more comment on tts frontend

paddlespeech/t2s/exps/syn_utils.py

@@ -99,14 +99,23 @@ def norm(data, mean, std):
     return (data - mean) / std
 
 
-def get_chunks(data, block_size: int, pad_size: int):
-    data_len = data.shape[1]
+def get_chunks(mel, chunk_size: int, pad_size: int):
+    """
+    Split mel by chunk size with left and right context.
+
+    Args:
+        mel (paddle.Tensor): mel spectrogram, shape (B, T, D)
+        chunk_size (int): chunk size
+        pad_size (int): size for left and right context.
+    """
+    T = mel.shape[1]
+    n = math.ceil(T / chunk_size)
+
     chunks = []
-    n = math.ceil(data_len / block_size)
     for i in range(n):
-        start = max(0, i * block_size - pad_size)
-        end = min((i + 1) * block_size + pad_size, data_len)
-        chunks.append(data[:, start:end, :])
+        start = max(0, i * chunk_size - pad_size)
+        end = min((i + 1) * chunk_size + pad_size, T)
+        chunks.append(mel[:, start:end, :])
     return chunks
 
 
@@ -117,14 +126,10 @@ def get_sentences(text_file: Optional[os.PathLike], lang: str='zh'):
     with open(text_file, 'rt', encoding='utf-8') as f:
         for line in f:
             if line.strip() != "":
-                items = re.split(r"\s+", line.strip(), 1)
+                items = re.split(r"\s+", line.strip(), maxsplit=1)
+                assert len(items) == 2
                 utt_id = items[0]
-                if lang in {'zh', 'canton'}:
-                    sentence = "".join(items[1:])
-                elif lang == 'en':
-                    sentence = " ".join(items[1:])
-                elif lang == 'mix':
-                    sentence = " ".join(items[1:])
+                sentence = items[1]
             sentences.append((utt_id, sentence))
     return sentences
 
@@ -319,6 +324,7 @@ def run_frontend(
         input_ids = {}
         if text.strip() != "" and re.match(r".*?<speak>.*?</speak>.*", text,
                                            re.DOTALL):
+            # using ssml
             input_ids = frontend.get_input_ids_ssml(
                 text,
                 merge_sentences=merge_sentences,
@@ -359,6 +365,7 @@ def run_frontend(
         outs.update({'is_slurs': is_slurs})
     else:
         print("lang should in {'zh', 'en', 'mix', 'canton', 'sing'}!")
+
     outs.update({'phone_ids': phone_ids})
     return outs
 

paddlespeech/t2s/exps/synthesize_e2e.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 import argparse
 from pathlib import Path
+from pprint import pprint
 
 import paddle
 import soundfile as sf
@@ -78,6 +79,7 @@ def evaluate(args):
 
     # whether dygraph to static
     if args.inference_dir:
+        print("convert am and voc to static model.")
         # acoustic model
         am_inference = am_to_static(
             am_inference=am_inference,
@@ -92,6 +94,7 @@ def evaluate(args):
 
     output_dir = Path(args.output_dir)
     output_dir.mkdir(parents=True, exist_ok=True)
+
     merge_sentences = False
     # Avoid not stopping at the end of a sub sentence when tacotron2_ljspeech dygraph to static graph
     # but still not stopping in the end (NOTE by yuantian01 Feb 9 2022)
@@ -102,12 +105,18 @@ def evaluate(args):
     if am_name == 'speedyspeech':
         get_tone_ids = True
 
+    # wav samples
     N = 0
+    # inference time cost
     T = 0
+
+    # [(uid, text), ]
     if am_name == 'diffsinger':
         sentences = get_sentences_svs(text_file=args.text)
     else:
         sentences = get_sentences(text_file=args.text, lang=args.lang)
+    pprint(f"inputs: {sentences}")
+
     for utt_id, sentence in sentences:
         with timer() as t:
             if am_name == "diffsinger":
@@ -116,6 +125,8 @@ def evaluate(args):
             else:
                 text = sentence
                 svs_input = None
+
+            # frontend
             frontend_dict = run_frontend(
                 frontend=frontend,
                 text=text,
@@ -124,25 +135,33 @@ def evaluate(args):
                 lang=args.lang,
                 svs_input=svs_input)
             phone_ids = frontend_dict['phone_ids']
+            # pprint(f"process: {utt_id} {phone_ids}")
+
             with paddle.no_grad():
                 flags = 0
                 for i in range(len(phone_ids)):
+                    # sub phone, split by `sp` or punctuation.
                     part_phone_ids = phone_ids[i]
+
                     # acoustic model
                     if am_name == 'fastspeech2':
                         # multi speaker
                         if am_dataset in {"aishell3", "vctk", "mix", "canton"}:
+                            # multi-speaker
                             spk_id = paddle.to_tensor(args.spk_id)
                             mel = am_inference(part_phone_ids, spk_id)
                         else:
+                            # single-speaker
                             mel = am_inference(part_phone_ids)
                     elif am_name == 'speedyspeech':
                         part_tone_ids = frontend_dict['tone_ids'][i]
                         if am_dataset in {"aishell3", "vctk", "mix"}:
+                            # multi-speaker
                             spk_id = paddle.to_tensor(args.spk_id)
                             mel = am_inference(part_phone_ids, part_tone_ids,
                                                spk_id)
                         else:
+                            # single-speaker
                             mel = am_inference(part_phone_ids, part_tone_ids)
                     elif am_name == 'tacotron2':
                         mel = am_inference(part_phone_ids)
@@ -155,6 +174,7 @@ def evaluate(args):
                             note=part_note_ids,
                             note_dur=part_note_durs,
                             is_slur=part_is_slurs, )
+
                     # vocoder
                     wav = voc_inference(mel)
                     if flags == 0:
@@ -162,17 +182,23 @@ def evaluate(args):
                         flags = 1
                     else:
                         wav_all = paddle.concat([wav_all, wav])
+
         wav = wav_all.numpy()
         N += wav.size
         T += t.elapse
+
+        # samples per second
         speed = wav.size / t.elapse
+        # generate one second wav need `RTF` seconds
         rtf = am_config.fs / speed
         print(
             f"{utt_id}, mel: {mel.shape}, wave: {wav.shape}, time: {t.elapse}s, Hz: {speed}, RTF: {rtf}."
         )
+
         sf.write(
             str(output_dir / (utt_id + ".wav")), wav, samplerate=am_config.fs)
         print(f"{utt_id} done!")
+
     print(f"generation speed: {N / T}Hz, RTF: {am_config.fs / (N / T) }")
 
 

paddlespeech/t2s/frontend/arpabet.py

@@ -11,7 +11,6 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from paddlespeech.t2s.frontend.phonectic import Phonetics
 """
 A phonology system with ARPABET symbols and limited punctuations. The G2P 
 conversion is done by g2p_en.
@@ -19,55 +18,68 @@ conversion is done by g2p_en.
 Note that g2p_en does not handle words with hypen well. So make sure the input
 sentence is first normalized.
 """
-from paddlespeech.t2s.frontend.vocab import Vocab
 from g2p_en import G2p
 
+from paddlespeech.t2s.frontend.phonectic import Phonetics
+from paddlespeech.t2s.frontend.vocab import Vocab
+
 
 class ARPABET(Phonetics):
-    """A phonology for English that uses ARPABET as the phoneme vocabulary.
+    """A phonology for English that uses ARPABET without stress as the phoneme vocabulary.
+
+    47 symbols = 39 phones + 4 punctuations + 4 special tokens(<pad> <unk> <s> </s>)
+
+    The current phoneme set contains 39 phonemes, vowels carry a lexical stress marker:
+        0    — No stress
+        1    — Primary stress
+        2    — Secondary stress
+
+    Phoneme Set:
+        Phoneme Example Translation
+            ------- ------- -----------
+            AA	odd     AA D
+            AE	at	AE T
+            AH	hut	HH AH T
+            AO	ought	AO T
+            AW	cow	K AW
+            AY	hide	HH AY D
+            B 	be	B IY
+            CH	cheese	CH IY Z
+            D 	dee	D IY
+            DH	thee	DH IY
+            EH	Ed	EH D
+            ER	hurt	HH ER T
+            EY	ate	EY T
+            F 	fee	F IY
+            G 	green	G R IY N
+            HH	he	HH IY
+            IH	it	IH T
+            IY	eat	IY T
+            JH	gee	JH IY
+            K 	key	K IY
+            L 	lee	L IY
+            M 	me	M IY
+            N 	knee	N IY
+            NG	ping	P IH NG
+            OW	oat	OW T
+            OY	toy	T OY
+            P 	pee	P IY
+            R 	read	R IY D
+            S 	sea	S IY
+            SH	she	SH IY
+            T 	tea	T IY
+            TH	theta	TH EY T AH
+            UH	hood	HH UH D
+            UW	two	T UW
+            V 	vee	V IY
+            W 	we	W IY
+            Y 	yield	Y IY L D
+            Z 	zee	Z IY
+            ZH	seizure	S IY ZH ER
+
     See http://www.speech.cs.cmu.edu/cgi-bin/cmudict for more details.
-    Phoneme Example Translation
-        ------- ------- -----------
-        AA	odd     AA D
-        AE	at	AE T
-        AH	hut	HH AH T
-        AO	ought	AO T
-        AW	cow	K AW
-        AY	hide	HH AY D
-        B 	be	B IY
-        CH	cheese	CH IY Z
-        D 	dee	D IY
-        DH	thee	DH IY
-        EH	Ed	EH D
-        ER	hurt	HH ER T
-        EY	ate	EY T
-        F 	fee	F IY
-        G 	green	G R IY N
-        HH	he	HH IY
-        IH	it	IH T
-        IY	eat	IY T
-        JH	gee	JH IY
-        K 	key	K IY
-        L 	lee	L IY
-        M 	me	M IY
-        N 	knee	N IY
-        NG	ping	P IH NG
-        OW	oat	OW T
-        OY	toy	T OY
-        P 	pee	P IY
-        R 	read	R IY D
-        S 	sea	S IY
-        SH	she	SH IY
-        T 	tea	T IY
-        TH	theta	TH EY T AH
-        UH	hood	HH UH D
-        UW	two	T UW
-        V 	vee	V IY
-        W 	we	W IY
-        Y 	yield	Y IY L D
-        Z 	zee	Z IY
-        ZH	seizure	S IY ZH ER
     """
+    # 39 phonemes
     phonemes = [
         'AA', 'AE', 'AH', 'AO', 'AW', 'AY', 'B', 'CH', 'D', 'DH', 'EH', 'ER',
         'EY', 'F', 'G', 'HH', 'IH', 'IY', 'JH', 'K', 'L', 'M', 'N', 'NG', 'OW',
@@ -76,6 +88,8 @@ class ARPABET(Phonetics):
     ]
     punctuations = [',', '.', '?', '!']
     symbols = phonemes + punctuations
+    # vowels carry a lexical stress marker：
+    # 0 unstressed（无重音）, 1 primary stress（主重音）和 2 secondary stress（次重音）
     _stress_to_no_stress_ = {
         'AA0': 'AA',
         'AA1': 'AA',
@@ -124,7 +138,12 @@ class ARPABET(Phonetics):
         'UW2': 'UW'
     }
 
+    def __repr__(self):
+        fmt = "ARPABETWithoutStress(phonemes: {}, punctuations: {})"
+        return fmt.format(len(phonemes), punctuations)
+
     def __init__(self):
+        # https://github.com/Kyubyong/g2p/blob/master/g2p_en/g2p.py
         self.backend = G2p()
         self.vocab = Vocab(self.phonemes + self.punctuations)
 
@@ -139,6 +158,7 @@ class ARPABET(Phonetics):
         Returns:
             List[str]: The list of pronunciation sequence.
         """
+        # g2p and remove vowel stress
         phonemes = [
             self._remove_vowels(item) for item in self.backend(sentence)
         ]
@@ -158,6 +178,7 @@ class ARPABET(Phonetics):
         Returns:
             List[int]: The list of pronunciation id sequence.
         """
+        # phonemes to ids
         ids = [self.vocab.lookup(item) for item in phonemes]
         return ids
 
@@ -189,11 +210,16 @@ class ARPABET(Phonetics):
     def vocab_size(self):
         """ Vocab size.
         """
-        # 47 = 39 phones + 4 punctuations + 4 special tokens
+        # 47 = 39 phones + 4 punctuations + 4 special tokens(<pad> <unk> <s> </s>)
         return len(self.vocab)
 
 
 class ARPABETWithStress(Phonetics):
+    """
+    A phonology for English that uses ARPABET with stress as the phoneme vocabulary.
+
+    77 symbols = 69 phones + 4 punctuations + 4 special tokens
+    """
     phonemes = [
         'AA0', 'AA1', 'AA2', 'AE0', 'AE1', 'AE2', 'AH0', 'AH1', 'AH2', 'AO0',
         'AO1', 'AO2', 'AW0', 'AW1', 'AW2', 'AY0', 'AY1', 'AY2', 'B', 'CH', 'D',
@@ -206,6 +232,10 @@ class ARPABETWithStress(Phonetics):
     punctuations = [',', '.', '?', '!']
     symbols = phonemes + punctuations
 
+    def __repr__(self):
+        fmt = "ARPABETWithStress(phonemes: {}, punctuations: {})"
+        return fmt.format(len(phonemes), punctuations)
+
     def __init__(self):
         self.backend = G2p()
         self.vocab = Vocab(self.phonemes + self.punctuations)

paddlespeech/t2s/frontend/polyphonic.yaml

@@ -47,4 +47,5 @@ polyphonic:
     恶行: ['e4','xing2']
     唉: ['ai4']
     扎实: ['zha1','shi2']
-    干将: ['gan4','jiang4']
+    干将: ['gan4','jiang4']
\ No newline at end of file
+    陈威行: ['chen2', 'wei1', 'hang2']
\ No newline at end of file

paddlespeech/t2s/ssml/xml_processor.py → paddlespeech/t2s/frontend/ssml/xml_processor.py

@@ -90,13 +90,14 @@ class MixTextProcessor():
             dom = DomXml(in_xml)
             tags = dom.get_text_and_sayas_tags()
             ctlist.extend(tags)
-            
+
             ctlist.append(after_xml)
             return ctlist
         else:
             ctlist.append(mixstr)
         return ctlist
 
+
 class DomXml():
     def __init__(self, xmlstr):
         self.tdom = parseString(xmlstr)  #Document

paddlespeech/t2s/frontend/tone_sandhi.py

@@ -20,6 +20,9 @@ from pypinyin import Style
 
 
 class ToneSandhi():
+    def __repr__(self):
+        return "MandarinToneSandhi"
+
     def __init__(self):
         self.must_neural_tone_words = {
             '麻烦', '麻利', '鸳鸯', '高粱', '骨头', '骆驼', '马虎', '首饰', '馒头', '馄饨', '风筝',
@@ -69,6 +72,19 @@ class ToneSandhi():
         }
         self.punc = "：，；。？！“”‘’':,;.?!"
 
+    def _split_word(self, word: str) -> List[str]:
+        word_list = jieba.cut_for_search(word)
+        word_list = sorted(word_list, key=lambda i: len(i), reverse=False)
+        first_subword = word_list[0]
+        first_begin_idx = word.find(first_subword)
+        if first_begin_idx == 0:
+            second_subword = word[len(first_subword):]
+            new_word_list = [first_subword, second_subword]
+        else:
+            second_subword = word[:-len(first_subword)]
+            new_word_list = [second_subword, first_subword]
+        return new_word_list
+
     # the meaning of jieba pos tag: https://blog.csdn.net/weixin_44174352/article/details/113731041
     # e.g.
     # word: "家里"
@@ -154,18 +170,8 @@ class ToneSandhi():
                             finals[i] = finals[i][:-1] + "4"
         return finals
 
-    def _split_word(self, word: str) -> List[str]:
-        word_list = jieba.cut_for_search(word)
-        word_list = sorted(word_list, key=lambda i: len(i), reverse=False)
-        first_subword = word_list[0]
-        first_begin_idx = word.find(first_subword)
-        if first_begin_idx == 0:
-            second_subword = word[len(first_subword):]
-            new_word_list = [first_subword, second_subword]
-        else:
-            second_subword = word[:-len(first_subword)]
-            new_word_list = [second_subword, first_subword]
-        return new_word_list
+    def _all_tone_three(self, finals: List[str]) -> bool:
+        return all(x[-1] == "3" for x in finals)
 
     def _three_sandhi(self, word: str, finals: List[str]) -> List[str]:
 
@@ -207,9 +213,6 @@ class ToneSandhi():
 
         return finals
 
-    def _all_tone_three(self, finals: List[str]) -> bool:
-        return all(x[-1] == "3" for x in finals)
-
     # merge "不" and the word behind it
     # if don't merge, "不" sometimes appears alone according to jieba, which may occur sandhi error
     def _merge_bu(self, seg: List[Tuple[str, str]]) -> List[Tuple[str, str]]:
@@ -336,6 +339,9 @@ class ToneSandhi():
 
     def pre_merge_for_modify(
             self, seg: List[Tuple[str, str]]) -> List[Tuple[str, str]]:
+        """
+            seg: [(word, pos), ...]
+        """
         seg = self._merge_bu(seg)
         seg = self._merge_yi(seg)
         seg = self._merge_reduplication(seg)
@@ -346,7 +352,11 @@ class ToneSandhi():
 
     def modified_tone(self, word: str, pos: str,
                       finals: List[str]) -> List[str]:
-
+        """
+            word: 分词
+            pos: 词性
+            finals: 带调韵母, [final1, ..., finaln]
+        """
         finals = self._bu_sandhi(word, finals)
         finals = self._yi_sandhi(word, finals)
         finals = self._neural_sandhi(word, pos, finals)

paddlespeech/t2s/frontend/zh_frontend.py

@@ -31,9 +31,9 @@ from pypinyin_dict.phrase_pinyin_data import large_pinyin
 from paddlespeech.t2s.frontend.g2pw import G2PWOnnxConverter
 from paddlespeech.t2s.frontend.generate_lexicon import generate_lexicon
 from paddlespeech.t2s.frontend.rhy_prediction.rhy_predictor import RhyPredictor
+from paddlespeech.t2s.frontend.ssml.xml_processor import MixTextProcessor
 from paddlespeech.t2s.frontend.tone_sandhi import ToneSandhi
 from paddlespeech.t2s.frontend.zh_normalization.text_normlization import TextNormalizer
-from paddlespeech.t2s.ssml.xml_processor import MixTextProcessor
 
 INITIALS = [
     'b', 'p', 'm', 'f', 'd', 't', 'n', 'l', 'g', 'k', 'h', 'zh', 'ch', 'sh',
@@ -49,13 +49,18 @@ def intersperse(lst, item):
 
 
 def insert_after_character(lst, item):
+    """
+    inset `item` after finals.
+    """
     result = [item]
+
     for phone in lst:
         result.append(phone)
         if phone not in INITIALS:
             # finals has tones
             # assert phone[-1] in "12345"
             result.append(item)
+
     return result
 
 
@@ -85,9 +90,7 @@ class Frontend():
                  phone_vocab_path=None,
                  tone_vocab_path=None,
                  use_rhy=False):
-        self.mix_ssml_processor = MixTextProcessor()
-        self.tone_modifier = ToneSandhi()
-        self.text_normalizer = TextNormalizer()
+
         self.punc = "：，；。？！“”‘’':,;.?!"
         self.rhy_phns = ['sp1', 'sp2', 'sp3', 'sp4']
         self.phrases_dict = {
@@ -108,28 +111,7 @@ class Frontend():
             '嘞': [['lei5']],
             '掺和': [['chan1'], ['huo5']]
         }
-        self.use_rhy = use_rhy
-        if use_rhy:
-            self.rhy_predictor = RhyPredictor()
-            print("Rhythm predictor loaded.")
-        # g2p_model can be pypinyin and g2pM and g2pW
-        self.g2p_model = g2p_model
-        if self.g2p_model == "g2pM":
-            self.g2pM_model = G2pM()
-            self.pinyin2phone = generate_lexicon(
-                with_tone=True, with_erhua=False)
-        elif self.g2p_model == "g2pW":
-            # use pypinyin as backup for non polyphonic characters in g2pW
-            self._init_pypinyin()
-            self.corrector = Polyphonic()
-            self.g2pM_model = G2pM()
-            self.g2pW_model = G2PWOnnxConverter(
-                style='pinyin', enable_non_tradional_chinese=True)
-            self.pinyin2phone = generate_lexicon(
-                with_tone=True, with_erhua=False)
 
-        else:
-            self._init_pypinyin()
         self.must_erhua = {
             "小院儿", "胡同儿", "范儿", "老汉儿", "撒欢儿", "寻老礼儿", "妥妥儿", "媳妇儿"
         }
@@ -154,13 +136,51 @@ class Frontend():
             for tone, id in tone_id:
                 self.vocab_tones[tone] = int(id)
 
+        # SSML
+        self.mix_ssml_processor = MixTextProcessor()
+        # tone sandhi
+        self.tone_modifier = ToneSandhi()
+        # TN
+        self.text_normalizer = TextNormalizer()
+
+        # prosody
+        self.use_rhy = use_rhy
+        if use_rhy:
+            self.rhy_predictor = RhyPredictor()
+            print("Rhythm predictor loaded.")
+
+        # g2p
+        assert g2p_model in ('pypinyin', 'g2pM', 'g2pW')
+        self.g2p_model = g2p_model
+        if self.g2p_model == "g2pM":
+            self.g2pM_model = G2pM()
+            self.pinyin2phone = generate_lexicon(
+                with_tone=True, with_erhua=False)
+        elif self.g2p_model == "g2pW":
+            # use pypinyin as backup for non polyphonic characters in g2pW
+            self._init_pypinyin()
+            self.corrector = Polyphonic()
+            self.g2pM_model = G2pM()
+            self.g2pW_model = G2PWOnnxConverter(
+                style='pinyin', enable_non_tradional_chinese=True)
+            self.pinyin2phone = generate_lexicon(
+                with_tone=True, with_erhua=False)
+        else:
+            self._init_pypinyin()
+
     def _init_pypinyin(self):
+        """
+        Load pypinyin G2P module.
+        """
         large_pinyin.load()
         load_phrases_dict(self.phrases_dict)
         # 调整字的拼音顺序
         load_single_dict({ord(u'地'): u'de,di4'})
 
     def _get_initials_finals(self, word: str) -> List[List[str]]:
+        """
+        Get word initial and final by pypinyin or g2pM
+        """
         initials = []
         finals = []
         if self.g2p_model == "pypinyin":
@@ -171,11 +191,14 @@ class Frontend():
             for c, v in zip(orig_initials, orig_finals):
                 if re.match(r'i\d', v):
                     if c in ['z', 'c', 's']:
+                        # zi, ci, si
                         v = re.sub('i', 'ii', v)
                     elif c in ['zh', 'ch', 'sh', 'r']:
+                        # zhi, chi, shi
                         v = re.sub('i', 'iii', v)
                 initials.append(c)
                 finals.append(v)
+
         elif self.g2p_model == "g2pM":
             pinyins = self.g2pM_model(word, tone=True, char_split=False)
             for pinyin in pinyins:
@@ -192,58 +215,123 @@ class Frontend():
                     # If it's not pinyin (possibly punctuation) or no conversion is required
                     initials.append(pinyin)
                     finals.append(pinyin)
+
         return initials, finals
 
+    def _merge_erhua(self,
+                     initials: List[str],
+                     finals: List[str],
+                     word: str,
+                     pos: str) -> List[List[str]]:
+        """
+        Do erhub.
+        """
+        # fix er1
+        for i, phn in enumerate(finals):
+            if i == len(finals) - 1 and word[i] == "儿" and phn == 'er1':
+                finals[i] = 'er2'
+
+        # 发音
+        if word not in self.must_erhua and (word in self.not_erhua or
+                                            pos in {"a", "j", "nr"}):
+            return initials, finals
+
+        # "……" 等情况直接返回
+        if len(finals) != len(word):
+            return initials, finals
+
+        assert len(finals) == len(word)
+
+        # 不发音
+        new_initials = []
+        new_finals = []
+        for i, phn in enumerate(finals):
+            if i == len(finals) - 1 and word[i] == "儿" and phn in {
+                    "er2", "er5"
+            } and word[-2:] not in self.not_erhua and new_finals:
+                new_finals[-1] = new_finals[-1][:-1] + "r" + new_finals[-1][-1]
+            else:
+                new_initials.append(initials[i])
+                new_finals.append(phn)
+
+        return new_initials, new_finals
+
     # if merge_sentences, merge all sentences into one phone sequence
     def _g2p(self,
              sentences: List[str],
              merge_sentences: bool=True,
              with_erhua: bool=True) -> List[List[str]]:
+        """
+        Return: list of list phonemes.
+            [['w', 'o3', 'm', 'en2', 'sp'], ...]
+        """
         segments = sentences
         phones_list = []
+
+        # split by punctuation
         for seg in segments:
             if self.use_rhy:
                 seg = self.rhy_predictor._clean_text(seg)
-            phones = []
-            # Replace all English words in the sentence
+
+            # remove all English words in the sentence
             seg = re.sub('[a-zA-Z]+', '', seg)
+
+            # add prosody mark
             if self.use_rhy:
                 seg = self.rhy_predictor.get_prediction(seg)
+
+            # [(word, pos), ...]
             seg_cut = psg.lcut(seg)
-            initials = []
-            finals = []
+            # fix wordseg bad case for sandhi
             seg_cut = self.tone_modifier.pre_merge_for_modify(seg_cut)
+
             # 为了多音词获得更好的效果，这里采用整句预测
+            phones = []
+            initials = []
+            finals = []
             if self.g2p_model == "g2pW":
                 try:
+                    # undo prosody 
                     if self.use_rhy:
                         seg = self.rhy_predictor._clean_text(seg)
+
+                    # g2p
                     pinyins = self.g2pW_model(seg)[0]
                 except Exception:
-                    # g2pW采用模型采用繁体输入，如果有cover不了的简体词，采用g2pM预测
+                    # g2pW 模型采用繁体输入，如果有cover不了的简体词，采用g2pM预测
                     print("[%s] not in g2pW dict,use g2pM" % seg)
                     pinyins = self.g2pM_model(seg, tone=True, char_split=False)
+
+                # do prosody
                 if self.use_rhy:
                     rhy_text = self.rhy_predictor.get_prediction(seg)
                     final_py = self.rhy_predictor.pinyin_align(pinyins,
                                                                rhy_text)
                     pinyins = final_py
+
                 pre_word_length = 0
                 for word, pos in seg_cut:
                     sub_initials = []
                     sub_finals = []
                     now_word_length = pre_word_length + len(word)
+
+                    # skip english word
                     if pos == 'eng':
                         pre_word_length = now_word_length
                         continue
+
                     word_pinyins = pinyins[pre_word_length:now_word_length]
-                    # 矫正发音
+
+                    # 多音字消歧
                     word_pinyins = self.corrector.correct_pronunciation(
                         word, word_pinyins)
+
                     for pinyin, char in zip(word_pinyins, word):
                         if pinyin is None:
                             pinyin = char
+
                         pinyin = pinyin.replace("u:", "v")
+
                         if pinyin in self.pinyin2phone:
                             initial_final_list = self.pinyin2phone[
                                 pinyin].split(" ")
@@ -257,28 +345,41 @@ class Frontend():
                             # If it's not pinyin (possibly punctuation) or no conversion is required
                             sub_initials.append(pinyin)
                             sub_finals.append(pinyin)
+
                     pre_word_length = now_word_length
+                    # tone sandhi
                     sub_finals = self.tone_modifier.modified_tone(word, pos,
                                                                   sub_finals)
+                    # er hua                                
                     if with_erhua:
                         sub_initials, sub_finals = self._merge_erhua(
                             sub_initials, sub_finals, word, pos)
+
                     initials.append(sub_initials)
                     finals.append(sub_finals)
                     # assert len(sub_initials) == len(sub_finals) == len(word)
             else:
+                # pypinyin, g2pM
                 for word, pos in seg_cut:
                     if pos == 'eng':
+                        # skip english word
                         continue
+
+                    # g2p
                     sub_initials, sub_finals = self._get_initials_finals(word)
+                    # tone sandhi
                     sub_finals = self.tone_modifier.modified_tone(word, pos,
                                                                   sub_finals)
+                    # er hua
                     if with_erhua:
                         sub_initials, sub_finals = self._merge_erhua(
                             sub_initials, sub_finals, word, pos)
+
                     initials.append(sub_initials)
                     finals.append(sub_finals)
                     # assert len(sub_initials) == len(sub_finals) == len(word)
+
+                # sum(iterable[, start])
             initials = sum(initials, [])
             finals = sum(finals, [])
 
@@ -287,111 +388,34 @@ class Frontend():
                 # we discriminate i, ii and iii
                 if c and c not in self.punc:
                     phones.append(c)
+                # replace punctuation by `sp`
                 if c and c in self.punc:
                     phones.append('sp')
+
                 if v and v not in self.punc and v not in self.rhy_phns:
                     phones.append(v)
-            phones_list.append(phones)
-        if merge_sentences:
-            merge_list = sum(phones_list, [])
-            # rm the last 'sp' to avoid the noise at the end
-            # cause in the training data, no 'sp' in the end
-            if merge_list[-1] == 'sp':
-                merge_list = merge_list[:-1]
-            phones_list = []
-            phones_list.append(merge_list)
-        return phones_list
-
-    def _split_word_to_char(self, words):
-        res = []
-        for x in words:
-            res.append(x)
-        return res
-
-    # if using ssml, have pingyin specified, assign pinyin to words
-    def _g2p_assign(self,
-                    words: List[str],
-                    pinyin_spec: List[str],
-                    merge_sentences: bool=True) -> List[List[str]]:
-        phones_list = []
-        initials = []
-        finals = []
 
-        words = self._split_word_to_char(words[0])
-        for pinyin, char in zip(pinyin_spec, words):
-            sub_initials = []
-            sub_finals = []
-            pinyin = pinyin.replace("u:", "v")
-            #self.pinyin2phone: is a dict with all pinyin mapped with sheng_mu yun_mu
-            if pinyin in self.pinyin2phone:
-                initial_final_list = self.pinyin2phone[pinyin].split(" ")
-                if len(initial_final_list) == 2:
-                    sub_initials.append(initial_final_list[0])
-                    sub_finals.append(initial_final_list[1])
-                elif len(initial_final_list) == 1:
-                    sub_initials.append('')
-                    sub_finals.append(initial_final_list[1])
-            else:
-                # If it's not pinyin (possibly punctuation) or no conversion is required
-                sub_initials.append(pinyin)
-                sub_finals.append(pinyin)
-            initials.append(sub_initials)
-            finals.append(sub_finals)
+            phones_list.append(phones)
 
-        initials = sum(initials, [])
-        finals = sum(finals, [])
-        phones = []
-        for c, v in zip(initials, finals):
-            # NOTE: post process for pypinyin outputs
-            # we discriminate i, ii and iii
-            if c and c not in self.punc:
-                phones.append(c)
-            if c and c in self.punc:
-                phones.append('sp')
-            if v and v not in self.punc and v not in self.rhy_phns:
-                phones.append(v)
-        phones_list.append(phones)
+        # merge split sub sentence into one sentence.
         if merge_sentences:
+            # sub sentence phonemes
             merge_list = sum(phones_list, [])
             # rm the last 'sp' to avoid the noise at the end
             # cause in the training data, no 'sp' in the end
             if merge_list[-1] == 'sp':
                 merge_list = merge_list[:-1]
+
+            # sentence phonemes
             phones_list = []
             phones_list.append(merge_list)
-        return phones_list
-
-    def _merge_erhua(self,
-                     initials: List[str],
-                     finals: List[str],
-                     word: str,
-                     pos: str) -> List[List[str]]:
-        # fix er1
-        for i, phn in enumerate(finals):
-            if i == len(finals) - 1 and word[i] == "儿" and phn == 'er1':
-                finals[i] = 'er2'
-        if word not in self.must_erhua and (word in self.not_erhua or
-                                            pos in {"a", "j", "nr"}):
-            return initials, finals
-        # "……" 等情况直接返回
-        if len(finals) != len(word):
-            return initials, finals
 
-        assert len(finals) == len(word)
-
-        new_initials = []
-        new_finals = []
-        for i, phn in enumerate(finals):
-            if i == len(finals) - 1 and word[i] == "儿" and phn in {
-                    "er2", "er5"
-            } and word[-2:] not in self.not_erhua and new_finals:
-                new_finals[-1] = new_finals[-1][:-1] + "r" + new_finals[-1][-1]
-            else:
-                new_finals.append(phn)
-                new_initials.append(initials[i])
-        return new_initials, new_finals
+        return phones_list
 
     def _p2id(self, phonemes: List[str]) -> np.ndarray:
+        """
+        Phoneme to Index
+        """
         # replace unk phone with sp
         phonemes = [
             phn if phn in self.vocab_phones else "sp" for phn in phonemes
@@ -400,6 +424,9 @@ class Frontend():
         return np.array(phone_ids, np.int64)
 
     def _t2id(self, tones: List[str]) -> np.ndarray:
+        """
+        Tone to Index.
+        """
         # replace unk phone with sp
         tones = [tone if tone in self.vocab_tones else "0" for tone in tones]
         tone_ids = [self.vocab_tones[item] for item in tones]
@@ -407,6 +434,9 @@ class Frontend():
 
     def _get_phone_tone(self, phonemes: List[str],
                         get_tone_ids: bool=False) -> List[List[str]]:
+        """
+        Get tone from phonemes.
+        """
         phones = []
         tones = []
         if get_tone_ids and self.vocab_tones:
@@ -423,13 +453,14 @@ class Frontend():
                             -1] == 'r' and phone not in self.vocab_phones and phone[:
                                                                                     -1] in self.vocab_phones:
                         phones.append(phone[:-1])
-                        phones.append("er")
                         tones.append(tone)
+                        phones.append("er")
                         tones.append("2")
                     else:
                         phones.append(phone)
                         tones.append(tone)
                 else:
+                    # initals with 0 tone.
                     phones.append(full_phone)
                     tones.append('0')
         else:
@@ -443,6 +474,7 @@ class Frontend():
                     phones.append("er2")
                 else:
                     phones.append(phone)
+
         return phones, tones
 
     def get_phonemes(self,
@@ -451,10 +483,16 @@ class Frontend():
                      with_erhua: bool=True,
                      robot: bool=False,
                      print_info: bool=False) -> List[List[str]]:
+        """
+        Main function to do G2P
+        """
+        # TN & Text Segmentation
         sentences = self.text_normalizer.normalize(sentence)
+        # Prosody & WS & g2p & tone sandhi
         phonemes = self._g2p(
             sentences, merge_sentences=merge_sentences, with_erhua=with_erhua)
-        # change all tones to `1`
+
+        # simulate robot pronunciation, change all tones to `1`
         if robot:
             new_phonemes = []
             for sentence in phonemes:
@@ -466,6 +504,7 @@ class Frontend():
                     new_sentence.append(item)
                 new_phonemes.append(new_sentence)
             phonemes = new_phonemes
+
         if print_info:
             print("----------------------------")
             print("text norm results:")
@@ -476,25 +515,101 @@ class Frontend():
             print("----------------------------")
         return phonemes
 
-    #@an added for ssml pinyin 
+    def _split_word_to_char(self, words):
+        res = []
+        for x in words:
+            res.append(x)
+        return res
+
+    # if using ssml, have pingyin specified, assign pinyin to words
+    def _g2p_assign(self,
+                    words: List[str],
+                    pinyin_spec: List[str],
+                    merge_sentences: bool=True) -> List[List[str]]:
+        """
+        Replace phoneme by SSML
+        """
+        phones_list = []
+        initials = []
+        finals = []
+
+        # to charactor list
+        words = self._split_word_to_char(words[0])
+
+        for pinyin, char in zip(pinyin_spec, words):
+            sub_initials = []
+            sub_finals = []
+            pinyin = pinyin.replace("u:", "v")
+
+            #self.pinyin2phone: is a dict with all pinyin mapped with sheng_mu yun_mu
+            if pinyin in self.pinyin2phone:
+                initial_final_list = self.pinyin2phone[pinyin].split(" ")
+                if len(initial_final_list) == 2:
+                    sub_initials.append(initial_final_list[0])
+                    sub_finals.append(initial_final_list[1])
+                elif len(initial_final_list) == 1:
+                    sub_initials.append('')
+                    sub_finals.append(initial_final_list[1])
+            else:
+                # If it's not pinyin (possibly punctuation) or no conversion is required
+                sub_initials.append(pinyin)
+                sub_finals.append(pinyin)
+
+            initials.append(sub_initials)
+            finals.append(sub_finals)
+
+        initials = sum(initials, [])
+        finals = sum(finals, [])
+
+        phones = []
+        for c, v in zip(initials, finals):
+            # NOTE: post process for pypinyin outputs
+            # we discriminate i, ii and iii
+            if c and c not in self.punc:
+                phones.append(c)
+            # replace punc to `sp`
+            if c and c in self.punc:
+                phones.append('sp')
+            if v and v not in self.punc and v not in self.rhy_phns:
+                phones.append(v)
+        phones_list.append(phones)
+
+        if merge_sentences:
+            merge_list = sum(phones_list, [])
+            # rm the last 'sp' to avoid the noise at the end
+            # cause in the training data, no 'sp' in the end
+            if merge_list[-1] == 'sp':
+                merge_list = merge_list[:-1]
+            phones_list = []
+            phones_list.append(merge_list)
+
+        return phones_list
+
     def get_phonemes_ssml(self,
                           ssml_inputs: list,
                           merge_sentences: bool=True,
                           with_erhua: bool=True,
                           robot: bool=False,
                           print_info: bool=False) -> List[List[str]]:
+        """
+         Main function to do G2P with SSML support.
+        """
         all_phonemes = []
         for word_pinyin_item in ssml_inputs:
             phonemes = []
+            print("ssml inputs:", word_pinyin_item)
             sentence, pinyin_spec = itemgetter(0, 1)(word_pinyin_item)
+            print('ssml g2p:', sentence, pinyin_spec)
+            # TN & Text Segmentation
             sentences = self.text_normalizer.normalize(sentence)
             if len(pinyin_spec) == 0:
+                # g2p word w/o specified <say-as>
                 phonemes = self._g2p(
                     sentences,
                     merge_sentences=merge_sentences,
                     with_erhua=with_erhua)
             else:
-                # phonemes should be pinyin_spec 
+                # word phonemes specified by <say-as>
                 phonemes = self._g2p_assign(
                     sentences, pinyin_spec, merge_sentences=merge_sentences)
 
@@ -523,6 +638,9 @@ class Frontend():
         return [sum(all_phonemes, [])]
 
     def add_sp_if_no(self, phonemes):
+        """
+        Prosody mark #4 added at sentence end.
+        """
         if not phonemes[-1][-1].startswith('sp'):
             phonemes[-1].append('sp4')
         return phonemes
@@ -542,8 +660,11 @@ class Frontend():
             merge_sentences=merge_sentences,
             print_info=print_info,
             robot=robot)
+
+        # add #4 for sentence end.
         if self.use_rhy:
             phonemes = self.add_sp_if_no(phonemes)
+
         result = {}
         phones = []
         tones = []
@@ -551,28 +672,33 @@ class Frontend():
         temp_tone_ids = []
 
         for part_phonemes in phonemes:
+
             phones, tones = self._get_phone_tone(
                 part_phonemes, get_tone_ids=get_tone_ids)
+
             if add_blank:
                 phones = insert_after_character(phones, blank_token)
+
             if tones:
                 tone_ids = self._t2id(tones)
                 if to_tensor:
                     tone_ids = paddle.to_tensor(tone_ids)
                 temp_tone_ids.append(tone_ids)
+
             if phones:
                 phone_ids = self._p2id(phones)
                 # if use paddle.to_tensor() in onnxruntime, the first time will be too low
                 if to_tensor:
                     phone_ids = paddle.to_tensor(phone_ids)
                 temp_phone_ids.append(phone_ids)
+
         if temp_tone_ids:
             result["tone_ids"] = temp_tone_ids
         if temp_phone_ids:
             result["phone_ids"] = temp_phone_ids
+
         return result
 
-    # @an added for ssml
     def get_input_ids_ssml(
             self,
             sentence: str,
@@ -584,12 +710,15 @@ class Frontend():
             blank_token: str="<pad>",
             to_tensor: bool=True) -> Dict[str, List[paddle.Tensor]]:
 
+        # split setence by SSML tag.
         l_inputs = MixTextProcessor.get_pinyin_split(sentence)
+
         phonemes = self.get_phonemes_ssml(
             l_inputs,
             merge_sentences=merge_sentences,
             print_info=print_info,
             robot=robot)
+
         result = {}
         phones = []
         tones = []
@@ -599,21 +728,26 @@ class Frontend():
         for part_phonemes in phonemes:
             phones, tones = self._get_phone_tone(
                 part_phonemes, get_tone_ids=get_tone_ids)
+
             if add_blank:
                 phones = insert_after_character(phones, blank_token)
+
             if tones:
                 tone_ids = self._t2id(tones)
                 if to_tensor:
                     tone_ids = paddle.to_tensor(tone_ids)
                 temp_tone_ids.append(tone_ids)
+
             if phones:
                 phone_ids = self._p2id(phones)
                 # if use paddle.to_tensor() in onnxruntime, the first time will be too low
                 if to_tensor:
                     phone_ids = paddle.to_tensor(phone_ids)
                 temp_phone_ids.append(phone_ids)
+
         if temp_tone_ids:
             result["tone_ids"] = temp_tone_ids
         if temp_phone_ids:
             result["phone_ids"] = temp_phone_ids
+
         return result