Video Generation

mold supports generating video clips using LTX Video and LTX-2 models. LTX-2 distilled and one-stage checkpoints support chaining multiple clips together for longer videos with scene-by-scene direction. Two-stage dev checkpoints are single-clip pipelines and are rejected before a sequence job is created.

Single-clip generation

mold run ltx-2-19b-distilled:fp8 "a cat walks through autumn leaves" --frames 97

Multi-prompt scripts (v2)

Direct any-length video scene-by-scene with a TOML script. Each prompt becomes a stage; each boundary has a transition (smooth, cut, or fade).

Canonical form

mold run --script shot.toml
mold run --script shot.toml --dry-run   # print stage summary, don't submit
mold chain validate shot.toml            # parse without submitting

Sugar form (uniform smooth chains)

mold run ltx-2-19b-distilled:fp8 \
  --prompt "a cat walks into the autumn forest" \
  --prompt "the forest opens to a clearing" \
  --prompt "a spaceship lands" \
  --frames-per-clip 97

Per-stage transitions or per-stage frames require --script.

Transitions

Mode	Behavior
smooth (default)	Motion-tail carryover — prompt change produces a visual morph between scenes.
cut	Fresh latent, no carryover. If the stage has source_image, it's used as an image-to-video seed.
fade	Cut + post-stitch alpha blend of fade_frames (default 8) on each side of the boundary.

Example shot.toml

schema = "mold.chain.v1"

[chain]
model = "ltx-2-19b-distilled:fp8"
width = 1216
height = 704
fps = 24
seed = 42
steps = 8
guidance = 3.0
strength = 1.0
motion_tail_frames = 25
output_format = "mp4"

[[stage]]
prompt = "a cat walks into the autumn forest"
frames = 97

[[stage]]
prompt = "the forest opens to a clearing"
frames = 49

[[stage]]
prompt = "a spaceship lands"
frames = 97
transition = "cut"

[[stage]]
prompt = "the cat looks up in wonder"
frames = 97
transition = "fade"
fade_frames = 12

Sequences in the apps

On web, desktop, and iPhone, multi-clip video is a setting rather than a separate page. In Create, set Output (beside Model) to Sequence and the composer becomes a clip rail: clip pills carrying a prompt and frame count, joined by seam pills. Seams are named in words — Smooth, Cut, and Fade 8f — and a click opens the seam editor with its fade-length stepper. LTX-Video has no motion tail, so its seams read Join. New clips default to the selected model's advertised frame count. Frame choices and timeline metadata include their duration at the live model FPS, such as 97f · 4.0s.

Sequences run as durable jobs in the same activity strip as ordinary prints. Desktop and web show each scene as a 16:9 filmstrip tile with its poster, render progress, and cache state. As soon as a stage finishes, its play control opens the raw scene in the main Create canvas while later stages continue rendering; Return to live render switches the canvas back to progress. Desktop and web can edit a finished sequence in place: its clips reload onto the rail, each pill shows cached (✓) versus re-render (↻), and Update sequence re-renders only from the earliest changed clip — transition and fade-length edits re-stitch with no re-render at all. Every settled sequence job is listed in Library ▸ History ▸ Sequences, and a sequence print in the Library uses Edit sequence as its primary desktop/web action (re-enter the original job with its cached clips). Duplicate as new starts a fresh sequence from the recorded clips. Desktop and web keep TOML import/export for mold.chain.v1 scripts under the composer's file tools. Web also offers Validate plan: it asks the currently selected authenticated host to normalize the live draft, then shows each clip's input/output frames, transition, conditioning inputs, warnings, and VRAM estimate when available. Validation creates no job and starts no download or inference work.

TUI chain composer

Press c from Create's navigation mode in mold tui to author a mold.chain.v1 script with per-stage prompts, frame counts, source images, and smooth / cut / fade transitions. See the TUI guide.

Capabilities endpoint

GET /api/capabilities/chain-limits?model=<name>

Returns per-model caps used by every sequence UI:

{
  "model": "ltx-2-19b-distilled:fp8",
  "frames_per_clip_cap": 97,
  "frames_per_clip_recommended": 97,
  "max_stages": 16,
  "max_total_frames": 1552,
  "fade_frames_max": 32,
  "transition_modes": ["smooth", "cut", "fade"],
  "quantization_family": "ltx2",
  "supports_audio": true,
  "supports_sequence": true
}

frames_per_clip_recommended follows the model's own default frame count — 97 for LTX-2, 25 for LTX-Video — so clients do not have to hardcode one. supports_sequence is model-specific: a two-stage LTX-2 dev checkpoint reports false with a sequence_unsupported_reason. GET /api/models carries the matching per-model default_frames, default_fps, max_frames, and frame_step fields.