ValueError: n must be at least one

Author: ivostoykovCreated Jan 29, 2024Updated Jul 28, 2025

Hello there,

Following the instructions in Training.md those commands had been used as described in the file in the cloned piper local folder:

bash

cd piper/src/python
python3 -m venv .venv
source .venv/bin/activate
pip3 install --upgrade pip
pip3 install --upgrade wheel setuptools
pip3 install -e .

I got the following error executing the preprocess command:

python3 -m piper_train.preprocess --language bg --input-dir /Projects/TTS/test/ --output-dir /Projects/TTS/test/output/ --dataset-format ljspeech --single-speaker --sample-rate 22050
INFO:preprocess:Single speaker dataset
INFO:preprocess:Wrote dataset config
INFO:preprocess:Processing 11 utterance(s) with 20 worker(s)
Traceback (most recent call last):
  File "/usr/lib/python3.10/runpy.py", line 196, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/usr/lib/python3.10/runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "/Projects/Python/piper/src/python/piper_train/preprocess.py", line 502, in <module>
    main()
  File "/Projects/Python/piper/src/python/piper_train/preprocess.py", line 225, in main
    for utt_batch in batched(
  File "/Projects/Python/piper/src/python/piper_train/preprocess.py", line 491, in batched
    raise ValueError("n must be at least one")

the metadata.csv is (the text is Cyrillic - Bulgarian):

wav/000.wav|male1|Одата Левски от цикъл Епопея на забравените на Иван Вазов.
wav/001.wav|male1|Този запис е направен за либриво.
wav/002.wav|male1|Всички записи за либривокс са обществено достояние.
wav/003.wav|male1|За повече информация или за участие като доброволец,
wav/004.wav|male1|моля посетете либривокс точка орг.
wav/005.wav|male1|ЛЕВСКИ
wav/006.wav|male1|Манастирът тесен за мойта душа е.
wav/007.wav|male1|Кога човек дойде тук да се покае, трябва да забрави греховния мир,
wav/008.wav|male1|да бяга съблазни и да търси мир.
wav/009.wav|male1|Мойта съвест инак днеска ми говори.
wav/010.wav|male1|Това расо черно, що нося отгоре, не ме помирява с тия небеса

metadata.csv is in /Projects/TTS/test/:

ls /Projects/TTS/test/
metadata.csv  output  wav

I'll appreciate any comments/help.

Thank you Ivo

Source: rhasspy/piper

View original on GitHub View discussion on GitHub