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NaturalSpeech: End-to-End Text to Speech Synthesis with Human-Level Quality

This is an implementation of Microsoft's NaturalSpeech: End-to-End Text to Speech Synthesis with Human-Level Quality in Pytorch.

Contribution and pull requests are highly appreciated!

23.02.09: Demo samples (using the first 1800 epochs) are out. (link)

Overview

Naturalspeech is a VAE-based model that employs several techniques to improve the prior and simplify the posterior. It differs from VITS in several ways, including:

• Phoneme pre-training: Naturalspeech uses a pre-trained phoneme encoder on a large text corpus, obtained through masked language modeling on phoneme sequences.
• Differentiable durator: The posterior operates at the frame level, while the prior operates at the phoneme level. Naturalspeech uses a differentiable durator to bridge the length difference, resulting in soft and flexible features that are expanded.
• Bidirectional Prior/Posterior: Naturalspeech reduces the posterior and enhances the prior through normalizing flow, which maps in both directions with forward and backward loss.
• Memory-based VAE: The prior is further enhanced through a memory bank using Q-K-V attention."

Notes

• This implementation does not include pre-training of phonemes using a large-scale text corpus from the news-crawl dataset.
• The multiplier for each loss can be adjusted in the configuration file. Using losses without a multiplier may not lead to convergence.
• The tuning stage for the last 2k epochs has been omitted.
• Due to the high VRAM usage of the soft-dtw loss, there is an option to use a non-softdtw loss for memory efficiency.
• For the soft-dtw loss, the warp factor has been set to 134.4 (0.07 * 192) to match the non-softdtw loss, instead of 0.07.
• To train the duration predictor in the warm-up stage, duration labels are required. The paper suggests using any tool to provide the duration label. In this implementation, a pre-trained VITS model was used.
• To further improve memory efficiency during training, randomly silced sequences are fed to the decoder as in the VITS model.

How to train

0. # python >= 3.6
   pip install -r requirements.txt
   

1. clone this repository

2. download The LJ Speech Dataset: link

3. create symbolic link to ljspeech dataset:

   ln -s /path/to/LJSpeech-1.1/wavs/ DUMMY1
   

4. text preprocessing (optional, if you are using custom dataset):

   1. apt-get install espeak

   2. python preprocess.py --text_index 1 --filelists filelists/ljs_audio_text_train_filelist.txt filelists/ljs_audio_text_val_filelist.txt filelists/ljs_audio_text_test_filelist.txt
      

5. duration preprocessing (obtain duration labels using pretrained VITS):

   If you want to skip this section, use durations/durations.tar.bz2 and overwrite the durations folder.

   1. git clone https://github.com/jaywalnut310/vits.git; cd vits
   2. create symbolic link to ljspeech dataset

      ln -s /path/to/LJSpeech-1.1/wavs/ DUMMY1
      

   3. download pretrained VITS model described as from VITS official github: github link / pretrained models
   4. setup monotonic alignment search (for VITS inference):

      cd monotonic_align; mkdir monotonic_align; python setup.py build_ext --inplace; cd ..
      

   5. copy duration preprocessing script to VITS repo: cp /path/to/naturalspeech/preprocess_durations.py .

   6. python3 preprocess_durations.py --weights_path ./pretrained_ljs.pth --filelists filelists/ljs_audio_text_train_filelist.txt.cleaned filelists/ljs_audio_text_val_filelist.txt.cleaned filelists/ljs_audio_text_test_filelist.txt.cleaned
      

   7. once the duration labels are created, copy the labels to the naturalspeech repo: cp -r durations/ path/to/naturalspeech

6. train (warmup)

   python3 train.py -c configs/ljs.json -m [run_name] --warmup
   

   Note here that ljs.json is for low-resource training, which runs for 1500 epochs and does not use soft-dtw loss. If you want to reproduce the steps stated in the paper, use ljs_reproduce.json, which runs for 15000 epochs and uses soft-dtw loss.

7. initialize and attach memory bank after warmup:

     python3 attach_memory_bank.py -c configs/ljs.json --weights_path logs/[run_name]/G_xxx.pth
   

   if you lack memory, you can specify the --num_samples argument to use only a subset of samples.

8. train (resume)

     python3 train.py -c configs/ljs.json -m [run_name]
   

You can use tensorboard to monitor the training.

tensorboard --logdir /path/to/naturalspeech/logs

During each evaluation phase, a selection of samples from the test set is evaluated and saved in the logs/[run_name]/eval directory.

References

• VITS implemetation by @jaywalnut310 for normalizing flows, phoneme encoder, and hifi-gan decoder implementation
• Parallel Tacotron 2 Implementation by @keonlee9420 for learnable upsampling Layer
• soft-dtw implementation by @Maghoumi for sdtw loss