前言
使用C#做音频录制时需要获取音频设备信息，比如使用ffmpeg进行录制需要先获取音频设备名称，再Windows上获取音频设备的方法有不少，其中比较简单的就是使用winmm，这是一套比较旧的api但是使用方法简单，当然有个缺陷就是音频名称不能超过32个字符，超过会被截断，当然如果作为winmm的采集或播放配套使用则不会有问题。
一、如何实现？
需要先导入winmm的api，以及定义存放音频设备信息的实体，最后通过调用api实现枚举设备功能。
1、DllImport接口
导入相关的api
（1）、方法
[DllImport("winmm.dll")]
public static extern uint waveInGetNumDevs();
[DllImport("winmm.dll")]
public static extern uint waveOutGetNumDevs();
[DllImport("winmm.dll")]
public static extern MMRESULT waveInGetDevCapsW(uint uDeviceID, out WAVEINCAPS pwic, uint cbwic);
[DllImport("winmm.dll")]
public static extern MMRESULT waveOutGetDevCapsW(uint uDeviceID, out WAVEOUTCAPS pwoc, uint cbwoc);
（2）、结构体
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
public struct WAVEINCAPS
{
public ushort wMid;
public ushort wPid;
public uint vDriverVersion;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
public string szPname;
public uint dwFormats;
public ushort wChannels;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
public struct WAVEOUTCAPS
{
public ushort wMid;
public ushort wPid;
public uint vDriverVersion;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
public string szPname;
public uint dwFormats;
public ushort wChannels;
public WAVECAPS dwSupport;
}
public enum DWFormats
{
WAVE_INVALIDFORMAT = 0x00000000, /* invalid format */
WAVE_FORMAT_1M08 = 0x00000001, /* 11.025 kHz, Mono, 8-bit */
WAVE_FORMAT_1S08 = 0x00000002, /* 11.025 kHz, Stereo, 8-bit */
WAVE_FORMAT_1M16 = 0x00000004, /* 11.025 kHz, Mono, 16-bit */
WAVE_FORMAT_1S16 = 0x00000008, /* 11.025 kHz, Stereo, 16-bit */
WAVE_FORMAT_2M08 = 0x00000010, /* 22.05 kHz, Mono, 8-bit */
WAVE_FORMAT_2S08 = 0x00000020, /* 22.05 kHz, Stereo, 8-bit */
WAVE_FORMAT_2M16 = 0x00000040, /* 22.05 kHz, Mono, 16-bit */
WAVE_FORMAT_2S16 = 0x00000080, /* 22.05 kHz, Stereo, 16-bit */
WAVE_FORMAT_4M08 = 0x00000100, /* 44.1 kHz, Mono, 8-bit */
WAVE_FORMAT_4S08 = 0x00000200, /* 44.1 kHz, Stereo, 8-bit */
WAVE_FORMAT_4M16 = 0x00000400, /* 44.1 kHz, Mono, 16-bit */
WAVE_FORMAT_4S16 = 0x00000800, /* 44.1 kHz, Stereo, 16-bit */
WAVE_FORMAT_44M08 = 0x00000100, /* 44.1 kHz, Mono, 8-bit */
WAVE_FORMAT_44S08 = 0x00000200, /* 44.1 kHz, Stereo, 8-bit */
WAVE_FORMAT_44M16 = 0x00000400, /* 44.1 kHz, Mono, 16-bit */
WAVE_FORMAT_44S16 = 0x00000800, /* 44.1 kHz, Stereo, 16-bit */
WAVE_FORMAT_48M08 = 0x00001000, /* 48 kHz, Mono, 8-bit */
WAVE_FORMAT_48S08 = 0x00002000, /* 48 kHz, Stereo, 8-bit */
WAVE_FORMAT_48M16 = 0x00004000, /* 48 kHz, Mono, 16-bit */
WAVE_FORMAT_48S16 = 0x00008000, /* 48 kHz, Stereo, 16-bit */
WAVE_FORMAT_96M08 = 0x00010000, /* 96 kHz, Mono, 8-bit */
WAVE_FORMAT_96S08 = 0x00020000, /* 96 kHz, Stereo, 8-bit */
WAVE_FORMAT_96M16 = 0x00040000, /* 96 kHz, Mono, 16-bit */
WAVE_FORMAT_96S16 = 0x00080000, /* 96 kHz, Stereo, 16-bit */
}
2、定义实体
需要定义声音格式
class SampleFormat
{
/// <summary>
/// 声道数
/// </summary>
public ushort Channels { set; get; }
/// <summary>
/// 采样率
/// </summary>
public uint SampleRate { set; get; }
/// <summary>
/// 位深
/// </summary>
public ushort BitsPerSample { set; get; }
};
以及声音设备实体
class AudioDevice
{
/// <summary>
/// 设备Id
/// </summary>
public uint Id { set; get; }
/// <summary>
/// 设备名称
/// </summary>
public string Name { set; get; } = "";
/// <summary>
/// 声道数
/// </summary>
public int Channels { set; get; }
/// <summary>
/// 支持的格式
/// </summary>
public IEnumerable<SampleFormat>? SupportedFormats { set; get; }
};
3、实现枚举
音频采集设备
/// <summary>
/// 枚举声音采集设备
/// </summary>
public static IEnumerable<AudioDevice> WaveInDevices
{
get
{
var deviceCount = waveInGetNumDevs();
for (uint i = 0; i < deviceCount; i++)
{
var sd = GetWaveInDeviceById(i);
if (sd != null) yield return sd;
}
}
}
/// <summary>
/// 通过id获取声音采集设备信息
/// </summary>
/// <param name="id">设备id</param>
/// <returns>设备对象</returns>
public static AudioDevice? GetWaveInDeviceById(uint id)
{
WAVEINCAPS pwic;//声音设备功能信息
var result = waveInGetDevCapsW(id, out pwic, (uint)Marshal.SizeOf<WAVEINCAPS>());
if (result != MMRESULT.MMSYSERR_NOERROR) return null;
AudioDevice sd = new AudioDevice();
sd.Id = id;
sd.Channels = pwic.wChannels;
sd.Name = pwic.szPname;
sd.SupportedFormats = _GetSurportFormats(pwic.dwFormats);
return sd;
}
音频播放设备
/// <summary>
/// 枚举声音播放设备
/// </summary>
public static IEnumerable<AudioDevice> WaveOutDevices
{
get
{
var deviceCount = waveOutGetNumDevs();
for (uint i = 0; i < deviceCount; i++)
{
var sd = GetWaveOutDeviceById(i);
if (sd != null) yield return sd;
}
}
}
/// <summary>
/// 通过id获取声音播放设备信息
/// </summary>
/// <param name="id">设备id</param>
/// <returns>设备对象</returns>
public static AudioDevice? GetWaveOutDeviceById(uint id)
{
WAVEOUTCAPS pwic;//声音设备功能信息
var result = waveOutGetDevCapsW(id, out pwic, (uint)Marshal.SizeOf<WAVEOUTCAPS>());
if (result != MMRESULT.MMSYSERR_NOERROR) return null;
AudioDevice sd = new AudioDevice();
sd.Id = id;
sd.Channels = pwic.wChannels;
sd.Name = pwic.szPname;
sd.SupportedFormats = _GetSurportFormats(pwic.dwFormats);
return sd;
}
二、完整代码
class Winmm
{
/// <summary>
/// 枚举声音采集设备
/// </summary>
public static IEnumerable<AudioDevice> WaveInDevices
{
get
{
var deviceCount = waveInGetNumDevs();
for (uint i = 0; i < deviceCount; i++)
{
var sd = GetWaveInDeviceById(i);
if (sd != null) yield return sd;
}
}
}
/// <summary>
/// 枚举声音播放设备
/// </summary>
public static IEnumerable<AudioDevice> WaveOutDevices
{
get
{
var deviceCount = waveOutGetNumDevs();
for (uint i = 0; i < deviceCount; i++)
{
var sd = GetWaveOutDeviceById(i);
if (sd != null) yield return sd;
}
}
}
/// <summary>
/// 通过id获取声音采集设备信息
/// </summary>
/// <param name="id">设备id</param>
/// <returns>设备对象</returns>
public static AudioDevice? GetWaveInDeviceById(uint id)
{
WAVEINCAPS pwic;//声音设备功能信息
var result = waveInGetDevCapsW(id, out pwic, (uint)Marshal.SizeOf<WAVEINCAPS>());
if (result != MMRESULT.MMSYSERR_NOERROR) return null;
AudioDevice sd = new AudioDevice();
sd.Id = id;
sd.Channels = pwic.wChannels;
sd.Name = pwic.szPname;
sd.SupportedFormats = _GetSurportFormats(pwic.dwFormats);
return sd;
}
/// <summary>
/// 通过id获取声音播放设备信息
/// </summary>
/// <param name="id">设备id</param>
/// <returns>设备对象</returns>
public static AudioDevice? GetWaveOutDeviceById(uint id)
{
WAVEOUTCAPS pwic;//声音设备功能信息
var result = waveOutGetDevCapsW(id, out pwic, (uint)Marshal.SizeOf<WAVEOUTCAPS>());
if (result != MMRESULT.MMSYSERR_NOERROR) return null;
AudioDevice sd = new AudioDevice();
sd.Id = id;
sd.Channels = pwic.wChannels;
sd.Name = pwic.szPname;
sd.SupportedFormats = _GetSurportFormats(pwic.dwFormats);
return sd;
}
static List<SampleFormat> _GetSurportFormats(uint foramts)
{
var sfs = new List<SampleFormat>();
foreach (var j in Enum.GetValues<DWFormats>())
{
if ((foramts & (uint)j) != 0)
{
var name = Enum.GetName(j)!.Split("_").Last();
var sp = name.Substring(0, name.Length - 3);
var ch = name.Substring(name.Length - 3, 1);
var bp = name.Substring(name.Length - 2, 2);
uint isp = 0;
switch (sp)
{
case "1": isp = 11025; break;
case "2": isp = 22050; break;
case "4": isp = 44100; break;
case "44": isp = 44100; break;
case "48": isp = 48000; break;
case "96": isp = 96000; break;
}
sfs.Add(new SampleFormat() { Channels = (ushort)(ch == "S" ? 1 : 2), SampleRate = isp, BitsPerSample = ushort.Parse(bp) });
}
}
return sfs;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
public struct WAVEINCAPS
{
public ushort wMid;
public ushort wPid;
public uint vDriverVersion;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
public string szPname;
public uint dwFormats;
public ushort wChannels;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
public struct WAVEOUTCAPS
{
public ushort wMid;
public ushort wPid;
public uint vDriverVersion;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
public string szPname;
public uint dwFormats;
public ushort wChannels;
public WAVECAPS dwSupport;
}
public enum DWFormats
{
WAVE_INVALIDFORMAT = 0x00000000, /* invalid format */
WAVE_FORMAT_1M08 = 0x00000001, /* 11.025 kHz, Mono, 8-bit */
WAVE_FORMAT_1S08 = 0x00000002, /* 11.025 kHz, Stereo, 8-bit */
WAVE_FORMAT_1M16 = 0x00000004, /* 11.025 kHz, Mono, 16-bit */
WAVE_FORMAT_1S16 = 0x00000008, /* 11.025 kHz, Stereo, 16-bit */
WAVE_FORMAT_2M08 = 0x00000010, /* 22.05 kHz, Mono, 8-bit */
WAVE_FORMAT_2S08 = 0x00000020, /* 22.05 kHz, Stereo, 8-bit */
WAVE_FORMAT_2M16 = 0x00000040, /* 22.05 kHz, Mono, 16-bit */
WAVE_FORMAT_2S16 = 0x00000080, /* 22.05 kHz, Stereo, 16-bit */
WAVE_FORMAT_4M08 = 0x00000100, /* 44.1 kHz, Mono, 8-bit */
WAVE_FORMAT_4S08 = 0x00000200, /* 44.1 kHz, Stereo, 8-bit */
WAVE_FORMAT_4M16 = 0x00000400, /* 44.1 kHz, Mono, 16-bit */
WAVE_FORMAT_4S16 = 0x00000800, /* 44.1 kHz, Stereo, 16-bit */
WAVE_FORMAT_44M08 = 0x00000100, /* 44.1 kHz, Mono, 8-bit */
WAVE_FORMAT_44S08 = 0x00000200, /* 44.1 kHz, Stereo, 8-bit */
WAVE_FORMAT_44M16 = 0x00000400, /* 44.1 kHz, Mono, 16-bit */
WAVE_FORMAT_44S16 = 0x00000800, /* 44.1 kHz, Stereo, 16-bit */
WAVE_FORMAT_48M08 = 0x00001000, /* 48 kHz, Mono, 8-bit */
WAVE_FORMAT_48S08 = 0x00002000, /* 48 kHz, Stereo, 8-bit */
WAVE_FORMAT_48M16 = 0x00004000, /* 48 kHz, Mono, 16-bit */
WAVE_FORMAT_48S16 = 0x00008000, /* 48 kHz, Stereo, 16-bit */
WAVE_FORMAT_96M08 = 0x00010000, /* 96 kHz, Mono, 8-bit */
WAVE_FORMAT_96S08 = 0x00020000, /* 96 kHz, Stereo, 8-bit */
WAVE_FORMAT_96M16 = 0x00040000, /* 96 kHz, Mono, 16-bit */
WAVE_FORMAT_96S16 = 0x00080000, /* 96 kHz, Stereo, 16-bit */
}
[DllImport("winmm.dll")]
public static extern uint waveInGetNumDevs();
[DllImport("winmm.dll")]
public static extern uint waveOutGetNumDevs();
[DllImport("winmm.dll")]
public static extern MMRESULT waveInGetDevCapsW(uint uDeviceID, out WAVEINCAPS pwic, uint cbwic);
[DllImport("winmm.dll")]
public static extern MMRESULT waveOutGetDevCapsW(uint uDeviceID, out WAVEOUTCAPS pwoc, uint cbwoc);
}
三、使用示例
foreach (var i in Winmm.WaveInDevices)
{
Console.WriteLine("音频采集设备" + i.Id + "：" + i.Name);
}
foreach (var i in Winmm.WaveOutDevices)
{
Console.WriteLine("音频播放设备"+i.Id+"：" +i.Name);
}
总结
以上就是今天要讲的内容，使用winnm枚举设备还是比较简单的，唯一麻烦一点的地方就是支持格式的获取，但是通过C#使用字符串处理，实现也变得很简单。总的来说，这算是一种获取音频设备信息的方法，能够满足一些使用场景的需求。