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HyperFrames owns media playback; a companion media pipeline resolves everything else — voice, music, sound effects, images, icons, logos, captions, and background removal. You reach all of it by describing what the composition needs, and the agent resolves each need to a frozen local file. The craft here is precision: vague media asks (“add some music,” “no sound”) are the ones that come back wrong, because the pipeline does exactly what the words say.

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Voiceover (TTS)

Text-to-speech runs locally through Kokoro — no API key needed — with a HeyGen TTS upsell behind it. Describe the content and the agent picks a fitting voice, or name the voice, tone, and speed directly:
Generate narration for this script with a professional female voice.
Add TTS voiceover, British male voice, at 1.1× speed.
The Vocabulary table maps content types to Kokoro voices (for example af_heart / af_nova for a product demo, am_adam / bf_emma for a tutorial, af_sky / am_michael for marketing). Name one directly if you already know it; otherwise describe the read and let the agent choose.
  • ❌ add a voice
  • ✅ warm, unhurried female narration of the quoted script — tone and pace are what actually change the delivery

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Background music

Music resolves from a large catalog by mood, and it should almost always sit under the narration, not compete with it. Give the mood and a loudness target — the pipeline can duck and normalize to a level, so an explicit target lands a mix instead of a guess:
Add subtle electronic BGM, kept under −18 dB so it stays beneath the voiceover.
Upbeat tech-launch music bed at a low level, ducking under narration.
  • ❌ add background music — you’ll get a full-volume track fighting the VO
  • ✅ subtle background music, ducked ~12 dB under the voice — a mix instruction the pipeline can execute
A stated loudness target (“under −18 dB,” “ducked under the voice”) is the difference between music that supports the piece and music that buries it. When there’s narration, always say the bed goes under it.

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Sound effects

SFX resolve from a small bundled library plus the catalog. Cue them to specific moments — a transition, a stamp-in, an impact — rather than sprinkling them:
Add a whoosh on each of the three scene transitions.
Put a soft click on the button press at 0:04.

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Captions and transcription

Captions come from word-level timestamps. When you generate a voiceover, the timing comes with it; for existing footage, transcription produces the timing (Parakeet by default, with a whisper.cpp fallback). Scaffolding a project from a source video can generate captions from its audio directly.
Transcribe the narration and add karaoke-style captions synced to it.
Generate captions from assets/interview.mp4 and style them hype, scale-pop.
Caption look is its own vocabulary (tone, size, per-word emphasis) — see Captions catalog for the styles. This page is about producing the timed text; that page is about styling it.

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Background removal (transparent cutouts)

The remove-background command mattes a subject out of a video or image locally and hands you a transparent WebM you can drop into any scene as a <video>:
Remove the background from assets/presenter.mp4 and float the subject over the scene.
One caveat is load-bearing: the built-in model is purpose-built for people — head-and-shoulders or full-body, reasonably stable framing, a background that contrasts with the subject. It returns a mostly-empty mask on non-human subjects (products, animals, objects). If you need to cut out a product, say so — the agent should route to a different tool rather than run the person model and get nothing.
  • ❌ remove the background from this product shot with the built-in command — the human-matting model can’t see it
  • ✅ matte the presenter out of assets/talk.mp4 (person) — or, for a product, flag that it’s a non-human subject so a different matter is used
The Remove background guide covers the person-only caveat, the two-layer plate for text-behind-subject, and alternatives for objects and hair-fine mattes.

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Video-in-video and picture-in-picture

Layering footage — a talking head over a scene, a subject in front of a headline, PiP inset — is a compositing prompt. Two grounded rules keep it frame-accurate, and the agent applies them for you, but naming the layout you want helps:
Put the transparent presenter cutout in the bottom-right, over the chart scene.
Layer the headline behind the presenter so their silhouette occludes the text.
Two mechanics the workflow skills handle automatically (from the Remove background guide): a cutout that reveals into view is wrapped in a non-timed <div> and the wrapper is animated (the framework forces opacity: 1 on timed clips, so animating the video directly does nothing); and both the base video and the cutout mount at data-start="0" so their decoders stay in sync at the cut. You rarely need to say this — but it’s why “late-mounting” a PiP clip can land a frame off.

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The supplied-assets rule

The single most reliable media instruction is an explicit path. The agent will search when you describe an asset, but a path removes every ambiguity about which file — and for your own brand assets, it’s the only way to guarantee the right one:
  • ❌ use my logo
  • ✅ use assets/logo.svg
This matters even when resolution would otherwise work: brand and entity assets should point at your file, not a resolved lookalike. (Third-party logos are a separate case — the pipeline pulls official marks from a logo cascade and never hand-redraws them, so “add the LinkedIn logo” is fine; “add my company’s logo” needs a path.)

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Say what “no sound” actually means

The most common audio mistake is a negative that means less than you think. “No narration” removes the voiceover — it does not silence music or sound effects. If you want genuine silence, say so:
  • ❌ no narration when you mean a completely silent video — music and SFX can still be added
  • ✅ no audio at all — the unambiguous way to ask for silence
This mirrors the negatives discipline in Anatomy: close the gap explicitly, because the engine acts on the literal words.

Vocabulary

Voice names, caption tones, and audio-reactive mappings

Captions catalog

Styling the timed text this page produces

Remove background guide

The matting command, its person-only caveat, and alternatives

Video components

Installable overlays, captions, and effects