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Digital audio terms
ADPCM
Adaptive Differential Pulse Code Modulation (ADPCM), is a form of pulse code modulation
(PCM) that produces a digital signal with a lower bit rate than standard PCM. The Rio 800
uses ADPCM for voice recording. ADPCM produces a lower bit rate by recording only the dif-
ference between samples and adjusting the coding scale dynamically to accommodate large
and small differences.
Bitrate
Bitrate denotes the number of bits per second used to represent an audio signal. The size
and quality of a digital audio file is determined by the bitrate used when encoding the file. The
higher the bitrate used, the higher the sound quality and the larger the file size. For example,
with MP3, a bitrate of 128k is usually very close to CD quality, and takes up about 1MB per
minute of music. At a 64k bitrate, the sound quality is similar to that of an FM radio signal, but
you can get around two minutes of music in that same 1MB of storage space.
CDDB
See
Gracenote.
Codec
Depending on the context and kind of technology involved, codec can be defined in two
ways. In telecommunications, a codec is usually a "coding/decoding" chip used to translate
between digital and analog transmissions. A modem uses one to interpret incoming analog
signals and converts the digital data stream coming from the computer into analog. Codec is
also defined as a compression/decompression algorithm. Codecs are used to compress
audio data into a file, often for efficient transmission over a network, and then decode it for
playback.
The Rio One supports the following digital audio file codecs:
•
MP3
•
WMA
DRM, security
Digital Rights Management (DRM) technologies protect copyright ownership of digital infor-
mation. DRM became an issue with the rise of MP3 technology and Internet distribution of
music. DRM platforms serve as a security "wrapper" around digital audio supporting Internet
distribution while at the same time protecting and managing rights related to that digital infor-
mation.
Encoding, or Ripping (a CD)
Encoding, or "ripping", refers to converting an audio file from an audio CD into a compressed
digital audio format, such as MP3 or WMA, that can be played on the Rio or on the computer.
Digital audio terms
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