23 Jan
2015
23 Jan
'15
5:05 p.m.
On Wed, 21 Jan 2015, Leonardo Gabrielli wrote:
The machine I'm referring to is a Cortex A8 using its own audio codec, and
I think the drivers are not exceptional. Lowering the period size was not
possible. I was using Debian Stable.
(going off-topic): what sound card did you use to get the 0.66ms latency
and what distro?
Other comments: network audio requires to serve not only audio card
interrupts but also NIC interrupts in case of ethernet, or USB/SPI in case
of wifi chips. The drivers must written very carefully. I've often seen the
NIC interrupt routine preempt jack audio clients. Furthermore, network
drivers are written for throughput, not latency. These two issues make me
wonder whether a general purpose OS could serve the purpose well. Or maybe
it's just I tend to prefer the low-level solutions...
One thing yet to check: the original 802.11 specifications allowed for a
contention-free period, still have to check whether current 802.11n and
802.1ac AP still allow for it.
Best,
Leonardo
In reality of the 16ms latency I mentioned, 5.3ms
are the A/D and 5.3ms
are the
D/A (48khz, 2 periods of 128 samples in JACK at
both sides). The
remainder
That does not need to be. My 10 year old P4 was running an ice1712 at
48k/16/2 (.66ms) with no xruns.