support nodejs (#438)

nodejs-examples/test-online-transducer.js

@@ -0,0 +1,102 @@
+// Copyright (c)  2023  Xiaomi Corporation (authors: Fangjun Kuang)
+//
+const fs = require('fs');
+const {Readable} = require('stream');
+const wav = require('wav');
+
+const sherpa_onnx = require('sherpa-onnx');
+
+function createRecognizer() {
+  const featConfig = new sherpa_onnx.FeatureConfig();
+  featConfig.sampleRate = 16000;
+  featConfig.featureDim = 80;
+
+  // test online recognizer
+  const transducer = new sherpa_onnx.OnlineTransducerModelConfig();
+  transducer.encoder =
+      './sherpa-onnx-streaming-zipformer-bilingual-zh-en-2023-02-20/encoder-epoch-99-avg-1.int8.onnx';
+  transducer.decoder =
+      './sherpa-onnx-streaming-zipformer-bilingual-zh-en-2023-02-20/decoder-epoch-99-avg-1.onnx';
+  transducer.joiner =
+      './sherpa-onnx-streaming-zipformer-bilingual-zh-en-2023-02-20/joiner-epoch-99-avg-1.onnx';
+  const tokens =
+      './sherpa-onnx-streaming-zipformer-bilingual-zh-en-2023-02-20/tokens.txt';
+
+  const modelConfig = new sherpa_onnx.OnlineModelConfig();
+  modelConfig.transducer = transducer;
+  modelConfig.tokens = tokens;
+  modelConfig.modelType = 'zipformer';
+
+  const recognizerConfig = new sherpa_onnx.OnlineRecognizerConfig();
+  recognizerConfig.featConfig = featConfig;
+  recognizerConfig.modelConfig = modelConfig;
+  recognizerConfig.decodingMethod = 'greedy_search';
+
+  recognizer = new sherpa_onnx.OnlineRecognizer(recognizerConfig);
+  return recognizer;
+}
+recognizer = createRecognizer();
+stream = recognizer.createStream();
+
+const waveFilename =
+    './sherpa-onnx-streaming-zipformer-bilingual-zh-en-2023-02-20/test_wavs/0.wav';
+
+const reader = new wav.Reader();
+const readable = new Readable().wrap(reader);
+
+function decode(samples) {
+  stream.acceptWaveform(recognizer.config.featConfig.sampleRate, samples);
+
+  while (recognizer.isReady(stream)) {
+    recognizer.decode(stream);
+  }
+  const r = recognizer.getResult(stream);
+  console.log(r.text);
+}
+
+reader.on('format', ({audioFormat, bitDepth, channels, sampleRate}) => {
+  if (sampleRate != recognizer.config.featConfig.sampleRate) {
+    throw new Error(`Only support sampleRate ${
+        recognizer.config.featConfig.sampleRate}. Given ${sampleRate}`);
+  }
+
+  if (audioFormat != 1) {
+    throw new Error(`Only support PCM format. Given ${audioFormat}`);
+  }
+
+  if (channels != 1) {
+    throw new Error(`Only a single channel. Given ${channel}`);
+  }
+
+  if (bitDepth != 16) {
+    throw new Error(`Only support 16-bit samples. Given ${bitDepth}`);
+  }
+});
+
+fs.createReadStream(waveFilename, {'highWaterMark': 4096})
+    .pipe(reader)
+    .on('finish', function(err) {
+      // tail padding
+      const floatSamples =
+          new Float32Array(recognizer.config.featConfig.sampleRate * 0.5);
+      decode(floatSamples);
+      stream.free();
+      recognizer.free();
+    });
+
+readable.on('readable', function() {
+  let chunk;
+  while ((chunk = readable.read()) != null) {
+    const int16Samples = new Int16Array(
+        chunk.buffer, chunk.byteOffset,
+        chunk.length / Int16Array.BYTES_PER_ELEMENT);
+
+    const floatSamples = new Float32Array(int16Samples.length);
+
+    for (let i = 0; i < floatSamples.length; i++) {
+      floatSamples[i] = int16Samples[i] / 32768.0;
+    }
+
+    decode(floatSamples);
+  }
+});