From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: MIME-Version: 1.0 In-Reply-To: <70154da5-5a09-28a8-c527-695a6bf499a2@gmail.com> References:

<70154da5-5a09-28a8-c527-695a6bf499a2@gmail.com> From: Luiz Augusto von Dentz Date: Thu, 23 Jun 2016 14:24:39 +0300 Message-ID: Subject: Re: AVRCP 1.6 To: Niek Vlessert Cc: "linux-bluetooth@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-bluetooth-owner@vger.kernel.org List-ID: Hi Niek, On Thu, Jun 23, 2016 at 12:15 AM, Niek Vlessert wrote: > >>> - Bluez supports AVRCP up to 1.5 >> >> >> Actually we can do up to 1.6 but just the mandatory commands which >> don't include the ones necessary for cover art, etc. > > > Ok, great! > >> >> Android has support only to 1.3, there are vendors that extend to >> 1.4/1.5 like samsung but they have to change all the way from HAL to >> java to interface this to the application. >> > Interesting, do you know any reasons why Google won't incorperate a newer > version ? I guess it will demand some effort given that it affects not only the stack but the API in the players to deal with the new commands. But as far as cover art is concern I guess it is a no go because OBEX in Android is actually implemented in java which would probably not interact that well when called directly from the underline stack. >> >> You can use tools/bluetooth-player if you want to control it from the >> command line, another alternative is to use tools/mpris-proxy and then >> control it using a MPRIS controller. > > > Great, I've been looking into those. It seems to me bluetooth-player as the > CT and mprix-proxy as the TG can provide a test setup for future AVRCP 1.6 > testing. It's interesting to see that the mpris spec supports an artUrl > already: > https://www.freedesktop.org/wiki/Specifications/mpris-spec/metadata/#index3h4. > I'm thinking bluetooth-player sends the image through AVRCP 1.6 to the > mpris-proxy. mpris-proxy puts it in /tmp/ and provides a url like > file:///tmp/.bmp to the mediaplayer through the Art URL. What > do you think of this approach? Yep, it was made to be easy to interact with MPRIS which is a more common interface for media players in Linux, but note that it is usually the other way around as bluetooth-player is the CT it should be the one receiving the cover art from the mpris-proxy TG which can of course use the artUrl. You can also use 2 instances of mpris-proxy, one in each box, or just one if you have 2 bluetooth controllers plugged in the same host, mpris-proxy works both ways as it can create MPRIS players from remote devices as well as expose local players. > >> >>> - Would you consider it possible to put the right hex into my Android app >>> and transmit that to my Bluetooth connection so I can implement it >>> without >>> the Android Bluez stack supporting it? If target devices will ever >>> support >>> it... Since it's serial communication, I thought why not? I never did >>> anything like this with Bluetooth programming so forgive my ignorance. :) >>> Something like this: create L2CAP channel with the Cover Art UUID. Wait >>> for >>> response; encode picture in the right data packages, and here we go. >>> Leave >>> other Bluetooth communication requirements to Android. >> >> >> You can do whatever you want, but since it would be non-standard this >> would limit a lot the usage. > > > Well, I was hoping I could keep it standard compliant using this method. > However since you responded like this; do you think it's not possible to > create the correct hex strings in my own program for some reason? AVRCP has its own commands to transfer the cover art using OBEX, and as far I know it is the only adopted profile capable of doing this. >> >>> - Or maybe I could use the cddb support? Maybe it's possible to redirect >>> traffic to cddb to somewhere else, provide the cddb interface and offer >>> the >>> image like that? I know, it's horrible... ;) >> >> >> Also non-standard, perhaps investing time in doing a AVRCP 1.6 would be >> better. > > > That would be awesome. I'm not that good at c but maybe I can try to > implement it in the player and the proxy with tips from you, adding it to > BlueZ however is another story I guess. :) You would be very welcome if you do that. -- Luiz Augusto von Dentz