Expose A2DP on the proxy

[mcitew]

Is there a way to expose A2DP on the proxy ? I had a long chat with the AI, it seems when A2DP is exposed on the proxy, the 'Media Audio' will still be disabled by android auto anyway, but there is a subtle difference. Without the A2DP exposed on the proxy, android auto will disable the 'Media Audio' of the car. If the proxy exposed A2DP, it will leave the 'media audio' of the car untouched. This has been verified by my testing on a patched built. I need to leave the car 'media audio' untouched for various reasons. And the AI I spoke to says exposing A2DP on the proxy results in 'cleaner' voice routing. ;)

[manio]

From the discussion here it sounds like the main benefit isn't that A2DP would actually be used for media while AA is running. The reported behavior is that advertising A2DP on the proxy prevents Android Auto from disabling the car's "Media Audio" profile, even though AA still won't route media through it.

Can you explain your use case a bit more? Why is it important that the car's Media Audio stays enabled? Also, if you have a patched build that already does this, could you open a PR or share the changes? It would be much easier to review the implementation than to discuss it theoretically.

[mcitew]

Yes the primary reason for keep an a2dp end point is to make the music applications updates its lyrics. Chinese music applications uses this to feed live lyrics. A phone music application will be able to "listen" to the music audio and lyrics and compose a music graphics for android auto.

I have the patch. It is mostly written with the help of AI and I tested it. But I only half understood the codes, it might contain unnecessary duplicates or redundant code. I can post the patch here.s

1. Need to mod Cargo.toml add one line
2. Need to also mod /etc/bluetooth/main.conf perhaps

dependencies
#zbus = { version = "4.0", default-features = false, features = ["tokio"] }

0001_stop_aa_from_disable_media_audio.patch

[manio]

This patch doesn't seem big and if it is a benefit to some I am okay to add this... but it need to be polished a bit and make it configurable... Why /etc/bluetooth/main.conf has to be adjusted and how?

[mcitew]

main.conf :-

[General]
Class = 0x200414

Enable = Source,Sink,Media,Socket

JustWorksRepairing = always
DeviceID = false

[manio]

Can you check 049d809 @mcitew?

[mcitew]

Tested, it works for me.

By the way, I wasn't expecting you - patch it so fast. :) I was hoping I could hear others confirming the mod can take effect.

[manio]

Thanks, we should probably also make some notes about the main.conf change somewhere, so I am keeping this open...