On the audio issue, has this been solved? I have a 16GB 3" touchscreen 2706 based player with a speaker. One of the player's annoyances is that with
sensitive earbuds, you can hear the display chirp like a ticker when it scrolls text, so I hoped that different firmware might improve the problem. (You can only hear the ticker when the display is lit.)
I installed some different firmware and the chirp went away. Also, the external speaker went away. I thought it was a good trade-off until I really listened to some songs, and realized they sounded like something in karaoke mode (which I think removes the similarities between channels, in an attempt to remove the vocals which tend to be spatially in the center of a stereo song), or like when my PC's audio drivers are misconfigured for a surround system, when I've actually only got two speakers.
Would it help to compare the two firmwares in a disassembler? If you knew where to look, it might be revealing.
I think what you're encountering is probably a feature, not a bug.
Is there a channel mixer somewhere in all the goodness? I think you can swap the left/right channels in "software", since there's an icon for it in my bmp0, but my player doesn't have that functionality.
I can compile the SDK to run on my player, but the buttons don't work, not to mention the touchscreen. It's not reading them at all, as it turns the backlight off and I can't wake it back up (I think this is what's happening, I suppose it could be crashing). The off-button doesn't even work, so I have to either reset it or plug in the USB to wake it back up.
I have this exact player:
Amazon.com: Pro Ebiz NEW 16gb 3" TFT Touchscreen Mp3 / Mp4 / Mp5 Player (Plays Avi/rm/rmvb/flv Without Conversion): Electronicss=electronics&qid=1255963455&sr=8-1
It's a nice player. I've had it opened and it has two visible Samsung chips but most of the electronics are covered by a large "Sony Fukushima Sew UP42367A6H" battery. The screen is an "AA003AH", which works with the FD5420 driver in the SDK. You have to change the backlight PWM frequency in hw_backlight.c, BL_Init() from 10000 to 15000 to keep the screen from giving an audible whine. I got the 15000 value from analyzing the original firmware.