fix(voice): #1824 handle odd-length audio buffers in StreamedAudioResult (#2456)

Author: weiguangli-io

src/agents/voice/result.py

@@ -88,7 +88,12 @@ async def _add_error(self, error: Exception):
     def _transform_audio_buffer(
         self, buffer: list[bytes], output_dtype: npt.DTypeLike
     ) -> npt.NDArray[np.int16 | np.float32]:
-        np_array = np.frombuffer(b"".join(buffer), dtype=np.int16)
+        combined_buffer = b"".join(buffer)
+        if len(combined_buffer) % 2 != 0:
+            # np.int16 needs 2-byte alignment; pad odd-length chunks safely.
+            combined_buffer += b"\x00"
+
+        np_array = np.frombuffer(combined_buffer, dtype=np.int16)
 
         if output_dtype == np.int16:
             return np_array
@@ -118,6 +123,7 @@ async def _stream_audio(
                 first_byte_received = False
                 buffer: list[bytes] = []
                 full_audio_data: list[bytes] = []
+                pending_byte = b""
 
                 async for chunk in self.tts_model.run(text, self.tts_settings):
                     if not first_byte_received:
@@ -128,15 +134,33 @@ async def _stream_audio(
                         buffer.append(chunk)
                         full_audio_data.append(chunk)
                         if len(buffer) >= self._buffer_size:
-                            audio_np = self._transform_audio_buffer(buffer, self.tts_settings.dtype)
-                            if self.tts_settings.transform_data:
-                                audio_np = self.tts_settings.transform_data(audio_np)
-                            await local_queue.put(
-                                VoiceStreamEventAudio(data=audio_np)
-                            )  # Use local queue
+                            combined = pending_byte + b"".join(buffer)
+                            if len(combined) % 2 != 0:
+                                pending_byte = combined[-1:]
+                                combined = combined[:-1]
+                            else:
+                                pending_byte = b""
+
+                            if combined:
+                                audio_np = self._transform_audio_buffer(
+                                    [combined], self.tts_settings.dtype
+                                )
+                                if self.tts_settings.transform_data:
+                                    audio_np = self.tts_settings.transform_data(audio_np)
+                                await local_queue.put(
+                                    VoiceStreamEventAudio(data=audio_np)
+                                )  # Use local queue
                             buffer = []
                 if buffer:
-                    audio_np = self._transform_audio_buffer(buffer, self.tts_settings.dtype)
+                    combined = pending_byte + b"".join(buffer)
+                else:
+                    combined = pending_byte
+
+                if combined:
+                    # Final flush: pad the remaining half sample if needed.
+                    if len(combined) % 2 != 0:
+                        combined += b"\x00"
+                    audio_np = self._transform_audio_buffer([combined], self.tts_settings.dtype)
                     if self.tts_settings.transform_data:
                         audio_np = self.tts_settings.transform_data(audio_np)
                     await local_queue.put(VoiceStreamEventAudio(data=audio_np))  # Use local queue

tests/voice/test_pipeline.py

@@ -1,18 +1,84 @@
 from __future__ import annotations
 
+import asyncio
+
 import numpy as np
 import numpy.typing as npt
 import pytest
 
 try:
-    from agents.voice import AudioInput, TTSModelSettings, VoicePipeline, VoicePipelineConfig
+    from agents.voice import (
+        AudioInput,
+        StreamedAudioResult,
+        TTSModelSettings,
+        VoicePipeline,
+        VoicePipelineConfig,
+        VoiceStreamEvent,
+        VoiceStreamEventAudio,
+        VoiceStreamEventLifecycle,
+    )
 
     from .fake_models import FakeStreamedAudioInput, FakeSTT, FakeTTS, FakeWorkflow
     from .helpers import extract_events
 except ImportError:
     pass
 
 
+def test_streamed_audio_result_odd_length_buffer_int16() -> None:
+    result = StreamedAudioResult(
+        FakeTTS(),
+        TTSModelSettings(dtype=np.int16),
+        VoicePipelineConfig(),
+    )
+
+    transformed = result._transform_audio_buffer([b"\x01"], np.int16)
+
+    assert transformed.dtype == np.int16
+    assert transformed.tolist() == [1]
+
+
+def test_streamed_audio_result_odd_length_buffer_float32() -> None:
+    result = StreamedAudioResult(
+        FakeTTS(),
+        TTSModelSettings(dtype=np.float32),
+        VoicePipelineConfig(),
+    )
+
+    transformed = result._transform_audio_buffer([b"\x01"], np.float32)
+
+    assert transformed.dtype == np.float32
+    assert transformed.shape == (1, 1)
+    assert transformed[0, 0] == pytest.approx(1 / 32767.0)
+
+
+@pytest.mark.asyncio
+async def test_streamed_audio_result_preserves_cross_chunk_sample_boundaries() -> None:
+    class SplitSampleTTS(FakeTTS):
+        async def run(self, text: str, settings: TTSModelSettings):
+            del text, settings
+            yield b"\x01"
+            yield b"\x00"
+
+    result = StreamedAudioResult(
+        SplitSampleTTS(),
+        TTSModelSettings(buffer_size=1, dtype=np.int16),
+        VoicePipelineConfig(),
+    )
+    local_queue: asyncio.Queue[VoiceStreamEvent | None] = asyncio.Queue()
+
+    await result._stream_audio("hello", local_queue, finish_turn=True)
+
+    audio_chunks: list[bytes] = []
+    while True:
+        event = await local_queue.get()
+        if isinstance(event, VoiceStreamEventAudio) and event.data is not None:
+            audio_chunks.append(event.data.tobytes())
+        if isinstance(event, VoiceStreamEventLifecycle) and event.event == "turn_ended":
+            break
+
+    assert audio_chunks == [np.array([1], dtype=np.int16).tobytes()]
+
+
 @pytest.mark.asyncio
 async def test_voicepipeline_run_single_turn() -> None:
     # Single turn. Should produce a single audio output, which is the TTS output for "out_1".