---
name: text-to-speech-known-limitations
title: Known issues
description: '[IBM Cloud Pak for Data] [IBM Software Hub]'
last-updated: 2025-02-05
---

> ## Documentation Index
> The table of contents for this documentation set is at https://cloud.ibm.com/docs/text-to-speech?format=markdown
> The index for all IBM Cloud docs is at: https://cloud.ibm.com/docs/llms.txt
> Use these files to discover more information as needed.

# Known issues
{: #known-limitations}

[IBM Cloud Pak for Data]{: tag-cp4d} [IBM Software Hub]{: tag-teal}

Known issues are listed by the release in which they were identified.

## 5.1.x releases
{: #51-release-issues}

[Limitations and known issues in Watson Speech services](https://www.ibm.com/docs/en/software-hub/5.1.x?topic=issues-watson-speech-services){: external}.

## 5.0.x releases
{: #50-release-issues}

[Limitations and known issues in Watson Speech services](https://www.ibm.com/docs/en/cloud-paks/cp-data/5.0.x?topic=issues-watson-speech-services){: external}.

## 4.8.x releases
{: #48-release-issues}

[Limitations and known issues in Watson Speech services](https://www.ibm.com/docs/en/cloud-paks/cp-data/4.8.x?topic=limitations-watson-speech-services){: external}.

## 4.7.x releases
{: #47-release-issues}

[Limitations and known issues in Watson Speech services](https://www.ibm.com/docs/en/cloud-paks/cp-data/4.7.x?topic=limitations-watson-speech-services){: external}.

## 4.6.x releases
{: #46-release-issues}

[Limitations and known issues in Watson Speech services](https://www.ibm.com/docs/en/cloud-paks/cp-data/4.6.x?topic=issues-watson-speech-services){: external}.

## 4.5.x releases
{: #45-release-issues}

[Limitations and known issues in Watson Speech services](https://www.ibm.com/docs/en/cloud-paks/cp-data/4.5.x?topic=issues-watson-speech-services){: external}.

The following known issues apply to service functionality that spans releases for all platforms. 

## Issue: The Ogg audio format is not supported with the Safari browser
{: #limitation-ogg-safari}

**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](https://cloud.ibm.com/docs/text-to-speech?topic=text-to-speech-audio-formats&format=markdown#formats-supported).
-   For more information about specifying a format, see [Specifying an audio format](https://cloud.ibm.com/docs/text-to-speech?topic=text-to-speech-audio-formats&format=markdown#formats-specify).

## Issue: Sampling rate for ogg format with opus codec is always 48 kHz
{: #limitation-opus-rate}

**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.