ESPnet3 Config Resolvers

ESPnet3 registers a small set of OmegaConf resolvers to pull external data into YAML configs at load time. These are defined in espnet3.utils.config and are available in all stage configs.

✅ At a glance

Resolver	Description
load_line	Load lines from a text file into a list.
load_yaml	Load a YAML file or a specific key from it.

load_line

Use load_line to read a text file (one entry per line) and inject it into a config. This is commonly used for vocab or token lists.

Sample file:

<blank>
<sos/eos>
<unk>

token_list: ${load_line:conf/token_list.txt}

When the config is loaded, token_list becomes:

token_list:
  - "<blank>"
  - "<sos/eos>"
  - "<unk>"

load_yaml

Use load_yaml to load an entire YAML file or a single value from it.

Sample file (conf/train.yaml):

exp_tag: asr_template_train
exp_dir: ${recipe_dir}/exp/${exp_tag}

exp_tag: ${load_yaml:conf/train.yaml,exp_tag}
full_cfg: ${load_yaml:conf/train.yaml}

When the config is loaded, the values are resolved from the referenced file.

Example of the resolved result in a second config:

exp_tag: asr_template_train
full_cfg:
  exp_tag: asr_template_train
  exp_dir: ${recipe_dir}/exp/${exp_tag}

When a key is provided, it uses dot notation and raises an error if the key is missing.