[ale] Report on vehicle MP3 Player

[Gonzo]

yeah but 64 Megabytes is not much space at all. You 
might as well get a regular CD player for that price.
 
- Luis
'gonzo'
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  ----- Original Message ----- 
  <DIV 
  style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black">From: 
  Chris 
  Fowler 
  To: <A title=byron at cc.gatech.edu 
  href="mailto:'byron at cc.gatech.edu'">'byron at cc.gatech.edu' ; <A 
  title=ale at ale.org href="mailto:ale at ale.org">ale at ale.org 
  Sent: Monday, November 20, 2000 12:04 
  PM
  Subject: RE: [ale] Report on vehicle MP3 
  Player
  
  At COMDEX 2000 I saw a device that was shaped like a cassette 
  tape.  It has 64 MB or memory and could play MP3s through headphones with 
  control buttons on the side.  The headphones could be unpluged and then 
  the cassette tape device could be inserted into a tape deck of any 
  stereo.  This unit retails for $200
  Chris 
  -----Original Message----- From: <A 
  href="mailto:byron at cc.gatech.edu">byron at cc.gatech.edu [<A 
  href="mailto:byron at cc.gatech.edu">mailto:byron at cc.gatech.edu] 
  Sent: Monday, November 20, 2000 11:56 AM <FONT 
  size=2>To: ale at ale.org Subject: [ale] Report on 
  vehicle MP3 Player 
  Over the last year or so I've been piecing together a MP3 
  player for use in my car. This weekend I finally 
  fielded a working prototype. I thought the list might 
  be interested in the setup, results, and whatnot. 
  Hardware Setup -------------- 
  The box has two primary goals: Carry all my music and carry 
  it cheap. To accomplish the cheap aspect I fielded the 
  box with only off the shelf components: 
  - AMD K6/2 350Mhz CPU - PCChips M571 
  all in one baby AT MB with SIS video and CMI 8330 audio <FONT 
  size=2>- Western Digital 8.4GB disk - 64MB 
  SDRAM 
  This setup has been sitting in a normal case and functioning 
  as an office MP3 player for awhile now. But a 
  scheduled trip to Savannah prompted the move to making 
  it portable. This is a case/PS issue. 
  For the power supply I bought an Aztec laptop DC/DC converter 
  from Marlon P. Jones and Associates (www.mpja.com). 
  It's a 43 watt unit that generates all the PC 
  voltages, power good, and even a -26V reference for driving LCD 
  contrast all from a 12-20V DC source. The cost is $14.95. The 
  AT power supply cables were built by cutting off an 
  internal flat ribbon cable from a parallel power 
  connector and hooking it to AT power and disk power connectors 
  cut from an abandoned PC power supply. 
  Scrounging up a case is always a task. I settled on a plastic 
  organization case from the Home Depot. Dimensions 
  approximately 14x9x2.5. This case had removable 
  buckets and was deep enough to handle the CPU fan and RAM sticking 
  up from the MB. The clear plastic lid and easily drillable 
  plastic sides sealed the deal. $14.95. 
  I mounted the HD and MB on the case using 1 inch standoffs. 
  The power supply takes standard 4/40 screws and is 
  mounted to the side of the case. I settled on but not 
  yet installed a 1/4" mono plug for a power connector and an 1/8" 
  plug for the power supply switch connector. Right now the 
  power switch is a standard light switch in a shallow 
  box mounted to the underside lid of my truck 
  console. 
  The unit is interfaced to the car stereo via a CD to tape 
  adapter. RatShack $21.95. Pricey but this unit had the 
  correct functionality so that my auto sensing 
  auto-reversing tape desk didn't kick it out upon insertion. 
  The machine is located under one of the back seats and is 
  powered from the 12V power socket. 
  Note that currently the machine has no external user 
  interfaces. More on that later. 
  Software Setup -------------- 
  KISS. The machine has a standard Slackware 7.0 installation 
  and plays MP3s using mpg123. The CMI8330 requires the 
  ALSA sound drivers. I find that ALSA isn't too 
  difficult as long as you load and use the oss and oss_mixer modules. 
  Experimentation with the 8330 chip has shown that it just 
  doesn't operate too well at 44100 Khz. So currently 
  the machine outputs sound at 22 Khz. 
  The play currently operates in jukebox format. It has a 
  continous play script that will scan all the mp3s in 
  the /mp3 partition, randomize them, then play the 
  random list. At last count there were over 500 pieces taking <FONT 
  size=2>nearly 30 hours to play. 
  Results ------- <FONT 
  size=2>It nearly meets expectations. Basically I turn the machine on, and 
  select the tape player on the truck. It selects songs 
  and plays them. Much of the music that I own, 
  including several CD's that are missing, cracked, or scratched 
  are now available in the car. And with the handy carrying 
  handle, hole for the KB, and flippabil lid, the unit 
  is transportable enough to bring into the office, drop 
  in a network card, and upload/play music outside the truck. 
  Next Steps ---------- <FONT 
  size=2>There are a few items I'm disappointed with. First and foremost is 
  simple sound quality. Between the 8330 sound chip and 
  CD/tape interface there are hiss and balance problems. 
  At some point I'll need to search for a better onboard 
  sound card and also investigate the use of a stereo FM transmitter. 
  I tried a $30 transmitter from the RatShack but the 
  performance was horrible. I may investigate getting a 
  FM10A kit from Ramsey Electronics and see if it does 
  any better. 
  The second problem is getting the unit on and off. Modern 
  vehicles simply do not have any simple accessory 
  interfaces. The power sockets are on all the time and 
  power connectors for the radio and whatnot are inaccessible. It looks 
  like I'll end up intercepting a fuse connection from the 
  fusebox and using it to signal the system when the 
  truck is on/off. A secondary issue is that electronics 
  lose power when the engine is turning over. Eventually I'll need 
  to add a battery to act as a UPS when the truck is 
  starting. 
  Software wise there are a few directions to go. First is 
  coupled with the power issue above. A machine fscking 
  the disk each boot isn't real cool. I've taken a look 
  a powerd and I think it'll help. The other idea is to have <FONT 
  size=2>basically all the the filesystems read-only or ramdisk based so that 
  power off has to effect upon the system. 
  Also the jukebox format is interesting. You come across 
  interesting stuff when you just play randomly.  
  However some measure of control is required: 
  1) All CDs do not rip at the same level of volume. Instead of 
  trying to autocorrect I think I'll just KISS and 
  simply drop a mixer volume setting in the directory 
  with the MP3 for an album because each album is in its own <FONT 
  size=2>directory. So before each song I'll reset the mixer volume. 
  2) There needs to be a couple of useful selection mechanisms. 
  One is switching from random to directed mode for the 
  artist, album, or genre so that when a song for a 
  particular category pops up, you can switch to just that artist. 
  3) Unfortunately I'm not the only listener ;-) . So having 
  both categories on a per person basis, and the ability 
  to build adhoc categories like 30% of my stuff, 50% of 
  the kids stuff, and 20% random. Also have 'hate em' picks so <FONT 
  size=2>that a group of folks can pick a consesus of tunes to listen to while 
  rejecting music that makes one of the group wretch 
  violently. 
  4) I need to add permanancy to the random list selection. 
  Currently the box regenerates the list each boot. 
  However with 30+ hours of music (and I'm ripping 9 
  more CDs even as we speak) it'll never all get heard in a single 
  session. It would be better to play an entire session though 
  carrying over between reboots. So then it'll be no 
  repeats all the time. I'm still working out how to 
  manage this with a all read-only filesystem. I'm thinking of <FONT 
  size=2>adding a small EEPROM or a PIC microcontroller with EEPROM to help 
  manage that. Basically generate the list once and 
  store the index into the EEPROM. 
  Lastly but the one I'll probably tackle first is that picking 
  up the title, album, and sometimes artist on a song 
  isn't always obvious. I had been thinking of an LCD 
  display interface, but the more that I think of this system as 
  custom radio, the more I think that a disk jockey is in 
  order. I'm planning to getting a speech synth hooked 
  into the system to announce the songs that have played 
  and probably the artists and albums of the ones that are coming 
  up. A logical next step is to extend everything to a voice 
  interface out of the system. I think I'll still need a 
  button interface in however because the environment is 
  too noisy to have useful voice recog. I'm trying to get <FONT 
  size=2>festival together so that it can announce what's played and what's 
  coming up. 
  Anyway I just thought that ya'll might be interested in the 
  project. If anyone can suggest a onboard sound system 
  that works really well, I'd sure like to hear from 
  you. 
  Later, 
  BAJ -- To 
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