> ## Documentation Index > Fetch the complete documentation index at: https://docs.slng.ai/llms.txt > Use this file to discover all available pages before exploring further. # Parameters coverage > Compatibility matrix for the SLNG Unified API. Which TTS and STT request parameters are supported by Deepgram, ElevenLabs, Cartesia, Sarvam, and Rime. The SLNG Unified API accepts a common set of parameters across all providers. Some parameters are universal, others depend on the model. Provider-specific values (like voice identifiers or language codes) are passed through the same fields. The platform forwards them to the underlying provider. ## TTS parameters | Parameter | Type | Required | Description | | -------------------- | ------- | -------- | ------------------------------------------------------------------ | | `text` | string | Yes | Text to synthesize | | `voice` | string | No | Voice identifier. Accepted values depend on the provider and model | | `config.sample_rate` | integer | No | Output sample rate in Hz | | `config.encoding` | string | No | Output encoding format | | `config.language` | string | No | Language code. Accepted values depend on the provider | | `config.speed` | number | No | Speech speed multiplier | ### TTS provider support The matrix below covers the most commonly used SLNG-hosted models. Providers not listed here (Cartesia Sonic 3, Murf Falcon, Kugel, Soniox TTS v1) accept the same `text` and `voice` fields. Check each model's [API reference](/api-reference) for the exact list of supported `config.*` fields. | Parameter | Rime Arcana | Deepgram Aura 2 | Sarvam Bulbul | | -------------------- | ----------- | --------------- | ------------- | | `voice` | Yes | Yes | Yes | | `config.sample_rate` | Yes | Yes | Yes | | `config.encoding` | Yes | Yes | Yes | | `config.language` | Yes | Yes | Yes | | `config.speed` | — | Yes | — | ### Provider-specific values The `voice` and `config.language` fields accept provider-specific values. For example: * **Rime Arcana** voices: `luna`, `orion`, `astra`, `nova` * **Deepgram Aura 2** voices: `aura-2-thalia-en`, `aura-2-asteria-en`, `aura-2-celeste-es` (set the `voice` field explicitly) * **Rime Arcana** language codes: `en`, `fr`, `es`, `hi`, `ar`, `de` * **Cartesia Sonic 3**, **Murf Falcon**, **Kugel**, **Soniox TTS v1**: see the [voice catalog](/voices) for each provider's `voice_id` values The platform passes these values directly to the provider. If you send a voice identifier that the selected model does not support, the provider returns an error through the standard error response format. ### Supported sample rates and encodings Sample-rate and encoding support varies by model and protocol. The Unified API uses a common request shape, but the selected model still controls which audio formats are valid. | Model or endpoint family | Common sample rates | Encoding support | Notes | | ---------------------------- | ---------------------------------- | ------------------------------------------ | ------------------------------------------------------------------------------------- | | Unified TTS bridge | `8000`-`48000` Hz, model-dependent | `linear16`, `mp3`, `opus`, `mulaw`, `alaw` | Accepted by the bridge schema; the selected model may still reject unsupported values | | Deepgram Aura 2, proxied | See endpoint reference | `linear16`, `mp3`, `opus` | Use the direct Aura 2 reference for provider-specific behavior | | Deepgram Aura 2, SLNG-hosted | See endpoint reference | `linear16`, `mulaw`, `alaw` | Optimized for real-time and telephony-style output | | Sarvam Bulbul | See endpoint reference | `mp3`, `linear16`, `mulaw`, `alaw`, `opus` | Indian-language TTS provider | | Cartesia Sonic 3 | See endpoint reference | `linear16`, `mulaw`, `alaw` | Streaming TTS over WebSocket | For exact allowed values, use the model-specific API reference page as the source of truth. ## STT parameters | Parameter | Type | Required | Description | | ----------------- | ------- | -------- | ----------------------------------------------------- | | `audio` | file | Yes | Audio file to transcribe | | `language` | string | No | Language code. Accepted values depend on the provider | | `sample_rate` | integer | No | Audio sample rate in Hz | | `encoding` | string | No | Audio encoding format | | `enable_vad` | boolean | No | Enable voice activity detection | | `enable_partials` | boolean | No | Enable partial transcription results | ### STT provider support | Parameter | Deepgram Nova 3 | Deepgram Nova 2 | Soniox Speech AI v4 | | ----------------- | --------------- | --------------- | ------------------- | | `language` | Yes | Yes | Auto-detect | | `sample_rate` | Yes | Yes | Yes | | `encoding` | Yes | Yes | Yes | | `enable_vad` | Yes | Yes | Yes | | `enable_partials` | Yes | Yes | Yes | ### Supported STT encodings `linear16`, `mp3`, `opus`. ## How provider-specific parameters work The Unified API uses a schema-driven approach. All parameters are defined in the request schema. There is no generic passthrough or arbitrary key-value mechanism. The `voice`, `language`, and `config` fields accept provider-specific values as strings, and the platform forwards them to the underlying provider without transformation. This means: * You use the same field names regardless of provider * Provider-specific values (voice names, language codes) go into the same fields * Validation happens at the provider level. If a value is not supported, you get a standard error response with the provider's error message ## Model identifiers Models follow the pattern `provider/model:variant` for third-party and `slng/provider/model:variant` for SLNG-hosted. For example: * `deepgram/aura:2`: third-party, proxied to Deepgram * `slng/deepgram/aura:2-en`: SLNG-hosted Deepgram Aura 2 (English) * `slng/rime/arcana:3-en`: SLNG-hosted Rime Arcana v3 (English) For the full list of model identifiers, see [Supported models](/execution-layer/unified-api-models).