How to film a cover song video with both iPhone cameras

One microphone, so the balance is set live, not fixed later

DualCam records a single AAC track at 44.1 kHz, mono, from whatever iOS has set as the default audio input, alongside the composited video in one MP4. If a backing track is playing out loud in the room while you sing, your voice and the track land in that one track together, mixed at whatever ratio the room actually produces — there is no per-source volume to pull apart afterward, the same way there is no separate audio for the front camera and the back camera.

Distance still does more than anything else you could try. If your voice is getting buried under the backing track, the fix is moving the phone closer to you, not turning the speaker down — halving the distance to a source roughly doubles how much of it reaches the microphone, and that holds for a voice the same way it holds for a spoken sentence.

Decide how the backing track reaches the recording

Play it out loud

The simplest option: a speaker in the room, the phone recording as normal. Your voice and the instrumental land in the same track at the balance the room gives you, in one take, with nothing to assemble afterward. This is the right call when you are happy treating that live balance as the final mix, the way most cover performances actually get filmed.

Record silent and add the track afterward

DualCam’s mute switch removes the audio track from the file entirely rather than just lowering it, and because the track is created the moment recording starts, mute has to be set before you press record. Miming to a song you know well and adding the real track in an editor afterward gives you full control over the mix, at the cost of doing the sync yourself — DualCam has no idea what track you plan to add, so how closely your mimed performance matches the words you add later is entirely on you, the same as dubbing any other video.

Keep the track off the phone’s microphone with an earbud

Playing the backing track through a single earbud while singing into the phone’s own microphone gets you a private reference without it bleeding into the recording — but only if the phone is actually still using its own microphone. Connecting a Bluetooth earbud can switch iOS’s default audio input to it as well as its output, and if that happens, the recording captures through the earbud instead of the phone, with the latency and tone tradeoffs covered in the guide on using AirPods for dual-camera recording. Check Control Center before you record and confirm the phone’s built-in microphone, not the earbud, is the selected input.

Framing: your voice is the payoff, your hands are optional

A solo vocal with nothing else to show needs very little from the frame — picture-in-picture with your face filling the main view and nothing of substance in the small window still gets the job done, since there is no second subject competing for attention. A duet works better as a top-and-bottom or left-and-right split, giving both singers equal space rather than forcing one into a small inset that reads as secondary.

Singing while playing an instrument is a different framing problem, and it is the one covered in DualCam’s guide to filming a guitar practice video: point the back camera at your hands close enough that the technique is actually readable, and let the front camera carry your face in the inset, deciding in advance whether the take is really about the performance or the technique, because a wide shot that fits both rarely gives either one enough detail.

A held note punishes a reflective room harder than a sentence does

Echo comes from the room, not from recording two cameras at once, but a sung note is more exposed to it than ordinary speech: a held tone gives the room’s reflections a full beat to arrive and blur into the direct sound, where a short spoken sentence is often over before the reflection catches up. A tiled bathroom or an empty bedroom with bare walls will make a sustained note sound distant or metallic in a way it will not make a quick line of dialogue sound; a furnished room with soft, irregular surfaces absorbs far more of that reflection. The full breakdown of what causes it and what to change about the room is in DualCam’s guide to reducing echo.

A loud chorus and a quiet verse also land in the same track with no automatic leveling between them, since there is only the one microphone reading whatever level the room and the distance actually produce. If the whole recording turns out quieter than you would like, boosting the overall level afterward in an editor works the same way it does for any other quiet dual-camera recording — but it raises your voice and the backing track by the same amount, so it fixes a track that is too quiet, not a balance that is off between the two.