本文记录使用 PulseAudio 在 Linux 系统上进行设置和获取当前音量，以及是否静音。当系统音量发生变更时，收到事件通知
本文使用的工具类由 lsj 工具人提供，我只是代为记录
演示的使用方法的代码如下
if (!OperatingSystem.IsLinux())
{
return;
}
var pulseAudioVolumeManager = new PulseAudioVolumeManager();
await pulseAudioVolumeManager.Init();
pulseAudioVolumeManager.VolumeChanged += (sender, volume) =>
{
Console.WriteLine($"音量变化，当前音量：{volume}");
};
pulseAudioVolumeManager.MuteChanged += (sender, isMute) =>
{
Console.WriteLine($"静音变化，当前是否静音：{isMute}");
};
while (true)
{
Console.WriteLine($"是否静音：{await pulseAudioVolumeManager.GetMute()}; 音量：{await pulseAudioVolumeManager.GetVolume()}");
Console.WriteLine($"输入数字修改音量，输入 y/n 设置是否静音");
var line = Console.ReadLine();
if (int.TryParse(line, out var n))
{
Console.WriteLine($"设置音量为：{n}");
await pulseAudioVolumeManager.SetVolume(n);
}
else if(line is not null)
{
var text = line.ToLowerInvariant();
if (text == "y")
{
Console.WriteLine($"设置是否静音：是");
await pulseAudioVolumeManager.SetMute(true);
}
else if (text == "n")
{
Console.WriteLine($"设置是否静音：否");
await pulseAudioVolumeManager.SetMute(false);
}
}
}
此代码是完全 C# dotnet 系列的，意味着不挑 UI 框架，可以在 Avalonia 或 UNO 或 CPF 等上层 UI 框架里使用
以上代码用到的 PulseAudioVolumeManager 封装代码如下
/// <summary>
/// “脉冲”音量管理，这是基于 PulseAudio 的封装
/// </summary>
[SupportedOSPlatform("linux")]
public partial class PulseAudioVolumeManager
{
private TaskCompletionSource<bool>? _initTaskCompletionSource;
private IntPtr _mainLoop;
private IntPtr _context;
private readonly pa_context_subscribe_cb_t _contextSubscribeCallback;
private int? _volume;
private bool? _mute;
private readonly string _applicationName;
public event EventHandler<int>? VolumeChanged;
public event EventHandler<bool>? MuteChanged;
/// <summary>
/// 创建“脉冲”音量管理
/// </summary>
/// <param name="applicationName">应用名，可选，只是用于调用 pa_context_new 时传入，无特别含义和作用</param>
public PulseAudioVolumeManager(string? applicationName = null)
{
_applicationName = applicationName ?? Path.GetRandomFileName().Replace('.', '_');
_contextSubscribeCallback = ContextSubscribeCallback;
}
public async Task<bool> Init()
{
if (_initTaskCompletionSource == null)
{
bool isReady = false;
_initTaskCompletionSource = new TaskCompletionSource<bool>();
_mainLoop = pa_threaded_mainloop_new();
if (_mainLoop != IntPtr.Zero)
{
var mainloopApi = pa_threaded_mainloop_get_api(_mainLoop);
if (mainloopApi != IntPtr.Zero)
{
var context = pa_context_new(mainloopApi, _applicationName);
if (context != IntPtr.Zero)
{
pa_context_set_state_callback(context, ContextStateCallback, IntPtr.Zero);
await Task.Run(() =>
{
var result = pa_context_connect(context, IntPtr.Zero, 0, IntPtr.Zero);
if (result < 0)
{
return;
}
result = pa_threaded_mainloop_start(_mainLoop);
if (result < 0)
{
return;
}
while (true)
{
var state = pa_context_get_state(context);
if (state == pa_context_state_t.PA_CONTEXT_READY)
{
isReady = true;
_context = context;
break;
}
if (!PA_CONTEXT_IS_GOOD(state))
{
return;
}
pa_threaded_mainloop_wait(_mainLoop);
}
});
}
}
}
_initTaskCompletionSource.SetResult(isReady);
return isReady;
}
else
{
return await _initTaskCompletionSource.Task;
}
}
private void ContextStateCallback(IntPtr c, IntPtr userdata)
{
switch (pa_context_get_state(c))
{
case pa_context_state_t.PA_CONTEXT_READY:
pa_context_set_subscribe_callback(c, _contextSubscribeCallback, IntPtr.Zero);
var op = pa_context_subscribe(c, pa_subscription_mask_t.PA_SUBSCRIPTION_MASK_SINK, IntPtr.Zero, IntPtr.Zero);
pa_operation_unref(op);
pa_threaded_mainloop_signal(_mainLoop, 0);
break;
case pa_context_state_t.PA_CONTEXT_TERMINATED:
case pa_context_state_t.PA_CONTEXT_FAILED:
pa_threaded_mainloop_signal(_mainLoop, 0);
break;
}
}
private void ContextSubscribeCallback(IntPtr c, pa_subscription_event_type_t t, uint idx, IntPtr userdata)
{
if ((t & pa_subscription_event_type_t.PA_SUBSCRIPTION_EVENT_FACILITY_MASK) == pa_subscription_event_type_t.PA_SUBSCRIPTION_EVENT_SINK)
{
Task.Run(() =>
{
int? volume = null;
bool? mute = null;
pa_threaded_mainloop_lock(_mainLoop);
var sinkName = GetDefaultSinkName(c);
if (sinkName != null)
{
var info = GetSinkInfo(c, sinkName);
volume = GetVolumeValue(info.volume);
mute = info.mute;
}
pa_threaded_mainloop_unlock(_mainLoop);
if (volume is int volumeVal && volumeVal != _volume)
{
_volume = volumeVal;
VolumeChanged?.Invoke(this, volumeVal);
}
if (mute is bool muteVal && muteVal != _mute)
{
_mute = muteVal;
MuteChanged?.Invoke(this, muteVal);
}
});
}
}
private void ServerInfoCallback(IntPtr c, in pa_server_info i, IntPtr userdata)
{
unsafe
{
#pragma warning disable CS8500
*(string*) userdata = Marshal.PtrToStringUTF8(i.default_sink_name);
#pragma warning restore CS8500
pa_threaded_mainloop_signal(_mainLoop, 0);
}
}
private void SinkInfoCallback(IntPtr c, in pa_sink_info i, int eol, IntPtr userdata)
{
if (eol != 0)
{
pa_threaded_mainloop_signal(_mainLoop, 0);
return;
}
unsafe
{
*((pa_cvolume, bool)*) userdata = (i.volume, i.mute != 0);
}
}
public async Task<bool> GetMute()
{
bool result = false;
if (_context != IntPtr.Zero)
{
await Task.Run(() =>
{
pa_threaded_mainloop_lock(_mainLoop);
var sinkName = GetDefaultSinkName(_context);
if (sinkName != null)
{
var (volume, mute) = GetSinkInfo(_context, sinkName);
result = mute;
}
pa_threaded_mainloop_unlock(_mainLoop);
});
}
return result;
}
public async Task<int> GetVolume()
{
int result = 50;
if (_context != IntPtr.Zero)
{
await Task.Run(() =>
{
pa_threaded_mainloop_lock(_mainLoop);
var sinkName = GetDefaultSinkName(_context);
if (sinkName != null)
{
var (volume, mute) = GetSinkInfo(_context, sinkName);
result = GetVolumeValue(volume);
}
pa_threaded_mainloop_unlock(_mainLoop);
});
}
return result;
}
public async Task SetMute(bool mute)
{
if (_context != IntPtr.Zero)
{
await Task.Run(() =>
{
pa_threaded_mainloop_lock(_mainLoop);
var sinkName = GetDefaultSinkName(_context);
if (sinkName != null)
{
pa_context_set_sink_mute_by_name(_context, sinkName, mute ? 1 : 0, IntPtr.Zero, IntPtr.Zero);
}
pa_threaded_mainloop_unlock(_mainLoop);
});
}
}
public async Task SetVolume(int volume)
{
if (_context != IntPtr.Zero)
{
await Task.Run(() =>
{
pa_threaded_mainloop_lock(_mainLoop);
var sinkName = GetDefaultSinkName(_context);
if (sinkName != null)
{
var info = GetSinkInfo(_context, sinkName);
pa_cvolume_set(ref info.volume, info.volume.channels, (uint) (volume * 65536 / 100));
pa_context_set_sink_volume_by_name(_context, sinkName, info.volume, IntPtr.Zero, IntPtr.Zero);
}
pa_threaded_mainloop_unlock(_mainLoop);
});
}
}
/// <summary>
/// 获取默认的输出设备名称
/// 这个方法要在 pa_threaded_mainloop_lock 和 pa_threaded_mainloop_unlock 之间调用
/// </summary>
/// <returns></returns>
private string? GetDefaultSinkName(IntPtr context)
{
unsafe
{
string? sinkName = null;
// 取 sinkName 地址，相当于 ref string 用法，在 ServerInfoCallback 给 sinkName 赋值
var op = pa_context_get_server_info(context, ServerInfoCallback, (IntPtr) (&sinkName));
while (pa_operation_get_state(op) == pa_operation_state_t.PA_OPERATION_RUNNING)
{
pa_threaded_mainloop_wait(_mainLoop);
}
pa_operation_unref(op);
return sinkName;
}
}
/// <summary>
/// 获取默认的输出设备信息
/// 这个方法要在 pa_threaded_mainloop_lock 和 pa_threaded_mainloop_unlock 之间调用
/// </summary>
/// <param name="context"></param>
/// <param name="sinkName"></param>
/// <returns></returns>
private (pa_cvolume volume, bool mute) GetSinkInfo(IntPtr context, string sinkName)
{
unsafe
{
(pa_cvolume, bool) info;
var op = pa_context_get_sink_info_by_name(context, sinkName, SinkInfoCallback, (IntPtr) (&info));
while (pa_operation_get_state(op) == pa_operation_state_t.PA_OPERATION_RUNNING)
{
pa_threaded_mainloop_wait(_mainLoop);
}
pa_operation_unref(op);
return info;
}
}
private int GetVolumeValue(in pa_cvolume volume)
{
var val = pa_cvolume_avg(volume);
return (int) Math.Round((val * 100d / 65536));
}
}
public partial class PulseAudioVolumeManager
{
public static class PInvoke
{
public enum pa_context_state_t
{
PA_CONTEXT_UNCONNECTED,
PA_CONTEXT_CONNECTING,
PA_CONTEXT_AUTHORIZING,
PA_CONTEXT_SETTING_NAME,
PA_CONTEXT_READY,
PA_CONTEXT_FAILED,
PA_CONTEXT_TERMINATED,
}
[Flags]
public enum pa_subscription_event_type_t : uint
{
PA_SUBSCRIPTION_EVENT_SINK = 0x0000U,
PA_SUBSCRIPTION_EVENT_SOURCE = 0x0001U,
PA_SUBSCRIPTION_EVENT_SINK_INPUT = 0x0002U,
PA_SUBSCRIPTION_EVENT_SOURCE_OUTPUT = 0x0003U,
PA_SUBSCRIPTION_EVENT_MODULE = 0x0004U,
PA_SUBSCRIPTION_EVENT_CLIENT = 0x0005U,
PA_SUBSCRIPTION_EVENT_SAMPLE_CACHE = 0x0006U,
PA_SUBSCRIPTION_EVENT_SERVER = 0x0007U,
PA_SUBSCRIPTION_EVENT_AUTOLOAD = 0x0008U,
PA_SUBSCRIPTION_EVENT_CARD = 0x0009U,
PA_SUBSCRIPTION_EVENT_FACILITY_MASK = 0x000FU,
PA_SUBSCRIPTION_EVENT_NEW = 0x0000U,
PA_SUBSCRIPTION_EVENT_CHANGE = 0x0010U,
PA_SUBSCRIPTION_EVENT_REMOVE = 0x0020U,
PA_SUBSCRIPTION_EVENT_TYPE_MASK = 0x0030U,
}
public enum pa_subscription_mask_t : uint
{
PA_SUBSCRIPTION_MASK_NULL = 0x0000U,
PA_SUBSCRIPTION_MASK_SINK = 0x0001U,
PA_SUBSCRIPTION_MASK_SOURCE = 0x0002U,
PA_SUBSCRIPTION_MASK_SINK_INPUT = 0x0004U,
PA_SUBSCRIPTION_MASK_SOURCE_OUTPUT = 0x0008U,
PA_SUBSCRIPTION_MASK_MODULE = 0x0010U,
PA_SUBSCRIPTION_MASK_CLIENT = 0x0020U,
PA_SUBSCRIPTION_MASK_SAMPLE_CACHE = 0x0040U,
PA_SUBSCRIPTION_MASK_SERVER = 0x0080U,
PA_SUBSCRIPTION_MASK_AUTOLOAD = 0x0100U,
PA_SUBSCRIPTION_MASK_CARD = 0x0200U,
PA_SUBSCRIPTION_MASK_ALL = 0x02ffU,
}
public enum pa_sample_format_t
{
PA_SAMPLE_U8,
PA_SAMPLE_ALAW,
PA_SAMPLE_ULAW,
PA_SAMPLE_S16LE,
PA_SAMPLE_S16BE,
PA_SAMPLE_FLOAT32LE,
PA_SAMPLE_FLOAT32BE,
PA_SAMPLE_S32LE,
PA_SAMPLE_S32BE,
PA_SAMPLE_S24LE,
PA_SAMPLE_S24BE,
PA_SAMPLE_S24_32LE,
PA_SAMPLE_S24_32BE,
PA_SAMPLE_MAX,
PA_SAMPLE_INVALID = -1
}
public enum pa_operation_state_t
{
PA_OPERATION_RUNNING,
PA_OPERATION_DONE,
PA_OPERATION_CANCELLED,
}
[StructLayout(LayoutKind.Sequential)]
public struct pa_server_info
{
public IntPtr user_name;
public IntPtr host_name;
public IntPtr server_version;
public IntPtr server_name;
pa_sample_spec sample_spec;
public IntPtr default_sink_name;
public IntPtr default_source_name;
public uint cookie;
pa_channel_map channel_map;
}
[StructLayout(LayoutKind.Sequential)]
public struct pa_sample_spec
{
public pa_sample_format_t format;
public uint rate;
public byte channels;
}
[StructLayout(LayoutKind.Sequential, Size = 132)]
public struct pa_channel_map
{
public byte channels;
//public pa_channel_position_t map[PA_CHANNELS_MAX];
}
[StructLayout(LayoutKind.Sequential, Size = 132)]
public struct pa_cvolume
{
public byte channels;
//public pa_volume_t values[PA_CHANNELS_MAX];
}
[StructLayout(LayoutKind.Sequential)]
public struct pa_sink_info
{
public IntPtr name;
public uint index;
public IntPtr description;
public pa_sample_spec sample_spec;
public pa_channel_map channel_map;
public uint owner_module;
public pa_cvolume volume;
public int mute;
public uint monitor_source;
public IntPtr monitor_source_name;
public ulong latency;
public IntPtr driver;
public uint flags;
public IntPtr proplist;
public ulong configured_latency;
public uint base_volume;
public uint state;
public uint n_volume_steps;
public uint card;
public uint n_ports;
public IntPtr ports;
public IntPtr active_port;
public byte n_formats;
public IntPtr formats;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static bool PA_CONTEXT_IS_GOOD(pa_context_state_t x)
{
return x == pa_context_state_t.PA_CONTEXT_CONNECTING || x == pa_context_state_t.PA_CONTEXT_AUTHORIZING ||
x == pa_context_state_t.PA_CONTEXT_SETTING_NAME || x == pa_context_state_t.PA_CONTEXT_READY;
}
public delegate void pa_context_notify_cb_t(IntPtr c, IntPtr userdata);
public delegate void pa_context_subscribe_cb_t(IntPtr c, pa_subscription_event_type_t t, uint idx, IntPtr userdata);
public delegate void pa_server_info_cb_t(IntPtr c, in pa_server_info i, IntPtr userdata);
public delegate void pa_sink_info_cb_t(IntPtr c, in pa_sink_info i, int eol, IntPtr userdata);
[DllImport("libpulse.so.0")]
public static extern IntPtr pa_threaded_mainloop_new();
[DllImport("libpulse.so.0")]
public static extern IntPtr pa_threaded_mainloop_get_api(IntPtr m);
[DllImport("libpulse.so.0")]
public static extern IntPtr pa_context_new(IntPtr mainloop, [MarshalAs(UnmanagedType.LPUTF8Str)] string name);
[DllImport("libpulse.so.0")]
public static extern void pa_context_set_state_callback(IntPtr c, pa_context_notify_cb_t cb, IntPtr userdata);
[DllImport("libpulse.so.0")]
public static extern int pa_context_connect(IntPtr c, IntPtr server, uint flags, IntPtr api);
[DllImport("libpulse.so.0")]
public static extern int pa_threaded_mainloop_start(IntPtr m);
[DllImport("libpulse.so.0")]
public static extern pa_context_state_t pa_context_get_state(IntPtr c);
[DllImport("libpulse.so.0")]
public static extern void pa_threaded_mainloop_wait(IntPtr m);
[DllImport("libpulse.so.0")]
public static extern void pa_context_set_subscribe_callback(IntPtr c, pa_context_subscribe_cb_t cb, IntPtr userdata);
[DllImport("libpulse.so.0")]
public static extern IntPtr pa_context_subscribe(IntPtr c, pa_subscription_mask_t m, IntPtr cb, IntPtr userdata);
[DllImport("libpulse.so.0")]
public static extern void pa_operation_unref(IntPtr o);
[DllImport("libpulse.so.0")]
public static extern void pa_threaded_mainloop_signal(IntPtr m, int wait_for_accept);
[DllImport("libpulse.so.0")]
public static extern void pa_threaded_mainloop_lock(IntPtr m);
[DllImport("libpulse.so.0")]
public static extern void pa_threaded_mainloop_unlock(IntPtr m);
[DllImport("libpulse.so.0")]
public static extern IntPtr pa_context_get_server_info(IntPtr c, pa_server_info_cb_t cb, IntPtr userdata);
[DllImport("libpulse.so.0")]
public static extern pa_operation_state_t pa_operation_get_state(IntPtr o);
[DllImport("libpulse.so.0")]
public static extern IntPtr pa_context_get_sink_info_by_name(IntPtr c, [MarshalAs(UnmanagedType.LPUTF8Str)] string name, pa_sink_info_cb_t cb, IntPtr userdata);
[DllImport("libpulse.so.0")]
public static extern uint pa_cvolume_avg(in pa_cvolume a);
[DllImport("libpulse.so.0")]
public static extern IntPtr pa_cvolume_set(ref pa_cvolume a, uint channels, uint v);
[DllImport("libpulse.so.0")]
public static extern IntPtr pa_context_set_sink_mute_by_name(IntPtr c, [MarshalAs(UnmanagedType.LPUTF8Str)] string name, int mute, IntPtr cb, IntPtr userdata);
[DllImport("libpulse.so.0")]
public static extern IntPtr pa_context_set_sink_volume_by_name(IntPtr c, [MarshalAs(UnmanagedType.LPUTF8Str)] string name, in pa_cvolume volume, IntPtr cb, IntPtr userdata);
}
}
本文代码放在 github 和 gitee 上，可以使用如下命令行拉取代码
先创建一个空文件夹，接着使用命令行 cd 命令进入此空文件夹，在命令行里面输入以下代码，即可获取到本文的代码
git init
git remote add origin https://gitee.com/lindexi/lindexi_gd.git
git pull origin 7dc9f2c0ab4fd8557202b28e752aaff5a730ff9d
以上使用的是 gitee 的源，如果 gitee 不能访问，请替换为 github 的源。请在命令行继续输入以下代码，将 gitee 源换成 github 源进行拉取代码
git remote remove origin
git remote add origin https://github.com/lindexi/lindexi_gd.git
git pull origin 7dc9f2c0ab4fd8557202b28e752aaff5a730ff9d
获取代码之后，进入 LiwhallyawhuleLaqarhifehawhedem 文件夹，即可获取到源代码