HiFi DACS with USB Vs Pro Audio DACS

[Themis]

CRCs are usually used to detect errors, not correct them. It's not clear to me how USB handles the situation when an error is detected. If there''s no resend, then the usual options are to do some form of interpolation, or simply to repeat the previous packet.

http://www.cs.nmsu.edu/~pfeiffer/cla...notes/ecc.html
I hope it's not too complicated...

Otherwise, there is some (simpler) info here : http://en.wikipedia.org/wiki/Error_d...and_correction

USB uses a CRC-5 type.

[dave2010]

http://www.cs.nmsu.edu/~pfeiffer/cla...notes/ecc.html
I hope it's not too complicated...

Otherwise, there is some (simpler) info here : http://en.wikipedia.org/wiki/Error_d...and_correction

USB uses a CRC-5 type.

I think I'm sticking with what I wrote earlier. If you want to do forward error correction then a code such as a Reed-Solomon code is needed. I don't think the CRC-5 coding is going to work for correction, and I'm unaware that USB uses any really complex codes to support FEC. It would be possible to use a k out of n block erasure code, with the CRC used on each block to decide whether to accept it or not, but isn't that too complex for the particular application? If the error rate is not excessively high, it should be possible to implement an FEC above the USB level, but that would require (probably) device specific code. My contention is that USB does not do this.