Using AVRCP with current BlueZ

Using AVRCP with current BlueZ

[Csillag Kristóf]

Hi there!

The wiki page at http://wiki.bluez.org/wiki/HOWTO/AudioDevices says that
I no longer not need bluetooth-alsa, plugz, btsco or the like for audio
to work - they are now obsolete.

My question is, how can I use AVRCP now? bluetooth-alsa used to contain
some support for it, but now I guess it's gone. Browsing the source
code of bluez-utils, I see some dbus interface, but I can not find
any example demonstrating how to use this.

Could you please point me to the right documentation (if it exists)?

Thank you for your help:

   Kristof Csillag

Re: [Bluez-users] Using AVRCP with current BlueZ

[Johan Hedberg]

Hi Kristof,

On Nov 22, 2007 6:26 PM, Csillag Krist=F3f <csillag.kristof@gmail.com> wrot=
e:
> My question is, how can I use AVRCP now? bluetooth-alsa used to contain
> some support for it, but now I guess it's gone. Browsing the source
> code of bluez-utils, I see some dbus interface, but I can not find
> any example demonstrating how to use this.
>
> Could you please point me to the right documentation (if it exists)?

I don't think there is any proper documentation yet. bluez-utils-3.22
has some preliminary AVRCP support but by default it's disabled. You
need to add a line "Enable=3DControl" to the General section in
/etc/bluetooth/audio.conf to enable it. Currently no D-Bus signals or
or methods are supported. Instead, the audio service uses the kernel
uinput interface (you need to have the uinput module loaded) to inject
keypress events to the kernel input subsystem. You can see what kind
of AVRCP->keycode mappings are used by looking in the audio/control.c
file from bluez-utils.

Johan

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Re: [Bluez-users] Using AVRCP with current BlueZ

[\x11]

Thanks,Johan.
im also wondering how i can do avrcp and now here's the answer.



semiyd




> Date: Thu, 22 Nov 2007 19:13:55 +0200
> From: johan.hedberg@gmail.com
> To: bluez-users@lists.sourceforge.net
> Subject: Re: [Bluez-users] Using AVRCP with current BlueZ
>
> Hi Kristof,
>
> On Nov 22, 2007 6:26 PM, Csillag Krist=F3f  wrote:
>> My question is, how can I use AVRCP now? bluetooth-alsa used to contain
>> some support for it, but now I guess it's gone. Browsing the source
>> code of bluez-utils, I see some dbus interface, but I can not find
>> any example demonstrating how to use this.
>>
>> Could you please point me to the right documentation (if it exists)?
>
> I don't think there is any proper documentation yet. bluez-utils-3.22
> has some preliminary AVRCP support but by default it's disabled. You
> need to add a line "Enable=3DControl" to the General section in
> /etc/bluetooth/audio.conf to enable it. Currently no D-Bus signals or
> or methods are supported. Instead, the audio service uses the kernel
> uinput interface (you need to have the uinput module loaded) to inject
> keypress events to the kernel input subsystem. You can see what kind
> of AVRCP->keycode mappings are used by looking in the audio/control.c
> file from bluez-utils.
>
> Johan
>
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> Bluez-users@lists.sourceforge.net
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Re: [Bluez-users] Using AVRCP with current BlueZ

[Csillag Kristóf]

[-- Attachment #1: Type: text/plain, Size: 1329 bytes --]

Hi Johan,

2007/11/22, Johan Hedberg <johan.hedberg@gmail.com>:
> I don't think there is any proper documentation yet. bluez-utils-3.22
> has some preliminary AVRCP support but by default it's disabled. You
> need to add a line "Enable=Control" to the General section in
> /etc/bluetooth/audio.conf to enable it. Currently no D-Bus signals or
> or methods are supported. Instead, the audio service uses the kernel
> uinput interface (you need to have the uinput module loaded) to inject
> keypress events to the kernel input subsystem. You can see what kind
> of AVRCP->keycode mappings are used by looking in the audio/control.c
> file from bluez-utils.

Thanks, now it works great!

One more question: what was the reason to use

KEY_NEXT and KEY_PREVIOUS, instead of
KEY_NEXTSONG and KEY_PREVIOUSSONG?

The latter are below-256 keycodes (like KEY_PLAYPAUSE,
which is used by BlueZ for pause) handled nicely by
all applications (like keytouch), where the former, which
are currently used, are extended codes, mostly unsupported
in user-space.

As far as I am interested, I changed the codes in my local
BlueZ installation so that I do not have to change keytouch.

Now it works nice with keytouch and hence audacious.

Thank you:

    Kristóf

ps. Here is a patch, if anybody is interested.

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: keycode_change.patch --]
[-- Type: text/x-diff; name=keycode_change.patch, Size: 1804 bytes --]

--- control.c~	2007-10-26 01:09:15.000000000 +0200
+++ control.c	2007-11-23 12:34:52.000000000 +0100
@@ -447,8 +447,8 @@
 
 	ioctl(fd, UI_SET_KEYBIT, KEY_PLAYPAUSE);
 	ioctl(fd, UI_SET_KEYBIT, KEY_STOP);
-	ioctl(fd, UI_SET_KEYBIT, KEY_NEXT);
-	ioctl(fd, UI_SET_KEYBIT, KEY_PREVIOUS);
+	ioctl(fd, UI_SET_KEYBIT, KEY_NEXTSONG);
+	ioctl(fd, UI_SET_KEYBIT, KEY_PREVIOUSSONG);
 	ioctl(fd, UI_SET_KEYBIT, KEY_REWIND);
 	ioctl(fd, UI_SET_KEYBIT, KEY_FORWARD);
 
@@ -560,11 +560,11 @@
 		break;
 	case NEXT_OP:
 		debug("AVRCP: NEXT %s", status);
-		send_key(session->uinput, KEY_NEXT, pressed);
+		send_key(session->uinput, KEY_NEXTSONG, pressed);
 		break;
 	case PREV_OP:
 		debug("AVRCP: PREV %s", status);
-		send_key(session->uinput, KEY_PREVIOUS, pressed);
+		send_key(session->uinput, KEY_PREVIOUSSONG, pressed);
 		break;
 	case REWIND_OP:
 		debug("AVRCP: REWIND %s", status);
--- bluez-utils-3.22/audio/control.c~	2007-10-26 01:09:15.000000000 +0200
+++ bluez-utils-3.22/audio/control.c	2007-11-23 12:34:52.000000000 +0100
@@ -447,8 +447,8 @@
 
 	ioctl(fd, UI_SET_KEYBIT, KEY_PLAYPAUSE);
 	ioctl(fd, UI_SET_KEYBIT, KEY_STOP);
-	ioctl(fd, UI_SET_KEYBIT, KEY_NEXT);
-	ioctl(fd, UI_SET_KEYBIT, KEY_PREVIOUS);
+	ioctl(fd, UI_SET_KEYBIT, KEY_NEXTSONG);
+	ioctl(fd, UI_SET_KEYBIT, KEY_PREVIOUSSONG);
 	ioctl(fd, UI_SET_KEYBIT, KEY_REWIND);
 	ioctl(fd, UI_SET_KEYBIT, KEY_FORWARD);
 
@@ -560,11 +560,11 @@
 		break;
 	case NEXT_OP:
 		debug("AVRCP: NEXT %s", status);
-		send_key(session->uinput, KEY_NEXT, pressed);
+		send_key(session->uinput, KEY_NEXTSONG, pressed);
 		break;
 	case PREV_OP:
 		debug("AVRCP: PREV %s", status);
-		send_key(session->uinput, KEY_PREVIOUS, pressed);
+		send_key(session->uinput, KEY_PREVIOUSSONG, pressed);
 		break;
 	case REWIND_OP:
 		debug("AVRCP: REWIND %s", status);

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Re: [Bluez-users] Using AVRCP with current BlueZ

[Johan Hedberg]

On Nov 23, 2007, at 14:00, Csillag Krist=F3f wrote:
> One more question: what was the reason to use
>
> KEY_NEXT and KEY_PREVIOUS, instead of
> KEY_NEXTSONG and KEY_PREVIOUSSONG?

No special reason, except that the names of the key codes matched more  =

precisely the AVRCP spec.

> The latter are below-256 keycodes (like KEY_PLAYPAUSE,
> which is used by BlueZ for pause) handled nicely by
> all applications (like keytouch), where the former, which
> are currently used, are extended codes, mostly unsupported
> in user-space.

If this improves interoperability with existing applications then it's  =

probably a good idea to apply your patch. I'll commit it to CVS later  =

today unless somebody has a good reason why it shouldn't be done.

Johan
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