Add option to not remove preceding silence in AbsTokenizer (#110)

* fix reqs

* add support for preceding silence

aria/tokenizer/tokenizer.py

@@ -72,20 +72,20 @@ def tokenize(self, midi_dict: MidiDict, **kwargs):
         required. For instance, in fine-tuning tokenizer you may want to insert
         additional tokens. The default behavior is to call tokenize_midi_dict.
         """
-        return self._tokenize_midi_dict(midi_dict)
+        return self._tokenize_midi_dict(midi_dict, **kwargs)
 
     def _detokenize_midi_dict(self, tokenized_seq: list):
         """Abstract method for de-tokenizing a sequence of tokens into a
         MidiDict Object."""
         raise NotImplementedError
 
-    def detokenize(self, tokenized_seq: list):
+    def detokenize(self, tokenized_seq: list, **kwargs):
         """Detokenizes a MidiDict object.
 
         This function should be overridden if additional are required during
         detokenization. The default behavior is to call detokenize_midi_dict.
         """
-        return self._detokenize_midi_dict(tokenized_seq)
+        return self._detokenize_midi_dict(tokenized_seq, **kwargs)
 
     def export_data_aug(cls):
         """Abstract method for exporting a list of all data augmentation
@@ -411,7 +411,9 @@ def truncate_by_time(self, tokenized_seq: list, trunc_time_ms: int):
 
         return tokenized_seq
 
-    def _tokenize_midi_dict(self, midi_dict: MidiDict):
+    def _tokenize_midi_dict(
+        self, midi_dict: MidiDict, remove_preceding_silence: bool = True
+    ):
         ticks_per_beat = midi_dict.ticks_per_beat
         midi_dict.remove_instruments(self.config["ignore_instruments"])
 
@@ -450,9 +452,13 @@ def _tokenize_midi_dict(self, midi_dict: MidiDict):
             prefix.insert(0, ("prefix", "genre", genre))
         random.shuffle(prefix)
 
-        # NOTE: Any preceding silence is removed implicitly
         tokenized_seq = []
-        initial_onset_tick = midi_dict.note_msgs[0]["data"]["start"]
+
+        if remove_preceding_silence is False:
+            initial_onset_tick = 0
+        else:
+            initial_onset_tick = midi_dict.note_msgs[0]["data"]["start"]
+
         curr_time_since_onset = 0
         for _, msg in enumerate(midi_dict.note_msgs):
             # Extract msg data
@@ -543,12 +549,14 @@ def _detokenize_midi_dict(self, tokenized_seq: list):
 
         # Add non-drum instrument_msgs, breaks at first note token
         channel_idx = 0
+        curr_tick = 0
         for idx, tok in enumerate(tokenized_seq):
             if channel_idx == 9:  # Skip channel reserved for drums
                 channel_idx += 1
 
             if tok in self.special_tokens:
-                # Skip special tokens
+                if tok == self.time_tok:
+                    curr_tick += self.abs_time_step
                 continue
             elif (
                 tok[0] == "prefix"
@@ -590,7 +598,6 @@ def _detokenize_midi_dict(self, tokenized_seq: list):
 
         # Note messages
         note_msgs = []
-        curr_tick = 0
         for tok_1, tok_2, tok_3 in zip(
             tokenized_seq[start:],
             tokenized_seq[start + 1 :],