USB Audio adaptive transfer rate.

RE: USB Audio adaptive transfer rate.

keith v — Wed, 17 Jul 2019 15:09:13 GMT

Thank you.

is there anyway for me to know if/when any action has been taken on the request?

RE: USB Audio adaptive transfer rate.

Håkon Alseth — Wed, 17 Jul 2019 11:34:24 GMT

Hi,

I've inputted this as a feature request internally to our SDK team.

Kind regards,

Håkon

RE: USB Audio adaptive transfer rate.

keith v — Mon, 15 Jul 2019 14:30:43 GMT

Yes I think that is what is needed.

Please ask your USB developers to provide guidance on how to specify the required endpoint

RE: USB Audio adaptive transfer rate.

Håkon Alseth — Mon, 15 Jul 2019 07:28:18 GMT

[quote user="kvasilakes@intricon.com"]Is it possible for us to add the feedback endpoint? or does that have to be done at a level we don't have access to?[/quote]

It is possible, but this is then something you need to develop and add the proper handling of this in the sources. Unfortunately, I do not have experience with adding such features, but I suppose you can start by look at the app_usbd_audio.c file and see what needs to be setup on a descriptor level first.

Kind regards,

Håkon

RE: USB Audio adaptive transfer rate.

keith v — Fri, 12 Jul 2019 14:04:19 GMT

Yes we are trying using asynchronous audio transfer, either implicit or explicit feedback would be acceptable, but explicit is preferred

Is it possible for us to add the feedback endpoint? or does that have to be done at a level we don't have access to?

RE: USB Audio adaptive transfer rate.

Håkon Alseth — Fri, 12 Jul 2019 12:41:20 GMT

Hi,

Sample rate conversion is normally done on the side that has the most processing (normally a PC).

It sounds like you are doing asynchronous audio transfers to the usb host, and there's no ready made libraries to do feedback / conversion in the SDK (bSynchAddress is 0 in the usbd audio class files, thus no endpoint feedback is setup).

Kind regards,

Håkon

RE: USB Audio adaptive transfer rate.

keith v — Thu, 11 Jul 2019 14:58:38 GMT

Yes the problem is our proprietary audio sample rate is fixed due to the fact it has to coexist with BLE. So we need to convince the host to adjust it's sample rate. This a BLE feature we just can't figure out how to get the Nordic library to do it.

Sample rate conversion on the nRF side doesn't seem feasible due to processing time constraints.

Thank you

Keith

RE: USB Audio adaptive transfer rate.

Håkon Alseth — Thu, 11 Jul 2019 10:59:31 GMT

Hi,

[quote user=""]What support does the SDK have for USB audio sample rate feedback?[/quote]

Resampling and such is normally done on the host side, but you can use the SOF event to get a timing anchor for your firmware. Based on your description, I am not 100% sure where the issue occurs in your system. Is this due to the asynchronous radio communication?

Kind regards,

Håkon