ssml-split

SSML Split

Splits SSML strings into batches AWS Polly ánd Google's Text to Speech API can consume.

Based on polly-ssml-split by @oleglegun

Changes in this package:

Added includeSSMLTagsInCounter: boolean option to count characters based on the complete SSML tag and not just the included text characters.

For example: <speak><p>some text</p></speak>

The default behaviour would count that as 9 characters, which is fine for AWS Polly, but not for Google's Text to Speech API.

With includeSSMLTagsInCounter: true it will be count as 31 characters, just like Google's Text to Speech API counts it.

Example:

const ssmlSplit = require('ssml-split')

const options = {
  softLimit: 4000, // Allow the splitter to find the correct split moment between 4000-5000 characters
  hardLimit: 5000, // Google Text to Speech limitation
  includeSSMLTagsInCounter: true // Set true when using Google Text to Speech API, set to false with AWS Polly
}

ssmlSplit.configure(options)

const batches = ssmlSplit.split('<speak>your long text here</speak>')

For other documentation, please check the original repo: https://github.com/oleglegun/polly-ssml-split

Why?

AWS Polly just counts the characters between the SSML tags. Google's Text to Speech is a little bit different, it includes the SSML tag characters in the character count of the 5000 character limit.

The polly-ssml-split library already handles splitting of SSML correctly for AWS Polly, but wasn't working properly for Google's Text to Speech.

By adding the option includeSSMLTags to include the SSML tag characters in the calculation on when to split the SSML, makes the library also work with Google's Text to Speech API.

This package should prevent you from seeing this error when using Google's Text to Speech API: INVALID_ARGUMENT: 5000 characters limit exceeded.

Source

https://cloud.google.com/text-to-speech/pricing?hl=en

Note that Speech Synthesis Markup Language (SSML) tags are included in the character count for billing purposes. For example, this input counts as 79 characters, including the SSML tags, newlines, and spaces:

<speak>
 <say-as interpret-as="cardinal">12345</say-as> and one more
</speak>