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50 lines
1.9 KiB
Python
50 lines
1.9 KiB
Python
#!/usr/bin/env python3
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# Copyright 2023 Xiaomi Corp. (Author: Weiji Zhuang,
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# Liyong Guo)
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#
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# See ../../../../LICENSE for clarification regarding multiple authors
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from typing import List
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def ctc_trivial_decoding_graph(wakeup_word_tokens: List[int]):
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"""
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A graph starts with blank/unknown and follwoing by wakeup word.
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Args:
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wakeup_word_tokens: A sequence of token ids corresponding wakeup_word.
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It should not contain 0 and 1.
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We assume 0 is for blank and 1 is for unknown.
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"""
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assert 0 not in wakeup_word_tokens
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assert 1 not in wakeup_word_tokens
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assert len(wakeup_word_tokens) >= 2
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keyword_ilabel_start = wakeup_word_tokens[0]
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fst_graph = ""
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for non_wake_word_token in range(keyword_ilabel_start):
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fst_graph += f"0 0 {non_wake_word_token} 0\n"
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cur_state = 1
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for token_idx in range(len(wakeup_word_tokens) - 1):
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token = wakeup_word_tokens[token_idx]
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fst_graph += f"{cur_state - 1} {cur_state} {token} 0\n"
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fst_graph += f"{cur_state} {cur_state} {token} 0\n"
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cur_state += 1
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token = wakeup_word_tokens[-1]
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fst_graph += f"{cur_state - 1} {cur_state} {token} 1\n"
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fst_graph += f"{cur_state} {cur_state} {token} 0\n"
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fst_graph += f"{cur_state}\n"
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return fst_graph
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