[INFERENCE][BUG] Fix last audio chunk sent twice during inference

simulstream/inference.py

@@ -53,14 +53,10 @@ def process_audio(
     # one speech chunk is the following
     samples_per_chunk = int(
         sample_rate * message_processor.speech_processor.speech_chunk_size)
-    i = 0
+
     for i in range(0, len(data), samples_per_chunk):
         output = message_processor.process_speech(data[i:i + samples_per_chunk].tobytes())
         LOGGER.debug(f"response: {output}")
-    # send last part of the audio
-    if i < len(data):
-        output = message_processor.process_speech(data[i:].tobytes())
-        LOGGER.debug(f"response: {output}")
 
 
 def run_inference(

uts/test_inference.py

@@ -0,0 +1,93 @@
+# Copyright 2026 FBK
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License
+
+import unittest
+from unittest.mock import MagicMock
+import numpy as np
+
+from simulstream.inference import process_audio
+from simulstream.server.message_processor import MessageProcessor
+from simulstream.server.speech_processors import SAMPLE_RATE
+from simulstream.server.speech_processors.incremental_output import IncrementalOutput
+
+
+def make_speech_processor(chunk_size_seconds=1.0):
+    """Creates a mock SpeechProcessor with the minimal interface needed."""
+    mock_output = IncrementalOutput(
+        new_tokens=[], deleted_tokens=0, new_string="", deleted_string="")
+    processor = MagicMock(
+        spec=["speech_chunk_size", "process_chunk", "end_of_stream", "clear", "tokens_to_string"])
+    processor.speech_chunk_size = chunk_size_seconds
+    processor.process_chunk.return_value = mock_output
+    processor.end_of_stream.return_value = mock_output
+    processor.tokens_to_string.return_value = ""
+    return processor
+
+
+def make_message_processor(chunk_size_seconds=1.0):
+    speech_processor = make_speech_processor(chunk_size_seconds)
+    return MessageProcessor(client_id=0, speech_processor=speech_processor)
+
+
+class TestProcessAudio(unittest.TestCase):
+
+    def test_exact_multiple(self):
+        chunk_size = 1.0
+        message_processor = make_message_processor(chunk_size)
+        # 2 Full chunks, no reminder
+        data = np.zeros(SAMPLE_RATE * 2, dtype=np.int16)
+
+        process_audio(message_processor, SAMPLE_RATE, data)
+
+        self.assertEqual(message_processor.speech_processor.process_chunk.call_count, 2)
+        self.assertEqual(message_processor.client_buffer, b'')
+
+    def test_remainder_chunk_not_sent_twice(self):
+        chunk_size = 1.0
+        message_processor = make_message_processor(chunk_size)
+        # 2 Full chunks + a remainder of 0.5s
+        data = np.zeros(int(SAMPLE_RATE * 2.5), dtype=np.int16)
+
+        process_audio(message_processor, SAMPLE_RATE, data)
+
+        # Process_chunk processes full chunks only; remainder stays buffered for end_of_stream
+        self.assertEqual(message_processor.speech_processor.process_chunk.call_count, 2)
+        # Each sample is int16 (2 bytes), so the buffer size in bytes is samples * 2
+        self.assertEqual(len(message_processor.client_buffer), int(SAMPLE_RATE * 0.5) * 2)
+
+    def test_single_chunk(self):
+        chunk_size = 1.0
+        message_processor = make_message_processor(chunk_size)
+        # Data smaller than one chunk (process_chunk not called, data stays buffered)
+        data = np.zeros(SAMPLE_RATE // 2, dtype=np.int16)  # 0.5s
+
+        process_audio(message_processor, SAMPLE_RATE, data)
+
+        message_processor.speech_processor.process_chunk.assert_not_called()
+        # Each sample is int16 (2 bytes), so the buffer size in bytes is samples * 2
+        self.assertEqual(len(message_processor.client_buffer), int(SAMPLE_RATE * 0.5) * 2)
+
+    def test_empty_data(self):
+        message_processor = make_message_processor()
+        # Empty array (process_chunk never called, buffer remains empty)
+        data = np.array([], dtype=np.int16)
+
+        process_audio(message_processor, SAMPLE_RATE, data)
+
+        message_processor.speech_processor.process_chunk.assert_not_called()
+        self.assertEqual(message_processor.client_buffer, b'')
+
+
+if __name__ == "__main__":
+    unittest.main()