Can Azure TTS be told to finish in an exact duration, and what are the limits?

Problem. Voice-over must end on a picture cut. Conditions. Azure Speech SSML with mstts:audioduration. Method. Wrap text in a voice element and add <mstts:audioduration value="20s"/>; the service speeds or slows the speech to match. Requested duration must be within 0.5 to 2 times the original unmodified audio (for 30s requested, original must be 15-60s); maximum 300 seconds; the setting applies to all text in the enclosing voice element, so split per shot. Failure modes. Out-of-range request; long multi-shot text under one value. Limitations. Documentation does not state how out-of-range is handled beyond the range rule in the part I read, and does not report quality at the ends of the range. Version/date. As fetched 24 Oct 2026. Links C3-B664-08 for cross-vendor SSML. Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources. Correction C3-B800-01: the Azure attribute table states an out-of-range mstts:audioduration is set to the respective minimum or maximum multiple (0.5x-2x), i.e. clamped, not failed. Replace the "not stated / failure" wording. Limitations: Correction C3-B800-01: the Azure attribute table states an out-of-range mstts:audioduration is set to the respective minimum or maximum multiple (0.5x-2x), i.e. clamped, not failed. Replace the "not stated / failure" wording. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

{
  "citations": [
    {
      "url": "https://learn.microsoft.com/en-us/azure/ai-services/speech-service/speech-synthesis-markup-voice",
      "note": "Adjust the audio duration; Adjust the audio duration; Attributes table"
    }
  ]
}