Numark D2 Director Reference Manual page 32

Some encoders offer a choice of sample rates from 8KHz to 48KHz, however D2 Director always
resamples to 44.1KHz so there's nothing to be gained from encoding at a higher rate than that.
D2 Director can extract tags from MP3 files using the popular ID3 format. We recommend using ID3v2,
as this offers greater flexibility in the length of tags and types of information that can be stored (BPM for
example).
Many packages support encoding to MP3, some commercial and some free. Some suppliers charge an
additional fee for MP3 encoding above 64Kbps (which is far too low a bitrate for professional use).
AAC
This format, invented in the late 90s, also started out in the broadcast industry. Its breakthrough in the
music industry came with its adoption as the default format for Apple iTunes and the iPod portable music
player. Sometimes this format is known as MP4 or MPEG-4 although more correctly it is Part 3 of the
MPEG-4 standard. The most common file extension is .M4A.
AAC has improved performance over the older MP3 format leading to superior sound reproduction for the
size of file. The greatest improvement is with low bitrate files, but this is less relevent to the professional
user and at higher bitrates the formats are considered about equal in sound quality.
D2 Director can extract tags from AAC files using the M4A format, supported by many popular audio
applications.
If you use iTunes to encode your music collection the chances are it is in AAC format (using the M4A file
extension). However if you purchased music from the online iTunes Music Store you should be aware
that this protected content cannot be played by D2 Director, or by any other digital music player other
than the Apple iPod at this time. This limitation is imposed by Apple.
WAV
WAV (or Wave) format has been in use for many years and is a simple (usually uncompressed) audio
format. Although the file extension is the same, WAV files can contain various formats of digital audio -
D2 Director can play the popular 16-bit PCM format. At 44.1KHz sample rate this is a faithful
reproduction of CD audio. The format is useful if you want to be sure of the best possible sound quality,
but as a result the files are large (typically five to ten times larger than an MP3 file).
There is no standard for tagging within WAV files and at this time D2 Director will use only the filename to
identify a track (this is represented as the track title).
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