As of v1.8, the API of scripts/ has changed. This script now takes command line arguments instead of environment variables (--num_gpus=8 instead of NUM_GPUS=8). For backwards compatibility, the script scripts/legacy/ still uses the former API but it doesn't support features introduced after v1.7.1, and will be removed in a future release.

Validation Command

Quick Start

To run validation, execute:


By default, a checkpoint saved at /results/, with the testing-1023sp_run.yaml model config, is evaluated on the /datasets/LibriSpeech/librispeech-dev-clean-wav.json manifest.


Customise validation by specifying the --checkpoint, --model_config, and --val_manifests arguments to adjust the model checkpoint, model YAML configuration, and validation manifest file(s), respectively.

To save the predictions, pass --dump_preds as described here.

See args/ and args/ for the complete set of arguments and their respective docstrings.

Further Detail

  • All references and hypotheses are normalized with the Whisper normalizer before calculating WERs, as described in the WER calculation docs. To switch off normalization, modify the respective config file entry to read standardize_wer: false.
  • During validation the state resets technique is applied by default in order to increase the model's accuracy.
  • Validating on long utterances is calibrated to not run out of memory on a single 11 GB GPU. If a smaller GPU is used, or utterances are longer than 2 hours, refer to this document.

Next Step

See the hardware export documentation for instructions on exporting a hardware checkpoint for inference on an accelerator.