Support decoding multiple streams in Java API. (#2149)

.github/workflows/run-java-test.yaml

@@ -166,6 +166,8 @@ jobs:
           rm -rf sherpa-onnx-fire-red-*
 
           ./run-non-streaming-decode-file-whisper.sh
+
+          ./run-non-streaming-decode-file-whisper-multiple.sh
           rm -rf sherpa-onnx-whisper-*
 
           ./run-non-streaming-decode-file-nemo.sh

java-api-examples/NonStreamingDecodeFileWhisperMultiple.java

@@ -0,0 +1,59 @@
+// Copyright 2025 Xiaomi Corporation
+
+// This file shows how to use an offline whisper, i.e., non-streaming whisper,
+// to decode files.
+import com.k2fsa.sherpa.onnx.*;
+
+public class NonStreamingDecodeFileWhisperMultiple {
+  public static void main(String[] args) {
+    // please refer to
+    // https://k2-fsa.github.io/sherpa/onnx/pretrained_models/whisper/tiny.en.html
+    // to download model files
+    String encoder = "./sherpa-onnx-whisper-tiny.en/tiny.en-encoder.int8.onnx";
+    String decoder = "./sherpa-onnx-whisper-tiny.en/tiny.en-decoder.int8.onnx";
+    String tokens = "./sherpa-onnx-whisper-tiny.en/tiny.en-tokens.txt";
+
+    String waveFilename0 = "./sherpa-onnx-whisper-tiny.en/test_wavs/0.wav";
+    String waveFilename1 = "./sherpa-onnx-whisper-tiny.en/test_wavs/1.wav";
+
+    WaveReader reader0 = new WaveReader(waveFilename0);
+    WaveReader reader1 = new WaveReader(waveFilename1);
+
+    OfflineWhisperModelConfig whisper =
+        OfflineWhisperModelConfig.builder().setEncoder(encoder).setDecoder(decoder).build();
+
+    OfflineModelConfig modelConfig =
+        OfflineModelConfig.builder()
+            .setWhisper(whisper)
+            .setTokens(tokens)
+            .setNumThreads(1)
+            .setDebug(true)
+            .build();
+
+    OfflineRecognizerConfig config =
+        OfflineRecognizerConfig.builder()
+            .setOfflineModelConfig(modelConfig)
+            .setDecodingMethod("greedy_search")
+            .build();
+
+    OfflineRecognizer recognizer = new OfflineRecognizer(config);
+    OfflineStream stream0 = recognizer.createStream();
+    stream0.acceptWaveform(reader0.getSamples(), reader0.getSampleRate());
+
+    OfflineStream stream1 = recognizer.createStream();
+    stream1.acceptWaveform(reader1.getSamples(), reader1.getSampleRate());
+
+    OfflineStream[] ss = new OfflineStream[] {stream0, stream1};
+    recognizer.decode(ss);
+
+    String text0 = recognizer.getResult(stream0).getText();
+    String text1 = recognizer.getResult(stream1).getText();
+
+    System.out.printf("filename0:%s\nresult0:%s\n\n", waveFilename0, text0);
+    System.out.printf("filename1:%s\nresult1:%s\n\n", waveFilename1, text1);
+
+    stream0.release();
+    stream1.release();
+    recognizer.release();
+  }
+}

java-api-examples/run-non-streaming-decode-file-whisper-multiple.sh

@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+
+set -ex
+
+if [[ ! -f ../build/lib/libsherpa-onnx-jni.dylib  && ! -f ../build/lib/libsherpa-onnx-jni.so ]]; then
+  mkdir -p ../build
+  pushd ../build
+  cmake \
+    -DSHERPA_ONNX_ENABLE_PYTHON=OFF \
+    -DSHERPA_ONNX_ENABLE_TESTS=OFF \
+    -DSHERPA_ONNX_ENABLE_CHECK=OFF \
+    -DBUILD_SHARED_LIBS=ON \
+    -DSHERPA_ONNX_ENABLE_PORTAUDIO=OFF \
+    -DSHERPA_ONNX_ENABLE_JNI=ON \
+    ..
+
+  make -j4
+  ls -lh lib
+  popd
+fi
+
+if [ ! -f ../sherpa-onnx/java-api/build/sherpa-onnx.jar ]; then
+  pushd ../sherpa-onnx/java-api
+  make
+  popd
+fi
+
+if [ ! -f ./sherpa-onnx-whisper-tiny.en/tiny.en-tokens.txt ]; then
+  curl -SL -O https://github.com/k2-fsa/sherpa-onnx/releases/download/asr-models/sherpa-onnx-whisper-tiny.en.tar.bz2
+
+  tar xvf sherpa-onnx-whisper-tiny.en.tar.bz2
+  rm sherpa-onnx-whisper-tiny.en.tar.bz2
+fi
+
+java \
+  -Djava.library.path=$PWD/../build/lib \
+  -cp ../sherpa-onnx/java-api/build/sherpa-onnx.jar \
+  NonStreamingDecodeFileWhisperMultiple.java

sherpa-onnx/java-api/src/com/k2fsa/sherpa/onnx/OfflineRecognizer.java

@@ -17,6 +17,14 @@ public class OfflineRecognizer {
         decode(ptr, s.getPtr());
     }
 
+    public void decode(OfflineStream[] ss) {
+        long[] streamPtrs = new long[ss.length];
+        for (int i = 0; i < ss.length; ++i) {
+            streamPtrs[i] = ss[i].getPtr();
+        }
+        decodeStreams(ptr, streamPtrs);
+    }
+
     public OfflineStream createStream() {
         long p = createStream(ptr);
         return new OfflineStream(p);
@@ -55,5 +63,7 @@ public class OfflineRecognizer {
 
     private native void decode(long ptr, long streamPtr);
 
+    private native void decodeStreams(long ptr, long[] streamPtrs);
+
     private native Object[] getResult(long streamPtr);
 }

sherpa-onnx/java-api/src/com/k2fsa/sherpa/onnx/OnlineRecognizer.java

@@ -18,6 +18,14 @@ public class OnlineRecognizer {
         decode(ptr, s.getPtr());
     }
 
+    public void decode(OnlineStream[] ss) {
+        long[] streamPtrs = new long[ss.length];
+        for (int i = 0; i < ss.length; ++i) {
+            streamPtrs[i] = ss[i].getPtr();
+        }
+        decodeStreams(ptr, streamPtrs);
+    }
+
     public boolean isReady(OnlineStream s) {
         return isReady(ptr, s.getPtr());
     }
@@ -68,6 +76,8 @@ public class OnlineRecognizer {
 
     private native void decode(long ptr, long streamPtr);
 
+    private native void decodeStreams(long ptr, long[] streamPtrs);
+
     private native boolean isEndpoint(long ptr, long streamPtr);
 
     private native boolean isReady(long ptr, long streamPtr);

sherpa-onnx/jni/offline-recognizer.cc

@@ -366,21 +366,43 @@ Java_com_k2fsa_sherpa_onnx_OfflineRecognizer_createStream(JNIEnv * /*env*/,
 
 SHERPA_ONNX_EXTERN_C
 JNIEXPORT void JNICALL Java_com_k2fsa_sherpa_onnx_OfflineRecognizer_decode(
-    JNIEnv *env, jobject /*obj*/, jlong ptr, jlong streamPtr) {
+    JNIEnv *env, jobject /*obj*/, jlong ptr, jlong stream_ptr) {
   SafeJNI(env, "OfflineRecognizer_decode", [&] {
     if (!ValidatePointer(env, ptr, "OfflineRecognizer_decode",
                          "OfflineRecognizer pointer is null.") ||
-        !ValidatePointer(env, streamPtr, "OfflineRecognizer_decode",
+        !ValidatePointer(env, stream_ptr, "OfflineRecognizer_decode",
                          "OfflineStream pointer is null.")) {
       return;
     }
 
     auto recognizer = reinterpret_cast<sherpa_onnx::OfflineRecognizer *>(ptr);
-    auto stream = reinterpret_cast<sherpa_onnx::OfflineStream *>(streamPtr);
+    auto stream = reinterpret_cast<sherpa_onnx::OfflineStream *>(stream_ptr);
     recognizer->DecodeStream(stream);
   });
 }
 
+SHERPA_ONNX_EXTERN_C
+JNIEXPORT void JNICALL
+Java_com_k2fsa_sherpa_onnx_OfflineRecognizer_decodeStreams(
+    JNIEnv *env, jobject /*obj*/, jlong ptr, jlongArray stream_ptrs) {
+  SafeJNI(env, "OfflineRecognizer_decode_streams", [&] {
+    if (!ValidatePointer(env, ptr, "OfflineRecognizer_decode_streams",
+                         "OfflineRecognizer pointer is null.")) {
+      return;
+    }
+
+    auto recognizer = reinterpret_cast<sherpa_onnx::OfflineRecognizer *>(ptr);
+
+    jlong *p = env->GetLongArrayElements(stream_ptrs, nullptr);
+    jsize n = env->GetArrayLength(stream_ptrs);
+
+    auto ss = reinterpret_cast<sherpa_onnx::OfflineStream **>(p);
+    recognizer->DecodeStreams(ss, n);
+
+    env->ReleaseLongArrayElements(stream_ptrs, p, JNI_ABORT);
+  });
+}
+
 SHERPA_ONNX_EXTERN_C
 JNIEXPORT jobjectArray JNICALL
 Java_com_k2fsa_sherpa_onnx_OfflineRecognizer_getResult(JNIEnv *env,

sherpa-onnx/jni/online-recognizer.cc

@@ -339,6 +339,22 @@ JNIEXPORT void JNICALL Java_com_k2fsa_sherpa_onnx_OnlineRecognizer_decode(
   recognizer->DecodeStream(stream);
 }
 
+SHERPA_ONNX_EXTERN_C
+JNIEXPORT void JNICALL
+Java_com_k2fsa_sherpa_onnx_OnlineRecognizer_decodeStreams(
+    JNIEnv *env, jobject /*obj*/, jlong ptr, jlongArray stream_ptrs) {
+  auto recognizer = reinterpret_cast<sherpa_onnx::OnlineRecognizer *>(ptr);
+
+  jlong *p = env->GetLongArrayElements(stream_ptrs, nullptr);
+  jsize n = env->GetArrayLength(stream_ptrs);
+
+  auto ss = reinterpret_cast<sherpa_onnx::OnlineStream **>(p);
+
+  recognizer->DecodeStreams(ss, n);
+
+  env->ReleaseLongArrayElements(stream_ptrs, p, JNI_ABORT);
+}
+
 SHERPA_ONNX_EXTERN_C
 JNIEXPORT jlong JNICALL
 Java_com_k2fsa_sherpa_onnx_OnlineRecognizer_createStream(JNIEnv *env,