proud-battery-54912
12/27/2025, 8:45 AMtall-airline-16756
12/27/2025, 8:45 AMtall-airline-16756
12/27/2025, 8:45 AMverbalize_time as an LLM tool or inside the TTS layer, and how each affects latency. Quick answer up front:
• Use the TTS layer for minimal latency and deterministic current-time announcements.
• Use an LLM tool only if you need the model to reason about time (e.g., “three business days from now,” relative times, or context-aware phrasing).
Short rationale and implementation notes
• TTS-layer approach (recommended for most cases)
◦ How: Insert a placeholder (e.g., [TIME]) in the LLM output or detect time tokens just before synthesis, then replace with a formatted spoken string (like “The time is 2:35 PM”) or SSML.
◦ Latency: Low — no extra LLM round-trip. Only TTS synthesis time applies (fastest path for real-time agents).
◦ When to pick: Real-time clocks, periodic announcements, or deterministic phrasing.
• LLM-tool approach
◦ How: Expose verbalize_time as a callable tool/function the model can invoke to generate a natural-language time string, then feed that output to TTS.
◦ Latency: Higher — adds LLM inference time and tool-invocation processing (time-to-first-token + model reasoning). Use this when the model must decide to call the tool or compute relative/complex times.
◦ When to pick: Context-aware responses, complex temporal reasoning, or when phrasing must be dynamically composed by the model.
Practical suggestions
• If you choose TTS-layer: format timestamps centrally (single function) so phrasing/locale/SSML is consistent and easy to change.
• If you need some reasoning but want lower latency: let the LLM output a lightweight placeholder plus optional relative phrasing (e.g., “in two hours — [TIME]”), then have a small local helper convert relative times to absolute text before TTS.
• Test latency end-to-end (agent decision -> text -> TTS audio) in your environment to measure actual TTFT and TTS times.
If you want, tell me:
• whether you need relative/complex time reasoning or only current-time announcements, and
• your TTS provider (or if you plan to use SSML),
and I’ll provide a small example tailored to that setup.
Sources: Tool definition and use | LiveKit docs | Agent speech and audio | LiveKit docs | Cartesia TTS plugin guide | LiveKit docsproud-battery-54912
12/27/2025, 8:48 AMtall-airline-16756
12/27/2025, 8:49 AM[TIME] with a formatted string produced by a small, deterministic function.
◦ This can live in the TTS pipeline or a lightweight middleware right after RAG/LLM output.
1. Use explicit rules for common patterns (examples)
◦ Exact hour (10:00 AM) -> "सुबह दस बजे"
◦ Half hour (10:30 AM) -> "सुबह साढ़े दस बजे"
◦ Quarter past (10:15 AM) -> "सुबह सवा दस बजे"
◦ Quarter to (9:45 AM) -> "दस बजे से चौथे मिनट पहले" — but prefer "सवा चार" patterns for common usage (see below)
◦ Minutes 1–29 -> "X बजे Y मिनट" only when no idiomatic phrase exists
◦ Prefer idiomatic Hindi for halves/quarters and common colloquial forms:
▪︎ :15 -> "सवा [hour]" (e.g., 10:15 -> "सवा दस बजे" or "सवा दस")
▪︎ :30 -> "साढ़े [hour]" (e.g., 10:30 -> "साढ़े दस बजे")
▪︎ :45 -> "पौने [next_hour]" (e.g., 9:45 -> "पौने दस बजे")
◦ Use period-of-day prefixes: रात/सुबह/दोपहर/शाम based on hour ranges (e.g., 5–11 -> सुबह, 12–15 -> दोपहर, 16–19 -> शाम, 20–4 -> रात)
1. Example deterministic function (pseudo)
def verbalize_hindi(dt):
h = dt.hour % 12 or 12
m = dt.minute
period = choose_period(dt.hour) # returns 'सुबह','दोपहर','शाम','रात'
if m == 0:
return f"{period} {h} बजे"
if m == 30:
return f"{period} साढ़े {h} बजे"
if m == 15:
return f"{period} सवा {h} बजे"
if m == 45:
next_h = (h % 12) + 1
return f"{period} पौने {next_h} बजे"
return f"{period} {h} बजकर {m} मिनट" # fallback
(Adjust wording to your preferred register and remove "बजे" if Cartesia voices prefer shorter phrases.)
1. Cartesia-specific notes
• Cartesia supports SSML; use it to control prosody/pause around the time phrase for clearer speech.
• Send the fully formed Hindi string to Cartesia (avoid leaving time-formatting to the LLM).
• This keeps latency minimal: only your small formatting function + Cartesia TTS synthesis time.
1. Handling mixed cases
• If you need context-aware phrasing (e.g., “in two hours” or business-day logic), compute that programmatically and pass the resolved absolute time into the same deterministic formatter before TTS.
• If you must let the LLM craft the phrase, constrain it tightly with a function tool that returns the preformatted Hindi string (but expect higher latency).
If you want, I can:
• Provide a ready-to-copy implementation in your language (Python/Node) for Cartesia integration and SSML wrapping.
• Add locale rules for formal vs. colloquial Hindi phrasing.
Which would help you most: a full code example in Python or Node?