Can you post audio only on Instagram? Meta wants a visual component

Not as a bare audio file. Instagram's guidelines for music in video say: "There should always be a visual component to your video; recorded audio should not be the primary purpose." So a podcast clip or a voice memo has to ride on something you can see. The simplest version is one still image held for the length of the audio, rendered to a vertical MP4. Sume's Timeline 1.0 does that: stills are allowed as video slots, and the audio spine sets the length.

What do Meta's pages say about the visual?

Two Meta pages matter. The music guidelines contain the sentence above and apply to all account types: pages, profiles, and verified and unverified accounts. The 2026 Reels guide says Reels run from 3 seconds to 3 minutes and that you can create a Reel "entirely from photos" that plays as a slideshow. Neither page defines how much of the picture must move, so a still is not ruled out by the text I read, but I would not treat it as approved either. A picture that changes, or captions that appear and change, is the safer design.

How do I turn one audio file into a Reel?

Import the audio and a cover image so both live on media.sume.com. Then declare the audio as audio.url with its duration_seconds, and one video[] slot with the still. The slot's duration must reach within 0.5 seconds of the spine. For a longer piece, add more stills with start times that increase and a short transition, so something changes on screen.

curl -X POST https://api.sume.com/v1/timeline-1.0/render \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: audio-reel-001" \
  -d '{
    "audio": { "url": "https://media.sume.com/artifacts/artf_demo/voice.wav", "duration_seconds": 30 },
    "video": [
      { "source_url": "https://media.sume.com/artifacts/artf_demo/cover.jpg", "start": 0, "duration": 15, "fit": "cover" },
      { "source_url": "https://media.sume.com/artifacts/artf_demo/quote.jpg", "start": 15, "duration": 15, "fit": "cover",
        "transition": { "type": "fade", "duration": 0.5 } }
    ],
    "output": { "fade_out_seconds": 1 }
  }'

What if I only have a script?

Generate the sound first. The Music Router makes a music bed from a prompt, and it rejects duration fields, so ask for the length in words, such as a 30-second track, then declare the same length as audio.duration_seconds. Stills can come from Sume's image models, which return up to 10 images per request in ratios that include 9:16. Keep the render at 1080x1920 so the picture fills the Reel frame.

What should I check before posting?

Play the MP4 once with the screen on and once with the sound off. The first should match the audio, and the second should still make sense, because the picture is the part Meta's page asks for. If your audio is recorded music, read Meta's music page again, since it says the more full-length recorded tracks a video holds, the more likely it may be limited.