fix: silence GenAI audio optional dependency import warning

util/opentelemetry-util-genai/CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+- Avoid import-time warnings when optional audio dependencies for PCM16-to-WAV conversion are not installed.
+
 ## Version 0.3b0 (2026-02-20)
 
 - Add `gen_ai.tool_definitions` to completion hook ([#4181](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/4181))

util/opentelemetry-util-genai/src/opentelemetry/util/genai/_multimodal_upload/pre_uploader.py

@@ -78,12 +78,6 @@
 
 _logger = logging.getLogger(__name__)
 
-# Log warning if audio libraries are not available
-if not _audio_libs_available:
-    _logger.warning(
-        "numpy or soundfile not available, PCM16 to WAV conversion will be skipped"
-    )
-
 # Supported modality types for pre-upload (derived from Modality type)
 _SUPPORTED_MODALITIES = get_args(Modality)
 
@@ -591,9 +585,6 @@ def _convert_pcm16_to_wav(
             Byte data in WAV format, None if conversion fails
         """
         if not _audio_libs_available or np is None or sf is None:
-            _logger.warning(
-                "Cannot convert PCM16 to WAV: numpy or soundfile not available"
-            )
             return None
 
         try:

util/opentelemetry-util-genai/tests/_multimodal_upload/test_pre_uploader_audio.py

@@ -18,6 +18,10 @@
 and audio format conversion (e.g., PCM16 to WAV)
 """
 
+import os
+import subprocess
+import sys
+import textwrap
 from pathlib import Path
 from unittest.mock import patch
 
@@ -65,6 +69,55 @@ def _read_audio_file(filename: str) -> bytes:
         with open(filepath, "rb") as file_obj:
             return file_obj.read()
 
+    @staticmethod
+    def test_import_without_audio_libs_does_not_write_to_standard_streams():
+        """Missing optional audio libs should not emit import-time output."""
+        project_root = Path(__file__).parents[4]
+        util_genai_src = Path(__file__).parents[2] / "src"
+        instrumentation_src = (
+            project_root / "opentelemetry-instrumentation" / "src"
+        )
+        env = os.environ.copy()
+        pythonpath_parts = [
+            str(util_genai_src),
+            str(instrumentation_src),
+            env.get("PYTHONPATH", ""),
+        ]
+        env["PYTHONPATH"] = os.pathsep.join(
+            part for part in pythonpath_parts if part
+        )
+
+        script = textwrap.dedent(
+            """
+            import importlib.abc
+            import logging
+            import sys
+
+            class BlockAudioLibs(importlib.abc.MetaPathFinder):
+                def find_spec(self, fullname, path=None, target=None):
+                    if fullname == "numpy" or fullname.startswith("numpy."):
+                        raise ImportError(fullname)
+                    if fullname == "soundfile" or fullname.startswith("soundfile."):
+                        raise ImportError(fullname)
+                    return None
+
+            sys.meta_path.insert(0, BlockAudioLibs())
+            logging.basicConfig(level=logging.WARNING, stream=sys.stdout)
+            import opentelemetry.util.genai._multimodal_upload.pre_uploader  # noqa: F401
+            """
+        )
+
+        completed = subprocess.run(
+            [sys.executable, "-c", script],
+            env=env,
+            check=True,
+            capture_output=True,
+            text=True,
+        )
+
+        assert completed.stdout == ""
+        assert completed.stderr == ""
+
     # ========== Edge Case Tests ==========
 
     @staticmethod
@@ -174,6 +227,53 @@ def test_pcm16_to_wav_conversion(pre_uploader, pcm_mime_type):
             # If library unavailable, should keep original format
             assert uploads[0].content_type == pcm_mime_type
 
+    @staticmethod
+    def test_pcm16_conversion_missing_audio_libs_logs_single_warning(
+        caplog,
+    ):
+        """Missing optional audio libs should only log the actual conversion skip."""
+        with (
+            patch(
+                "opentelemetry.util.genai._multimodal_upload.pre_uploader._audio_libs_available",
+                False,
+            ),
+            patch(
+                "opentelemetry.util.genai._multimodal_upload.pre_uploader.np",
+                None,
+            ),
+            patch(
+                "opentelemetry.util.genai._multimodal_upload.pre_uploader.sf",
+                None,
+            ),
+        ):
+            pre_uploader = MultimodalPreUploader(base_path="/tmp/test_upload")
+            part = Blob(
+                content=b"\x00\x01" * 1000,
+                mime_type="audio/pcm16",
+                modality="audio",
+            )
+            input_messages = [InputMessage(role="user", parts=[part])]
+
+            with caplog.at_level(
+                "WARNING",
+                logger=(
+                    "opentelemetry.util.genai._multimodal_upload.pre_uploader"
+                ),
+            ):
+                uploads = pre_uploader.pre_upload(
+                    span_context=None,
+                    start_time_utc_nano=1000000000000000000,
+                    input_messages=input_messages,
+                    output_messages=None,
+                )
+
+        assert len(uploads) == 1
+        assert uploads[0].content_type == "audio/pcm16"
+        warning_messages = [record.getMessage() for record in caplog.records]
+        assert warning_messages == [
+            "Failed to convert PCM16 to WAV, using original format"
+        ]
+
     @staticmethod
     def test_pcm16_conversion_disabled_by_default():
         """Test PCM16 conversion stays disabled when env var is unset"""