控制音量混合器

Question

我希望控制其他应用程序（如Firefox）的音量。

我可以使用 音量混合器 进行操作。

音量混合器 的库是什么？

- user1974519

---

这在Windows上是通过WASAPI（Windows音频会话API）实现的。您需要使用一个包装器，可以通过搜索"c# wasapi"来寻找相关信息。 - Hans Passant

@Simon Mourier 我认为这段代码控制了系统音量。我想仅控制 Firefox 的音量。 - user1974519

我一直在开发一个CoreAudio库，用于.NET。该库是免费且开源的。 商业版的MixerProNET库提供了更强大的实现。 - xfx

Answer 1

这是一个示例C#控制台应用程序，它可以做到这一点。它基于Windows核心音频库。它仅适用于Windows 7及更高版本。

using System;
using System.Runtime.InteropServices;
using System.Collections.Generic;

namespace SetAppVolumne
{
    class Program
    {
        static void Main(string[] args)
        {
            const string app = "Mozilla Firefox";

            foreach (string name in EnumerateApplications())
            {
                Console.WriteLine("name:" + name);
                if (name == app)
                {
                    // display mute state & volume level (% of master)
                    Console.WriteLine("Mute:" + GetApplicationMute(app));
                    Console.WriteLine("Volume:" + GetApplicationVolume(app));

                    // mute the application
                    SetApplicationMute(app, true);

                    // set the volume to half of master volume (50%)
                    SetApplicationVolume(app, 50);
                }
            }
        }

        public static float? GetApplicationVolume(string name)
        {
            ISimpleAudioVolume volume = GetVolumeObject(name);
            if (volume == null)
                return null;

            float level;
            volume.GetMasterVolume(out level);
            return level * 100;
        }

        public static bool? GetApplicationMute(string name)
        {
            ISimpleAudioVolume volume = GetVolumeObject(name);
            if (volume == null)
                return null;

            bool mute;
            volume.GetMute(out mute);
            return mute;
        }

        public static void SetApplicationVolume(string name, float level)
        {
            ISimpleAudioVolume volume = GetVolumeObject(name);
            if (volume == null)
                return;

            Guid guid = Guid.Empty;
            volume.SetMasterVolume(level / 100, ref guid);
        }

        public static void SetApplicationMute(string name, bool mute)
        {
            ISimpleAudioVolume volume = GetVolumeObject(name);
            if (volume == null)
                return;

            Guid guid = Guid.Empty;
            volume.SetMute(mute, ref guid);
        }

        public static IEnumerable<string> EnumerateApplications()
        {
            // get the speakers (1st render + multimedia) device
            IMMDeviceEnumerator deviceEnumerator = (IMMDeviceEnumerator)(new MMDeviceEnumerator());
            IMMDevice speakers;
            deviceEnumerator.GetDefaultAudioEndpoint(EDataFlow.eRender, ERole.eMultimedia, out speakers);

            // activate the session manager. we need the enumerator
            Guid IID_IAudioSessionManager2 = typeof(IAudioSessionManager2).GUID;
            object o;
            speakers.Activate(ref IID_IAudioSessionManager2, 0, IntPtr.Zero, out o);
            IAudioSessionManager2 mgr = (IAudioSessionManager2)o;

            // enumerate sessions for on this device
            IAudioSessionEnumerator sessionEnumerator;
            mgr.GetSessionEnumerator(out sessionEnumerator);
            int count;
            sessionEnumerator.GetCount(out count);

            for (int i = 0; i < count; i++)
            {
                IAudioSessionControl ctl;
                sessionEnumerator.GetSession(i, out ctl);
                string dn;
                ctl.GetDisplayName(out dn);
                yield return dn;
                Marshal.ReleaseComObject(ctl);
            }
            Marshal.ReleaseComObject(sessionEnumerator);
            Marshal.ReleaseComObject(mgr);
            Marshal.ReleaseComObject(speakers);
            Marshal.ReleaseComObject(deviceEnumerator);
        }

        private static ISimpleAudioVolume GetVolumeObject(string name)
        {
            // get the speakers (1st render + multimedia) device
            IMMDeviceEnumerator deviceEnumerator = (IMMDeviceEnumerator)(new MMDeviceEnumerator());
            IMMDevice speakers;
            deviceEnumerator.GetDefaultAudioEndpoint(EDataFlow.eRender, ERole.eMultimedia, out speakers);

            // activate the session manager. we need the enumerator
            Guid IID_IAudioSessionManager2 = typeof(IAudioSessionManager2).GUID;
            object o;
            speakers.Activate(ref IID_IAudioSessionManager2, 0, IntPtr.Zero, out o);
            IAudioSessionManager2 mgr = (IAudioSessionManager2)o;

            // enumerate sessions for on this device
            IAudioSessionEnumerator sessionEnumerator;
            mgr.GetSessionEnumerator(out sessionEnumerator);
            int count;
            sessionEnumerator.GetCount(out count);

            // search for an audio session with the required name
            // NOTE: we could also use the process id instead of the app name (with IAudioSessionControl2)
            ISimpleAudioVolume volumeControl = null;
            for (int i = 0; i < count; i++)
            {
                IAudioSessionControl ctl;
                sessionEnumerator.GetSession(i, out ctl);
                string dn;
                ctl.GetDisplayName(out dn);
                if (string.Compare(name, dn, StringComparison.OrdinalIgnoreCase) == 0)
                {
                    volumeControl = ctl as ISimpleAudioVolume;
                    break;
                }
                Marshal.ReleaseComObject(ctl);
            }
            Marshal.ReleaseComObject(sessionEnumerator);
            Marshal.ReleaseComObject(mgr);
            Marshal.ReleaseComObject(speakers);
            Marshal.ReleaseComObject(deviceEnumerator);
            return volumeControl;
        }
    }

    [ComImport]
    [Guid("BCDE0395-E52F-467C-8E3D-C4579291692E")]
    internal class MMDeviceEnumerator
    {
    }

    internal enum EDataFlow
    {
        eRender,
        eCapture,
        eAll,
        EDataFlow_enum_count
    }

    internal enum ERole
    {
        eConsole,
        eMultimedia,
        eCommunications,
        ERole_enum_count
    }

    [Guid("A95664D2-9614-4F35-A746-DE8DB63617E6"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    internal interface IMMDeviceEnumerator
    {
        int NotImpl1();

        [PreserveSig]
        int GetDefaultAudioEndpoint(EDataFlow dataFlow, ERole role, out IMMDevice ppDevice);

        // the rest is not implemented
    }

    [Guid("D666063F-1587-4E43-81F1-B948E807363F"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    internal interface IMMDevice
    {
        [PreserveSig]
        int Activate(ref Guid iid, int dwClsCtx, IntPtr pActivationParams, [MarshalAs(UnmanagedType.IUnknown)] out object ppInterface);

        // the rest is not implemented
    }

    [Guid("77AA99A0-1BD6-484F-8BC7-2C654C9A9B6F"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    internal interface IAudioSessionManager2
    {
        int NotImpl1();
        int NotImpl2();

        [PreserveSig]
        int GetSessionEnumerator(out IAudioSessionEnumerator SessionEnum);

        // the rest is not implemented
    }

    [Guid("E2F5BB11-0570-40CA-ACDD-3AA01277DEE8"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    internal interface IAudioSessionEnumerator
    {
        [PreserveSig]
        int GetCount(out int SessionCount);

        [PreserveSig]
        int GetSession(int SessionCount, out IAudioSessionControl Session);
    }

    [Guid("F4B1A599-7266-4319-A8CA-E70ACB11E8CD"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    internal interface IAudioSessionControl
    {
        int NotImpl1();

        [PreserveSig]
        int GetDisplayName([MarshalAs(UnmanagedType.LPWStr)] out string pRetVal);

        // the rest is not implemented
    }

    [Guid("87CE5498-68D6-44E5-9215-6DA47EF883D8"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    internal interface ISimpleAudioVolume
    {
        [PreserveSig]
        int SetMasterVolume(float fLevel, ref Guid EventContext);

        [PreserveSig]
        int GetMasterVolume(out float pfLevel);

        [PreserveSig]
        int SetMute(bool bMute, ref Guid EventContext);

        [PreserveSig]
        int GetMute(out bool pbMute);
    }
}

注意：我并没有完全定义接口，只定义了必要的接口以使代码正常工作。

- Simon Mourier

---

或许你可以尝试使用“Spotify”代替“Mozilla Firefox”。 - Simon Mourier

已经尝试过了，但音量混合器没有返回Spotify的“DisplayName”，它只会返回Firefox和某些.dll文件的“DisplayName”。 - joostmakaay

在Windows 7上，有一个名为IAudioSessionControl2的接口，可以获取进程ID。从那里，您可以确定它是否是Spotify。如果您不知道如何操作，请提出另一个问题。 - Simon Mourier

@bliss - 这是另一个问题，所以像我说的那样，你应该提出另一个问题。 - Simon Mourier

@Simon Mourier - 我在 EnumerateApplications() 函数中遇到了这个错误 - 这是截图：http://i.imgur.com/YzbgOKH.png 你能帮忙吗？ - csharp newbie

Answer 2

我知道现在可能太晚了，但最近我需要这个。我尝试了Simon的答案，但无法使其工作。我也尝试了ElektroStudios的评论和Simon的其他回答，但还是没有效果。我不知道哪里出了问题，但最终放弃了。

后来我发现这个答案，并使用CSCore，使其成功运行。

private static void Main(string[] args)
{
    using (var sessionManager = GetDefaultAudioSessionManager2(DataFlow.Render))
    {
        using (var sessionEnumerator = sessionManager.GetSessionEnumerator())
        {
            foreach (var session in sessionEnumerator)
            {
                using (var simpleVolume = session.QueryInterface<SimpleAudioVolume>())
                using (var sessionControl = session.QueryInterface<AudioSessionControl2>())
                {
                    if (sessionControl.ProcessID == 2436)
                        simpleVolume.MasterVolume = 0.5f;
                }
            }
        }
    }

    Console.ReadKey();
}

private static AudioSessionManager2 GetDefaultAudioSessionManager2(DataFlow dataFlow)
{
    using (var enumerator = new MMDeviceEnumerator())
    {
        using (var device = enumerator.GetDefaultAudioEndpoint(dataFlow, Role.Multimedia))
        {
            Debug.WriteLine("DefaultDevice: " + device.FriendlyName);
            var sessionManager = AudioSessionManager2.FromMMDevice(device);
            return sessionManager;
        }
    }
}

- Elfor