perf(cli): open the mic, camera and capture content concurrently when recording starts

[richiemcilroy]

cap record start set up its inputs one after another: camera, then mic, then the ScreenCaptureKit shareable content, then the actor. The mic name check also called MicrophoneFeed::list(), which opens and queries every input device for a usable config. That cost 200-680 ms before the mic was even opened.

flowchart LR
  subgraph before
    A1[camera open + lock] --> B1["MicrophoneFeed::list()<br/>(probes every device)"] --> C1[mic open + 100 ms warm-up + lock] --> D1[ShareableContent] --> E1[build actor]
  end
  subgraph after
    A2[ShareableContent] --> E2[build actor]
    B2["list_names() + mic open + warm-up + lock"] --> E2
    C2[camera open + lock] --> E2
  end

Loading

• apps/cli/src/record.rs: the shareable content fetch, open_mic_feed and open_camera_feed run under one tokio::try_join!. The actor builders get the same locks and the same ShareableContent as before.
• The mic name check uses MicrophoneFeed::list_names(), the same list cap targets mics prints. Opening the device still fails with the existing error if it can't be used.
• The 100 ms mic warm-up stays. Removing it moved Instant audio start relative to video.
• Stacked on perf(cli): skip the unused camera in macOS Instant recordings #2588 (the camera future keeps its macOS Instant skip).

Benchmark

Launch to "Recording started", real devices (built-in camera, MacBook Pro mic, system audio), median of 3, M4 Max:

Setup	main	This PR
Studio, mic + system audio	552 ms	292 ms (−47%)
Instant, mic + system audio	612 ms	313 ms (−49%)
Studio, camera + mic + system audio	1383 ms	841 ms (−39%)
Screen only	139 ms	141 ms

• Every stream is present in all A/B recordings, and per-track start times match main.
• The audio lead in Instant files is unchanged.

Confidence Score: 5/5

The PR appears safe to merge; no actionable issues were found.

Summary

Prepares capture content, microphone, and camera together when recording starts.

• Recording starts sooner when its inputs prepare together.

_{Reviews (2) · Last reviewed commit: "perf(cli): open the mic, camera and capt..." · Reviewed by Greptile}

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Project	Deployment	Actions	Updated
cap-status	Ready	Preview	Oct 20, 2026 12:16pm UTC

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