diff --git a/api/src/routers/development.py b/api/src/routers/development.py
index 96f94ea..6a0de60 100644
--- a/api/src/routers/development.py
+++ b/api/src/routers/development.py
@@ -120,7 +120,7 @@ async def generate_from_phonemes(
             except Exception as e:
                 logger.error(f"Error in audio generation: {str(e)}")
                 # Clean up writer on error
-                writer.write_chunk(finalize=True)
+                writer.close()
                 # Re-raise the original exception
                 raise
 
@@ -236,6 +236,7 @@ async def create_captioned_speech(
                         # Ensure temp writer is closed
                         if not temp_writer._finalized:
                             await temp_writer.__aexit__(None, None, None)
+                        writer.close()
 
                 # Stream with temp file writing
                 return JSONStreamingResponse(
@@ -267,6 +268,7 @@ async def create_captioned_speech(
                                 
                 except Exception as e:
                     logger.error(f"Error in single output streaming: {e}")
+                    writer.close()
                     raise
 
             # Standard streaming without download link
@@ -294,10 +296,8 @@ async def create_captioned_speech(
             
             audio_data = await AudioService.convert_audio(
                 audio_data,
-                24000,
                 request.response_format,
                 writer,
-                is_first_chunk=True,
                 is_last_chunk=False,
                 trim_audio=False,
             )
@@ -305,10 +305,8 @@ async def create_captioned_speech(
             # Convert to requested format with proper finalization
             final = await AudioService.convert_audio(
                 AudioChunk(np.array([], dtype=np.int16)),
-                24000,
                 request.response_format,
                 writer,
-                is_first_chunk=False,
                 is_last_chunk=True,
             )
             output=audio_data.output + final.output
@@ -316,6 +314,9 @@ async def create_captioned_speech(
             base64_output= base64.b64encode(output).decode("utf-8")
             
             content=CaptionedSpeechResponse(audio=base64_output,audio_format=content_type,timestamps=audio_data.word_timestamps).model_dump()
+
+            writer.close()
+
             return JSONResponse(
                 content=content,
                 media_type="application/json",
@@ -328,6 +329,12 @@ async def create_captioned_speech(
     except ValueError as e:
         # Handle validation errors
         logger.warning(f"Invalid request: {str(e)}")
+
+        try:
+            writer.close()
+        except:
+            pass
+
         raise HTTPException(
             status_code=400,
             detail={
@@ -339,6 +346,12 @@ async def create_captioned_speech(
     except RuntimeError as e:
         # Handle runtime/processing errors
         logger.error(f"Processing error: {str(e)}")
+
+        try:
+            writer.close()
+        except:
+            pass
+
         raise HTTPException(
             status_code=500,
             detail={
@@ -350,6 +363,12 @@ async def create_captioned_speech(
     except Exception as e:
         # Handle unexpected errors
         logger.error(f"Unexpected error in captioned speech generation: {str(e)}")
+
+        try:
+            writer.close()
+        except:
+            pass
+
         raise HTTPException(
             status_code=500,
             detail={
diff --git a/api/src/routers/openai_compatible.py b/api/src/routers/openai_compatible.py
index 6d37e71..742c216 100644
--- a/api/src/routers/openai_compatible.py
+++ b/api/src/routers/openai_compatible.py
@@ -240,6 +240,7 @@ async def create_speech(
                         # Ensure temp writer is closed
                         if not temp_writer._finalized:
                             await temp_writer.__aexit__(None, None, None)
+                        writer.close()
 
                 # Stream with temp file writing
                 return StreamingResponse(dual_output(), media_type=content_type, headers=headers)
@@ -252,6 +253,7 @@ async def create_speech(
                             yield chunk_data.output
                 except Exception as e:
                     logger.error(f"Error in single output streaming: {e}")
+                    writer.close()
                     raise
 
             # Standard streaming without download link
@@ -281,15 +283,13 @@ async def create_speech(
                 lang_code=request.lang_code,
             )
 
-            audio_data = await AudioService.convert_audio(audio_data, 24000, request.response_format, writer, is_first_chunk=True, is_last_chunk=False, trim_audio=False)
+            audio_data = await AudioService.convert_audio(audio_data, request.response_format, writer, is_last_chunk=False, trim_audio=False)
 
             # Convert to requested format with proper finalization
             final = await AudioService.convert_audio(
                 AudioChunk(np.array([], dtype=np.int16)),
-                24000,
                 request.response_format,
                 writer,
-                is_first_chunk=False,
                 is_last_chunk=True,
             )
             output = audio_data.output + final.output
@@ -321,6 +321,7 @@ async def create_speech(
                     # Ensure temp writer is closed
                     if not temp_writer._finalized:
                         await temp_writer.__aexit__(None, None, None)
+                    writer.close()
 
             return Response(
                 content=output,
@@ -331,6 +332,12 @@ async def create_speech(
     except ValueError as e:
         # Handle validation errors
         logger.warning(f"Invalid request: {str(e)}")
+        
+        try:
+            writer.close()
+        except:
+            pass
+
         raise HTTPException(
             status_code=400,
             detail={
@@ -342,6 +349,12 @@ async def create_speech(
     except RuntimeError as e:
         # Handle runtime/processing errors
         logger.error(f"Processing error: {str(e)}")
+
+        try:
+            writer.close()
+        except:
+            pass
+
         raise HTTPException(
             status_code=500,
             detail={
@@ -353,6 +366,12 @@ async def create_speech(
     except Exception as e:
         # Handle unexpected errors
         logger.error(f"Unexpected error in speech generation: {str(e)}")
+
+        try:
+            writer.close()
+        except:
+            pass
+
         raise HTTPException(
             status_code=500,
             detail={
@@ -361,6 +380,7 @@ async def create_speech(
                 "type": "server_error",
             },
         )
+    
 
 
 @router.get("/download/{filename}")
diff --git a/api/src/services/audio.py b/api/src/services/audio.py
index d0aed80..5e344ec 100644
--- a/api/src/services/audio.py
+++ b/api/src/services/audio.py
@@ -108,17 +108,13 @@ class AudioService:
         },
     }
 
-    _writers = {}
-
     @staticmethod
     async def convert_audio(
         audio_chunk: AudioChunk,
-        sample_rate: int,
         output_format: str,
         writer: StreamingAudioWriter,
         speed: float = 1,
         chunk_text: str = "",
-        is_first_chunk: bool = True,
         is_last_chunk: bool = False,
         trim_audio: bool = True,
         normalizer: AudioNormalizer = None,
@@ -127,12 +123,12 @@ class AudioService:
 
         Args:
             audio_data: Numpy array of audio samples
-            sample_rate: Sample rate of the audio
             output_format: Target format (wav, mp3, ogg, pcm)
+            writer: The StreamingAudioWriter to use
             speed: The speaking speed of the voice
             chunk_text: The text sent to the model to generate the resulting speech
-            is_first_chunk: Whether this is the first chunk
             is_last_chunk: Whether this is the last chunk
+            trim_audio: Whether audio should be trimmed
             normalizer: Optional AudioNormalizer instance for consistent normalization
 
         Returns:
@@ -153,15 +149,6 @@ class AudioService:
             if trim_audio == True:
                 audio_chunk = AudioService.trim_audio(audio_chunk,chunk_text,speed,is_last_chunk,normalizer)
             
-            # Get or create format-specific writer
-            """writer_key = f"{output_format}_{sample_rate}"
-            if is_first_chunk or writer_key not in AudioService._writers:
-                AudioService._writers[writer_key] = StreamingAudioWriter(
-                    output_format, sample_rate
-                )
-                
-            writer = AudioService._writers[writer_key]"""
-            
             # Write audio data first
             if len(audio_chunk.audio) > 0:
                 chunk_data = writer.write_chunk(audio_chunk.audio)
diff --git a/api/src/services/streaming_audio_writer.py b/api/src/services/streaming_audio_writer.py
index 71dcd32..763c5eb 100644
--- a/api/src/services/streaming_audio_writer.py
+++ b/api/src/services/streaming_audio_writer.py
@@ -22,7 +22,7 @@ class StreamingAudioWriter:
 
         codec_map = {"wav":"pcm_s16le","mp3":"mp3","opus":"libopus","flac":"flac", "aac":"aac"}
         # Format-specific setup
-        if self.format in ["wav", "opus","flac","mp3","aac","pcm"]:
+        if self.format in ["wav","flac","mp3","pcm","aac","opus"]:
             if self.format != "pcm":
                 self.output_buffer = BytesIO()
                 self.container = av.open(self.output_buffer, mode="w", format=self.format)
@@ -31,6 +31,13 @@ class StreamingAudioWriter:
         else:
             raise ValueError(f"Unsupported format: {format}")
 
+    def close(self):
+        if hasattr(self, "container"):
+            self.container.close()
+
+        if hasattr(self, "output_buffer"):
+            self.output_buffer.close()
+
     def write_chunk(
         self, audio_data: Optional[np.ndarray] = None, finalize: bool = False
     ) -> bytes:
@@ -48,7 +55,7 @@ class StreamingAudioWriter:
                     self.container.mux(packet)
                     
                 data=self.output_buffer.getvalue()
-                self.container.close()
+                self.close()
                 return data
 
         if audio_data is None or len(audio_data) == 0:
diff --git a/api/src/services/tts_service.py b/api/src/services/tts_service.py
index 1b31eab..f740a29 100644
--- a/api/src/services/tts_service.py
+++ b/api/src/services/tts_service.py
@@ -70,12 +70,10 @@ class TTSService:
                         return
                     chunk_data = await AudioService.convert_audio(
                         AudioChunk(np.array([], dtype=np.float32)),  # Dummy data for type checking
-                        24000,
                         output_format,
                         writer,
                         speed,
                         "",
-                        is_first_chunk=False,
                         normalizer=normalizer,
                         is_last_chunk=True,
                     )
@@ -105,12 +103,10 @@ class TTSService:
                             try:
                                 chunk_data = await AudioService.convert_audio(
                                     chunk_data,
-                                    24000,
                                     output_format,
                                     writer,
                                     speed,
                                     chunk_text,
-                                    is_first_chunk=is_first and chunk_index == 0,
                                     is_last_chunk=is_last,
                                     normalizer=normalizer,
                                 )
@@ -139,12 +135,10 @@ class TTSService:
                         try:
                             chunk_data = await AudioService.convert_audio(
                                 chunk_data,
-                                24000,
                                 output_format,
                                 writer,
                                 speed,
                                 chunk_text,
-                                is_first_chunk=is_first,
                                 normalizer=normalizer,
                                 is_last_chunk=is_last,
                             )
diff --git a/api/tests/conftest.py b/api/tests/conftest.py
index b8dd761..dee66f9 100644
--- a/api/tests/conftest.py
+++ b/api/tests/conftest.py
@@ -70,16 +70,3 @@ def test_voice():
     """Return a test voice name."""
     return "voice1"
 
-
-@pytest.fixture(scope="session")
-def event_loop():
-    """Create an instance of the default event loop for the test session."""
-    import asyncio
-
-    try:
-        loop = asyncio.get_event_loop()
-    except RuntimeError:
-        loop = asyncio.new_event_loop()
-        asyncio.set_event_loop(loop)
-    yield loop
-    loop.close()
diff --git a/api/tests/test_audio_service.py b/api/tests/test_audio_service.py
index 3d53322..9351454 100644
--- a/api/tests/test_audio_service.py
+++ b/api/tests/test_audio_service.py
@@ -34,8 +34,11 @@ async def test_convert_to_wav(sample_audio):
     writer = StreamingAudioWriter("wav", sample_rate=24000)
     # Write and finalize in one step for WAV
     audio_chunk = await AudioService.convert_audio(
-        AudioChunk(audio_data), sample_rate, "wav", writer, is_first_chunk=True, is_last_chunk=False
+        AudioChunk(audio_data), "wav", writer, is_last_chunk=False
     )
+
+    writer.close()
+
     assert isinstance(audio_chunk.output, bytes)
     assert isinstance(audio_chunk, AudioChunk)
     assert len(audio_chunk.output) > 0
@@ -52,8 +55,11 @@ async def test_convert_to_mp3(sample_audio):
     writer = StreamingAudioWriter("mp3", sample_rate=24000)
 
     audio_chunk = await AudioService.convert_audio(
-        AudioChunk(audio_data), sample_rate, "mp3", writer
+        AudioChunk(audio_data), "mp3", writer
     )
+
+    writer.close()
+
     assert isinstance(audio_chunk.output, bytes)
     assert isinstance(audio_chunk, AudioChunk)
     assert len(audio_chunk.output) > 0
@@ -64,13 +70,17 @@ async def test_convert_to_mp3(sample_audio):
 @pytest.mark.asyncio
 async def test_convert_to_opus(sample_audio):
     """Test converting to Opus format"""
+
     audio_data, sample_rate = sample_audio
 
     writer = StreamingAudioWriter("opus", sample_rate=24000)
 
     audio_chunk = await AudioService.convert_audio(
-        AudioChunk(audio_data), sample_rate, "opus",writer
+        AudioChunk(audio_data), "opus",writer
     )
+
+    writer.close()
+
     assert isinstance(audio_chunk.output, bytes)
     assert isinstance(audio_chunk, AudioChunk)
     assert len(audio_chunk.output) > 0
@@ -86,8 +96,11 @@ async def test_convert_to_flac(sample_audio):
     writer = StreamingAudioWriter("flac", sample_rate=24000)
 
     audio_chunk = await AudioService.convert_audio(
-        AudioChunk(audio_data), sample_rate, "flac", writer
+        AudioChunk(audio_data), "flac", writer
     )
+
+    writer.close()
+
     assert isinstance(audio_chunk.output, bytes)
     assert isinstance(audio_chunk, AudioChunk)
     assert len(audio_chunk.output) > 0
@@ -103,8 +116,11 @@ async def test_convert_to_aac(sample_audio):
     writer = StreamingAudioWriter("aac", sample_rate=24000)
 
     audio_chunk = await AudioService.convert_audio(
-        AudioChunk(audio_data), sample_rate, "aac", writer
+        AudioChunk(audio_data), "aac", writer
     )
+
+    writer.close()
+    
     assert isinstance(audio_chunk.output, bytes)
     assert isinstance(audio_chunk, AudioChunk)
     assert len(audio_chunk.output) > 0
@@ -120,8 +136,11 @@ async def test_convert_to_pcm(sample_audio):
     writer = StreamingAudioWriter("pcm", sample_rate=24000)
 
     audio_chunk = await AudioService.convert_audio(
-        AudioChunk(audio_data), sample_rate, "pcm", writer
+        AudioChunk(audio_data), "pcm", writer
     )
+
+    writer.close()
+
     assert isinstance(audio_chunk.output, bytes)
     assert isinstance(audio_chunk, AudioChunk)
     assert len(audio_chunk.output) > 0
@@ -131,12 +150,9 @@ async def test_convert_to_pcm(sample_audio):
 @pytest.mark.asyncio
 async def test_convert_to_invalid_format_raises_error(sample_audio):
     """Test that converting to an invalid format raises an error"""
-    audio_data, sample_rate = sample_audio
+    #audio_data, sample_rate = sample_audio
     with pytest.raises(ValueError, match="Unsupported format: invalid"):
-        StreamingAudioWriter("invalid", sample_rate=24000)
-
-    with pytest.raises(ValueError, match="Format invalid not supported"):
-        await AudioService.convert_audio(audio_data, sample_rate, "invalid", None)
+        writer = StreamingAudioWriter("invalid", sample_rate=24000)
 
 
 @pytest.mark.asyncio
@@ -150,8 +166,11 @@ async def test_normalization_wav(sample_audio):
     large_audio = audio_data * 1e5
     # Write and finalize in one step for WAV
     audio_chunk = await AudioService.convert_audio(
-        AudioChunk(large_audio), sample_rate, "wav", writer, is_first_chunk=True
+        AudioChunk(large_audio), "wav", writer
     )
+
+    writer.close()
+
     assert isinstance(audio_chunk.output, bytes)
     assert isinstance(audio_chunk, AudioChunk)
     assert len(audio_chunk.output) > 0
@@ -167,7 +186,7 @@ async def test_normalization_pcm(sample_audio):
     # Create audio data outside int16 range
     large_audio = audio_data * 1e5
     audio_chunk = await AudioService.convert_audio(
-        AudioChunk(large_audio), sample_rate, "pcm", writer
+        AudioChunk(large_audio), "pcm", writer
     )
     assert isinstance(audio_chunk.output, bytes)
     assert isinstance(audio_chunk, AudioChunk)
@@ -197,8 +216,11 @@ async def test_different_sample_rates(sample_audio):
         writer = StreamingAudioWriter("wav", sample_rate=rate)
 
         audio_chunk = await AudioService.convert_audio(
-            AudioChunk(audio_data), rate, "wav", writer, is_first_chunk=True
+            AudioChunk(audio_data), "wav", writer
         )
+
+        writer.close()
+
         assert isinstance(audio_chunk.output, bytes)
         assert isinstance(audio_chunk, AudioChunk)
         assert len(audio_chunk.output) > 0
@@ -213,7 +235,7 @@ async def test_buffer_position_after_conversion(sample_audio):
 
     # Write and finalize in one step for first conversion
     audio_chunk1 = await AudioService.convert_audio(
-        AudioChunk(audio_data), sample_rate, "wav", writer, is_first_chunk=True, is_last_chunk=True
+        AudioChunk(audio_data), "wav", writer, is_last_chunk=True
     )
     assert isinstance(audio_chunk1.output, bytes)
     assert isinstance(audio_chunk1, AudioChunk)
@@ -222,7 +244,7 @@ async def test_buffer_position_after_conversion(sample_audio):
     writer = StreamingAudioWriter("wav", sample_rate=24000)
 
     audio_chunk2 = await AudioService.convert_audio(
-        AudioChunk(audio_data), sample_rate, "wav", writer, is_first_chunk=True, is_last_chunk=True
+        AudioChunk(audio_data), "wav", writer, is_last_chunk=True
     )
     assert isinstance(audio_chunk2.output, bytes)
     assert isinstance(audio_chunk2, AudioChunk)
diff --git a/api/tests/test_openai_endpoints.py b/api/tests/test_openai_endpoints.py
index 527cb1f..0f89a6c 100644
--- a/api/tests/test_openai_endpoints.py
+++ b/api/tests/test_openai_endpoints.py
@@ -4,6 +4,8 @@ import os
 from typing import AsyncGenerator, Tuple
 from unittest.mock import AsyncMock, MagicMock, patch
 
+from api.src.services.streaming_audio_writer import StreamingAudioWriter
+
 from api.src.inference.base import AudioChunk
 import numpy as np
 import pytest
@@ -159,10 +161,14 @@ async def test_stream_audio_chunks_client_disconnect():
         speed=1.0,
     )
 
+    writer = StreamingAudioWriter("mp3", 24000)
+
     chunks = []
-    async for chunk in stream_audio_chunks(mock_service, request, mock_request):
+    async for chunk in stream_audio_chunks(mock_service, request, mock_request, writer):
         chunks.append(chunk)
 
+    writer.close()
+
     assert len(chunks) == 0  # Should stop immediately due to disconnect
 
 
@@ -483,7 +489,11 @@ async def test_streaming_initialization_error():
         speed=1.0,
     )
 
+    writer = StreamingAudioWriter("mp3", 24000)
+
     with pytest.raises(RuntimeError) as exc:
-        async for _ in stream_audio_chunks(mock_service, request, MagicMock()):
+        async for _ in stream_audio_chunks(mock_service, request, MagicMock(), writer):
             pass
+
+    writer.close()
     assert "Failed to initialize stream" in str(exc.value)
diff --git a/pyproject.toml b/pyproject.toml
index d0ff675..3b9e486 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -37,7 +37,7 @@ dependencies = [
     "en-core-web-sm @ https://github.com/explosion/spacy-models/releases/download/en_core_web_sm-3.7.1/en_core_web_sm-3.7.1-py3-none-any.whl",
     "inflect>=7.5.0",
     "phonemizer-fork>=3.3.2",
-    "av>=14.1.0",
+    "av>=14.2.0",
 ]
 
 [project.optional-dependencies]
@@ -48,10 +48,10 @@ cpu = [
     "torch==2.6.0",
 ]
 test = [
-    "pytest==8.0.0",
-    "pytest-cov==4.1.0",
+    "pytest==8.3.5",
+    "pytest-cov==6.0.0",
     "httpx==0.26.0",
-    "pytest-asyncio==0.23.5",
+    "pytest-asyncio==0.25.3",
     "openai>=1.59.6",
     "tomli>=2.0.1",
 ]
@@ -91,5 +91,5 @@ packages.find = {where = ["api/src"], namespaces = true}
 [tool.pytest.ini_options]
 testpaths = ["api/tests", "ui/tests"]
 python_files = ["test_*.py"]
-addopts = "--cov=api --cov=ui --cov-report=term-missing --cov-config=.coveragerc"
-asyncio_mode = "strict"
+addopts = "--cov=api --cov=ui --cov-report=term-missing --cov-config=.coveragerc --full-trace" 
+asyncio_mode = "auto"