Why game sound and picture drift apart on stream, and how to fix it
You watch your stream back and the shot lands before the muzzle flash, or after it. It's subtle, but viewers notice. Here's where drift comes from and how to fix it for good.
Where drift comes from
Sound and picture leave your phone together, but they don't travel the same road. The picture is compressed, sent and decoded; the sound is captured, sent and buffered so it plays without gaps. Each step takes a little time, and the two roads rarely take exactly the same time.
So on the PC, one of them arrives a bit later. Usually it's the sound.
How to check yours
- Record 30 seconds in OBS with something that makes a sharp sound: single shots, a door, a jump.
- Play it back frame by frame.
- Does the sound start with the flash or movement? A frame or so either way is fine. More than that, and it's worth adjusting.
How to fix it with Casttit
Casttit's Sync slider holds the picture back just enough for the sound to catch up. Because it acts on the picture in Casttit's own window, it fixes your OBS source too: one change, everything in step.
- Casttit suggests a value for your kind of phone, measured with real games. Start there.
- If your recording still shows drift, move the slider a little and record again.
- Each kind of phone keeps its own value, so switching between Android and iPhone doesn't undo your work.
The details: Sound and sync.
Sync on stream vs what you hear
Sync lines up your stream. What you hear in your own headset while you play is a separate thing: it's the sound's trip from the phone to your ears. Two tips keep it short:
- Play with wired headphones. Bluetooth adds a long delay of its own, and no app can take it away.
- Use a cable for the phone. It's steadier than Wi-Fi. USB or Wi-Fi?
In OBS
Keep the game's picture and sound in one source (the Casttit Preview Window Capture with Capture Audio on), so they move together. Use OBS's Sync Offset in Advanced Audio Properties only for your mic or camera, if they're out of step with the game.
Questions
Should I fix sync in Casttit or in OBS?
In Casttit, with its Sync slider: it lines up the picture in Casttit's window and in OBS together. Use OBS's Sync Offset only for other sources, like your mic or camera.
Why does it feel late in my headset but look fine on stream?
Those are different things. Sync lines up your stream. What you hear in your headset has its own small delay; Bluetooth headphones make it much longer, so play with wired ones.
How do I check my sync?
Record a short clip in OBS with a sharp sound in it, like a single shot or a door, and step through it frame by frame: the sound should start with the flash or the movement.