A Go port of the aeneas forced audio/text alignment library — pure Go core, espeak-ng for synthesis, FFmpeg for audio decode. Maintained by Digital Bible Society.

• Multi-level alignment supported (task_granularity=2|3 for mplain / munparsed input): paragraph → sentence → phrase → word, each level aligned independently within its parent's audio window.
• Automatic transliteration for languages without an espeak-ng voice: when a fragment's language falls back to English AND its text is in a non-Latin script (Greek, Hebrew, Devanagari, Syriac, …), the text is romanised before synthesis so the timestamps stay accurate. Toggle with tts_auto_transliterate=false. Powered by digitalbiblesociety/transliterate.

go build -o dido ./cmd/dido

./dido audio.wav text.txt \
  "task_language=eng|is_text_type=plain|os_task_file_format=srt" \
  output.srt

Run ./dido --help for the full list of config keys and output formats.

Batch mode

Align many tasks from a single JSON file (the schema matches SIL go-aeneas / SAB's AeneasTask; both a bare array and {"tasks":[…]} are accepted):

./dido --batch tasks.json

Each task has the fields description, audioFilename, phraseFilename, parameters, outputFilename. The first error aborts the rest of the queue.

Environment

• DIDO_ESPEAK_NG_PATH — espeak-ng binary (overridable per-task with tts_path).
• DIDO_TTS_WORKERS — cap on parallel TTS subprocesses (0 = NumCPU).
• DIDO_BATCH_WORKERS — parallel tasks in --batch mode (default 2; each task already fans MFCC/DTW across NumCPU).

Requirements

• Go ≥ 1.26
• espeak-ng on PATH for TTS synthesis. Override per-task with the tts_path config key, or globally with the DIDO_ESPEAK_NG_PATH env var.
• ffmpeg on PATH for audio decoding. Mono PCM 16-bit WAV at the target sample rate (16 kHz by default) is read directly without going through ffmpeg, so a WAV-only pipeline doesn't need it.
• Python aeneas is only required for the parity tests and the parity-report tool — never at runtime.

Build

go build ./...

Or just the CLI:

go build -o dido ./cmd/dido
./dido --help

Test

The standard suite is fast and self-contained:

go test ./...

The internal/parity package additionally compares each numeric stage to the upstream Python implementation. It's skipped automatically if Python or aeneas isn't importable.

# Compare Go vs Python on the standard fixtures (skips when Python aeneas
# is unavailable):
go test ./internal/parity/

# Regenerate the cross-implementation summary table:
go run ./cmd/parity-report   # writes docs/PARITY_REPORT.md

End-to-end alignment parity on a real-world corpus (KJV-Scorby Psalms — 150 chapters, ~4.3 h of audio) runs as a Go benchmark. Point it at a fixtures directory holding wav/001.wav … 150.wav and text/001.txt … 150.txt:

PSALMS_PARITY_DIR=/path/to/fixtures \
  go test -run x -bench BenchmarkPsalmsBook ./internal/parity/

License

AGPL v3.