fix(azure): correct volume attribute format and eliminate spurious xmlns/version warnings (#42) (#43)

Drop the % suffix from all three prosody volume emission sites so Azure
receives the correct absolute format (volume="75") rather than a
relative change (volume="75%").

Also reorder prepareSSML so validation runs after processing, removing
two spurious warnings that fired on every plain-text call.

Author: OwenMcGirr

__tests__/azure-ssml.test.ts

@@ -0,0 +1,86 @@
+/**
+ * Tests for Azure SSML generation correctness (issue #42)
+ */
+
+import * as SSMLUtils from "../src/core/ssml-utils";
+
+// Minimal stub so we can import AzureTTSClient without real credentials
+jest.mock("../src/core/abstract-tts", () => {
+  return {
+    AbstractTTSClient: class {
+      voiceId = "en-US-AriaNeural";
+      lang = "en-US";
+      properties: Record<string, unknown> = { rate: "medium", pitch: "medium", volume: 100 };
+      timings: unknown[] = [];
+      on() {}
+      emit() {}
+    },
+  };
+});
+
+// We test the SSML utilities directly — no network calls needed.
+
+describe("createProsodyTag — volume format", () => {
+  it("emits an absolute volume value without a % suffix", () => {
+    const result = SSMLUtils.createProsodyTag("hello", { volume: 75 });
+    // volume="75" is the absolute format (0-100 scale).
+    // volume="75%" would be a relative +75% change — wrong.
+    expect(result).toContain('volume="75"');
+    expect(result).not.toContain('volume="75%"');
+  });
+
+  it("emits volume=100 without % when at full volume", () => {
+    const result = SSMLUtils.createProsodyTag("hello", { volume: 100 });
+    expect(result).toContain('volume="100"');
+    expect(result).not.toContain('volume="100%"');
+  });
+
+  it("emits volume=0 without % when muted", () => {
+    const result = SSMLUtils.createProsodyTag("hello", { volume: 0 });
+    expect(result).toContain('volume="0"');
+    expect(result).not.toContain('volume="0%"');
+  });
+});
+
+describe("Azure prepareSSML — no spurious xmlns/version warnings", () => {
+  let warnSpy: jest.SpyInstance;
+
+  beforeEach(() => {
+    warnSpy = jest.spyOn(console, "warn").mockImplementation(() => {});
+  });
+
+  afterEach(() => {
+    warnSpy.mockRestore();
+  });
+
+  it("does not warn about missing xmlns or version when synthesising plain text", async () => {
+    // Import lazily so mock is in place
+    const { AzureTTSClient } = await import("../src/engines/azure");
+    const client = new AzureTTSClient({ subscriptionKey: "key", region: "eastus" });
+
+    // Access the private method via type cast
+    const ssml = await (client as any).prepareSSML("Hello world");
+
+    const xmnsWarning = warnSpy.mock.calls.some((args) =>
+      args.some(
+        (a: unknown) =>
+          typeof a === "string" && a.includes("xmlns") ||
+          (Array.isArray(a) && a.some((s: unknown) => typeof s === "string" && s.includes("xmlns")))
+      )
+    );
+    const versionWarning = warnSpy.mock.calls.some((args) =>
+      args.some(
+        (a: unknown) =>
+          typeof a === "string" && a.includes("version") ||
+          (Array.isArray(a) && a.some((s: unknown) => typeof s === "string" && s.includes("version")))
+      )
+    );
+
+    expect(xmnsWarning).toBe(false);
+    expect(versionWarning).toBe(false);
+
+    // Sanity: output should actually have the attributes
+    expect(ssml).toContain('xmlns="http://www.w3.org/2001/10/synthesis"');
+    expect(ssml).toContain('version="1.0"');
+  });
+});

src/__tests__/azure-mstts-namespace.test.ts

@@ -175,14 +175,15 @@ describe("Azure MSTTS Namespace Handling", () => {
 
     it("should normalise 0-1 volume fraction to 0-100 percentage", async () => {
       // Regression test for: https://github.com/willwade/js-tts-wrapper/issues/40
-      // Callers commonly pass volume as a 0-1 float; 0.8 should become volume="80%", not "0.8%".
+      // Callers commonly pass volume as a 0-1 float; 0.8 should become volume="80" (absolute, 0-100 scale), not "0.8" or "80%".
       const plainSSML = `<speak>Hello world</speak>`;
       const options = { volume: 0.8 };
 
       const result = (client as any).ensureAzureSSMLStructure(plainSSML, "en-US-JennyNeural", options);
 
-      expect(result).toContain('volume="80%"');
-      expect(result).not.toContain('volume="0.8%"');
+      expect(result).toContain('volume="80"');
+      expect(result).not.toContain('volume="0.8"');
+      expect(result).not.toContain('volume="80%"');
     });
   });
 });

src/__tests__/ssml-utils.test.ts

@@ -53,7 +53,7 @@ describe("SSMLUtils", () => {
 
     it("should create prosody tag with volume", () => {
       const result = SSMLUtils.createProsodyTag("Hello", { volume: 80 });
-      expect(result).toBe('<prosody volume="80%">Hello</prosody>');
+      expect(result).toBe('<prosody volume="80">Hello</prosody>');
     });
 
     it("should create prosody tag with multiple attributes", () => {
@@ -64,7 +64,7 @@ describe("SSMLUtils", () => {
       });
       expect(result).toContain('rate="slow"');
       expect(result).toContain('pitch="high"');
-      expect(result).toContain('volume="80%"');
+      expect(result).toContain('volume="80"');
     });
 
     it("should return original text if no options provided", () => {

src/core/abstract-tts.ts

@@ -993,7 +993,7 @@ export abstract class AbstractTTSClient {
     }
 
     if (this.properties.volume) {
-      attrs.push(`volume="${this.properties.volume}%"`);
+      attrs.push(`volume="${this.properties.volume}"`);
     }
 
     if (attrs.length === 0) {

src/core/ssml-utils.ts

@@ -68,7 +68,7 @@ export function createProsodyTag(text: string, options?: SpeakOptions): string {
 
   if (options.rate) attrs.push(`rate="${options.rate}"`);
   if (options.pitch) attrs.push(`pitch="${options.pitch}"`);
-  if (options.volume !== undefined) attrs.push(`volume="${options.volume}%"`);
+  if (options.volume !== undefined) attrs.push(`volume="${options.volume}"`);
 
   if (attrs.length === 0) return text;
 

src/engines/azure.ts

@@ -556,7 +556,11 @@ export class AzureTTSClient extends AbstractTTSClient {
     // Use voice from options or the default voice
     const voiceId = options?.voice || this.voiceId;
 
-    // Validate and process SSML for Azure compatibility
+    // Process and structure SSML first so required attributes are present before validation
+    ssml = SSMLUtils.processSSMLForEngine(ssml, "azure", voiceId || undefined);
+    ssml = this.ensureAzureSSMLStructure(ssml, voiceId, options);
+
+    // Validate after processing so warnings reflect what Azure actually receives
     const validation = SSMLUtils.validateSSMLForEngine(ssml, "azure", voiceId || undefined);
     if (validation.warnings.length > 0) {
       console.warn("Azure SSML warnings:", validation.warnings);
@@ -566,12 +570,6 @@ export class AzureTTSClient extends AbstractTTSClient {
       throw new Error(`Invalid SSML for Azure: ${validation.errors.join(", ")}`);
     }
 
-    // Process SSML for Azure compatibility
-    ssml = SSMLUtils.processSSMLForEngine(ssml, "azure", voiceId || undefined);
-
-    // Ensure proper SSML structure for Azure
-    ssml = this.ensureAzureSSMLStructure(ssml, voiceId, options);
-
     return ssml;
   }
 
@@ -648,7 +646,7 @@ export class AzureTTSClient extends AbstractTTSClient {
         const attrs: string[] = [];
         if (rate && rate !== DEFAULT_RATE) attrs.push(`rate="${rate}"`);
         if (pitch && pitch !== DEFAULT_PITCH) attrs.push(`pitch="${pitch}"`);
-        if (volume !== DEFAULT_VOLUME) attrs.push(`volume="${volume}%"`);
+        if (volume !== DEFAULT_VOLUME) attrs.push(`volume="${volume}"`);
 
         // <prosody> must be nested inside <voice>, not as a direct child of <speak>.
         // Azure rejects: Node [speak] should not contain node [prosody] with type [Others].