MiniMax H3 Selective Repair Compose / 修复合成 (Advanced)

This is where the Selective Repair chain finally touches a rendered file. The design principle underneath it: the original accepted segments are immutable base media, and accepted repairs are overlays. Compose is the node that streams both - untouched base segments plus the repaired overlays - into one bounded-memory MP4. It never re-encodes the whole timeline, never re-generates anything, and never touches the base files. The render is a muxing pass, not a re-creation.

The immutability pays off here in the feature that sounds like a typo until you need it: compose_mode = base_rollback. That mode simply ignores the overlays and renders the base chain as-is - a one-click rollback that deletes nothing. You can flip between repair_overlay (default) and base_rollback to compare "with my fixes" vs "the original cut" as actual MP4s, forever. That's the whole reason the chain refuses to let anything overwrite the base.

Inputs that matter

• chain_id - the production chain, matching the Bind node's.
• repair_manifest_path - the manifest from SelectiveRepairAccept (the repair_manifest_path output). Empty or stale = no overlay applied.
• compose_mode - repair_overlay (default) or base_rollback.
• filename_prefix (H3_Selective_Repair), crf (18).
• require_final_segment - default true; refuses to ship a cut that's missing its final segment.
• audio_seam_policy (cosine_bridge default) and bridge_ms (5) - how repaired-audio seams get stitched. A 5ms cosine bridge is the conservative default; raising it changes how audible the seam is but also how much of the real audio it smooths over.

Outputs: output_video_path and report_json. Output node - it's the terminal step.

Installing

In the T8mars MiniMax H3 Audio T8 pack (Manager → "MiniMax H3 Audio T8" or git clone https://github.com/T8mars/comfyui-minimax-h3-audio-T8 into custom_nodes), restart. No pip deps, but ffmpeg must be on PATH - the streaming encode is FFmpeg's job and the node errors clearly if it's missing.

The take

The workflow arc: Plan → Bind → regenerate → Stage → Accept → Compose. If you only run Compose without accepting anything, you get a base render - which is actually a useful smoke test. The seam controls are where the craft lives: with a repaired segment, the audio join is the thing people notice, and audio_seam_policy/bridge_ms are your only levers, so budget time to A/B them. And keep require_final_segment true; a "finished" MP4 that's missing the ending is the kind of mistake this whole pipeline was built to prevent.