site_archiver@lists.apple.com Delivered-To: bluetooth-dev@lists.apple.com User-agent: Roundcube Webmail/1.3.8 Thank you Samuel for your input. Regards Paul Tay From: JOHN WESTING <john.blank.westing@gmail.com> Date: Sat, Oct 24, 2020 at 11:45 PM Subject: Re: Bluetooth Audio stuttering when more than 4 ios devices with bluetooth devices in close proximity To: <taykh@raynet.com.sg> Cc: <bluetooth-dev@lists.apple.com>, <csppoh@raynet.com.sg>, <kktan@raynet.com.sg> 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 _______________________________________________ Do not post admin requests to the list. They will be ignored. Bluetooth-dev mailing list (Bluetooth-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/bluetooth-dev/john.blank.westing%40g... This email sent to john.blank.westing@gmail.com [1] Virus-free. www.avast.com [1] Links: ------ [1] https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail _______________________________________________ Do not post admin requests to the list. They will be ignored. Bluetooth-dev mailing list (Bluetooth-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/bluetooth-dev/site_archiver%40lists.... This email sent to site_archiver@lists.apple.com The connection is 1 iOS device to 1 bluetooth device. There won't be multiple connection to one sink in our case. In https://developer.apple.com/documentation/corebluetooth, I see CBError inside Core Bluetooth API. I am not sure whether iOS app able to capture Baseband CRC error using CBError but we will ask the developer to try it out.