Again, quality of video playback, audio sync and CPU usage are the big things to focus on here.
For our 720p playback results you can see the AMD CPU does a far better job here, keeping under 50% load both with and without discrete graphics. It's a lot smoother and you can still multi-task and open up web pages.
We decided to add another layer in our media playback and that is MP3 playback. If you're going to have a car PC it's usually to play movies and audio on, so it's fitting to add this to the list. A personal favorite of mine, War of the Worlds: the musical is played back and the CPU usage is recorded. Winamp is used to play back the audio.
MP3 playback performance across both systems is identical and it's clear MP3s are simply no challenge for today's CPU's.