CTX-txt2vec, the Acoustic Model with Contextual VQ-Diffusion

This is the official implementation of CTX-txt2vec TTS model in the AAAI-2024 paper UniCATS: A Unified Context-Aware Text-to-Speech Framework with Contextual VQ-Diffusion and Vocoding.

Environment Setup

This repo is tested on python 3.7 on Linux. You can set up the environment with conda

# Install required packages
conda create -n ctxt2v python=3.7 # or any name you like
conda activate ctxt2v
pip install -r requirements.txt

Every time you enter this project, you can do conda activate ctxt2v or source path.sh.

Also, you can perform chmod +x utils/* to ensure those scipts are executable.

Data Preparation

Here we take the LibriTTS preparation pipeline for example. Other datasets can be set up in the same way.

1. Please download the data manifests from huggingface (38MB). Then, unzip it to data/ in the project directory. The contents are as follows:

   ├── train_all
   │         ├── duration    # the integer duration for each utterance. Frame shift is 10ms.
   │         ├── feats.scp   # the VQ index for each utterance. Will be explained later.
   │         ├── text   # the phone sequence for each utterance
   │         └── utt2num_frames   # the number of frames of each utterance.
   ├── eval_all
   │         ...  # similar four files
   │── dev_all
   │         ...
   └── lang_1phn
             └── train_all_units.txt  # mapping between valid phones and their indexes
   

2. Here, the feats.scp is the Kaldi-style feature specifier pointing to feats/label/.../feats.ark. We also provide it online (432MB), so please download it and unzip to feats in the project directory. These features are the 1-D flatten indexes of the vq-wav2vec features. You can verify the shape of features by utils/feat-to-shape.py scp:feats/label/dev_all/feats.scp | head. The codebook feats/vqidx/codebook.npy has shape [2, 320, 256].

💡 That is, we extracted discrete codebook indxes using fairseq's vq-wav2vec model , the kmeans Librispeech version, which contained 2 groups of integer indexes each ranging from 0 to 319. We then find the occurrences of these pairs and label them using another index, which counts to 23632. The mapping between this label index and original vq-wav2vec codebook index can be found at feats/vqidx/label2vqidx. We use the 23632 labels to train the VQ-diffusion model.

After constructing the directories properly, the model can be trained.

Training

Training the CTX-txt2vec model can be simply done by

python train.py --name Libritts --config_file configs/Libritts.yaml --num_node 1 --tensorboard --auto_resume

where --name specifies the output directory name. Check out configs/Libritts.yaml for detailed configurations. Multi-GPU training is automatically handled by the program (default to use all visible devices).

After the training starts, checkpoints and logs will be saved in OUTPUT/Libritts.

Decoding to VQ indexes

The decoding of CTX-txt2vec always rely on prompts that provide contextual information. In other words, before decoding, there should be a utt2prompt file that looks like:

1089_134686_000002_000001 1089_134686_000032_000008
1089_134686_000007_000005 1089_134686_000032_000008
1089_134686_000009_000003 1089_134686_000032_000008
1089_134686_000009_000008 1089_134686_000032_000008
1089_134686_000015_000003 1089_134686_000032_000008

where every line is organized as utt-to-synthesize prompt-utt. The utt-to-synthesize and prompt-utt keys should both be present in feats.scp for indexing.

💡 We recommend using the official utt2prompt file for test set B in the paper. You can download that and save to data/eval_all/utt2prompt.

After that, decoding with context prepended (a.k.a. continuation) can be performed by

python continuation.py --eval-set eval_all
# will only synthesize utterances in `utt2prompt`. Check the necessary files in `data/${eval_set}`.

The decoded VQ-indexes (2-dim) will be saved to OUTPUT/Libritts/syn/${eval_set}/.

💡Note that the model actually samples from 23631 distinct VQ "labels". In this code we transform it back to 2-dim VQ indexes using feats/vqidx/label2vqidx.

Vocoding to waveform

For vocoding to waveform, the counterpart "CTX-vec2wav" is highly recommended. You can set up CTX-vec2wav by

git clone https://github.com/cantabile-kwok/UniCATS-CTX-vec2wav.git

and then follow the environmental instruction there.

After decoding to VQ indexes, vocoding can be achieved by

syn_dir=$PWD/OUTPUT/Libritts/syn/eval_all/
utt2prompt_file=$PWD/data/eval_all/utt2prompt
v2w_dir=/path/to/CTX-vec2wav/

cd $v2w_dir || exit 1;
source path.sh
# now, in CTX-vec2wav's environment

feat-to-len.py scp:$syn_dir/feats.scp > $syn_dir/utt2num_frames
# construct acoustic prompt specifier (mel spectrograms) using utt2prompt
python ./local/get_prompt_scp.py feats/normed_fbank/eval_all/feats.scp ${utt2prompt_file} > $syn_dir/prompt.scp

decode.py --feats-scp $syn_dir/feats.scp \
          --prompt-scp $syn_dir/prompt.scp \
          --num-frames $syn_dir/utt2num_frames \
          --outdir $syn_dir/wav/ \
          --checkpoint /path/to/checkpoint

Acknowledgement

During the development, the following repositories were referred to:

• ESPnet, for the model architecture in ctx_text2vec/modeling/transformers/espnet_nets and utility scripts in utils.
• Kaldi, for most utility scripts in utils.
• VQ-Diffusion, from which the model structures and training pipeline are mostly inherited.
• CTX-vec2wav for vocoding!