[...] the delivered data should be identical [...] so long as it's sent via a reliable link or protocol.
The signal the HDMI output sends gets transfered pristinely and without degradation, however that signal is not a bit for bit identical copy of the file on the disc/hard drive, it is a converted version of that file, which to the best of my knowledge can not be reassembled on the receiving end to make an exact copy of the file from the original source. [Even if there weren't copy protection schemes in place to prevent it and pretending for the moment that there were stand alone recorders with HDMI in]. HDMI streaming is not the same as a USB file transfer.
I don't know if the same is true for HDMI. Old receivers had horrible jitter problems but I guess this problem was fixed one or two years ago.
Unlike TCP, there is no retry if delivery of data failed, no guarantee of delivery. In fact, isochronous transfer is unidirectional.
As an isochronous stream is a soft real time stream, a retry will always be too late.
However USB in isochronous mode does reserve the appropriate bandwidth.So delivery is guaranteed downstream but delivering of the right bits is not
One can combine isochronous (that’s the way USB audio works) with 3 different type of synchronization.
I guess I should have been more pedantic with the terms I used before.
If frames need to arrive every ms but do not it doesn't matter how much bandwidth is reserved. Also, most glitches occur because data doesn't arrive in time (DPC latency on Windows), not because of flipped bits.
Nope and that's why I didn't make that claim, but such amounts of jitter have a big measurable negative effect on SNR. I can imagine that it could be audible with highly dynamic recordings if you turn up the volume quite a bit.
For example the Yamaha RX-V3900 was measured to have 7660 ps of jitter.
(If that was even a problem, as others are saying.)
So with that in mind if you wanted portable audiophile sound quality, all you'd need is any flac or wav player (quality not particularly important) with a digital out, good headphones and a good portable DAC? Does such a DAC exist? How do they compare to AV receivers?
QuoteIf frames need to arrive every ms but do not it doesn't matter how much bandwidth is reserved. Also, most glitches occur because data doesn't arrive in time (DPC latency on Windows), not because of flipped bits.It works slightly different.The frames always arrive in time, that’s the way USB works.The bandwidth is reserved on the hub to avoid interference of other USB devices.But this is downstream not upstream.The frames will always arrive in time but you might get glitches due to an insufficient amount of data in the frame e.g. due to DPC latency upstream BTW: a lot of new USB DACs support async: http://thewelltemperedcomputer.com/HW/USB_DAC_Async.htm
As I said, isochronous (adaptive) transfer can work perfectly fine.
A test by Jim Lesurf: http://www.audiomisc.co.uk/Linux/Sound3/TimeForChange.html
All we seem to have is these anecdotes.