Text to Speech engine based on the Tacotron architecture, initially implemented by Keith Ito. Few minor changes on model architecture, and speech synthesizing
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README.md
TRAINING_DATA.md
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README.md

mimic2

This is a fork of keithito/tacotron with tooling and code enhancements. This repo is actively developed on by the Mycroft AI team and community.

Background

Google published a paper, Tacotron: A Fully End-to-End Text-To-Speech Synthesis Model, where they present a neural text-to-speech model that learns to synthesize speech directly from (text, audio) pairs. However, they didn't release their source code or training data. This is an attempt to provide an open-source implementation of the model described in their paper.

The quality isn't as good as Google's demo yet, but hopefully, it will get there someday :-). Pull requests are welcome!

Samples

Here you can find audio samples on a model trained using this repo. The data had 16 hours of training data recorded by a single english speaker. Sample were generated using non training data.

Contributions

Contributions are accepted! We'd love the communities help in building a better speech synthesis engine; weather it be code, or, update on the README, bug reports, etc. For real time conversations, join our mattermost chat and enter the machinelearning channel.

Quick Start

Installing dependencies

using docker (recommended)

  1. make sure you have Docker installed

  2. Build Docker

    The Dockerfile comes with a GPU option or CPU option. If you want to use the GPU in docker make sure you have nvidia-docker installed

    gpu: docker build -t mycroft/mimic2:gpu -f gpu.Dockerfile .

    cpu: docker build -t mycroft/mimic2:cpu -f cpu.Dockerfile .

  3. Run Docker

    gpu: nvidia-docker run -it -p 3000:3000 mycroft/mimic2:gpu

    cpu: docker run -it -p 3000:3000 mycroft/mimic2:cpu

manually

  1. Install Python 3.

  2. Install the latest version of TensorFlow for your platform. For better Performance, install with GPU support if it's available. This code has been tested on tensorflow 1.8.

  3. Install requirements:

    pip install -r requirements.txt
    

Training

Note: you need at least 40GB of free disk space to train a model.

  1. Download a speech dataset.

    The following are supported out of the box:

    You can use other datasets if you convert them to the right format. See TRAINING_DATA.md for more info.

  2. Unpack the dataset into ~/tacotron

    After unpacking, your tree should look like this for LJ Speech:

    tacotron
      |- LJSpeech-1.1
          |- metadata.csv
          |- wavs
    

    alternatively, like this for Blizzard 2012:

    tacotron
      |- Blizzard2012
          |- ATrampAbroad
          |   |- sentence_index.txt
          |   |- lab
          |   |- wav
          |- TheManThatCorruptedHadleyburg
              |- sentence_index.txt
              |- lab
              |- wav
    

    alternatively, like this for CSS10, German dataset (make sure to adjust text/symbols.py in order to meet the character set):

    tacotron
      |- css10
          |- achtgesichterambiwasse
          |- meisterfloh
          |- serapionsbruederauswahl
          |- transcript.txt
    

    For M-AILABS follow the directory structure from here

  3. Preprocess the data

    python3 preprocess.py --dataset ljspeech
    
    • other datasets can be used, i.e. --dataset blizzard for Blizzard data
    • for the mailabs dataset, do preprocess.py --help for options. Also, note that mailabs uses sample_size of 16000
    • you may want to create your own preprocessing script that works for your dataset. You can follow examples from preprocess.py and ./datasets

    preprocess.py creates a train.txt and metadata.txt. train.txt is the file you use to pass to the train.py input parameter. metadata.txt can be used as a reference to get max input length, max output length, and how many hours is your dataset.

    NOTE modify hparams.py to cater to your dataset.

  4. Train a model

    python3 train.py
    

    Tunable hyperparameters are found in hparams.py. You can adjust these at the command line using the --hparams flag, for example --hparams="batch_size=16,outputs_per_step=2". Hyperparameters should generally be set to the same values at both training and eval time. I highly recommend setting the params in the hparams.py file to guarantee consistency during preprocessing, training, evaluating, and running the demo server. The --hparams flag will be deprecated soon

    During training, the script will save the models progress every 1000 steps. You can monitor the progress using tensorboard and also listening to the output of the model. You can find the wav file and alignment chart in a format of step-*. See below for an example of what an alignment should look like.

  5. Monitor with Tensorboard (optional)

    tensorboard --logdir ~/tacotron/logs-tacotron
    

    The trainer dumps audio and alignments every 1000 steps. You can find these in ~/tacotron/logs-tacotron.

  6. Synthesize from a checkpoint

    python3 demo_server.py --checkpoint ~/tacotron/logs-tacotron/model.ckpt-185000
    

    Replace "185000" with the checkpoint number that you want to use, then open a browser to localhost:3000 and type what you want to speak. Alternately, you can run eval.py at the command line:

    python3 eval.py --checkpoint ~/tacotron/logs-tacotron/model.ckpt-185000
    

    If you set the --hparams flag when training, set the same value here.

    eval.py will output sampels define in the sentence list found here. You may modify to your use case. eval.py will also output two things, the wavfile, and alignment chart. To have a good alignment, the alignment chart should generally be linear. Below is a good example of a model that output a good alignment for a sample.

    alchart

  7. Analyzing Data

    You can visualize your data set after preprocessing the data. See more details info here

Notes and Common Issues

  • TCMalloc seems to improve Training speed and avoids occasional slowdowns seen with the default allocator. You can enable it by installing it and setting LD_PRELOAD=/usr/lib/libtcmalloc.so. With TCMalloc, you can get around 1.1 sec/step on a GTX 1080Ti.

  • You can train with CMUDict by downloading the dictionary to ~/tacotron/training and then passing the flag --hparams="use_cmudict=True" to train.py. This will allow you to pass ARPAbet phonemes enclosed in curly braces at eval time to force a particular pronunciation, e.g. Turn left on {HH AW1 S S T AH0 N} Street.

  • If you pass a Slack incoming webhook URL as the --slack_url flag to train.py, it will send you progress updates every 1000 steps.

  • Occasionally, you may see a spike in the loss, and the model will forget how to attend (the Alignments will no longer make sense). Although it will recover eventually, it may save time to restart at a checkpoint before the spike by passing the --restore_step=150000 flag to train.py (replacing 150000 with a step number before the spike). Update: a recent fix to gradient clipping by @candlewill may have fixed this.

  • During eval and training, audio length is limited to max_iters * outputs_per_step * frame_shift_ms milliseconds. With the defaults (max_iters=200, outputs_per_step=5, frame_shift_ms=12.5), this is 12.5 seconds.

    If your training examples are longer, you will see an error like this: Incompatible shapes: [32,1340,80] vs. [32,1000,80]

    To fix this, you can set a larger value of max_iters by passing --hparams="max_iters=300" to train.py (replace "300" with a value based on how long your audio is and the formula above).

  • Here is the expected loss curve when training on LJ Speech with the default hyperparameters: Loss curve

Other Implementations

Visualizing Your Data

analyze.py is a tool to visualize your dataset after preprocessing. This step is important to ensure quality in the voice generation. The analyze tool takes in train.txt as the data input to do visualizations. train.txt is a file created from preprocess.py.

Example

    python analyze.py --train_file_path=~/tacotron/training/train.txt --save_to=~tacotron/visuals --cmu_dict_path=~/cmudict-0.7b

cmu_dict_path is optional if you'd like to visualize the distribution of the phonemes.

analyze.py outputs 6 different plots.

Average Seconds vs Character Lengths

avgsecvslen

This plot shows the average seconds of your audio sample per character length of the sample. This tells you what your audio data looks like in the time perspective.

E.g. So for all 50 character samples, the average audio length is 3 seconds. Your data should show a linear pattern like the example above.

Having a linear pattern for time vs. character lengths is vital to ensure a consistent speech rate during audio generation.

Below is a bad example of average seconds vs. character lengths in your dataset. You can see that there is an inconsistency towards the higher character lengths range. At 180, the average audio length was 8 seconds while at 185 the average was 6.

badavgsec

Median Seconds vs Character Lengths

medsecvslen

Another perspective for the time that plots the median.

Mode Seconds vs Character Lengths

modesecvslen

Another perspective for the time that plots the mode.

Standard Deviation vs Character Lengths

stdvslen

Plots the standard deviation or spread of your dataset. The standard deviation should stay in a range no larger than 0.8.

E.g. For samples with 100 character lengths, the average audio length is 6 seconds. According to the chart above, 100 character lengths have an std of about 0.6. That means most samples in the 100 character length range should be no more than 6.6 seconds and no less than 5.2 seconds.

Having a low standard deviation is vital to ensure a consistent speech rate during audio generation.

Below is an example of a bad distribution of standard deviations.

badstd

Number of Samples vs Character Lengths

numvslen

Plots the number of samples you have in character lengths range.

E.g. For samples in the 100 character lengths range, there are about 125 samples of it.

It's important for this plot to have a smooth distribution. Normal distribution is what we went with for our data set but a uniform distribution may also be of value. If the chart look's off balance, you may get weird speech rate during voice generation.

Below is an example of a bad distribution for the number of samples. This distribution will generate sequences in the 25 - 100 character lengths well, but anything past that will have bad quality. In this example, you may experience a speed up in speech rate as the model try to squish 150 characters in 3 seconds.

badnumsamp

Phonemes Distribution

phonemedist

This only outputs if you use the --cmu_dict_path parameter. The X-axis is the unique phonemes, and the Y-axis shows how many times that phoneme shows up in your dataset. We are still experimenting with how the distribution should look, but the theory is having a balanced distribution of phonemes will increase quality in pronunciation.

Tips

If your data looks bad you can try resampling methods to change the shape of your data.

  • For number of samples, you can try to delete samples and copy samples to make the chart look more normally distributed.
  • For standard deviation, you can remove data that causes your standard deviation of have a large spread.
  • For the average seconds, you can try to only include samples that follows a linear pattern