Blog Contents

Digifon Logo link to main page

26. Gimme Bandwidth! (More Bits Are Better)   11/2/12 by Dave Immer

Bandwidth, in the case of digital audio, can refer to 2 things:
1. The audio frequency response expressed in a range as in 30Hz - 20kHz.
2. The rate of data transfer (digital bandwidth), expressed in kbs (or Mbs) – really a misnomer but a generally accepted specification.

Data transfer rate translates to audio bandwidth (frequency response) for predictive coding like APTX. But for perceptive (bit-reduction) coding like MPEG layers II, III & AAC it’s a little trickier, translating more to waveform resolution and how much noise is being masked.

For instance, with MPEG coding it’s your choice to go for 48kHz sampling resulting in 20kHz audio and suffer more masked noise, or go for 32kHz sampling giving you 15kHz audio while masking less noise.

For ISDN users the data transfer rate would depend on what codec you are using and how many lines you have connected.

Over IP there is more flexibility. And as the internet data rates increase, one can expect the option to transmit/receive at higher codec bit rates. Soon we will have much higher digital bandwidth available via the internet. Hopefully the stability and latency with improve too.

When transmitting over IP, use the highest bit-rate you can while maintaining an acceptable trade-off between latency and stability.

-Dave