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MPX Player

>I saw in your website you have also done mp3 player project, right?
>But unfortunately all the information there is in czech language only.

Yes, sorry but if I would have to translate entire my web I will spend manymany time on that. So I chose some parts that would be most interesting for foreign visitors and translate it.

Well, I try to resume the history of my MP3 player. A long time ago one of my fried built hardware MP3 player from a PC with built-in 9" CRT monitor in full-custom chassis. It was a great thing in times when there was no commercial MP3 player in the market (in our country).

So it was an inspiration to build my own hardware player. I also used classic PC motherboard and hardware but I wanted to replace CRT monitor with something cheaper and smaller so I used 16x2 character alphanumeric LCD display. The goal was to fit the player to classic Hi-Fi component dimensions of 430mm width.

For this purpose I bought a 430mm slim-line PC case with 2x5.25" and 1x3.5" bays. Due to small height I was unable to simply pull the cards into motherboard - I had to use an ISA "tree" adapter to mount the cards horizontally. I don't know if there is available similar thing for PCI but I found nothing for a months. So I chose ISA sound card SoundBlaster AWE 64 and some Trident VGA.

The mainboard is ABIT PH5 socket 7 model with AMD K5-133@120MHz CPU (later replaced by intel Pentium 166MHz) and 8MB RAM. The system is booted from an old 64MB 2,5" HDD or 3.5" FDD (this allows me to easy upgrade the software). MP3 player is aimed to play MP3 CD-ROMs so I didn't equip it with large HDD but it wouldn't be problem to upgrade it. In other hand I may use CF/IDE adapter and boot form CompactFlash card to make it little bit faster and more reliable. CD-ROMs are played by an old low-spin drive (Toshiba 4x which has died, later replaced by AZTech 8x) making very low noise. Fortunately there is a software utility CDSPEED 1.1 to slow-down modern high-speed noisy drives.

The software is quite simple. I use IBM PC-DOS2000 and great DOS opensource multimedia player MPXPlay made by cool Hungarian guys. I wanted to avoid use M$ Windows opposite my friend to make it more stable and less hardware hungry. So I'm proud to made it 100% M$ free ;). Of course, Linux solution would probably the best but I'm not a Linux guru.

When PC-DOS is booting it initialize the hardware and set up RAMDISK where DOS core and MPXPlay is copied. Then HDD is turned off for the rest of operation time. The boot-up process takes about 33s from turn on the player. To be able to control the player via small LCD display I programmed a resident driver (using timer interrupt) which takes some contents of text-mode video RAM and forward it to LCD display attached to parallel port. I can switch between few modes displaying song name, time, bitrate, bass/trebble settings, MPXPlay file browser, VU-meter and spectrum analyser. The spectrum analyser looks very cool, I reprogrammed user character generator of LCD controller to be able to render the 7 types of bars representing bands levels.

Controlling the player is done via special mini-keyboard which was made from standard keyboard electronic PCB with 10 user keys attached. This mini-keyboard is connected via switch to KBD-in connector on mainboard so I can select between internal/external keyboard. After a year I decided that would be good to have some IR remote control. So I made very simple bastle with SFH506-xx IR receiver on serial port. It is handled with DOSGir software which allowed me to learn codes from my Sony CD-Player IR remote and then emulate keystrokes to control MPXplay. I can also attach my Atari portfolio handheld to second serial port and redirect DOS console input/output to make some debugging on player.

I think that the most difficult thing was the mechanical design of the player. It may not be seen but I have to tweak many things to make it nesting all together and the result is not just perfect but who cares... I have been using this player since summer 2001 till now without several problems. I measured the real RMS power consumption is about 47W that is surely x-times lower than standard PC.

Currently this times it lose the point to build MP3 player at home when you can buy one very cheaply in wide market supply. But it was a great experience for me and I don't regret that spent time...




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Aktualizováno 12.8.2005 v 01:49

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