Clarify that midi_tempo only sets MIDI header tempo, not note timing.

basic_pitch/inference.py

@@ -458,6 +458,9 @@ def predict(
         multiple_pitch_bends: If True, allow overlapping notes in midi file to have pitch bends.
         melodia_trick: Use the melodia post-processing step.
         debug_file: An optional path to output debug data to. Useful for testing/verification.
+        midi_tempo: The tempo, in BPM, written to the output MIDI file's header. This only sets the
+            tempo metadata; note start/end times are taken from the audio in absolute seconds and are
+            not rescaled, so it does not change note timing or playback duration.
     Returns:
         The model output, midi data and note events from a single prediction
     """
@@ -544,6 +547,9 @@ def predict_and_save(
         melodia_trick: Use the melodia post-processing step.
         debug_file: An optional path to output debug data to. Useful for testing/verification.
         sonification_samplerate: Sample rate for rendering audio from MIDI.
+        midi_tempo: The tempo, in BPM, written to the output MIDI file's header. This only sets the
+            tempo metadata; note start/end times are taken from the audio in absolute seconds and are
+            not rescaled, so it does not change note timing or playback duration.
     """
     for audio_path in audio_path_list:
         print("")

basic_pitch/note_creation.py

@@ -232,6 +232,10 @@ def note_events_to_midi(
         multiple_pitch_bends : If True, allow overlapping notes to have pitch bends
             Note: this will assign each pitch to its own midi instrument, as midi does not yet
             support per-note pitch bends
+        midi_tempo : The tempo, in BPM, written to the output MIDI file's header via
+            initial_tempo. This only sets the tempo metadata, while the note start/end times are taken
+            from the audio in absolute seconds and are not rescaled, so it does not change note timing
+            or playback duration.
 
     Returns:
         pretty_midi.PrettyMIDI() object

basic_pitch/predict.py

@@ -122,7 +122,9 @@ def main() -> None:
         "--midi-tempo",
         type=float,
         default=120,
-        help="The tempo for the midi file.",
+        help="The tempo, in BPM, written to the MIDI file's header. Note: this only sets the tempo "
+        "metadata and does not change note timing or playback duration, which always follow the "
+        "original audio.",
     )
     parser.add_argument(
         "--debug-file",