choplin/explainer-studio/explainer-audio-cast-base

Audio cast base

Owns the cast pairs: one self-contained file per pair under references/, holding its two speakers, their voices, and how they behave toward each other. There is no roster of casts anywhere else, and a voice id appears nowhere but in its own pair file.

The model

A cast pair names two characters and assigns the roles. The roles are fixed for every pair:

• the learner is speaker A — the listener who has not understood yet;
• the explainer is speaker B — the one who has.

They differ in understanding, and that asymmetry is why a script is a dialogue rather than a narration. A pair chooses voices, register, and the relationship between the two. It does not choose whether the learner can be wrong. Every pattern in explainer-audio-dialogue/references/conversational-act-patterns.md requires the learner's moves to expose an inference, doubt, demand, paraphrase, or revised judgment; a cast that cannot do that cannot hold the learner role, whatever its voice. Each pair file records which patterns it performs most naturally — a tilt, not a restriction: the pattern is chosen per act from that act's obstacle.

Pairs

Each pair's file — references/pair-<id>.md — is the complete definition: speakers, personas, relationship, one worked conversational act, and the spoken orientation in that register. Read only the selected pair's file. They are deliberately self-contained so that writing one pair never drags another pair's register into the draft.

Each file opens with the machine-readable binding that narration reads:

cast-binding learner   <cast-id> <voicevox-style-id>
cast-binding explainer <cast-id> <voicevox-style-id>

Choosing a pair

The Guide plan's cast_pair policy value records the choice. There is no rule table mapping policy values to pairs, and none should be added: this is a judgment. Weigh these.

• Who is listening. A newcomer audience is served by a learner who says the

wrong thing plainly and is corrected without ceremony. An expert audience hears that as condescension; there the learner's error should be a matter of precision, not of basic misunderstanding.

• What the source sounds like. A standard, a specification, or a paper whose

own register is exact loses credibility when explained through a casual pair. An introductory or practical source survives, and often benefits from, one.

• How wrong the listener is likely to be. When the obstacle is a widespread

misconception, prefer a pair whose learner states things outright, so the wrong idea is built and visibly broken. When the material is subtle rather than counter-intuitive, prefer a precise learner, so the correction lands as a refinement.

• How long the guide is. A strong character register carries a short guide

and tires over a long one; a plainer pair sustains length better.

When these pull apart, the audience decides. Record the reason in the Guide plan so the next revision is not a coin flip.

Voices available to the local engine are listed by curl http://127.0.0.1:50021/speakers.