23 Nov
2017
23 Nov
'17
12:50 a.m.
On Wed, Nov 22, 2017 at 1:15 PM, David Kastrup <dak(a)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