site_archiver@lists.apple.com Delivered-To: bluetooth-dev@lists.apple.com Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Ol7gIlW1ls8/vOXgaX5LdDlHEyNHPUzCIsJqSkTeogE=; b=VLjD05tKRsOhphKx42CyTl3rNcgKUWRuXCigb1uhKwP8rjtuU6QFlbnzQq3A0Bk803 FK+yigSv6b4tEniGkUuvX+Rh3kBpa42DTXK2wLtquFkP3HhCwzz2EPj/5+k7JFwk31iL J5OL+wRJ2AV9BddYuuetBCdEU1gT0SqjFz8UJerp2c2T2Q39VgQWrBcHOAjxCSDAP7LM mh3LuWz8yrXjRR5WjbaoQvWZ8n1Hoo6/dUG9Cg7tq+9PTIGuYQ6lBReJFSd9T48/eGT8 dNzQJX7DhVVPtY0iSibW+ZqRvna6XVyM/Vf0QtvUXUwmuGAcNGGZwUtpYCwxzpuUvc3H OWvQ== What’s your pico net look like? For 1 connection it’s optimal for the audio source to be the master. For multiple connections to one sink, it’s better for the sink to be master. iOS devices do all they can to become master, especially in newer releases of iOS, since about 3 years now. Samuel On Sat, Oct 24, 2020 at 9:20 AM taykh--- via Bluetooth-dev < bluetooth-dev@lists.apple.com> wrote:

Hello everyone,

We encountered a serious bluetooth audio stuttering problem that need expert advice. We are using Microchip BM62 solution which has Ble and A2DP.

Scenario is this: Our customer has started roadshows and they put up at least 4 bluetooth products for demo in each location. Demo would last for hours, with each product connected and bluetooth paired to an iOS device; with iOS app running and controlling the product through Ble and playing music. And all are in close proximity to one another.

What happen is at least 1 iOS device playing music to bluetooth device start to audio stutter for no particular reason. It can happen just a short moment to hours after music played. Sometime audio stuttering would disappear and normal music continue.

Our supplier performed bluetooth sniffing to capture the protocols using bluetooth protocol analyzer. We have the cfa files. I did not attached to the email because the file size is greater than 200MB. Please let us know if anyone need to the file. We will send to him.

We use ComProbe software to view to result.

Result showed that baseband layer have multiple CRC errors. In Message Sequence Chart, where frame consists CRC Error, it showed flow from BB_M to BB_S. See image

http://www.raynet.com.sg/bluetooth/music_break_v1_APP_music_message_sequence...

And using Audio Expert System analyzer, we can see visually the break or absent of audio protocol and even hear the audio stuttering. See image

http://www.raynet.com.sg/bluetooth/music_break_v1_APP_music_audio_expert_sys...

Our supplier is unable to conclude the cause to the problem. Or solution to audio stuttering.

Therefore, we wrote to seek for expert advise to help to solve this audio stuttering problem.

We suspect there is RF interference - multiple iOS devices usage audio stuttering would occur. Single iOS device usage does not see the problem.

What puzzle us is that multiple android devices usage also does not see the problem.

We hope Apple experts could advise us on this.

Lastly, is it possible to get an event when bluetooth baseband CRC error occur? We want to see whether iOS app could capture this event and subsequent stop music when audio stuttering happen.

Thank you.

Regards, Paul Tay Raynet Technologies Pte Ltd Singapore

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