1 (edited by croennecke 2022-07-06 16:44:59)

Topic: Multiple Stream Formats after Clock Change


I have a working setup with 12mic, Digiface AVB, AVB Tool and an Presonus AVB Switch, clocked by Digiface AVB Master CRF Stream 48k PCM. No red marked Streams or anything, Audio is in sync. I used the latest firmware in any device.

Now i use HIVE -> Media Clock Management and switch to 2FS or 4FS. HIVE ist warning me, that my stream formats are conflicting with this new sample rate. After ignoring this, my system is running out of sync. While stream Debugging in HIVE, i see, that near every output stream, e.g. in 12mic is still in 48k, also the CRF Streams... The WEB UI is giving me Error "SamplingRateMismatch 48000" eg in a 2 Channel AAF Stream.

But sry, i cant switch every AVB Stream by hand everytime i switch the sample rate, this should be done automatic shouldn't it? What is my mistake here...

I know, that i can not use any Stream Size with any Sample Rate, but i think my 12 channel AAF Stream in 96k is fine. I tried also clock switching in RMEs AVDECC Controller, same result.

Re: Multiple Stream Formats after Clock Change


yepp, that's an ongoing discussion in the AVB/Milan community. The standard (1722.1) doesn't cover automatic changes of stream formats along with a sampling rate change, so it is up to the controller to realize this.
There is however some ceremony involved in this, as stream formats can be only changed if the stream is not connected or stopped.

If you use the 12Mic's or AVB Tool's Web Interface, this will be done for you, i.e. when a sampling rate change is requested, every stream is stopped, format is changed, stream is started again.
This should be the case for the Digiface AVB as well, weird that it didn't work in your case. Please give both methods (web interface and RME AVDECC controller) another try and let me know if there are still issues.

12Mic and AVB Tool support AAF/12 channel/96 kHz streams.

BTW, we are currently discussing this with Hive's main developer, as I think this would be a handy feature for Hive as well.


3 (edited by uwekirst 2023-01-09 10:55:36)

Re: Multiple Stream Formats after Clock Change

The rme avb controller does the following if the sample rate is changed:
-It lockes the entity
-stops streaming of every stream that is listening
-stops streaming of every stream that is talking
-sets the stream format of every stream. The new format is calculated from the existing format, but with the new sample rate inside.
-sets the sampling rate
-restarts the streaming
-unlocks the entity
This procedure is the same that motu avb devices use.