livekit-plugins-tts-cache-router

LiveKit Agents plugin for tts-cache-router: Sarvam, Raya and ElevenLabs text-to-speech, with every sentence your agent has said before served from a per-account cache.

Same output whether you call the provider directly or through the router: each sentence reaches the provider verbatim with your exact settings, and a cache hit replays a real provider take for that exact request.

Full documentation: docs.ttscacherouter.dev/livekit.

Install

pip install livekit-plugins-tts-cache-router

Usage

from livekit.plugins import tts_cache_router

tts = tts_cache_router.TTS(
    provider=tts_cache_router.Sarvam(model="bulbul:v3", speaker="shubh", language="hi-IN"),
)
# or
tts = tts_cache_router.TTS(
    provider=tts_cache_router.Raya(
        model="standard", voice_id="d6a002d0-230c-49b1-a137-b8a7d564b1ae", language="hi"
    ),
)
# or
tts = tts_cache_router.TTS(
    provider=tts_cache_router.ElevenLabs(voice_id="JBFqnCBsd6RMkjVDRZzb", model="eleven_flash_v2_5"),
)

session = AgentSession(tts=tts, ...)

Before the first request, store your Sarvam, Raya or ElevenLabs API key in the dashboard at ttscacherouter.dev. The router keeps it encrypted and uses it only to call that provider for your requests.

Set TTS_CACHE_ROUTER_API_KEY to your router API key, from the same dashboard (or pass api_key=).

TTS(...)

How long cached audio is kept is your org's retention setting, in the dashboard.

Sarvam(...)

model ("bulbul:v3" or "bulbul:v4-flash"), speaker, language (e.g. "hi-IN"), pace (0.5–2.0, default 1.0), temperature (0.01–1.0, default 0.6), dict_id, and for bulbul:v4-flash only: pitch (-0.5–0.5), loudness (0.1–2.5), enable_preprocessing; min_buffer_size (30–200) and max_chunk_length (50–500; by default each sentence is synthesized whole).

Raya(...)

model ("standard" or "m1"), voice_id, language (e.g. "hi"), speed (0.5–1.5, default 1.0).

ElevenLabs(...)

The settings of ElevenLabs' own LiveKit plugin: voice_id, model (default "eleven_turbo_v2_5"; eleven_v3 and eleven_v4 models go through ElevenLabs' text-to-dialogue API), language (optional; "en-US" or "english" is sent as "en", as ElevenLabs' plugin sends it), voice_settings (VoiceSettings(stability, similarity_boost, style=None, speed=None, use_speaker_boost=None); the voice's stored settings when omitted), apply_text_normalization ("auto", "on" or "off"), apply_language_text_normalization, enable_ssml_parsing, enable_logging, pronunciation_dictionary_locators (PronunciationDictionaryLocator(pronunciation_dictionary_id, version_id), up to 3), sync_alignment (default True: word-level timed transcripts) and preferred_alignment ("normalized" or "original").

Changing settings mid-session

tts.update_options(speaker="priya", pace=1.1)  # the current provider's settings, by name
tts.update_options(provider=tts_cache_router.Raya(...))  # or another provider

Replies that start afterwards use the new settings.

Interruptions

When the agent is interrupted, the plugin cancels the router segment and keeps the connection open, so the next reply starts on a warm connection.

Metrics

TTSMetrics.characters_count counts only characters the provider synthesized (and billed) for the request; sentences served from the cache count zero. provider and model report the underlying provider, so usage dashboards attribute cost correctly.