Remove custom flashlight import

torchaudio/models/decoder/__init__.py

@@ -1,5 +1,4 @@
-_INITIALIZED = False
-_LAZILY_IMPORTED = [
+_CTC_DECODERS = [
     "CTCHypothesis",
     "CTCDecoder",
     "CTCDecoderLM",
@@ -10,12 +9,12 @@
 
 
 def __getattr__(name: str):
-    if name in _LAZILY_IMPORTED:
+    if name in _CTC_DECODERS:
         try:
             from . import _ctc_decoder
-        except AttributeError as err:
+        except Exception as err:
             raise RuntimeError(
-                "CTC decoder requires the decoder extension. Please set BUILD_CTC_DECODER=1 when building from source."
+                "CTC Decoder suit requires flashlight-text package and optionally KenLM. Please install them."
             ) from err
 
         item = getattr(_ctc_decoder, name)
@@ -25,7 +24,7 @@ def __getattr__(name: str):
 
 
 def __dir__():
-    return sorted(__all__ + _LAZILY_IMPORTED)
+    return sorted(__all__)
 
 
-__all__ = []
+__all__ = _CTC_DECODERS

torchaudio/models/decoder/_ctc_decoder.py

@@ -2,69 +2,38 @@
 
 import itertools as it
 
-import warnings
 from abc import abstractmethod
 from collections import namedtuple
 from typing import Dict, List, NamedTuple, Optional, Tuple, Union
 
 import torch
-import torchaudio
-from torchaudio.utils import download_asset
-
 
-# We prioritize the version from upstream flashlight here.
-# This will allow applications that use the upstream flashlight
-# alongside torchaudio.
-if torchaudio._internal.module_utils.is_module_available("flashlight"):
-    from flashlight.lib.text.decoder import (
-        CriterionType as _CriterionType,
-        LexiconDecoder as _LexiconDecoder,
-        LexiconDecoderOptions as _LexiconDecoderOptions,
-        LexiconFreeDecoder as _LexiconFreeDecoder,
-        LexiconFreeDecoderOptions as _LexiconFreeDecoderOptions,
-        LM as _LM,
-        LMState as _LMState,
-        SmearingMode as _SmearingMode,
-        Trie as _Trie,
-        ZeroLM as _ZeroLM,
-    )
-    from flashlight.lib.text.dictionary import (
-        create_word_dict as _create_word_dict,
-        Dictionary as _Dictionary,
-        load_words as _load_words,
-    )
+from flashlight.lib.text.decoder import (
+    CriterionType as _CriterionType,
+    LexiconDecoder as _LexiconDecoder,
+    LexiconDecoderOptions as _LexiconDecoderOptions,
+    LexiconFreeDecoder as _LexiconFreeDecoder,
+    LexiconFreeDecoderOptions as _LexiconFreeDecoderOptions,
+    LM as _LM,
+    LMState as _LMState,
+    SmearingMode as _SmearingMode,
+    Trie as _Trie,
+    ZeroLM as _ZeroLM,
+)
+from flashlight.lib.text.dictionary import (
+    create_word_dict as _create_word_dict,
+    Dictionary as _Dictionary,
+    load_words as _load_words,
+)
+from torchaudio.utils import download_asset
 
+try:
+    from flashlight.lib.text.decoder.kenlm import KenLM as _KenLM
+except Exception:
     try:
         from flashlight.lib.text.decoder import KenLM as _KenLM
     except Exception:
         _KenLM = None
-else:
-    torchaudio._extension._load_lib("libflashlight-text")
-    from torchaudio.lib.flashlight_lib_text_decoder import (
-        CriterionType as _CriterionType,
-        KenLM as _KenLM,
-        LexiconDecoder as _LexiconDecoder,
-        LexiconDecoderOptions as _LexiconDecoderOptions,
-        LexiconFreeDecoder as _LexiconFreeDecoder,
-        LexiconFreeDecoderOptions as _LexiconFreeDecoderOptions,
-        LM as _LM,
-        LMState as _LMState,
-        SmearingMode as _SmearingMode,
-        Trie as _Trie,
-        ZeroLM as _ZeroLM,
-    )
-    from torchaudio.lib.flashlight_lib_text_dictionary import (
-        create_word_dict as _create_word_dict,
-        Dictionary as _Dictionary,
-        load_words as _load_words,
-    )
-
-    warnings.warn(
-        "The built-in flashlight integration is deprecated, and will be removed in future release. "
-        "Please install flashlight-text. https://pypi.org/project/flashlight-text/ "
-        "For the detail of CTC decoder migration, please see https://github.com/pytorch/audio/issues/3088."
-    )
-
 
 __all__ = [
     "CTCHypothesis",
@@ -450,7 +419,10 @@ def ctc_decoder(
 
     if type(lm) == str:
         if _KenLM is None:
-            raise RuntimeError("flashlight is installed, but KenLM is not installed. Please install KenLM.")
+            raise RuntimeError(
+                "flashlight-text is installed, but KenLM is not installed. "
+                "Please refer to https://github.com/kpu/kenlm#python-module for how to install it."
+            )
         lm = _KenLM(lm, word_dict)
     elif lm is None:
         lm = _ZeroLM()