Don't reset the parameters unless they have been set.

This is based on a patch by Samuel Thibault.

This is needed when espeak_Cancel is called before espeak_Synth,
like can be done in brltty.

CHANGELOG.md

@@ -26,6 +26,7 @@ bug fixes:
 *  Fixes for running the spect code on big-endian architectures.
 *  Fix determining the voice directory when installing the 32-bit Windows
    binaries on a 64-bit Windows system.
+*  Don't reset the speech parameters unless they have already been set.
 
 updated languages:
 

src/libespeak-ng/speech.c

@@ -73,6 +73,7 @@ static espeak_ng_OUTPUT_MODE my_mode = ENOUTPUT_MODE_SYNCHRONOUS;
 static int out_samplerate = 0;
 static int voice_samplerate = 22050;
 static espeak_ng_STATUS err = ENS_OK;
+static int did_save_parameters = 0;
 
 t_espeak_callback *synth_callback = NULL;
 int (*uri_callback)(int, const char *, const char *) = NULL;
@@ -488,6 +489,7 @@ espeak_ng_STATUS sync_espeak_Synth(unsigned int unique_identifier, const void *t
 	my_unique_identifier = unique_identifier;
 	my_user_data = user_data;
 
+	did_save_parameters = 1;
 	for (int i = 0; i < N_SPEECH_PARAM; i++)
 		saved_parameters[i] = param_stack[0].parameter[i];
 
@@ -827,8 +829,11 @@ ESPEAK_NG_API espeak_ng_STATUS espeak_ng_Cancel(void)
 #endif
 	embedded_value[EMBED_T] = 0; // reset echo for pronunciation announcements
 
-	for (int i = 0; i < N_SPEECH_PARAM; i++)
-		SetParameter(i, saved_parameters[i], 0);
+	if (did_save_parameters) {
+		for (int i = 0; i < N_SPEECH_PARAM; i++)
+			SetParameter(i, saved_parameters[i], 0);
+		did_save_parameters = 0;
+	}
 
 	return ENS_OK;
 }