Timeline 60 vs 61 seconds: the minute boundary that doubles the bill

Timeline 1.0 on Sume costs $0.10 per ceil(output minute), so a 60-second ad is $0.10 and a 61-second ad is $0.20. The render is rated by whole minutes of output length, and the reserve is ceil(audio.duration_seconds / 60). Trim one second and you halve the bill on a short spot.

The boundaries

The price rises at 61, 121, 181 seconds and every minute after, up to the 1,800-second cap. The cap means the most a single render can cost is 30 x $0.10 = $3.00.

Where this bites

Short-form ads are the common case. A 30-second jingle render and a 59-second voice-over render both cost $0.10. A 61-second voice-over costs $0.20, and so does a 120-second one. If your script reads at 62 seconds, cutting two seconds of silence or one sentence gives you the cheaper minute. The audio generation costs do not move with length: Music 1.0 is flat $0.125, and TTS bills by character.

Across 100 spots a month, the difference between 59 and 61 seconds is 100 x $0.10 = $10.00.

Set the length yourself

audio.duration_seconds is required and sets the output length (1 to 1,800). Set it to the real length of the spine, not a rounded-up guess. If you pad to the next whole minute for safety you pay for that minute anyway, so rounding up your estimate has no extra cost but also no benefit. The plan call returns billable_minutes before you commit.

If the spine is shorter than audio.duration_seconds, Timeline fails the request with audio_parts_shorter_than_duration when you use parts, so keep the two aligned.

A rule of thumb

Write to 58 seconds, not 60. Voice-over speed varies a little between takes, and a take that lands at 60.4 seconds will not trim itself. The 2-second margin protects the minute boundary. For longer pieces use the same margin, 3 to 5 seconds under the next whole minute.

If a client wants exactly 60 seconds, set audio.duration_seconds to 60 and trim the spine to match; the output length is what you set.