MiniMax H3 Reel Delivery Compose / 成片合成 (Advanced)

This is the second half of the Reel Delivery pair: the Plan node validates your edit list and fingerprints every source file, and this Compose node actually streams it all into a finished MP4. The trick that makes it worth caring about is in the first sentence of its description - it "never materializes the whole reel as a ComfyUI IMAGE/AUDIO batch." A 3-minute reel of H3 clips decoded into tensors would blow up your RAM; this node reads and muxes at the file level, so memory stays bounded no matter how long the reel gets.

It's an output node with a safety culture: confirm_compose defaults to false, and nothing gets written until you flip it. That's not ceremony - the Plan node's fingerprints are checked against the actual files during compose, and the whole render is assembled atomically (a failed run shouldn't leave a half-written MP4 pretending to be a finished reel). It also supports hash-verified phase resume, so if a long render dies partway, you resume from a verified checkpoint instead of restarting from zero.

Inputs that matter

• reel_plan - the H3_T8_REEL_DELIVERY_PLAN handle from ReelDeliveryPlan. Required.
• confirm_compose - the explicit go/no-go, default false. This is the "I reviewed the plan" handshake.
• filename_prefix - output name prefix, H3_Reel default.
• crf - H.264 quality, 18 default (lower = heavier/better).
• peak_policy - block_if_clipping default: if the audio peaks clip, it blocks rather than shipping a distorted master. Peak-checking is a rare courtesy in these node packs.

Outputs: output_video_path (where the MP4 landed) and report_json.

Installing

In the T8mars MiniMax H3 Audio T8 pack:

cd ComfyUI/custom_nodes
git clone https://github.com/T8mars/comfyui-minimax-h3-audio-T8

or ComfyUI Manager → "MiniMax H3 Audio T8", then restart. No pip deps - but you absolutely need ffmpeg on PATH, since compose is FFmpeg-driven file streaming. Missing it is the most common "why won't this write anything" failure, and the node will tell you clearly if it can't find it.

The take

Where this shines is long delivery renders you don't want babysat: set the plan, flip confirm_compose, walk away, and come back to an atomic MP4 or an honest error with a resume point. Where it bites is the workflow discipline - you have to actually run the Plan node first and feed its handle in, because Compose refuses to guess. If you're doing a one-off 5-second clip, skip this whole pair; it's built for the person assembling a multi-shot reel where RAM and interrupted runs are the real enemies.