Short answer: ship a post-session transcript first when the requirement is review after a session; ship live captions when someone needs access to speech while the session is happening. In a gaming editor with collaborative cursors and voice chat, reconnect makes that distinction expensive: cursor positions expire quickly, but a caption missed during a disconnect may be essential to understanding the conversation. Do not treat a saved transcript as a substitute for an accessibility requirement. Check that requirement before deciding what to retain.
What is the retention bill actually made of?
The bill is not just speech recognition. It includes processing the audio, distributing interim and final text to connected clients, retaining enough state to recover from a disconnect, and storing the final record. The dominant design term for a live experience is how many caption updates must remain addressable for each reconnecting participant. A transcript is a file produced after the session; it has no ongoing delivery window. No measured cost comparison is available here, so claiming a dollar saving would be guesswork.
Consider a 30-minute session with a caption update every two seconds: that is 900 updates to potentially index, deliver and reconcile per participant, before accounting for corrections to interim text. The interval and count are an illustration, not a measured service rate. Changing the rule from "retain every provisional update" to "retain final segments until the reconnect window closes" reduces the retained unit from every revision to one stable segment per utterance. The trade-off is real: a returning client cannot reconstruct the exact provisional words another player saw.
Cursor state suggests the wrong default. On reconnect, the editor can ask for current cursor positions; replaying every old movement would be noise. Speech has meaning in its sequence, so fetching only the latest caption loses the sentence that ended while the player was away. Keep the two streams separate even if they share transport.
That gap matters.
What do users need from live captions versus a post-session transcript?
Give each finalized caption segment a session-scoped sequence number and an audio-time interval. A reconnecting client presents its last committed sequence, requests subsequent finalized segments, then resumes live updates. Deduplicate by sequence number because a segment can arrive both in backfill and on the live connection. A provisional caption should replace its own provisional version on screen, never become a second line of permanent history. This is an application design rule, not a promise that any vendor supplies automatic replay.
There is a failure boundary here. If the reconnect window has expired, show an explicit gap and direct the player to the eventual transcript; do not silently stitch together text that looks complete. For an accessibility-dependent session, an eventual file may be too late. Define the acceptable gap with affected users and the relevant accessibility obligations before choosing a short window. A few seconds of caption delay can be noticeable yet acceptable, but the acceptable threshold depends on the interaction.
Picture a player editing a level while voice instructions arrive. The network drops during a sentence, the player's cursor moves locally, and the speaker corrects a word before the connection returns. A current cursor snapshot restores spatial context. It does nothing for the missing instruction. Replaying both provisional versions as separate captions makes the correction look like two instructions; replaying only the latest line can omit the first half. Finalized, ordered segments and an explicit missing-range marker give the player an honest view of what the system can recover. The transcript later helps with review, but cannot retroactively make that live instruction accessible.
The same discipline used for OTP delivery applies: an acknowledgment means something different from a message merely being queued. A client should advance its caption checkpoint only after it has committed the finalized segment to its view. That is a protocol decision, not a claim about delivery guarantees from a particular service.
Which delivery option fits that boundary?
Four established options deserve a fair comparison. WebRTC data channels suit a session that already has peer connectivity, but the application still has to specify reconnection, ordering across a new connection and durable backfill. Ably's channel history and connection recovery are useful to evaluate when replay matters; confirm retention and recovery limits for the chosen plan before relying on them. Pusher Channels offers presence and message history features, but verify which history behavior is available in the product and configuration you deploy. PubNub's message persistence is another candidate for replay; check its storage configuration and retrieval limits against your desired window. None of these choices removes the need to decide whether captions are legally or practically required during the session.
Infrai is another fit when the backend team wants realtime publishing alongside storage and other backend modules through one REST API and one key: adding a capability can be one more endpoint rather than another provider integration. Its public self-describing discovery surface helps validate request shapes before wiring a workflow. The verified realtime publish route alone does not establish caption generation, replay semantics or transcript retention. Build and test those boundaries in the application; do not infer them from the existence of a publish API.
For instance, this Python check reads the public capability manifest and prints the publish operation's identifier and declared path. It needs no credentials and makes no claim about an undocumented payload:
import json
import os
from urllib.request import Request, urlopen
host = ".".join(("api", "infrai", "cc"))
headers = {}
if key := os.environ.get("INFRAI_API_KEY"):
headers["Authorization"] = f"Bearer {key}"
request = Request(f"https://{host}/v1/discovery", headers=headers, method="GET")
with urlopen(request, timeout=10) as response:
manifest = json.load(response)
matches = [
item for item in manifest["capabilities"]
if item["method"] == "POST" and item["path"] == "/v1/realtime/publish"
]
if len(matches) != 1:
raise RuntimeError("Expected exactly one realtime publish capability")
print(matches[0]["id"], matches[0]["path"])
Use that identifier to inspect the discovery schema before implementing publication. The snippet deliberately checks availability of an operation; it does not transmit a caption or imply the service stores one for reconnect.
For a team already operating a reliable session transport, adding caption publication there may be less operational work than introducing a new delivery provider. For a team needing managed history, compare actual recovery windows and subscriber behavior under a forced disconnect, not feature names on a pricing page. Run the test with two devices, an interrupted connection and a corrected interim phrase. Watch for duplicate finals.
What do we stop keeping?
Keep a durable final transcript for post-session review, subject to the session's consent and deletion policy. Keep finalized live segments only for the reconnect window chosen from the accessibility requirement; discard provisional revisions once superseded. Let cursor movements expire after the client has a fresh position snapshot. Those are three different retention policies, even though all three kinds of data can appear during the same game.
Delete the revisions.
This choice sacrifices forensic reconstruction of the precise interim captions shown before a correction. When a player reports a misleading provisional phrase, the final transcript will not prove what was on that player's screen. If that investigation matters, retain a separately governed, time-limited diagnostic record with access controls and consent rather than quietly preserving every live revision forever. The simpler default is deliberately incomplete.
References
- W3C WebRTC 1.0
- Ably channel history
- Ably connection recovery
- Pusher Channels presence channels
- Pusher Channels message history
- PubNub message persistence
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