[arm-allstar] usbaudio

[Doug Crompton]

Ken,

  It depends on a number of factors. One is how much of the DSP you use in usbradio and the other is the capability of the processor. We also think there is a much more important third factor of a code issue. It has nothing to do with equalization or level of the audio. It is a digital problem and it is hard to describe exactly what it sounds like. If you quantized an analog signal and then took out random bits it would add distortion and that is what it sounds like is happening. This is not like packet loss where you lose a complete set of data but rather just very small bits here and there. It is very real and I can usually pick out when someone is using usbradio. It sometimes is very mild and other times bad enough to be annoying. We are working on a code fix and if that works a much simplified channel driver that would do what usbradio does now but with good audio even on the BBB. Keep your fingers crossed. Hopefully the next release.  
73 Doug
WA3DSP
http://www.crompton.com/hamradio


To: arm-allstar at hamvoip.org
From: ke2n at cs.com
Date: Sun, 16 Nov 2014 21:13:34 -0500
Subject: [arm-allstar] usbaudio


"...characteristically distorted usbradio audio is much more of an 

annoying problem than improper equalization.."

 

What is the distortion in usbradio that is not present in simpleusb?

 

Is it something to do with filtering and pre-emphasis?  Other than that, and some added latency, I think the A/D D/A conversion and other audio stream manipulations are pretty much the same no?

 

Thanks

Ken

 

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