AudioConcatenate

Exactly what it says: takes two AUDIO clips and joins them into one. Not a crossfade, not a mix - a straight cut where one clip ends and the next begins. If you're building a longer soundtrack out of shorter generated segments, joining split TTS output back together, or extending an audio clip to cover more video frames, this is the plain, no-frills way to do it.

The inputs and outputs that matter

• audio1 / audio2 (AUDIO, required) - the two clips to join.
• direction (default right, choices right / left) - which side of the pairing audio2 lands on. As the naming and the right default suggest, right sticks audio2 onto the tail of audio1 - the order you'd expect if you're extending a clip forward - while left flips it, putting audio2 first. If your result comes out backwards from what you wanted, this is the one setting to flip.

Output: AUDIO - a single clip, ready to feed into whatever consumes audio downstream (a save node, a video-with-audio combiner, another AudioConcatenate if you're chaining more than two clips together).

How to install it

Via ComfyUI Manager: search KJNodes for ComfyUI, install, restart. Manually:

cd ComfyUI/custom_nodes
git clone https://github.com/kijai/ComfyUI-KJNodes
pip install -r ComfyUI-KJNodes/requirements.txt

Then restart. Pure audio-buffer manipulation - no models, no downloads.

Common issues & troubleshooting

The joined clip sounds sped up, slowed down, or garbled at the seam. This is the classic gotcha whenever you concatenate audio from two different sources rather than two clips cut from the same original - a TTS output paired with a separately loaded WAV file, for instance. If the two clips don't share a sample rate, or one is mono and the other stereo, the join can come out wrong even though neither individual clip has a problem on its own. Check that both inputs match on sample rate and channel count before they hit this node; resample or convert whichever one doesn't match.

You wanted a smooth transition, not a hard cut. This node concatenates, it doesn't blend - there's no fade at the seam. If you want that, you're looking for a crossfade tool rather than this one; this pack doesn't ship an audio crossfade equivalent to its CrossFadeImages node.

Joining more than two clips. There's no N-input version here - chain multiple AudioConcatenate nodes, feeding the output of one in as audio1 (or audio2) of the next, same pattern you'd use for any two-input combinator in ComfyUI.