Re: AVB

On Tue, February 26, 2019 14:46, Chris Caudle wrote:
>> The openavnu repository would be a start but I don't know of
>> anyone that has a full stack working.
>
> On a pretty long thread on the Ardour forums someone recently wrote this:
>  "The ALSA driver (based on the intel igb driver) can use any buffersize
> down to a single interval. "The lowest round trip latencies (analog to
> analog) on my 16A therefore are 1.5ms at 6/48kHz to 0.75 ms at 24/192kHz
> measured with jack2 in synchronous mode."
>
> No response after several days to my request for a link to a repository
> containing that ALSA driver.
>

This looks like an AVB ALSA driver:

https://github.com/induarun9086/beagleboard-linux/blob/4.4/sound/drivers/avb.c

It's somewhat buried in another repo.

From what I read it was a GSoC project:
-----
This is the fourth instalment of the weekly report for the GSoC beagle
board AVB stack project. The plan was to start the design and
implementation of the audio driver and more specifically to start the
implementing the Stream reservation protocol of the AVB stack. The current
status and the upcoming tasks are listed below,

Status:

  -> Improvements are done for the clock synchronization for gPTP.
  -> Now I can see improved synchronization errors in the range of
hundreds of nanoseconds to some tens of micro seconds.
  -> Started to design the ALSA audio driver required to implement the AVB
streaming (using the synchronized clock).

Next Tasks:

  -> Start coding for the ALSA audio driver for AVB and setup a barebones
driver at first.
  -> Start implementing the Stream reservation protocol inside it to start
streaming.
  -> Setup the hardware required (audio cards) to output the streamed
audio via ethernet AVB to speakers.
------

Not sure how mature the driver is in its current state or if it's only
useful for BB.

Greetings
Thomas