FunASR/docs/get_started.md

Get Started

Here we take "Training a paraformer model from scratch using the AISHELL-1 dataset" as an example to introduce how to use FunASR. According to this example, users can similarly employ other datasets (such as AISHELL-2 dataset, etc.) to train other models (such as conformer, transformer, etc.).

Overall Introduction

We provide a recipe egs/aishell/paraformer/run.sh for training a paraformer model on AISHELL-1 dataset. This recipe consists of five stages, supporting training on multiple GPUs and decoding by CPU or GPU. Before introducing each stage in detail, we first explain several parameters which should be set by users.

• CUDA_VISIBLE_DEVICES: visible gpu list
• gpu_num: the number of GPUs used for training
• gpu_inference: whether to use GPUs for decoding
• njob: for CPU decoding, indicating the total number of CPU jobs; for GPU decoding, indicating the number of jobs on each GPU
• data_aishell: the raw path of AISHELL-1 dataset
• feats_dir: the path for saving processed data
• nj: the number of jobs for data preparation
• speed_perturb: the range of speech perturbed
• exp_dir: the path for saving experimental results
• tag: the suffix of experimental result directory

Stage 0: Data preparation

This stage processes raw AISHELL-1 dataset $data_aishell and generates the corresponding wav.scp and text in $feats_dir/data/xxx. xxx means train/dev/test. Here we assume users have already downloaded AISHELL-1 dataset. If not, users can download data here and set the path for $data_aishell. The examples of wav.scp and text are as follows:

• wav.scp

BAC009S0002W0122 /nfs/ASR_DATA/AISHELL-1/data_aishell/wav/train/S0002/BAC009S0002W0122.wav
BAC009S0002W0123 /nfs/ASR_DATA/AISHELL-1/data_aishell/wav/train/S0002/BAC009S0002W0123.wav
BAC009S0002W0124 /nfs/ASR_DATA/AISHELL-1/data_aishell/wav/train/S0002/BAC009S0002W0124.wav
...

• text

BAC009S0002W0122 而 对 楼 市 成 交 抑 制 作 用 最 大 的 限 购
BAC009S0002W0123 也 成 为 地 方 政 府 的 眼 中 钉
BAC009S0002W0124 自 六 月 底 呼 和 浩 特 市 率 先 宣 布 取 消 限 购 后
...

These two files both have two columns, while the first column is wav ids and the second column is the corresponding wav paths/label tokens.

Stage 1: Feature Generation

This stage extracts FBank features from wav.scp and apply speed perturbation as data augmentation according to speed_perturb. Users can set nj to control the number of jobs for feature generation. The generated features are saved in $feats_dir/dump/xxx/ark and the corresponding feats.scp files are saved as $feats_dir/dump/xxx/feats.scp. An example of feats.scp can be seen as follows:

• feats.scp

...
BAC009S0002W0122_sp0.9 /nfs/funasr_data/aishell-1/dump/fbank/train/ark/feats.16.ark:592751055
...

Note that samples in this file have already been shuffled randomly. This file contains two columns. The first column is wav ids while the second column is kaldi-ark feature paths. Besides, speech_shape and text_shape are also generated in this stage, denoting the speech feature shape and text length of each sample. The examples are shown as follows:

• speech_shape

...
BAC009S0002W0122_sp0.9 665,80
...

• text_shape

...
BAC009S0002W0122_sp0.9 15
...

These two files have two columns. The first column is wav ids and the second column is the corresponding speech feature shape and text length.

Stage 2: Dictionary Preparation

This stage processes the dictionary, which is used as a mapping between label characters and integer indices during ASR training. The processed dictionary file is saved as $feats_dir/data/$lang_toekn_list/$token_type/tokens.txt. An example of tokens.txt is as follows:

• tokens.txt

<blank>
<s>
</s>
一
丁
...
龚
龟
<unk>

• <blank>: indicates the blank token for CTC
• <s>: indicates the start-of-sentence token
• </s>: indicates the end-of-sentence token
• <unk>: indicates the out-of-vocabulary token

Stage 3: Training

This stage achieves the training of the specified model. To start training, users should manually set exp_dir, CUDA_VISIBLE_DEVICES and gpu_num, which have already been explained above. By default, the best $keep_nbest_models checkpoints on validation dataset will be averaged to generate a better model and adopted for decoding.

• DDP Training

We support the DistributedDataParallel (DDP) training and the detail can be found here. To enable DDP training, please set gpu_num greater than 1. For example, if you set CUDA_VISIBLE_DEVICES=0,1,5,6,7 and gpu_num=3, then the gpus with ids 0, 1 and 5 will be used for training.

• DataLoader

We support an optional iterable-style DataLoader based on Pytorch Iterable-style DataPipes for large dataset and users can set dataset_type=large to enable it.

• Configuration

The parameters of the training, including model, optimization, dataset, etc., can be set by a YAML file in conf directory. Also, users can directly set the parameters in run.sh recipe. Please avoid to set the same parameters in both the YAML file and the recipe.

• Training Steps

We support two parameters to specify the training steps, namely max_epoch and max_update. max_epoch indicates the total training epochs while max_update indicates the total training steps. If these two parameters are specified at the same time, once the training reaches any one of these two parameters, the training will be stopped.

• Tensorboard

Users can use tensorboard to observe the loss, learning rate, etc. Please run the following command:

tensorboard --logdir ${exp_dir}/exp/${model_dir}/tensorboard/train

Stage 4: Decoding

This stage generates the recognition results and calculates the CER to verify the performance of the trained model.

• Mode Selection

As we support paraformer, uniasr, conformer and other models in FunASR, a mode parameter should be specified as asr/paraformer/uniasr according to the trained model.

• Configuration

We support CTC decoding, attention decoding and hybrid CTC-attention decoding in FunASR, which can be specified by ctc_weight in a YAML file in conf directory. Specifically, ctc_weight=1.0 indicates CTC decoding, ctc_weight=0.0 indicates attention decoding, 0.0<ctc_weight<1.0 indicates hybrid CTC-attention decoding.

• CPU/GPU Decoding

We support CPU and GPU decoding in FunASR. For CPU decoding, you should set gpu_inference=False and set njob to specify the total number of CPU decoding jobs. For GPU decoding, you should set gpu_inference=True. You should also set gpuid_list to indicate which GPUs are used for decoding and njobs to indicate the number of decoding jobs on each GPU.

• Performance

We adopt CER to verify the performance. The results are in $exp_dir/exp/$model_dir/$decoding_yaml_name/$average_model_name/$dset, namely text.cer and text.cer.txt. text.cer saves the comparison between the recognized text and the reference text while text.cer.txt saves the final CER result. The following is an example of text.cer:

• text.cer

...
BAC009S0764W0213(nwords=11,cor=11,ins=0,del=0,sub=0) corr=100.00%,cer=0.00%
ref:    构 建 良 好 的 旅 游 市 场 环 境
res:    构 建 良 好 的 旅 游 市 场 环 境
...