Make FFmpeg log level configurable (#2439)

Summary:
Undesired logs are one of the loudest UX complains we get.
Yet, loading media files involves uncertainty which is
difficult to debug without debug log.

This commit introduces utility functions to configure logging level
so that we can ask users to enable it when they encounter an issue,
while defaulting to non-verbose option.

Pull Request resolved: https://github.com/pytorch/audio/pull/2439

Reviewed By: hwangjeff, xiaohui-zhang

Differential Revision: D36903763

Pulled By: mthrok

fbshipit-source-id: f4ddd9915b13197c2a2eb97e965005b8b5b8d987

docs/source/utils.rst

@@ -11,3 +11,11 @@ This affects functionalities in :ref:`Sox IO backend<sox_io_backend>` and :ref:`
 
 .. automodule:: torchaudio.utils.sox_utils
    :members:
+
+torchaudio.utils.ffmpeg_utils
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Utility module to configure FFmpeg libraries.
+
+.. automodule:: torchaudio.utils.ffmpeg_utils
+   :members:

test/torchaudio_unittest/common_utils/case_utils.py

@@ -8,6 +8,7 @@ import time
 import unittest
 
 import torch
+import torchaudio
 from torch.testing._internal.common_utils import TestCase as PytorchTestCase
 from torchaudio._internal.module_utils import (
     is_kaldi_available,
@@ -112,22 +113,8 @@ class TorchaudioTestCase(TestBaseMixin, PytorchTestCase):
     pass
 
 
-_IS_FFMPEG_AVAILABLE = None
-
-
 def is_ffmpeg_available():
-    if _eval_env("TORCHAUDIO_TEST_IN_FBCODE", default=False):
-        return True
-
-    global _IS_FFMPEG_AVAILABLE
-    if _IS_FFMPEG_AVAILABLE is None:
-        try:
-            from torchaudio.io import StreamReader  # noqa: F401
-
-            _IS_FFMPEG_AVAILABLE = True
-        except Exception:
-            _IS_FFMPEG_AVAILABLE = False
-    return _IS_FFMPEG_AVAILABLE
+    return torchaudio._extension._FFMPEG_INITIALIZED
 
 
 _IS_CTC_DECODER_AVAILABLE = None

test/torchaudio_unittest/utils/ffmpeg_utils_test.py

+from torchaudio.utils import ffmpeg_utils
+from torchaudio_unittest.common_utils import PytorchTestCase, skipIfNoFFmpeg
+
+
+@skipIfNoFFmpeg
+class TestFFmpegUtils(PytorchTestCase):
+    """Smoke test for ffmpeg_utils module"""
+
+    def tearDown(self):
+        ffmpeg_utils.set_log_level(8)
+        super().tearDown()
+
+    def test_get_log_level(self):
+        """`get_log_level` does not exhibit abnormal behavior"""
+        for _ in range(10):
+            ffmpeg_utils.get_log_level()
+
+    def test_set_log_level(self):
+        """`set_log_level` persists log level"""
+        for i in range(-100, 100):
+            ffmpeg_utils.set_log_level(i)
+            assert ffmpeg_utils.get_log_level() == i

torchaudio/csrc/ffmpeg/stream_reader_binding.cpp

@@ -29,11 +29,12 @@ c10::intrusive_ptr<StreamReaderBinding> init(
 using S = const c10::intrusive_ptr<StreamReaderBinding>&;
 
 TORCH_LIBRARY_FRAGMENT(torchaudio, m) {
-  m.def("torchaudio::ffmpeg_init", []() {
-    avdevice_register_all();
-    if (av_log_get_level() == AV_LOG_INFO) {
-      av_log_set_level(AV_LOG_ERROR);
-    }
+  m.def("torchaudio::ffmpeg_init", []() { avdevice_register_all(); });
+  m.def("torchaudio::ffmpeg_get_log_level", []() -> int64_t {
+    return static_cast<int64_t>(av_log_get_level());
+  });
+  m.def("torchaudio::ffmpeg_set_log_level", [](int64_t level) {
+    av_log_set_level(static_cast<int>(level));
   });
   m.class_<StreamReaderBinding>("ffmpeg_StreamReader")
       .def(torch::init<>(init))

torchaudio/utils/__init__.py

 from torchaudio._internal import module_utils as _mod_utils
 
-from . import sox_utils
+from . import ffmpeg_utils, sox_utils
 from .download import download_asset
 
 if _mod_utils.is_sox_available():
     sox_utils.set_verbosity(0)
 
-
 __all__ = [
     "download_asset",
     "sox_utils",
+    "ffmpeg_utils",
 ]

torchaudio/utils/ffmpeg_utils.py

+import torch
+
+
+def get_log_level() -> int:
+    """Get the log level of FFmpeg.
+
+    See :py:func:`set_log_level` for the detailo.
+    """
+    return torch.ops.torchaudio.ffmpeg_get_log_level()
+
+
+def set_log_level(level: int):
+    """Set the log level of FFmpeg (libavformat etc)
+
+    Arguments:
+        level (int): Log level. The larger, the more verbose.
+
+            The following values are common values, the corresponding ``ffmpeg``'s
+            ``-loglevel`` option value and desription.
+
+                * ``-8`` (``quiet``):
+                  Print no output.
+                * ``0`` (``panic``):
+                  Something went really wrong and we will crash now.
+                * ``8`` (``fatal``):
+                  Something went wrong and recovery is not possible.
+                  For example, no header was found for a format which depends
+                  on headers or an illegal combination of parameters is used.
+                * ``16`` (``error``):
+                  Something went wrong and cannot losslessly be recovered.
+                  However, not all future data is affected.
+                * ``24`` (``warning``):
+                  Something somehow does not look correct.
+                  This may or may not lead to problems.
+                * ``32`` (``info``):
+                  Standard information.
+                * ``40`` (``verbose``):
+                  Detailed information.
+                * ``48`` (``debug``):
+                  Stuff which is only useful for libav* developers.
+                * ``56`` (``trace``):
+                  Extremely verbose debugging, useful for libav* development.
+
+    """
+    torch.ops.torchaudio.ffmpeg_set_log_level(level)