QUICK START CHECK (ALWAYS FIRST)
Camera (O4T9)
- Audio Device: Enable = ON
- Audio IN Device = MIC (built-in) or correct external source
- Input Volume (Gain) = 40–70 (start mid, adjust)
- Audio IN Encode = G711A
- Environmental Noise Filter = OFF (start clean)
Recorder (NRX / N32)
- Channel Audio = Enabled
- Live View: select correct audio channel
- Playback: use audio-enabled stream
- Monitor/HDMI audio not muted
FIELD-BY-FIELD (FROM SCREEN) + WHAT TO CHANGE
- Enable ® Must be ON. If OFF = no audio anywhere
- Audio IN Device ® MIC for passive mics; LINE for powered/amp. Mismatch = quiet or distortion.
- Input Volume ® Primary clarity control. Too low = faint; too high = clipping.
- Speaker (built-in) ® Affects talkback/feedback loops, not recording quality.
- LOUT (external) ® External speaker/talkback path.
- Audio Out Volume ® Playback loudness only.
- Audio IN Encode ® Use G711A for stability/clarity.
- Environmental Noise Filter ® ON reduces noise but can thin voice; OFF for evidence-quality.
SYMPTOM ⇒ WHAT TO CHANGE (CAMERA / NVR):
| Symptom | Likely Cause | Change (Camera / NVR) |
| No audio | Disabled or wrong input | Enable audio; set MIC/LINE correctly; enable channel |
| Too quiet | Low gain / wrong input | Increase Input Volume; ensure MIC for passive mic |
| Distorted | High gain / line into mic | Lower Input Volume; switch to LINE if powered source |
| Choppy (remote) | Network loss/jitter | Check PoE switch/cabling; reduce hops; test local vs remote |
| Echo/feedback | Speaker loop | Lower Audio Out; separate mic/speaker; adjust placement |
CAMERA vs RECORDER — WHERE TO ADJUST
|
Feature |
O4T9 Camera (Web UI) |
NRX / N32 Recorder |
|
Enable Audio |
Yes |
Yes (per channel) |
|
Input Type (MIC/LINE) |
Yes |
No |
|
Mic Gain (Input Volume) |
Full control |
No |
|
Audio Codec (G711A/U) |
Yes |
Limited |
|
Noise Filter |
Yes |
No |
|
External Mic Config |
Yes |
No |
|
Playback Volume |
Limited |
Yes |
Rule: Tune audio on the camera first; use the recorder for enable/playback.
EXTERNAL MICROPHONE CHECKLIST
- Set Audio IN Device correctly: MIC (passive) or LINE (powered)
- Start gain low ® increase until clear (avoid clipping)
- Use amplifier for line-level runs when needed
INSTALLATION BEST PRACTICES
- Place mic 6–12 ft from subject, aimed at speech
- Avoid HVAC, wind, traffic, reflective metal surfaces
- Lower mounting height improves intelligibility
30-SECOND DIAGNOSTIC
- Test local live view ® if bad: camera settings
- Test playback ® if bad only here: NVR config
- Test remote ® if bad only remote: network/ISP