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_utils and are available in all stage configs.

Important

Resolvers are resolved when the config is loaded. They are part of the config authoring model, not an extra runtime CLI layer.

✅ 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 ASR or speech-to-text token lists, which are often easier to manage in a separate text file than inline YAML.

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/training.yaml):

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

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

Warning

Use resolvers for shared config values and small external inputs. Do not turn them into a hidden replacement for normal recipe structure.

Related pages

Config Overview

See where resolvers fit in the overall config loading flow.

Training Config

See a larger config where resolvers are commonly used.

What Is a Recipe

See how recipe-local configs and files are structured.