Fix one wrong sentence in a voice-over: 130 characters, not 3,000

To fix one wrong sentence of 130 characters in a voice-over, regenerate only that sentence and rejoin: $0.006175 for the speech (0.13 x $0.0475) plus $0.01 for a Timeline audio concat, $0.016175 in all. Re-synthesizing the whole 3,000-character script costs $0.1425, nearly nine times as much. The saving is real only if you kept the voice-over as separate takes, so plan that before the first run.

Keep takes, not one file

Split the script by sentence or by paragraph and send each as its own TTS job with the same preset: voice selector, speed, volume, language and format. Store the audio URLs in order. A correction replaces one URL in that list, and one Timeline audio concat job, up to 20 parts, builds the new master. If the script has more than 20 parts, join in two stages.

The seam

Rejoining can leave a short pause or a change in tone at the cut. Use the same preset to keep the voice, and use WAV for the takes so the join adds no padding. If you need exact sentence times, the TTS timestamps option with sentence segmentation gives them; the docs note the boundary_lead_ms default of 70 ms and that emit_audio needs wav or raw.

When to redo it all

A change that affects pacing across the piece, such as switching voice or speed, means all takes must be regenerated, and that is the 3,000-character cost. A fix to a name or a number is the cheap case. The video render also repeats if the voice-over changes under finished video: $0.10 per output minute, rounded up.

A routine for corrections

Number the takes in the order of the script and keep a table of take number, text, audio URL and job id. When the client changes a line, edit its row, send one TTS job, and replace the URL. Rebuild the master with a concat job, check the seam by ear, and rerender the video. Ten corrections at the sentence level cost 10 x $0.016175 = $0.16175, about the cost of one full re-synthesis, but without disturbing the other takes.

If a correction touches the same sentence twice, you pay for it twice, so confirm the text before you send it.