Voice References

Reference voices

A zero-shot cloner copies whatever is in the reference clip: the voice, but also the room, the music, the mic and the mood. Most "the clone sounds wrong" problems are reference problems.

Rights first

Clone only voices the user has the rights to: their own, an actor who agreed, a licensed or generated voice. A game's characters are voiced by real people. For a private single-player experiment the user may decide to use the game's own audio; it still never goes into a repo, a release or a public video without the rights. npctalk check fails on audio files and .lab transcripts.

Good source audio

• One speaker, no music or effects under the voice (game cutscenes usually have both).
• Normal speaking level for the neutral voice; shouting goes in an angry mood folder, slurring in drunk.
• A minute or more of lines with pauses between them. More lines means more candidates to pick from.
• If music is unavoidable, isolate vocals first (Demucs, as server/finetune/prepare_dataset.py does).

Make the clips

bashCopy code
npctalk voice make --name Narrator --audio narrator.wav                   # neutral voice
npctalk voice make --name Narrator --audio narrator_angry.wav --mood angry  # lines tagged [angry]
npctalk voice upload voices/Narrator                                      # -> the server's /voices/Narrator

What voice make does (the same steps built the GTA V example's 13 voices):

1. Split into lines at pauses of 0.3 s (20 ms frames louder than -42 dBFS are speech).
2. Join runs of up to 4 neighbouring lines into 6-11 s candidates; score them for normal level (about -20 dBFS, -15 for angry), even loudness, no clipping, few joins, ~9 s; keep the best 12 that don't overlap.
3. Transcribe each with fal speech-to-text (FAL_KEY).
4. Drop candidates with fewer than 6 words or a speaking rate outside 1.4-4.8 words/s (screams, grunts, music, another language).
5. Write ref_0..2 (the best three) and clone.wav: the best candidates joined up to ~25 s. Every clip has a .lab transcript next to it; the cloner needs the exact words.

Copy code
voices/Narrator/clone.wav + clone.lab        what the server clones from by default ("Narrator/clone")
voices/Narrator/ref_0..2.wav + .lab          single clips, for engines that want a short one
voices/Narrator/angry/ref_0..1.wav + .lab    used when a line starts with [angry]
voices_work/Narrator/cand_*.wav + .lab       every candidate, to listen to (never commit)

Which clip to clone from (measured)

On Drama 3, the ~30 s clone.wav gave 0.680 voice match on Lamar's test lines; each of his single 6-10 s clips gave 0.610-0.630. Passing all four clips as references at once was no better than clone.wav alone. S2 Pro preferred a single clean clip (0.707 vs 0.680), so test both if you switch models (skill voice-likeness-eval).

Check them

• Listen to clone.wav. Anything in it (a laugh, a car, a second voice) shows up in every line.
• Read the .lab. A wrong transcript makes the cloner mumble or skip words; fix the text by hand.
• Say a test line: npctalk say "Testing, one two." --voice Narrator/clone --out t.wav.
• Moods: keep 2 clips per mood. If an angry line sounds like a different person, the mood clips are too far from the neutral ones (another recording session or mic): drop them.

Upload and use

The server reads /voices in its Modal volume when it starts, so restart it after an upload (modal app stop npcvoice-drama). A game refers to a voice by folder and clip name (Narrator/clone); mood folders are picked by the line's leading tag. Until a restart, a game can send the clip by URL with its transcript (reference_audio_url + reference_text), at ~9 s extra the first time.