[zetski210]

OK, first of all you need to pull the data pins down to GND with 15k resistors. This will enable "charging mode".

Also, a standard PC USB port can supply up to 500mA (wich is the maximum for USB2.0), so 160mA is much lower and this is why is only shows 2/3 battery level.

My wall charger can supply 1A although the MP4 player should only pull 500mA and it should be current limited internally anyway so you won't be able to get it to pull, say, 5A!! However, I haven't actually measured how much mine pulls whilst charging, so I wouldn't recommend going above 1A.

Also, make sure that your charger is current limited and has plenty of protection to prevent a smoking MP4 player.

Also, for USB data, it is not standard logic levels (0, 1), rather a duplex, differential signalling method.