A Webcam and a Screen Recording Drift Out of Sync

A 15 fps webcam with audio and a 5 fps screen recording will not stay in sync just because you pick a common frame rate. Each device recorded on its own clock. HandBrake can make both files a constant 30 fps and the voices will still wander away from the screen. The 10 fps gap is not the cause.

Sync them at one moment

You need one shared event. A clap on camera, or a click that the screen recording’s audio also heard, gives you a point to line up. Put both clips in a timeline, match that point, and listen. Premiere can sync by waveform if both files have audio of the same room. Merging the webcam audio onto the screen file with a muxer does not fix a drift that grows over time. It only moves the already-drifting audio into a new container.

When they pull apart

Unsynced clocks drift. A sync that is right at the start and late ten minutes later is normal for a webcam and a separate screen capture. Cut the audio at the point you can hear it slip, and slip that next piece back into place. Do this as often as the drift becomes audible. There is no frame-rate number that does this for you.

Next time, record the screen and the camera on one device, or clap at the start and the end so you can see how large the drift is before you start cutting. A constant frame rate is still worth making, so the edit plays evenly. It is a picture fix, not a sync fix.