School bake sale video: three small stills, free music, 53 cents

A bake sale video costs about $0.525 on Sume: three 0.5K stills ($0.225), a Timeline render with the free background music catalog ($0.10) and one caption job for the date and place ($0.20). The music has no charge because the BGM catalog is open without a key.

Volunteers want something quick, cheap and readable. A 0.5K image is plenty for a phone feed when it is shown for four seconds, and a silent spine with a soundtrack skips text-to-speech completely. Rates are from the Sume pricing code (read 2026-10-10).

What is the endpoint chain?

No voice, so the audio is only the bed.

• POST /v1/images x3 with google/nano-banana-2.1 at 0.5K ($0.075 each): cookies, a table of cupcakes, a lemon loaf.
• GET /v1/bgm/pick or /v1/bgm/catalog with no API key to choose a track; use a media.sume.com URL it returns.
• POST /v1/timeline-1.0/render with audio: {mode: "silence", duration_seconds: 12}, three slots at 0, 4 and 8 seconds, and soundtrack: {url, gain_db, fade_out_seconds}.
• POST /v1/video-captions with cues: 'Saturday 10 to 1' and 'School gym' timed over the slots.

What does it cost?

The still tier is the only choice that changes the bill.

What are the limits?

Silent mode needs a soundtrack, not a spine file: do not send url, parts, gain_db or source_in with audio.mode: "silence". Soundtrack ducking (duck_db) needs a real spine, so skip it here. Read the BGM docs for usage terms before publishing.

A 0.5K still shown full screen on a 1080 by 1920 video will look soft on a close look. If you want a poster for printing, a still at 2K is a better start ($0.15). Do not ask the model for the price tags or the school name inside the picture; the caption job prints them. See free BGM catalog for how to pick.

Where do the pieces live?

Everything is a media.sume.com file, so you can reuse the stills for a flyer, a story and a poster. Pair this with a music bed under a voice-over if you later add narration. The Timeline 1.0 page lists the silence and soundtrack rules.

Pre-publish checklist

Check the date, time and place cue on a phone with the sound off. This is the whole message and it is only text, so a typo is the one failure that matters.

If the date moves, recaption: it is one $0.20 job and keeps the render.

• Three stills at four seconds each give a 12-second video.
• Keep volume of the soundtrack low if you later add a voice.
• Post the link to the sign-up sheet in the caption, not in the video.