Amazon Polly vs Resemble AI Text-to-Speech API

Amazon Polly

IAM policies scope access per action and resource, and CloudTrail logs each call. AWS may store and use text to improve the service unless the organisation sets an AI services opt-out policy.

Resemble AI Text-to-Speech API

OpenAPI file in JSON and YAML, llms.txt and Markdown pages. Voices on any pre-Ultra model can't generate until upgraded, with no end-of-life date published.

Amazon Polly

1. Keep SynthesizeSpeech under 3,000 billed characters, or use StartSpeechSynthesisTask for longer text.
2. Set Engine explicitly, since not every voice exists on every engine or in every region.
3. Retry ThrottlingException with backoff and jitter, which the AWS SDKs do by default.
4. Check the generative SSML tag list before porting neural SSML.
5. Ask for OutputFormat json with speech marks when you need word timings.

Resemble AI Text-to-Speech API

1. Check the voice's model before synthesis, since voices on pre-Ultra models fail until upgraded.
2. Keep each synchronous request under 2,000 characters.
3. Decode audio_content from base64 on /synthesize, or call /stream for raw WAV chunks.
4. Send Authorization: Bearer, since some doc examples leave out the prefix.
5. Log the request ID with every failure, since the error body has no code.