（原创）c#调用开源espeak语音引擎实现中英文混读
需求
实际.net项目中需要用到TTS（文本转语音技术），实现语音播服务，需要中英文混读
方案
1，微软TTS语音引擎。
调用非常简单 ,也是我首先采用的方案，可参考如下微博:
https://www.cnblogs.com/JuneZhang/archive/2014/04/28/3696594.html
但有个缺点：依赖windows平台的语音引擎与Speech Api，使用过程中会发现：有的系统能用，有的系统用不了（据说是阉割版系统所致）；非中文版系统更惨，需要各种操作安装中文语音包，最后安装好了，可能发现还是用不了（项目中血淋淋的教训：windows server英文版系统，各种折腾最后用不了，甲方服务器，又不能随便重装系统），于是替代方案。
2，espeak方案
espeak是c语言写的一个小型的、开放源码的语音合成系统，支持多种语言，这里包括汉语，甚至是粤语等。
C++版开发教程可参考如下微博：
http://www.cnblogs.com/luochengor/p/3511165.html
http://cool.worm.blog.163.com/blog/static/6433900620097535713944/
上github找到了一个C#版本的espeak-ng调用demo，网址如下：
https://github.com/parhamdoustdar/espeak-ng-wrapper
没看懂espeak-ng，最后采用官网原生的espeak-1.48.04-source，并以github上c#框架进行改造，实现了c#调用开源espeak语音引擎TTS，摆脱了windows平台的语音引擎与Speech Api，实现了中英文混读的C#espeak方案。主要代码如下：
c#引用espeak_lib.dll中的函数
[DllImport("espeak_lib.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.Cdecl)]
static extern Error espeak_SetVoiceByName([MarshalAs(UnmanagedType.LPUTF8Str)] string name);
[DllImport("espeak_lib.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.Cdecl)]
static extern Error espeak_SetParameter(Parameter parameter, int value, ParameterType type);
[DllImport("espeak_lib.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.Cdecl)]
static extern Error espeak_Synchronize();
[DllImport("espeak_lib.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.Cdecl)]
static extern Error espeak_Terminate();
[DllImport("espeak_lib.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.Cdecl)]
static extern IntPtr espeak_GetCurrentVoice();
[DllImport("espeak_lib.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.Cdecl)]
static extern Error espeak_Synth([MarshalAs(UnmanagedType.LPUTF8Str)] string text, int size, uint startPosition = 0, PositionType positionType = PositionType.Character, uint endPosition = 0, SpeechFlags flags = SpeechFlags.CharsUtf8, UIntPtr uniqueIdentifier = default(UIntPtr), IntPtr userData = default(IntPtr));
[DllImport("espeak_lib.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.Cdecl)]
static extern int espeak_Initialize(AudioOutput output, int bufferLength, IntPtr path, int options);
[DllImport("espeak_lib.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.Cdecl)]
static extern Error espeak_Cancel();
[DllImport("espeak_lib.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.Cdecl)]
static extern void espeak_SetSynthCallback(EventHandler.SynthCallback callback);
c#对espeak_lib.dll函数进行封装
public static void Initialize(string path)
{
IntPtr ptr = Marshal.StringToHGlobalAnsi(path);
var result = espeak_Initialize(AudioOutput.Synchronous,100, ptr, 0);
// 释放 ptr 的内存
Marshal.FreeHGlobal(ptr);
if (result == (int)Error.EE_INTERNAL_ERROR)
{
throw new Exception(string.Format("Could not initialize ESpeak. Maybe there is no espeak data at {0}?", path));
}
espeak_SetSynthCallback(EventHandler.Handle);
Initialized = true;
}
public static bool SetRate(int rate)
{
if (rate < 80 && rate > 450)
{
throw new Exception("The rate must be between 80 and 450.");
}
var result = espeak_SetParameter(Parameter.Rate, rate, ParameterType.Absolute);
return CheckResult(result);
}
static bool CheckResult(Error result)
{
if (result == Error.EE_OK)
{
return true;
}
else if (result == Error.EE_BUFFER_FULL)
{
return false;
}
else if (result == Error.EE_INTERNAL_ERROR)
{
throw new Exception("Internal error in ESpeak.");
}
else
{
return false;
}
}
public static bool Speak(string text)
{
var result = espeak_Synth(text, text.Length * Marshal.SystemDefaultCharSize);
return CheckResult(result);
}
public static bool SpeakSSML(string text)
{
var result = espeak_Synth(text, text.Length * Marshal.SystemDefaultCharSize, 0, PositionType.Character, 0, SpeechFlags.CharsUtf8 | SpeechFlags.SSML);
return CheckResult(result);
}
public static bool Stop()
{
var result = espeak_Cancel();
return CheckResult(result);
}
public static bool Espeak_Synchronize()
{
var result = espeak_Synchronize();
return CheckResult(result);
}
public static bool Espeak_Terminate()
{
var result = espeak_Terminate();
return CheckResult(result);
}
public static bool SetVoiceByName(string name)
{
var result = espeak_SetVoiceByName(name);
return CheckResult(result);
}
public static Voice GetCurrentVoice()
{
IntPtr espeakVoicePtr = espeak_GetCurrentVoice();
ESpeakVoice espeakVoice = (ESpeakVoice)Marshal.PtrToStructure(espeakVoicePtr, typeof(ESpeakVoice));
if (espeakVoice.Equals(default(ESpeakVoice)))
{
throw new Exception("eSpeak returned an empty voice object. Did you call one of the ESpeak.SetVoice*() functions?");
}
return new Voice()
{
Name = espeakVoice.Name,
Languages = espeakVoice.Languages.Substring(1),
Priority = (int)espeakVoice.Languages[0],
Identifier = espeakVoice.Identifier,
};
}
c#控制台程序调用发声
class Program
{
static void Main(string[] args)
{
Client.Initialize("." );
Client.SetVoiceByName("zh+m10");
Client.Speak("Helloworld！");
// 等待发音结束
Client.Espeak_Synchronize();
//Client.Espeak_Terminate();
//Thread.Sleep(5000);
Client.Stop();
Client.Speak("你好。Hello world");
Client.Espeak_Synchronize();
Client.Espeak_Terminate();
Console.Read();
}
}
源码Github地址
因该模块开发主要得益于开源，故将源码开源：
https://github.com/mastertostar/Csharp-espeak-tts