Revert "Remove model_name param from Whisper-Metal (#15798)"

This reverts commit 6ca1db6.

Author: cccclai

examples/models/whisper/main.cpp

@@ -39,6 +39,10 @@ DEFINE_string(
     audio_path,
     "",
     "Path to input audio file. Accepts .wav or raw float .bin.");
+DEFINE_string(
+    model_name,
+    "base",
+    "Whisper model name (base, small, medium, large, large-v2, large-v3, large-v3-turbo).");
 DEFINE_double(
     temperature,
     0.0,
@@ -110,10 +114,21 @@ int main(int argc, char** argv) {
   config.max_new_tokens = FLAGS_max_new_tokens;
   config.temperature = static_cast<float>(FLAGS_temperature);
 
-  // All Whisper models from HuggingFace now use the v3 tokenizer format
-  // where token 50257 = <|endoftext|> and token 50258 = <|startoftranscript|>
-  config.decoder_start_token_id = 50258;
-  ET_LOG(Info, "Using decoder_start_token_id=50258");
+  // Set decoder_start_token_id based on model version
+  if (FLAGS_model_name == "large-v2" || FLAGS_model_name == "large-v3" ||
+      FLAGS_model_name == "large-v3-turbo") {
+    config.decoder_start_token_id = 50258;
+    ET_LOG(
+        Info,
+        "Using decoder_start_token_id=50258 for model: %s",
+        FLAGS_model_name.c_str());
+  } else {
+    config.decoder_start_token_id = 50257;
+    ET_LOG(
+        Info,
+        "Using decoder_start_token_id=50257 for model: %s",
+        FLAGS_model_name.c_str());
+  }
 
   auto result =
       runner.transcribe(features, config, [&](const std::string& piece) {