Add C API for streaming HLG decoding (#734)

go-api-examples/streaming-hlg-decoding/go.mod

@@ -0,0 +1,3 @@
+module streaming-hlg-decoding
+
+go 1.12

go-api-examples/streaming-hlg-decoding/main.go

@@ -0,0 +1,109 @@
+package main
+
+import (
+	"bytes"
+	"encoding/binary"
+	sherpa "github.com/k2-fsa/sherpa-onnx-go/sherpa_onnx"
+	"github.com/youpy/go-wav"
+	"log"
+	"os"
+	"strings"
+)
+
+func main() {
+	log.SetFlags(log.LstdFlags | log.Lmicroseconds)
+
+	config := sherpa.OnlineRecognizerConfig{}
+	config.FeatConfig = sherpa.FeatureConfig{SampleRate: 16000, FeatureDim: 80}
+
+	// please download model files from
+	// https://github.com/k2-fsa/sherpa-onnx/releases/download/asr-models/sherpa-onnx-streaming-zipformer-ctc-small-2024-03-18.tar.bz2
+	config.ModelConfig.Zipformer2Ctc.Model = "./sherpa-onnx-streaming-zipformer-ctc-small-2024-03-18/ctc-epoch-30-avg-3-chunk-16-left-128.int8.onnx"
+	config.ModelConfig.Tokens = "./sherpa-onnx-streaming-zipformer-ctc-small-2024-03-18/tokens.txt"
+
+	config.ModelConfig.NumThreads = 1
+	config.ModelConfig.Debug = 0
+	config.ModelConfig.Provider = "cpu"
+	config.CtcFstDecoderConfig.Graph = "./sherpa-onnx-streaming-zipformer-ctc-small-2024-03-18/HLG.fst"
+
+	wav_filename := "./sherpa-onnx-streaming-zipformer-ctc-small-2024-03-18/test_wavs/8k.wav"
+
+	samples, sampleRate := readWave(wav_filename)
+
+	log.Println("Initializing recognizer (may take several seconds)")
+	recognizer := sherpa.NewOnlineRecognizer(&config)
+	log.Println("Recognizer created!")
+	defer sherpa.DeleteOnlineRecognizer(recognizer)
+
+	log.Println("Start decoding!")
+	stream := sherpa.NewOnlineStream(recognizer)
+	defer sherpa.DeleteOnlineStream(stream)
+
+	stream.AcceptWaveform(sampleRate, samples)
+
+	tailPadding := make([]float32, int(float32(sampleRate)*0.3))
+	stream.AcceptWaveform(sampleRate, tailPadding)
+
+	for recognizer.IsReady(stream) {
+		recognizer.Decode(stream)
+	}
+	log.Println("Decoding done!")
+	result := recognizer.GetResult(stream)
+	log.Println(strings.ToLower(result.Text))
+	log.Printf("Wave duration: %v seconds", float32(len(samples))/float32(sampleRate))
+}
+
+func readWave(filename string) (samples []float32, sampleRate int) {
+	file, _ := os.Open(filename)
+	defer file.Close()
+
+	reader := wav.NewReader(file)
+	format, err := reader.Format()
+	if err != nil {
+		log.Fatalf("Failed to read wave format")
+	}
+
+	if format.AudioFormat != 1 {
+		log.Fatalf("Support only PCM format. Given: %v\n", format.AudioFormat)
+	}
+
+	if format.NumChannels != 1 {
+		log.Fatalf("Support only 1 channel wave file. Given: %v\n", format.NumChannels)
+	}
+
+	if format.BitsPerSample != 16 {
+		log.Fatalf("Support only 16-bit per sample. Given: %v\n", format.BitsPerSample)
+	}
+
+	reader.Duration() // so that it initializes reader.Size
+
+	buf := make([]byte, reader.Size)
+	n, err := reader.Read(buf)
+	if n != int(reader.Size) {
+		log.Fatalf("Failed to read %v bytes. Returned %v bytes\n", reader.Size, n)
+	}
+
+	samples = samplesInt16ToFloat(buf)
+	sampleRate = int(format.SampleRate)
+
+	return
+}
+
+func samplesInt16ToFloat(inSamples []byte) []float32 {
+	numSamples := len(inSamples) / 2
+	outSamples := make([]float32, numSamples)
+
+	for i := 0; i != numSamples; i++ {
+		s := inSamples[i*2 : (i+1)*2]
+
+		var s16 int16
+		buf := bytes.NewReader(s)
+		err := binary.Read(buf, binary.LittleEndian, &s16)
+		if err != nil {
+			log.Fatal("Failed to parse 16-bit sample")
+		}
+		outSamples[i] = float32(s16) / 32768
+	}
+
+	return outSamples
+}

go-api-examples/streaming-hlg-decoding/run.sh

@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+
+set -ex
+
+if [ ! -f ./sherpa-onnx-streaming-zipformer-ctc-small-2024-03-18/HLG.fst ]; then
+  curl -SL -O https://github.com/k2-fsa/sherpa-onnx/releases/download/asr-models/sherpa-onnx-streaming-zipformer-ctc-small-2024-03-18.tar.bz2
+  tar xvf sherpa-onnx-streaming-zipformer-ctc-small-2024-03-18.tar.bz2
+  rm sherpa-onnx-streaming-zipformer-ctc-small-2024-03-18.tar.bz2
+fi
+
+go mod tidy
+go build
+ls -lh
+./streaming-hlg-decoding