Add outLength to full API, tells caller how many samples were written

Includes both number of frames and number of samples for convenience and
to avoid confusion.

Real-world example usage:

```typescript
const outLength = {frames: 0};
resampler.full(res.samples, sampleBuffer, outLength);
res.samples = sampleBuffer.slice(0, outLength.samples);
```

README.md

@@ -149,11 +149,14 @@ simple(dataIn) { ... }
  *
  * More (and better) info available at: http://www.mega-nerd.com/SRC/api_full.html
  *
- * @param  {Float32Array}         dataIn  Float32Array containing mono|interleaved audio data where -1 < dataIn[i] < 1
- * @param  {Float32Array || null} dataOut Optionally, pass a Float32Array to avoid allocating an extra array for every esampling operation
- * @return {Float32Array}                 The resampled data. If dataOut != null, dataOut is returned
+ * @param {Float32Array}      dataIn              Float32Array containing mono|interleaved audio data where -1 < dataIn[i] < 1
+ * @param {Float32Array|null} dataOut             Optionally, pass a Float32Array to avoid allocating an extra array for every esampling operation
+ * @param {Object|null}       outLength           Amount of data written to dataOut
+ * @param {number}            [outLength.frames]  The number of frames in the output
+
+ * @return {Float32Array} The resampled data. If dataOut != null, dataOut is returned
  */
-full(dataIn, dataOut=null) { ... }
+full(dataIn, dataOut=null, outLength = null) { ... }
 ```
 
 ### `destroy`

dist/src.d.ts

@@ -45,9 +45,12 @@ export declare class SRC {
      *
      * @param dataIn Float32Array containing mono|interleaved audio data where -1 < dataIn[i] < 1
      * @param dataOut Optionally, pass a Float32Array to avoid allocating an extra array for every resampling operation
+     * @param outLength if resampleFunc === this.module.full, pass an optional object get get the number of frames written to dataOut
      * @returns The resampled data. If dataOut != null, dataOut is returned
      */
-    full(dataIn: Float32Array, dataOut?: Float32Array | null): Float32Array;
+    full(dataIn: Float32Array, dataOut?: Float32Array | null, outLength?: {
+        frames: number;
+    } | null): Float32Array;
     /**
      * Cleans up WASM SRC resources. Once this is called on an instance, that instance must be
      * reinitialized with src.init() before it can be used again.
@@ -77,7 +80,10 @@ export declare class SRC {
      * @param resampleFunc this.module.simple || this.module.full
      * @param dataIn Float32Array containing mono|interleaved audio data where -1 < dataIn[i] < 1
      * @param dataOut if resampleFunc === this.module.full, pass an optional resuable buffer to avoid extra allocations
+     * @param outLength if resampleFunc === this.module.full, pass an optional object get get the number of frames written to dataOut
      * @returns The resampled audio, if any
      */
-    _resample(resampleFunc: ModuleType['simple'] | ModuleType['full'], dataIn: Float32Array, dataOut?: Float32Array | null): Float32Array;
+    _resample(resampleFunc: ModuleType['simple'] | ModuleType['full'], dataIn: Float32Array, dataOut?: Float32Array | null, outLength?: {
+        frames: number;
+    } | null): Float32Array;
 }

src/src.ts

@@ -81,13 +81,15 @@ export class SRC {
 	 *
 	 * @param dataIn Float32Array containing mono|interleaved audio data where -1 < dataIn[i] < 1
 	 * @param dataOut Optionally, pass a Float32Array to avoid allocating an extra array for every resampling operation
+	 * @param outLength if resampleFunc === this.module.full, pass an optional object get get the number of frames written to dataOut
 	 * @returns The resampled data. If dataOut != null, dataOut is returned
 	 */
 	full(
 		dataIn: Float32Array,
-		dataOut: Float32Array | null = null
+		dataOut: Float32Array | null = null,
+		outLength: {frames: number} | null = null,
 	): Float32Array {
-		return this._resample(this.module.full, dataIn, dataOut);
+		return this._resample(this.module.full, dataIn, dataOut, outLength);
 	}
 
 	/**
@@ -206,12 +208,14 @@ export class SRC {
 	 * @param resampleFunc this.module.simple || this.module.full
 	 * @param dataIn Float32Array containing mono|interleaved audio data where -1 < dataIn[i] < 1
 	 * @param dataOut if resampleFunc === this.module.full, pass an optional resuable buffer to avoid extra allocations
+	 * @param outLength if resampleFunc === this.module.full, pass an optional object get get the number of frames written to dataOut
 	 * @returns The resampled audio, if any
 	 */
 	_resample(
 		resampleFunc: ModuleType['simple'] | ModuleType['full'],
 		dataIn: Float32Array,
-		dataOut: Float32Array | null = null
+		dataOut: Float32Array | null = null,
+		outLength: {frames: number} | null = null,
 	): Float32Array {
 		// if we don't actually need to resample, just copy values
 		if (this.inputSampleRate === this.outputSampleRate) return dataIn;
@@ -235,6 +239,10 @@ export class SRC {
 			this.outputSampleRate // ignored by module.full()
 		);
 
+		if (typeof outLength === 'object' && outLength !== null) {
+			outLength.frames = outputFrames;
+		}
+
 		return copyOrWriteArray(
 			outputFrames * this.nChannels,
 			this.targetArray,