Espeak TTS does not work on Linux

[tinxx]

The new help system makes use of espeak to read the help description.

However, on Linux espeak does not work and fail with the following log:

Could not start process: System.ComponentModel.Win32Exception (0x80004005): ApplicationName='espeak', CommandLine='-v "en-US+f4" -w "/tmp/University of Bremen and Axivion GmbH/SEE/rtvoice_97ce4575-8240-441c-9659-024b6e8ea72a.wav" -z  -m "Press Key W or S to move forwards or backwards."', CurrentDirectory='', Native error= Cannot find the specified file
  at System.Diagnostics.Process.StartWithCreateProcess (System.Diagnostics.ProcessStartInfo startInfo) [0x002f9] in <8e610fe3b48543c6942b64f6cad09e30>:0 
  at System.Diagnostics.Process.Start () [0x0003a] in <8e610fe3b48543c6942b64f6cad09e30>:0 
  at (wrapper remoting-invoke-with-check) System.Diagnostics.Process.Start()
  at Crosstales.RTVoice.Provider.MainVoiceProvider.startProcess (System.Diagnostics.Process process, System.Int32 timeout, System.Boolean eventOutputData, System.Boolean eventErrorData, System.Boolean redirectOutputData, System.Boolean redirectErrorData) [0x0005a] in /home/myuser/mypath/SEE/Assets/Plugins/crosstales/RTVoice/Scripts/Provider/BaseVoiceProvider.cs:259 
UnityEngine.Debug:LogError (object)
Crosstales.RTVoice.Provider.MainVoiceProvider:startProcess (System.Diagnostics.Process,int,bool,bool,bool,bool) (at Assets/Plugins/crosstales/RTVoice/Scripts/Provider/BaseVoiceProvider.cs:282)
Crosstales.RTVoice.Provider.VoiceProviderLinux/<>c__DisplayClass37_0:<Speak>b__0 () (at Assets/Plugins/crosstales/RTVoice/Scripts/Provider/VoiceProviderLinux.cs:234)
System.Threading.ThreadHelper:ThreadStart ()

InvalidOperationException: No process is associated with this object.
System.Diagnostics.Process.EnsureState (System.Diagnostics.Process+State state) (at <8e610fe3b48543c6942b64f6cad09e30>:0)
System.Diagnostics.Process.get_HasExited () (at <8e610fe3b48543c6942b64f6cad09e30>:0)
(wrapper remoting-invoke-with-check) System.Diagnostics.Process.get_HasExited()
Crosstales.RTVoice.Provider.VoiceProviderLinux+<Speak>d__37.MoveNext () (at Assets/Plugins/crosstales/RTVoice/Scripts/Provider/VoiceProviderLinux.cs:248)
UnityEngine.SetupCoroutine.InvokeMoveNext (System.Collections.IEnumerator enumerator, System.IntPtr returnValueAddress) (at /home/bokken/build/output/unity/unity/Runtime/Export/Scripting/Coroutines.cs:17)

Please note that /home/bokken/build/… on the second error is not a path on my machine.

[falko17]

I cannot reproduce this on my Linux machine. With espeak-ng installed (and espeak being on my path), TTS works in SEE for me. I'm not sure why this is different on your end, do you have any idea why Unity seemingly can't find the espeak executable?

[tinxx]

I see, so the idea is that everyone has to install that manually on their systems in addition to SEE?

[falko17]

Yes, pretty much. AFAIK, on Windows, we use the pre-installed TTS system, of which there isn't an equivalent on Linux (except for espeak, which isn't necessarily pre-installed). We could try providing a more explicit error message when espeak is not installed, although I think it's hard to catch the exception that causes the error message from the issue description.