Instagram Reel collab, up to 5 people: stitch their clips in one file

On Instagram you can invite up to 5 collaborators to a Reel, according to Meta's Reels tips: "Add up to 5 collaborators" when you want several people to work on a Reel together. The invite is an in-app step. The video itself is still one file, so if each collaborator films a clip on their own phone, someone has to put the clips together. Sume Timeline can do that assembly: import each clip, set the order and lengths, add one audio spine, and render one 1080x1920 MP4 you can upload.

What does the 5 mean?

Meta's page states the number for collaborators on a Reel and gives no more detail, so this post does not guess at roles or permissions. Meta's how-to guide also says a Reel can be "anywhere from 3 seconds to 3 minutes long" and that multiple clips "stitch together automatically" in the app. Those two facts frame the work: up to 5 people, a few seconds each, one file.

How do I budget the clips?

With 5 people and a 30 second Reel, each person gets about 6 seconds. Decide that before anyone films. Sume's timeline needs each slot to be at least 0.2 seconds, so the limit is Instagram's 3 second Reel minimum and what will look right, not the tool.

How do I stitch five clips?

Import each person's file so it sits on media.sume.com, then give the render an audio spine. If the Reel is music-led, use one music file as the spine. If it is talk-led, detach the audio of the main speaker and use that. Whatever you pick, the spine is what is heard. This builds a 5-slot body with short fades between people.

import json

clips = [f"https://media.sume.com/artifacts/artf_demo/person{i}.mp4" for i in range(1, 6)]
seg = 6
slots = []
for i, url in enumerate(clips):
    slot = {"source_url": url, "start": i * seg, "duration": seg}
    if i:
        slot["transition"] = {"type": "fade", "duration": 0.25}
    slots.append(slot)

body = {
    "audio": {"url": "https://media.sume.com/artifacts/artf_demo/bed.wav", "duration_seconds": seg * len(clips)},
    "video": slots,
}
print(json.dumps(body))

How do I keep the files consistent?

Phones film at different frame rates and shapes. If you omit output.fps, the render uses the rate the longest video source runs at and warns output_fps_resamples_sources when a source differs, so it is better to ask everyone for the same rate. video[].fit defaults to cover, which fills the frame and crops, so ask people to film vertical. If a clip is too long, trim it first with video trim, which returns a new MP4 and leaves the original alone.

What happens after the render?

Download the MP4, upload it to Instagram as a Reel, and invite your collaborators there, since that is the step Meta's page describes. Listen to the whole file before posting, because the audio spine decides what is heard and you may want to adjust it with audio.gain_db (-60 to 12).