AES67 — Audio over IP Interoperability Standard

AES67 (AES Standard for Audio Applications of Networks — High-Performance Streaming Audio over IP)

For full AES67 technical depth including PTP configuration, SDP/SAP discovery, and SMPTE ST 2110-30, see networking/aes67. For Dante/AES67 interoperability, see networking/dante-vs-aes67.

AES67 is an AES/SMPTE standard that defines a common audio-over-IP format so that devices from different proprietary platforms — Audinate Dante, Merging Technologies Ravenna, Axia Livewire, and QSC Q-LAN — can exchange audio with each other. Without AES67, these platforms are siloed: a Dante device cannot send audio directly to a Ravenna device. AES67 defines the common transport layer (RTP), clock synchronization (IEEE 1588 PTP), and stream description (SDP), so any AES67-compliant device can send to and receive from any other.

What AES67 Defines

• Transport: RTP (Real-time Transport Protocol) over UDP/IP for audio payload delivery
• Packet timing: 1 ms packet time (configurable: 125 µs, 250 µs, 333 µs, 1 ms, 4 ms)
• Clock sync: IEEE 1588v2 PTP (Precision Time Protocol) — all devices lock to a grandmaster clock via the network
• Stream format: LPCM at 48 kHz (or 96 kHz), 16/24/32-bit, 1–8 channels per stream
• Discovery: SDP (Session Description Protocol) files describe each stream; SAP (Session Announcement Protocol) broadcasts stream availability; AES70 (OCA) for device control
• Multicast: optional but recommended for efficient multi-receiver streams

AES67 is transport-only: it does not define device control, routing software, or a management interface. Each platform's control layer (Dante Controller, Ravenna ANEMAN, Q-SYS Designer) handles these.

AES67 Mode in Dante

Dante devices support AES67 interoperability via "AES67 Mode," enabled in Dante Device Manager. When enabled, the device generates an AES67-compatible SDP stream that Ravenna, Livewire, or other AES67 receivers can subscribe to. Dante also accepts incoming AES67 streams from non-Dante sources.

Limitations of Dante AES67 Mode:

• Requires all devices to be on the same PTP domain (clock sync must be established)
• AES67 streams appear in Dante Controller but with limited labeling compared to native Dante flows
• Dante's proprietary discovery (mDNS) does not carry over to AES67 receivers — manual SDP configuration may be required

AES67 and SMPTE ST 2110-30

SMPTE ST 2110-30 defines AES67 audio as the audio component of the ST 2110 professional media-over-IP suite (alongside ST 2110-20 for video and ST 2110-40 for ancillary data). In broadcast facilities using ST 2110, AES67 is the audio backbone. This is the most demanding AES67 deployment: tight PTP requirements (< 1 µs offset), high stream counts, and IGMPv3 source-specific multicast.

Common Pitfalls

• PTP domain mismatch between AES67 devices. IEEE 1588 PTP uses domain numbers (default 0). If a Dante device is on PTP domain 0 and a Ravenna device is on domain 127 (Ravenna default), they cannot synchronize clocks and audio will be intermittent or absent. Fix: configure all AES67 devices to use the same PTP domain number; verify in each device's network configuration.

• Attempting AES67 interoperability without a shared PTP grandmaster. AES67 requires all devices to be locked to the same PTP clock. Without a common grandmaster (or a switch providing boundary clock), devices drift apart and audio artifacts result. Fix: designate one stable hardware device as PTP grandmaster; configure switches to support PTP boundary clock on AES67 VLANs.

• Forgetting that AES67 requires IGMPv3 for source-specific multicast. AES67 receivers can use IGMPv3 INCLUDE mode to subscribe to specific source addresses. Switches configured for IGMPv2 only cannot process these membership reports. Fix: verify switch supports IGMPv3 snooping on the AES67 VLAN.

• Mixing AES67 packet times between sender and receiver. A sender at 1 ms packet time and a receiver expecting 125 µs causes buffer underruns and audio glitches. Fix: standardize packet time across all AES67 devices on the same system; 1 ms is the most compatible choice for non-broadcast applications.