Advanced workflows

Extend an existing video

Use MiniMax H3 Existing Video Context when scene 1 must continue a decoded video rather than start from an empty timeline. The complete experimental model is Extend Existing Video Model Workflow - MiniMax H3.

Plan ────────────────────────────────┐
Core Load Video (VIDEO) ─────────────┼→ Existing Video Context → Loop Start
Other loader IMAGE + AUDIO + FPS ────┘
H3 audio VAE ─────────────────────────────────────────────→ Loop Context

Use exactly one video route:

source_video accepts native ComfyUI VIDEO, including embedded audio and exact FPS. An explicit audio input overrides embedded audio.
source_frames accepts IMAGE from VHS or another decoder. Connect optional AUDIO and set the real decoded source_fps.

The adapter normalizes frames to the Plan canvas and H3's 24 fps, uses the last context_length frames as scene 1's predecessor, and can persist the normalized source as a prelude. In head mode:

scene 1 delivered frames = raw frames - imported context frames

Connect the audio VAE to Loop Context for imported-audio timeline guidance in generated_audio or source_plus_timeline. Visual continuation still works without imported audio.

With prepend_original=true, Assemble places the normalized original before generated scenes, including partial output. Arbitrary source codecs and frame rates cannot be stream-concatenated safely, so the prelude is encoded once at the Plan's segment_crf; generated H.264 segments remain stream-copied.

The imported tail is fingerprinted. Reconnect the same Plan and source when resuming; a changed source correctly invalidates dependent checkpoints.

Recommended first settings:

Chain Policy         Guide
encode_mode          video
anchor_mode          head
Loop Trim match_tail true
Spectrum             off

Chain Policy derives both visual and generated-audio overlap as 22 frames for Guide. Use the Legacy 0.4 Policy Adapter only when this imported-context workflow deliberately needs different visual and audio overlap lengths.

Long visual context

56 is a valid advanced context length. It carries 2.33 seconds of motion in 17 video latent steps, but head mode regenerates and removes all 56 frames from every continuation. Start with 22; use 56 when a long clip's camera move or performance genuinely needs more history.

Non-linear visual context

Scenes 2 and later normally take visual context from the immediately previous timeline scene. Visual context source in Plan or Plan Studio can instead select any earlier saved scene by stable scene ID:

{
  "id": "scene_5",
  "visual_context_source": "scene_3",
  "context_length": 39,
  "video_blend_frames": 0
}

This changes only the picture-side continuation edge. In this example scene 5 uses scene 3's retained RGB/video latent, while Generated continuity still uses scene 4's audio latent. The timeline, branch ancestry, soundtrack clock, and final ordering remain 1 → 2 → 3 → 4 → 5. With head anchoring, the repeated scene-3 prefix is removed by Loop Trim, so video_blend_frames: 0 delivers a hard cut from scene 4 to the newly generated part of scene 5.

Non-linear visual context requires a zero assembly blend because the visible incoming timeline boundary is still scene 4 → scene 5. Checkpoint preflight verifies both consumed dependencies independently: the selected visual scene and, when enabled, the immediate generated-audio predecessor. Other earlier scenes remain assembly-only and do not become false resume blockers.

Selecting a source segment instead of its tail

Plan Studio's Context tab previews the complete delivered video for every visual context block. The highlighted zone is the actual fixed-size context window: its width is proportional to the configured frame span. Drag that zone across the movie, place it near the player's current frame, or play only the selected window. The position snaps to H3's native 17-frame / five-latent- step temporal lattice. Tail (default), or Latest aligned (default) when that block's phase cannot end on the physical tail, removes the override.

The stored values are zero-based frame indexes within the source scene's delivered video (after that source's own incoming overlap was trimmed):

{
  "id": "scene_5",
  "context_length": 22,
  "visual_context_source": "scene_3",
  "visual_context_start_frame": 119,
  "video_blend_frames": 0
}

For an untrimmed source this selects delivered frames 119 through 140 from scene 3. Valid numeric starts depend on the source's own trimmed incoming prefix, so use Plan Studio instead of hand-authoring an arbitrary frame. The backend converts both ends to native latent-step boundaries and slices the saved video latent directly. It never replaces that crop with an RGB VAE re-encode; RGB Guide/mask consumers use retained frames or a decode-only mirror. Generated-audio continuity remains the immediate previous scene's tail.

Composed visual context

A continuation can use any ordered number of saved picture histories back to back. In Plan Studio's Context → Picture tab, select the total, the number of blocks, and the cumulative H3-native divisions. Every block then exposes its own earlier-scene source and exact latent-window selector. The last block sits immediately before the new generation:

{
  "id": "scene_5",
  "context_length": 39,
  "visual_context_blocks": [
    {"source": "scene_3", "frames": 5},
    {"source": "scene_4", "frames": 12, "start_frame": 0},
    {"source": "scene_3", "frames": 22}
  ],
  "video_blend_frames": 0
}

This example constructs one 39-frame visual prefix:

scene 3 block:  5 RGB frames / 2 video-latent steps
scene 4 block: 12 RGB frames / 3 video-latent steps
scene 3 block: 22 RGB frames / 7 video-latent steps
result:        39 RGB frames / 12 video-latent steps

The division selectors expose every valid ordered repartition without building an enormous combination menu. For example, three blocks within 39 include 5+12+22, 5+17+17, 5+29+5, 17+5+17, 17+17+5, and 22+12+5. Changing the count starts from a balanced valid repartition; moving each division explores all other native layouts.

The blocks are concatenated in their authored order; they are not blended or interpolated. Both 22+17 and 17+22 now select source windows on the target block's matching temporal phase and concatenate the saved latent crops directly. For an inverse layout, the first block's latest aligned crop can end before its source movie's physical tail; Plan Studio shows that position. Every source may be any earlier scene on the active branch. Sources do not need to be chronologically ordered and the same source can appear more than once with independent windows. The composed prefix remains one context, so its normal head trim or AV mask uses the selected total exactly once.

Composition changes only picture context. Generated audio remains one complete latent tail from the immediately previous timeline scene, so there is no audio splice at the internal visual seam and a scene's independent audio-context override still works. Final assembly still follows normal scene order and must use video_blend_frames: 0 at this boundary. Checkpoint preflight verifies every selected visual revision plus the immediate audio predecessor when that audio continuity is active.

Each visual_context_blocks item may omit start_frame to use its latest phase-aligned native crop. The released visual_context_source and visual_context_lead_* one/two-block fields remain accepted for existing Plans and checkpoints, but the new builder writes only the ordered list.

Independent audio context

Plan Studio's Context planner keeps Audio locked by default. This preserves the established behavior: picture may use one or more selected windows, while generated audio remains one continuous tail from the immediately previous timeline scene. Existing plans therefore do not change.

Choose Unlock audio context to reveal the Audio tab for that scene. It can select one earlier saved scene and an exact audio-latent range, or prepend a second independently positioned range. The two blocks are sequential context excerpts—not a decoded waveform mix—so they can, for example, expose voice regions from two characters before the new scene is generated:

{
  "id": "scene_5",
  "audio_context_unlocked": true,
  "audio_context_source": "scene_3",
  "audio_context_start_frame": 0,
  "audio_context_lead_source": "scene_4",
  "audio_context_lead_frames": 5,
  "audio_context_lead_start_frame": 12
}

The lead block is first and audio_context_source is nearest generation. Both sources may point to the same scene to select two different moments. Positions are delivered-frame indexes and snap to crops whose duration is exact on H3's 40 Hz audio-latent clock; the saved audio tensors are sliced directly without decode/re-encode. AV prefix implementations still use the picture context duration as their shared target span. Locking Audio again removes these custom fields and restores immediate-predecessor continuity.

Last-frame destinations

When stock H3 Image to Video supplies last_frame, Motion Context preserves that target on continuation scenes. The carried repeated head replaces a conflicting first_frame anchor because both cannot own the same opening coordinates.

Place official MiniMax H3 Add Guide nodes after Loop Context for additional scene-local image, video, or audio anchors.

Re-film a synchronized performance

The three-angle guitar workflow uses Reference Video Prep to convert native VIDEO or decoded IMAGE/AUDIO into exact 24 fps Ref2VA input. Its soundtrack is copied without padding or time-stretching, allowing one performance to be generated from multiple camera angles in one pass.

Reference Video Prep rejects sources shorter than the requested H3-valid length instead of silently padding or stretching them.

External stitchers

Loop Trim's images_with_overlap output exposes part of the repeated visual context while leaving its normal images and audio fully trimmed. Connect Current Shot → state to Loop Trim → state. Loop Trim then resolves each incoming scene's optional video_blend_frames override, or the Plan default when the scene value is blank. Scene N controls the N−1→N boundary. Keep it at 0 for a hard boundary. The old Plan/default and Current Shot/resolved integer outputs remain compatibility sockets only; do not wire either one in a 0.5 workflow.