Add extension_llm_runner to CMake deps (#19749)

examples/models/parakeet/main.cpp

@@ -152,13 +152,14 @@ int main(int argc, char** argv) {
     ET_LOG(Error, "Preprocessing failed.");
     return 1;
   }
-  auto mel_features = preprocess_result.get();
+  auto preprocess_out = preprocess_result.get();
 
   // --- Transcribe ---
   ET_LOG(Info, "Running TDT greedy decode...");
-  auto result = runner.transcribe(mel_features, [](const std::string& piece) {
-    std::cout << piece << std::flush;
-  });
+  auto result = runner.transcribe(
+      preprocess_out.features,
+      [](const std::string& piece) { std::cout << piece << std::flush; },
+      preprocess_out.length);
 
   if (!result.ok()) {
     ET_LOG(Error, "Transcription failed.");

extension/asr/runner/CMakeLists.txt

@@ -22,7 +22,7 @@ endif()
 include(${EXECUTORCH_ROOT}/tools/cmake/Utils.cmake)
 
 set(runner_deps executorch_core extension_module extension_tensor
-                tokenizers::tokenizers
+                extension_llm_runner tokenizers::tokenizers
 )
 
 # Define runner library

extension/asr/runner/transducer_runner.cpp

@@ -200,7 +200,7 @@ Error TransducerRunner::load() {
   return Error::Ok;
 }
 
-Result<::executorch::extension::TensorPtr> TransducerRunner::preprocess(
+Result<PreprocessResult> TransducerRunner::preprocess(
     ::executorch::extension::TensorPtr raw_audio) {
   if (!is_loaded()) {
     ET_CHECK_OK_OR_RETURN_ERROR(load());
@@ -229,20 +229,28 @@ Result<::executorch::extension::TensorPtr> TransducerRunner::preprocess(
       "Preprocessor returned unexpected output.");
 
   auto mel = outputs[0].toTensor();
-  return std::make_shared<::executorch::aten::Tensor>(std::move(mel));
+  int64_t mel_len = mel.sizes()[1]; // default to tensor dim
+  if (outputs.size() >= 2 && outputs[1].isTensor()) {
+    mel_len = outputs[1].toTensor().const_data_ptr<int64_t>()[0];
+  }
+  return PreprocessResult{
+      std::make_shared<::executorch::aten::Tensor>(std::move(mel)), mel_len};
 }
 
 Result<std::vector<Token>> TransducerRunner::transcribe(
     ::executorch::extension::TensorPtr preprocessed_features,
-    std::function<void(const std::string&)> token_callback) {
+    std::function<void(const std::string&)> token_callback,
+    int64_t features_length) {
   if (!is_loaded()) {
     ET_CHECK_OK_OR_RETURN_ERROR(load());
   }
 
   stats_.inference_start_ms = ::executorch::extension::llm::time_in_ms();
 
   // --- Encode ---
-  int64_t mel_len_value = preprocessed_features->size(1);
+  // Use provided length, or fall back to tensor dimension
+  int64_t mel_len_value =
+      features_length > 0 ? features_length : preprocessed_features->size(1);
   std::vector<int64_t> mel_len_data = {mel_len_value};
   auto mel_len = ::executorch::extension::from_blob(
       mel_len_data.data(), {1}, ::executorch::aten::ScalarType::Long);

extension/asr/runner/transducer_runner.h

@@ -29,6 +29,14 @@ using ::executorch::extension::llm::Stats;
 using ::executorch::runtime::Error;
 using ::executorch::runtime::Result;
 
+/**
+ * Preprocessed audio features with actual (unpadded) length.
+ */
+struct PreprocessResult {
+  ::executorch::extension::TensorPtr features;
+  int64_t length; // Actual number of valid frames (excluding padding)
+};
+
 /**
  * A decoded token with frame-level timing information.
  */
@@ -97,7 +105,7 @@ class ET_EXPERIMENTAL TransducerRunner {
    * @returns Preprocessed features tensor (e.g., mel spectrogram),
    *   ready to pass to transcribe().
    */
-  Result<::executorch::extension::TensorPtr> preprocess(
+  Result<PreprocessResult> preprocess(
       ::executorch::extension::TensorPtr raw_audio);
 
   /**
@@ -112,7 +120,8 @@ class ET_EXPERIMENTAL TransducerRunner {
    */
   Result<std::vector<Token>> transcribe(
       ::executorch::extension::TensorPtr preprocessed_features,
-      std::function<void(const std::string&)> token_callback = {});
+      std::function<void(const std::string&)> token_callback = {},
+      int64_t features_length = -1);
 
   /**
    * Returns a reference to the loaded tokenizer, or nullptr if not loaded.