Known limitations

The Text to Speech service has the following known limitations. These issues apply to service functionality that spans releases on all platforms. For information about known limitations specific to Text to Speech for IBM Cloud Pak for Data version 4.6.x, see Limitations and known issues in Watson Speech services.

Issue: The Ogg audio format is not supported with the Safari browser

9 September 2022: By default, the service returns audio in the Ogg audio format with the Opus codec (audio/ogg;codecs=opus). However, the Ogg audio format is not supported with the Safari browser. If you are using the Text to Speech service with the Safari browser, you must specify a different format in which you want the service to return the audio.

For more information about the available formats, see Supported audio formats.
For more information about specifying a format, see Specifying an audio format.

Issue: Sampling rate for ogg format with opus codec is always 48 kHz

22 August 2019: When you specify the audio/ogg;codecs=opus audio format, you can optionally specify a sampling rate other than the default 48,000 Hz. However, although the service accepts 48000, 24000, 16000, 12000, or 8000 as a valid sampling rate, it currently disregards a specified value and always returns the audio with a sampling rate of 48 kHz.