obul-x402engine-audio

x402engine Audio

x402engine provides pay-per-call text-to-speech and audio transcription endpoints. Convert text to speech using OpenAI or ElevenLabs voices, or transcribe audio files to text with speaker diarization. No API key needed — payment is handled automatically via obulx.

Authentication

All requests use the obulx CLI, which handles x402 payment automatically.

Common Operations

Text-to-Speech (OpenAI)

Generate speech audio from text using OpenAI's TTS models.

Pricing: $0.01

Request:

obulx -X POST -H "Content-Type: application/json" \
  -d '{"text": "Hello, this is a test of text-to-speech generation.", "voice": "alloy"}' \
  "https://x402engine.app/api/tts/openai" \
  -o output.mp3

Voices: alloy, echo, fable, onyx, nova, shimmer

Response: Returns audio data (MP3 or other format). Save to a file with -o filename.mp3.

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Text-to-Speech (ElevenLabs)

Generate ultra-realistic speech using ElevenLabs voices.

Pricing: $0.02

Request:

obulx -X POST -H "Content-Type: application/json" \
  -d '{"text": "Welcome to the future of AI-generated speech.", "voice": "rachel"}' \
  "https://x402engine.app/api/tts/elevenlabs" \
  -o output.mp3

Response: Returns ultra-realistic audio data. ElevenLabs voices are more natural and expressive than OpenAI, but cost 2x more.

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Audio Transcription (Deepgram Nova-3)

Transcribe audio files to text with speaker diarization.

Pricing: $0.10

Request:

obulx -X POST -H "Content-Type: multipart/form-data" \
  -F "[email protected]" \
  "https://x402engine.app/api/transcribe"

Response: JSON with transcribed text, speaker diarization labels, and timestamps.

Endpoint Pricing Reference

Endpoint	Price	Purpose
POST /api/tts/openai	$0.01	Text-to-speech with OpenAI voices
POST /api/tts/elevenlabs	$0.02	Text-to-speech with ElevenLabs voices
POST /api/transcribe	$0.10	Audio transcription with Deepgram

When to Use

• Text-to-speech — User wants to convert text to speech or generate audio from text
• Audio transcription — User wants to transcribe an audio file to text
• TTS specifically — User asks for TTS, text-to-speech, or voice generation
• Transcription — User asks for speech-to-text, transcription, or audio-to-text
• ElevenLabs/OpenAI — User mentions ElevenLabs, OpenAI TTS, or Deepgram

Best Practices

• OpenAI TTS — $0.01, reliable, 6 voices, HD quality, good for most use cases
• ElevenLabs TTS — $0.02, ultra-realistic, multilingual, best voice quality
• Transcription — $0.10 includes speaker diarization with labels and timestamps
• Save TTS output — TTS endpoints return audio binary; always use -o filename.mp3 to save output
• Multipart for transcription — For transcription, send the audio file as multipart form data

Error Handling

Error	Cause	Solution
402 Payment Required	Payment not processed or insufficient	Verify your obulx setup is correct and your account has sufficient balance at my.obul.ai.
400 Bad Request	Missing or invalid request body	Ensure text is present for TTS or file is provided for transcription.
415 Unsupported Media	Invalid audio format for transcription	Ensure the audio file is in a supported format.
429 Too Many Requests	Rate limit exceeded	Add a short delay between requests.
500 Internal Server Error	x402engine service issue	Wait a few seconds and retry. If persistent, the service may be experiencing downtime.