positron/doc/neuros.html

   1 <html>
   2 <head>
   3   <title>Positron Developer's Guide: An Overview of the Neuros</title>
   4 </head>
   5 <body>
   6 <h1>Positron Developer's Guide: An Overview of the Neuros</h1>
   7
   8 <p>
   9 This document describes the design and features of the Neuros from a
  10 developer's perspective.  It is not meant to be comprehensive, but
  11 rather it covers the aspects of the Neuros most likely to be of
  12 interest to someone writing software for it.
  13 </p>
  14
  15 <h2>General Design</h2>
  16
  17 <p>
  18 The Neuros is a portable music player designed to play compressed
  19 music formats, like MP3 and Ogg Vorbis, as well as FM radio.  It can
  20 also record to MP3 from either a microphone source or the radio.  A
  21 modest FM transmitter also allows the Neuros to broadcast audio to a
  22 nearby FM radio, thereby allowing cordless playback to things like car
  23 radios and home stereo systems.  The "HiSi" feature allows a 30 second
  24 clip from a song on the radio to be recorded in MP3 format and later
  25 identified when the Neuros is attached to the host computer.
  26 </p>
  27
  28 <p>
  29 The Neuros itself is a modular device composed of both a main unit,
  30 containing the DSP, flash memory and other electronics, and a backpack
  31 containing the battery and optionally a hard disk.  This allows the
  32 device to be upgraded by replacing the backpack to provide new
  33 capabilities.  Currently, the Neuros is available in the following
  34 configurations:
  35
  36 <ul>
  37
  38     <li>128 MB - The main unit has 128 MB of flash, and the backpack
  39     only contains a battery.</li>
  40
  41     <li>20 GB - The main unit has 64 MB of flash, and the backpack
  42     contains a battery and a 20 GB hard disk.</li>
  43
  44 </ul>
  45
  46 The HD backpack is sold separately, and can be attached to the 128 MB
  47 main unit.  All configurations are handled the same way by the
  48 synchronization software, with one exception documented in the <a
  49 href="#pathformat">File Structure</a> section.  Note that the current
  50 configuration of the Neuros cannot be straightforwardly detected in
  51 software.  Positron decides whether the HD or the flash memory is in
  52 use by looking at the size of the filesystem of the mounted Neuros.
  53 </p>
  54
  55 <h2>Interface</h2>
  56
  57 <p>
  58 All interfacing to the Neuros is done through a USB 1.1 port.  It
  59 presents itself as a USB Mass Storage device, so the standard USB
  60 drivers included with nearly all modern operating systems are used to
  61 communicate with the Neuros.  The Neuros can then treated as an
  62 external drive with a single FAT32 partition to be mounted using the
  63 standard operating system tools.  Beyond that, no special drivers are
  64 needed, which makes the Neuros (in principle) very portable between
  65 operating systems.
  66 </p>
  67
  68 <p>
  69 When connected to a host computer via the USB port, the Neuros goes
  70 into a synchronization mode where it simply acts as a passive hard
  71 disk.  The host does not directly send commands the Neuros, but rather
  72 copies files and manipulates a database stored on the filesystem,
  73 which is then read by the device firmware when the device is
  74 disconnected for normal use.
  75 </p>
  76
  77 <h2>Database</h2>
  78
  79 <p>
  80 Because the Neuros appears as a standard external hard drive when
  81 attached to the host computer, any type of file can be stored on it,
  82 regardless of whether it is a recognized audio file format.  Rather
  83 than spend extra time dynamically generating a list of available music
  84 files, a database of music files is maintained on the device.  Only
  85 those files listed in the database will be made available for
  86 playback.  The database also provides the ability to index files based
  87 upon the contents of various fields in the database, like artist or
  88 genre.  It is the job of the synchronization program running on the
  89 host computer to update the database to reflect changes in the list of
  90 files available for playback.
  91 </p>
  92
  93 <p>
  94 There are several databases kept on the Neuros.  One lists all the
  95 audio files, but others are used to keep track of HiSi clips which
  96 have been successfully identified, cannot be identified, or have not
  97 been identified yet, as well as the listing of all the music files
  98 stored on the host computer.
  99 </p>
 100
 101 <p>
 102 For more information about the database format, read
 103 <a href="database.html">Working With the Database</a>.
 104 </p>
 105
 106 <h2>File Structure</h2>
 107
 108 <p>The file structure of the device is:</p>
 109 <pre>
 110 /        - root directory
 111 /sn.txt  - contains the serial number of this Neuros
 112 /WOID_DB/ - directory for all databases
 113 /WOID_DB/audio/ - database of audio files stored on the Neuros
 114 /WOID_DB/failedhisi/ - database of HiSi clips that could not be identified
 115 /WOID_DB/idedhisi/ - database of HiSi clips that were identified
 116 /WOID_DB/pcaudio/ - database of audio files stored on the host computer
 117 /WOID_DB/unidedhisi/ - database of HiSi clips that have not been identified yet
 118 /WOID_SYNC/ - not sure what this is for
 119 /WOID_HISI/ - (Optional) directory for HiSi MP3 clips
 120 /WOID_RECORD/ - (Optional) directory for recordings (FM or Microphone)
 121 </pre>
 122 <p>Also note that the Windows Neuros Sync Manager and positron use
 123 <tt>/MUSIC/</tt> by default for storing music tracks, though that is
 124 in no way required.</p>
 125
 126 <a name="pathformat"/>
 127 <p>
 128 Pathnames in the databases use a strange hybrid Windows/Unix-like
 129 syntax.  The root directory on the Neuros is called "C:" if the Neuros
 130 is wearing the hard drive backpack, and "D:" if the flash memory is
 131 being used.  Forward slashes are used instead of backslashes.  For
 132 example, <tt>C:/WOID_RECORD/Mic 02-27-01 17-19-00.mp3</tt> is a
 133 possible filename for a track saved on the Neuros hard drive.
 134 </p>
 135
 136
 137 </body>
 138 </html>