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From:   Guillaume Martres <smarter@ubuntu.com>
To:     sathish.narasimman@intel.com, marcel@holtmann.org
Cc:     linux-bluetooth@vger.kernel.org
Subject: Re: [PATCH v6 2/2] bluetooth:btusb: handle msbc audio over USB Endpoints
Date:   Sat, 21 Mar 2020 17:55:51 +0100
Message-Id: <20200321165551.11928-1-smarter@ubuntu.com>
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From: Guillaume Martres <smarter3@gmail.com>

Hi Sathish, Marcel,

> I would really prefer to have some Tested-by lines from people that can verify that this patch works.

Here's my experience: a recent pulseaudio MR [1] added support for mSBC. When I
tried it using my laptop (Intel AX200) and headphones (Bose Headphone 700), the
voice quality was extremely bad. I eventually realized that this could be fixed
by ignoring all zero-filled packets sent by the headphones when decoding
mSBC [2], after that everything worked fine.

Since then, I was made aware of the existence of this patchset, after applying
this patch (and [3] which apparently only exists as v5 and not v6), my
headphones stopped sending zero-filled packets, but:
- the recorded audio quality is again extremely bad and robotic.
- when audio is being played, the headphones do not emit any sound.

Note that I applied this patchset on top of the current Ubuntu 20.04 kernel [4],
let me know if it's worth retesting on top of the mainline kernel, or if there
is something else I could try.

Hope this helps,
Guillaume


[1]: https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/merge_requests/254
[2]: https://gitlab.freedesktop.org/smarter/pulseaudio/-/commit/bb716b03002841e1092b4200935566d5c1a951fe
[3]: https://www.spinics.net/lists/linux-bluetooth/msg82149.html
[4]: https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/focal/commit/?h=Ubuntu-5.4.0-18.22&id=93dfa5b8e12fed29933f3451db44d88c0e4b5aed