Kling Mux POC — iOS Safari Verification

Tests Architecture B: real Kling 1440×1440 H.264 → 810×1440 9:16 crop → canvas.captureStream(24) → MediaRecorder MP4 with Web Audio tone. Deployed for Check 2 of comments-song Feature 5 spec.

1. Capability detection

2. Live preview

Source
1440×1440 24fps
(real Kling output)

Cropped 810×1440
(production transform)

Tap "Start preview" to see live crop output.

3. Recording

Idle. Tap "Start preview" first (required for iOS — must be user-gesture).

4. Result analysis

No recording yet.

5. Test report (fill in after recording)

A. Source video plays in <video> (no codec rejection) B. Cropped canvas preview shows correct centered 9:16 crop C. Recording started without error D. Downloaded file plays back in iOS Photos / Files / Safari E. Downloaded video frame rate looks smooth (no visible stuttering) F. Downloaded file has audible 440Hz tone (audio track present + synced) G. Recorded file is < 30MB (sanity bound on bitrate)

Free-form notes (failure modes, error messages, anything weird):