Upload And Extend Audio · V4.5PLUS

Of the two extend nodes in this pack, this is the one that doesn't demand a Suno-generated track. It works from a URL to any audio file, so it can extend a recording you made, a stem you bounced, or a track Suno made that you no longer have the ID for. The model doing the continuing is Suno's V4.5PLUS.

What it does

Posts a request to KIE.ai - transport model ai-music-api/upload-and-extend-audio, V4_5PLUS nested as the version - then blocks and polls until the job resolves or timeout_seconds (default 1200 seconds, twenty minutes) is spent. The finished audio is downloaded and decoded locally into a ComfyUI AUDIO object, using torchaudio with a PyAV fallback from ComfyUI's own environment.

Inputs that actually matter

upload_url is required, a public URL, and this build exposes it as a plain text box rather than an audio socket - so tracks created upstream in the same graph need to be hosted somewhere KIE can reach. The limit is 8 minutes on the source; longer files are rejected, not shortened.

continue_at (default 60, seconds) is where the extension begins. Put it at the end of the material you want to keep. Put it earlier and the model re-performs what follows, which is occasionally the fix for a weak bridge and usually not what you asked for.

prompt is required as a widget and functions as lyrics for the new section - but only when lyrics is empty; lyrics takes precedence. style should echo the source or you'll hear exactly where the two halves meet. instrumental defaults to true, and in that mode the docs say don't send prompt, lyrics or vocal_gender - clear the prompt box instead of leaving the placeholder text in it.

Then the usual dials: negative_tags for exclusions, variety for spread between takes, and style_weight / weirdness_constraint / audio_weight for gentle pushing. duration and persona_model are documented as V5.5/V6-family only, so they're dead controls on this version.

Outputs

audio is the extended track - wire it to SaveAudio, into a video pipeline, or into the pack's own audio utilities. all_urls_json holds every URL the provider returned (multiple takes are normal; the audio output is the first), url is the primary link, task_id is the KIE job ID, and raw_json is the full response for when you need to see what was actually sent. credits_consumed and credits_left report the cost of the run and both appear on the node face afterwards, so credit burn is visible while you work.

Install

Via ComfyUI Manager, search ComfyUI-KIE-Nodes-Next ("KIE.ai Nodes Next"). Or do it by hand:

cd ComfyUI/custom_nodes
git clone https://github.com/felipederosilva/ComfyUI-KIE-Nodes-Next

Restart ComfyUI. Nothing else to install - the pack's only requirements are requests, Pillow, numpy and PyYAML, which is why there are no model directories to populate and no VRAM involved. Then open Settings → KIE.ai Nodes Next → Connection, paste your KIE.ai API key, and let the pack validate it; the saved key lives outside your workflow JSON and shows up as a masked fingerprint. If you run headless, KIE_API_KEY in the environment takes priority over the saved value.

Things that catch people out

A hosted URL is not optional. A localhost link, a network share, or a local path won't work - KIE's servers fetch the audio. The pack ships upload helpers under KIE Next / Utility specifically for this.

Extending a cover or a mashup works, but style matching becomes your job. This endpoint has no memory of the original prompt, so if you don't set style to match, the second half will drift.

V4.5PLUS is retired-adjacent. KIE's parameter docs mark it (Discontinued) next to V4, V4.5, V4.5ALL, V5 and V5.5; V6, V6_MINI and V6_WILD are current. The node is legitimate - the page is still documented - but it's a legacy branch. If the API eventually refuses the version, the V5 variant of this node and the V6 family are the exits.

Paid, no preview. Each call spends credits. Chaining several extensions to build a long track is the most credit-hungry thing you can do with this pack, so plan the cut points before you hit Run.