Add Params#new_segment_callback= method

bindings/ruby/ext/ruby_whisper.cpp

@@ -73,6 +73,7 @@ static VALUE ruby_whisper_params_allocate(VALUE klass) {
   ruby_whisper_params *rwp;
   rwp = ALLOC(ruby_whisper_params);
   rwp->params = whisper_full_default_params(WHISPER_SAMPLING_GREEDY);
+  rwp->new_segment_callback = Qnil;
   return Data_Wrap_Struct(klass, rb_whisper_params_mark, rb_whisper_params_free, rwp);
 }
 
@@ -205,6 +206,28 @@ static VALUE ruby_whisper_transcribe(int argc, VALUE *argv, VALUE self) {
     };
     rwp->params.encoder_begin_callback_user_data = &is_aborted;
   }
+  {
+    // This cannot be used later because it is not incremented when new_segment_callback is not given.
+    static int n_segments = 0;
+
+    rwp->params.new_segment_callback = [](struct whisper_context * ctx, struct whisper_state * state, int n_new, void * user_data) {
+      VALUE callback = *(VALUE *)user_data;
+      if (NIL_P(callback)){
+        return;
+      }
+
+      for (int i = 0; i < n_new; i++) {
+        const int i_segment = n_segments + i;
+        const char * text = whisper_full_get_segment_text_from_state(state, i_segment);
+        // Multiplying 10 shouldn't cause overflow because to_timestamp() in whisper.cpp does it
+        const int64_t t0 = whisper_full_get_segment_t0_from_state(state, i_segment) * 10;
+        const int64_t t1 = whisper_full_get_segment_t1_from_state(state, i_segment) * 10;
+        rb_funcall(callback, rb_intern("call"), 4, rb_str_new2(text), INT2NUM(t0), INT2NUM(t1), INT2FIX(i_segment));
+      }
+      n_segments += n_new;
+    };
+    rwp->params.new_segment_callback_user_data = &rwp->new_segment_callback;
+  }
 
   if (whisper_full_parallel(rw->context, rwp->params, pcmf32.data(), pcmf32.size(), 1) != 0) {
     fprintf(stderr, "failed to process audio\n");
@@ -365,6 +388,12 @@ static VALUE ruby_whisper_params_set_max_text_tokens(VALUE self, VALUE value) {
   rwp->params.n_max_text_ctx = NUM2INT(value);
   return value;
 }
+static VALUE ruby_whisper_params_set_new_segment_callback(VALUE self, VALUE value) {
+  ruby_whisper_params *rwp;
+  Data_Get_Struct(self, ruby_whisper_params, rwp);
+  rwp->new_segment_callback = value;
+  return value;
+}
 
 void Init_whisper() {
   mWhisper = rb_define_module("Whisper");
@@ -412,6 +441,8 @@ void Init_whisper() {
 
   rb_define_method(cParams, "max_text_tokens", ruby_whisper_params_get_max_text_tokens, 0);
   rb_define_method(cParams, "max_text_tokens=", ruby_whisper_params_set_max_text_tokens, 1);
+
+  rb_define_method(cParams, "new_segment_callback=", ruby_whisper_params_set_new_segment_callback, 1);
 }
 #ifdef __cplusplus
 }

bindings/ruby/ext/ruby_whisper.h

@@ -10,6 +10,7 @@ typedef struct {
 typedef struct {
   struct whisper_full_params params;
   bool diarize;
+  VALUE new_segment_callback;
 } ruby_whisper_params;
 
 #endif