6 min read
Camera audio or external recorder: what you actually gain from dual system sound
Cameras record sound. Recorders record usable sound. The gap is mostly preamps, tracks and metadata.
Every camera has audio inputs, so the question is not whether you can record into the camera. It is whether the result survives an edit, a mix and a delivery spec.
What a recorder gives you
- Better preamps with real headroom and lower noise, which matters most on quiet dialogue.
- More inputs: boom plus several radio mics on discrete tracks instead of a summed stereo pair.
- Timecode generation and jam sync.
- Production metadata: scene, take, notes and per track names written into the file.
- 32 bit float on modern units, which removes the risk of a clipped shout.
When camera audio is genuinely fine
One person on a lav, short pieces to camera, run and gun documentary with no second operator, or any situation where losing sync would cost more than the quality gain. A good external mic into a decent hybrid camera is far better than a badly managed dual system rig.
The hybrid approach everyone should use
Record properly to the recorder and also feed a mix into the camera. The camera track becomes a scratch reference: it makes syncing trivial and it saves the day when a card fails. Extract that scratch track from the video file when you need to line things up in the edit.
What post receives
A recorder hands over poly WAVs with named channels, ready to split into boom and lav stems. A camera hands over an MP4 or MOV with AAC stereo. One of those becomes a dialogue edit, the other becomes a reference.
Both flows are supported here: split the recorder poly file into named mono stems, and extract the camera audio to WAV for syncing, all locally in the browser.
The cost of getting it wrong
Summed audio cannot be unsummed. If boom and lav were mixed into a stereo camera track, the editor cannot choose between them. That single limitation is the strongest argument for recording discrete tracks, whatever device you use.