[LAU] Recording from S/PDIF

[Len Ovens]

  On Wed, Nov 22, 2017 at 1:15 PM, David Kastrup <dak at gnu.org> wrote:
> 
> ​What could the Jack abstraction be?  Synthetic Midi signals could likely
> fit pretty well but probably cannot be delivered sample-accurate.

Sample accurate? Channel status is one _bit_ at a time and is 192 bits 
wide. That is, for one User Channel word or Channel status word to be 
derived from incoming data takes 192 samples of time. So jack at 64/2 has 
better MIDI timing... (taken from ebu tech3250 and tech3250s1 both of 
which are free to download... unlike AES documents)

I was unable to find how dat tape machines encode and send text and marker 
information. What I could find suggestes spdif is meant to be 20 bit and 
so it is possible the two least significant bits might be used for other 
purposes or that the dat is actually still 16 bit and the whole lower 8 
bit byte may have information that would allow tighter timing. but 192 
samples is the frame rate for most things so I expect that is what is 
used.

With regard to more than 2 channels, any format I know of is not open or 
free. Even ADAT requires (does it still?) licencing. Certainly anything 
with the name Dolby attached is closed... that is the only reason they 
exist.

--
Len Ovens
www.ovenwerks.net