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Filter usage

The following sections only show snippets of commands, as there are quite a number of filters available.

Annotation management#

  • strip-annotations - removes all annotations

Audio management#

  • convert-to-mono - ensures that audio data is mono
  • convert-to-wav - ensures that audio data is in WAV format
  • trim-silence - for removing chunks of silence


  • pitch-shift - for shifting the pitch of audio samples
  • time-stretch - for speeding up/slowing down samples

Meta-data management#

  • metadata - allows comparisons on meta-data values and whether to keep or discard a record in case of a match
  • metadata-from-name - allows extraction of meta-data value from the audio file name via a regular expression
  • split - adds the field split to the meta-data of the record passing through, which can be acted on with other filters (or stored in the output)

Record management#

A number of generic record management filters are available:

  • check-duplicate-filenames - when using multiple batches as input, duplicate file names can be an issue when creating a combined output
  • discard-negatives - removes records from the stream that have no annotations
  • max-records - limits the number of records passing through
  • randomize-records - when processing batches, this filter can randomize them (seeded or unseeded)
  • record-window - only lets a certain window of records pass through (e.g., the first 1000)
  • rename - allows renaming of audio files, e.g., prefixing them with a batch number/ID
  • sample - for selecting a random sub-sample from the stream


With the tee meta-filter, it is possible to filter the audio files coming through with a separate sub-pipeline. E.g., converting the incoming data into multiple output formats.

The following command loads the Festvox speech data and saves them in ADAMS and split ADAMS format in one command:

adc-convert \
  -l INFO \
  from-festvox-sp \
    -l INFO \
    -i "./festvox/*.txt" \
  tee \
    -f "to-adams-sp -o ./adams-tee/ -c transcript" \
  tee \
    -f "to-adams-sp -o ./adams-split-tee/ -c transcript --split_names train val test --split_ratios 70 15 15"