// Concept 1
Audio encoding - the four codecs
ONVIF cameras support four audio encoding formats. Each one makes a different trade-off between voice clarity, compression efficiency, device compatibility, and network cost.
AAC_LC
All regions
QualityHigh
BandwidthModerate
Advanced Audio Coding - Low Complexity. Best when audio clarity matters and the receiving system supports AAC decoding.
G.711U
North America / Japan
QualityModerate
BandwidthLow
Telephony-grade voice encoding optimized for North American and Japanese infrastructure. Useful on constrained networks.
G.711A
Europe / Rest of world
QualityModerate
BandwidthLow
A common ONVIF-friendly voice codec with excellent compatibility across cameras, VMS systems, and intercom workflows.
ADPCM_D
All regions
QualityLow
BandwidthVery low
A lightweight option for secondary audio capture where detecting sound matters more than understanding speech.
Compatibility note: G.711A and G.711U are similar in quality. Choose based on your camera, region, and receiving system. AAC_LC gives better quality, but older devices may not decode it.
// Concept 2
Sample rate - quality vs bandwidth
The sample rate controls how many times per second the audio signal is measured. Higher rates capture more detail, but they also increase bandwidth and storage requirements.
48 kHz
Professional / broadcast
Rule of thumb: For voice capture in surveillance contexts, 16 kHz is usually the sweet spot: clear enough for speech, light enough for predictable network use.
// Six ready-to-use configurations
Audio profile reference
These profile configurations cover the most common surveillance audio scenarios.
EncodingAAC_LC
Sample rate48 kHz
Use this when audio content has legal, compliance, or operational value. It is clear and detailed, but consumes the most bandwidth.
EncodingG.711U
Sample rate8 kHz
Captures basic sound presence without stressing the network. Good for alarms, loud events, and low-priority audio checks.
EncodingG.711A
Sample rate16 kHz
The practical default for many deployments: intelligible speech, broad compatibility, and moderate bandwidth usage.
EncodingADPCM_D
Sample rate8 kHz
Use this when audio is a secondary signal and you only need to know that something loud happened.
EncodingAAC_LC
Sample rate44.1 kHz
Near-CD quality capture for clear speech in controlled spaces, with slightly lower bandwidth than the 48 kHz profile.
EncodingG.711A
Sample rate16 kHz
A natural fit for live voice interaction: low latency, reliable compatibility, and enough clarity for two-way speech.
// Quick reference
Profile summary at a glance
Use this table when you know the scenario and need a quick recommended setting.
| Scenario | Codec | Sample rate | Best for |
|---|
| High-quality recording | AAC_LC | 48 kHz | Meetings, voice evidence, compliance |
| Minimal bandwidth | G.711U | 8 kHz | Remote sites, constrained networks |
| Real-time monitoring | G.711A | 16 kHz | General surveillance with speech |
| Background capture | ADPCM_D | 8 kHz | Secondary audio, noise detection only |
| Enhanced voice | AAC_LC | 44.1 kHz | Office speech, reception desks |
| Two-way / intercom | G.711A | 16 kHz | Entry intercoms, door cameras |
Not sure where to start? Profile 03, G.711A at 16 kHz, is the recommended default for most ONVIF surveillance deployments.