Glossary, Aac codec – Motorola m250 User Manual
Page 56
Glossary
Bass
Bass is the particular low-range area of the sound spectrum where low musical notes and sounds are located.
Increasing the bass value will make the low vocals and drums more prominent in your music. You can select the
amount of bass in your music by selecting various
Bitrate
Bitrate denotes the number of bits per second used by a digital music file. The size and quality of a compressed digital
audio file are determined by the bitrate used when encoding the file. Generally, the higher the bitrate used, the higher
the sound quality, and the larger the file size. For example, a bitrate of 96 kbps (96,000 bits per second) is generally
thought of as “CD quality” for WMA audio files, and takes up about 0.75 MB-per-minute of music. At a 64 kbps bitrate,
the sound quality of WMA is similar to that of an FM radio signal, but approximately two minutes of music will fit in 1
MB of space.
Codec
Depending on the context and kind of technology involved, codec can be defined as a compressed digital audio file
format (like MP3, WMA, etc.), a “coding/decoding” chip used to translate between digital and analog transmissions
(used in modems), or a compression/decompression algorithm. Codecs compress audio data into a file, often for
efficient transmission over a network, and then decode it for playback. While all the codecs perform similar
compression of digital audio, there are differences in technologies.
The m250/m500 supports the following digital audio codecs: MP3 and WMA. The Advanced Audio Coding (AAC)
Codec
2
, most closely identified with MPEG-4, is not currently supported by the m250/m500.
2
AAC was developed by the MPEG group that includes Dolby®, Fraunhofer ®(FhG), AT&T®, Sony®, and Nokia®—companies that have also
been involved in the development of audio codecs such as MP3 and AC3 (also known as Dolby Digital). The AAC codec in QuickTime® 6
builds upon new, state-of-the art signal processing technology from Dolby Laboratories and brings true Variable Bit Rate (VBR) audio encoding
to QuickTime.
m250/m500 DIGITAL AUDIO PLAYER
56