Add an example for streaming from file

package.json

@@ -45,6 +45,7 @@
         "@types/debug": "^4.1.5",
         "@types/jest": "^25.1.4",
         "@types/node": "^13.9.5",
+        "@types/throttle": "^1.0.0",
         "@types/ws": "^7.2.3",
         "@typescript-eslint/eslint-plugin": "^2.25.0",
         "@typescript-eslint/parser": "^2.25.0",
@@ -62,6 +63,7 @@
         "prettier": "^2.0.2",
         "shx": "^0.3.2",
         "standard-version": "^7.1.0",
+        "throttle": "^1.0.3",
         "ts-jest": "^25.2.1",
         "ts-node": "^8.8.1",
         "typedoc": "^0.17.3",

src/examples/stream-from-file.ts

@@ -0,0 +1,71 @@
+import * as fs from 'fs'
+import * as Throttle from 'throttle'
+import { AwsTranscribe, StreamingClient, TranscriptEvent } from "../index"
+
+const sampleRate = 16000
+/**
+ * You can run this file by running the npm script called example-stream-from-microphone
+ * npm run example-stream-from-microphone
+ * Ensure sox is installed and accessible from the cli
+ * http://sox.sourceforge.net
+ */
+
+/******************************************************************************
+ * Create AWS transcribe client
+ *******************************************************************************/
+
+const client = new AwsTranscribe({
+    // if these aren't provided, they will be taken from the environment
+    accessKeyId: "ACCESS KEY HERE",
+    secretAccessKey: "SECRET KEY HERE",
+})
+
+/**
+ * Note - currently, transcribe supports the following sample rate with the given languages
+ * 8 KHz and 16 KHz
+ * US English (en-US)
+ * US Spanish (es-US)
+ * 8 KHz only
+ * Australian English (en-AU)
+ * British English (en-GB)
+ * French (fr-FR)
+ * Canadian French (fr-CA)
+ */
+const transcribeStream = client
+    .createStreamingClient({
+        region: "eu-west-1",
+        sampleRate,
+        languageCode: "en-US",
+    })
+    // enums for returning the event names which the stream will emit
+    .on(StreamingClient.EVENTS.OPEN, () => console.log(`transcribe connection opened`))
+    .on(StreamingClient.EVENTS.ERROR, console.error)
+    .on(StreamingClient.EVENTS.CLOSE, () => console.log(`transcribe connection closed`))
+    .on(StreamingClient.EVENTS.DATA, (data: TranscriptEvent) => {
+        const results = data.Transcript.Results
+
+        if (!results || results.length === 0) {
+            return
+        }
+
+        const result = results[0]
+        const final = !result.IsPartial
+        const prefix = final ? "recognized" : "recognizing"
+        const text = result.Alternatives[0].Transcript
+        console.log(`${prefix} text: ${text}`)
+    })
+
+/******************************************************************************
+ * Stream the file. It must be LINEAR16 with the given sample rate
+ *******************************************************************************/
+fs.createReadStream('test.wav').pipe(new Throttle(sampleRate * 2)).pipe(transcribeStream)
+
+/******************************************************************************
+ * For closing the transcribe stream
+ *******************************************************************************/
+process.on("SIGINT", function () {
+    // call the destroy method on the transcribe stream to close the socket and end the stream
+    console.log("Goodbye")
+    transcribeStream.destroy()
+    process.exit(0)
+})