12. Tests

File Compatibility

In order to get an idea on the types of media that will play on the z556, I tested a variety of media types with the results summarized in Tables 4 - 6. After installing a DivX codec, OGG audio software and the latest version of Quicktime, I was able to play all of the formats shown except for 1080p Quicktime files, which would start to stutter about half way through playback.

Record / Playback Multitasking

I ran the z556 through a series of tests performing different combinations of recording, watching, time shifting and encoding to see if I could get the resulting recorded programs to jitter or freeze up. Table 7 summarizes the results and shows that I managed to reach the z556's limits in the last test. I should note that during the testing, I didn't see any problems when watching live TV.

The other observation of note is that anything that involved heavy CPU usage such as HD playback and video encoding made the CPU fan spin up ... usually quite loudly. For tests involving only TV recording and viewing, the fan stayed at a reasonable noise level.

Figure 24 provides a snapshot of the CPU load during one of the busier tests and Figure 25 shows CPU load during the one test that produced a corrupted recording. Whatever the problem was that caused the file corruption, it doesn't appear to be CPU-load related.

Figure 24: CPU Usage for two simultaneous SD and 1 HD recording while watching an Xvid SD video

Figure 25: CPU Usage for 2 simultaneous SD and 1 HD recording while watching HD recording in time shift mode