Digital audio signals
In most applications, analog sound is first sampled and converted into an integer at some sampling rate. With respect to the BeagleBoard, the conversion of analog sound into a digital audio signal is done by the TPS65950 chip. The two most important characters in digital audio are sampling rate and resolution. The sampling rate specifies how fast the sound is sampled, and resolution is defined as how many bits are used for representing one sample. The sound can be completely specified by the sequence of these integer numbers and the sample rate. The following table lists these characters in some common audio systems:
|
Application |
Sample rate |
Resolution |
Note |
|---|---|---|---|
|
Telephone |
8 kHz |
8-12 bits | |
|
Mobile phone |
8 kHz |
14-16 bits |
GSM |
|
Portable music player |
32 kHz |
14-16 bits |
MP3, WMA |
|
CD audio |
44.1 kHz |
16 bits |
Stored on CD |
