在过去的两天里，我一直在寻找一种通过Raspiberry pi无头扬声器控制iPhone上媒体播放的方法。
我已使用以下教程成功设置了pi： Headless A2DP Audio Streaming on Raspbian Stretch 现在我正在寻找一种方法来控制树莓派中音频流的播放。
我一直在研究MediaTransport1，MediaPlayer1，MediaControl1，但不幸的是我没有成功。
为您提供一些我所进行的反复试验的示例：
针对：
dbus-send --system --print-reply --dest=org.bluez /org/bluez/hci0/dev_C8_85_50_B1_C8_6B org.bluez.MediaPlayer1.Pause
我收到了：
Error org.freedesktop.DBus.Error.UnknownMethod: Method "Pause" with signature "" on interface "org.bluez.MediaPlayer1" doesn't exist
对于
qdbus --system org.bluez /org/bluez/hci0/dev_C8_85_50_B1_C8_6B/fd0 org.freedesktop.DBus.Properties.Set org.bluez.MediaTransport1 Volume 127
我收到了
Error: org.freedesktop.DBus.Error.InvalidSignature
Invalid signature for 'Volume'
另外，我发现一个播放器，我以为我可以用来构建自己的脚本作为示例Here，但出现错误：
pi@raspberrypi:~/blueutils $ python simpleplayer.py
Available commands:
PropertiesChanged(interface, properties)
help(cmd)
Use python syntax to pass arguments to available methods.
E.g.: PropertiesChanged({'Metadata' : {'Title': 'My title', 'Album': 'my album' }})
>>> <Interface <ProxyObject wrapping <dbus._dbus.SystemBus (system) at 0xb61968d0> :1.13 /org/bluez/hci0 at 0xb619db70> implementing 'org.bluez.Media1' at 0xb619dc50>
Traceback (most recent call last):
File "simpleplayer.py", line 197, in <module>
media.RegisterPlayer(dbus.ObjectPath(path), player.properties)
File "/usr/lib/python2.7/dist-packages/dbus/proxies.py", line 70, in __call__
return self._proxy_method(*args, **keywords)
File "/usr/lib/python2.7/dist-packages/dbus/proxies.py", line 145, in __call__
**keywords)
File "/usr/lib/python2.7/dist-packages/dbus/connection.py", line 651, in call_blocking
message, timeout)
dbus.exceptions.DBusException: org.bluez.Error.NotSupported: Operation is not supported
当我进行内省时
dbus-send --system --print-reply --dest=org.bluez /org/bluez/hci0 org.freedesktop.DBus.Introspectable.Introspect
我得到了他：
<node>
<interface name="org.freedesktop.DBus.Introspectable">
<method name="Introspect">
<arg name="xml" type="s" direction="out"/>
</method>
</interface>
<interface name="org.bluez.Adapter1">
<method name="StartDiscovery"></method>
<method name="SetDiscoveryFilter">
<arg name="properties" type="a{sv}" direction="in"/>
</method>
<method name="StopDiscovery"></method>
<method name="RemoveDevice">
<arg name="device" type="o" direction="in"/>
</method>
<property name="Address" type="s" access="read"></property>
<property name="Name" type="s" access="read"></property>
<property name="Alias" type="s" access="readwrite"></property>
<property name="Class" type="u" access="read"></property>
<property name="Powered" type="b" access="readwrite"></property>
<property name="Discoverable" type="b" access="readwrite"></property>
<property name="DiscoverableTimeout" type="u" access="readwrite"></property>]
<property name="Pairable" type="b" access="readwrite"></property>
<property name="PairableTimeout" type="u" access="readwrite"></property>
<property name="Discovering" type="b" access="read"></property>
<property name="UUIDs" type="as" access="read"></property>
<property name="Modalias" type="s" access="read"></property>
</interface>
<interface name="org.freedesktop.DBus.Properties">
<method name="Get">
<arg name="interface" type="s" direction="in"/>
<arg name="name" type="s" direction="in"/>
<arg name="value" type="v" direction="out"/>
</method>
<method name="Set">
<arg name="interface" type="s" direction="in"/>
<arg name="name" type="s" direction="in"/>
<arg name="value" type="v" direction="in"/>
</method>
<method name="GetAll">
<arg name="interface" type="s" direction="in"/>
<arg name="properties" type="a{sv}" direction="out"/>
</method>
<signal name="PropertiesChanged">
<arg name="interface" type="s"/>
<arg name="changed_properties" type="a{sv}"/>
<arg name="invalidated_properties" type="as"/>
</signal>
</interface>
<interface name="org.bluez.GattManager1">
<method name="RegisterApplication">
<arg name="application" type="o" direction="in"/>
<arg name="options" type="a{sv}" direction="in"/>
</method>
<method name="UnregisterApplication">
<arg name="application" type="o" direction="in"/>
</method>
</interface>
<interface name="org.bluez.Media1">
<method name="RegisterEndpoint">
<arg name="endpoint" type="o" direction="in"/>
<arg name="properties" type="a{sv}" direction="in"/>
</method>
<method name="UnregisterEndpoint">
<arg name="endpoint" type="o" direction="in"/>
</method>
<method name="RegisterPlayer">
<arg name="player" type="o" direction="in"/>
<arg name="properties" type="a{sv}" direction="in"/>
</method>
<method name="UnregisterPlayer">
<arg name="player" type="o" direction="in"/>
</method>
</interface>
<node name="dev_40_9C_28_07_63_DD"/>
<node name="dev_C8_85_50_B1_C8_6B"/>
</node>
有人可以帮我解决这个问题吗，或者有人知道使用树莓派控制手机上音乐播放的过程吗？
致谢。
更新1： 非常感谢@Parthiban，它的运行非常完美。
此外，我不得不说，我按照此处的指导Install bluez on the Raspberry Pi将bluez版本重新安装到5.50，因为我看不到/ playerX（本例中为0）。在我编译源代码之前，我做了一些额外的工作（不确定它是否相关，但是没有影响），我添加了.auto_connect = true
所示的avrcp配置文件：
希望这可以帮助所有可能遇到我问题的人
答案 0 :(得分：2)
您需要指定签名以将音量设置如下，
dbus-send --system --print-reply --type=method_call --dest='org.bluez' '/org/bluez/hci0/dev_C8_85_50_B1_C8_6B/fd0' org.freedesktop.DBus.Properties.Set string:"org.bluez.MediaTransport1" string:"Volume" variant:uint16:127
这是因为，如dbus specification中所述，使用set时需要指定三个参数，
对于暂停方法，请使用“ org.bluez.MediaPlayer1”浏览设备的“ org.freedesktop.DBus.Introspectable.Introspect”界面。您用于访问方法“暂停”的对象路径错误。如here所述，您需要使用“ [variable prefix]/{hci0,hci1,...}/dev_XX_XX_XX_XX_XX_XX/playerX”。
因此，就您而言，应该是
dbus-send --system --print-reply --type=method_call --dest='org.bluez' '/org/bluez/hci0/dev_C8_85_50_B1_C8_6B/playerX' org.bluez.MediaPlayer1.Pause
需要将播放器X替换为设备播放器的地方（您可以从Introspect获得该播放器，也可以观看“ InterfaceAdded”信号。