I bought one of these cheapo media players a while back:
Of course the first thing I did was open it up to see what was inside! The case is pretty flimsy, but inside the build quality and layout of the PCB seemed quite good. Other than a couple 4558 op amps there are 5 major ICs on the board:
AXP189 - power management IC Analogix ANX9030 - HDMI xmitter Samsung K4H561638J - 256 MB DDR "CHIPHD HD986" - CPU/video decoding SoC, a large QFP
A "DFT01GR08P1PM0" - I couldn't identify this IC; it's a 32 pin Type II TSSOP. Flash memory maybe?
The user interface is poorly coded and I managed to find several nasty bugs in just a few minutes of playng around with it - if one pulls the USB stick out while a video is playing the player often hangs until the watchdog timer resets it. Similarly, if one opens a text file in its "Ebook" browser, switches to the onscreen options display, and removes the USB stick, the directory structure will not be updated in the main menu. Selecting the same text file again will also cause the player to hang.
I thought it might make an interesting exercise to attempt to exploit one of its flaws and get arbitrary code running on the device. Information on the "HD986" is hard to come by, but I think these media player SoCs are all similar designs and use an ARM core for their RTOS. There may be a firmware image for the device available online somewhere and it could be interesting to look at it with a disassembler. Any other advice?