SMPTE ST 2110 and Audio
- ST 2110-30 defines how to transport 16-bit or 24-bit linear PCM audio, including AES67-compliant audio streams for the most compatibility.
- ST 2110-31 defines how to transport AES3-compliant audio and data such as Dolby®E and others. ST 2110-31 has been adopted from RAVENNA’s AM 824 audio format.
AES67
AES67 is an interoperability standard to allow different audio networking protocols to connect to each other. AES67 was created to be as compatible as possible with existing solutions. It defines transport protocols and synchronization mechanisms as well as a linear audio stream format of up to 8 channels, 48kHz sampling rate, and a 16 or 24-bit depth at a packet time of 1 ms.
Learn more about AES67 here.
Differences between SMPTE ST 2110-30 and AES67
ST 2110-30 and AES67 are compatible, but there are a couple of constraints:
- ST 2110-30 requires the use of ST 2059 for the PTP profile. AES-R16-2016 describes the operating parameters of AES67 media and ST 2059 PTP profiles and gives recommendations on common operating points.
- AES67 streams may have a random offset for their RTP stream clock; in ST 2110-30 that offset must be 0.
- ST 2110-10 requires devices to offer an option to work in PTP slave-only mode.
In essence, any ST 2110-30 sender will be compatible with AES67, whereas AES67 senders need to use an RTP stream clock offset of 0 (most known AES67 senders can do that). However, the ST 2110 receiver needs to be aware that when receiving an AES67 stream, the RTP stream clock offset might not be 0.
SMPTE ST 2110-31
While ST 2110-30 and AES67 address the transport of linear PCM audio (16 or 24 bit), both standards don’t cover the transport of AES3 signals. AES3 differs from PCM audio by defining additional status bits (PCUV), useful for transporting additional metadata and status information. Also, AES3 allows the transport of non-linear (compressed) audio formats (such as Dolby®E and others) and even non-audio data. ST 337 & 338 define such data formats.
Since RAVENNA was already capable of transporting AES3 (audio) data, its so-called AM 824 format was the blueprint for ST 2110-31. It simply builds on AES67 / ST 2110-30 but enhances the payload by 1 byte to transport the additional status bits. Of course, the new payload format needs to be signalled in the accompanying SDP file describing the stream setup, but any other definition of AES67 / ST 2110-30 remains unchanged.
Thus, AES67 / ST 2110-30 devices can relatively easily be enhanced to also support ST 2110-31 (as a manufacturer’s choice). Most RAVENNA devices can support ST 2110-31 out of the box.
RAVENNA covers it all!
By adopting RAVENNA audio networking into your products, automatic compatibility with ST 2110 audio is guaranteed.
RAVENNA offers pre-defined profiles to format audio data for different use cases. A profile defines the bit depth, number of audio channels, sampling rate, and packet time of a particular stream, among other parameters. RAVENNA’s generic profile is already AES67 & ST 2110 compatible, while its AM824 profile adds ST 2110-31 compatibility.
Multiple streams adhering to different profiles can be run across a network simultaneously. For example, streams for high-quality studio production with a Dolby®E profile for an immersive audio system could be run concurrently with low sample rate audio for intercom purposes.
While profiles cover the most commonly used stream setups, any stream configuration can be defined within RAVENNA to host a wide choice of sample rates, bit depths, channel counts, and packet times and format them in a manner compatible with ST 2110-30 or 31 and beyond.
AES67, ST 2110-30, and ST 2110-31 are all covered by RAVENNA!
SMPTE ST 2110 Conformance Levels
ST 2110 defines a variety of conformance levels, of which only Level A needs to be mandatorily supported. RAVENNA can support all 6 conformance levels.
| Level | To be Supported by the Reciever |
|---|---|
| A (Mandatory for AES67 Compliancy) | Reception of 48kHz streams with 1-8 audio channels at packet times of 1ms |
| B | Level A+ 1-8 channels at packet times of 125μs |
| C | Level A+ 1-64 channels at packet times of 125μs |
| AX | Level A (48kHz) + Reception of 96kHz streams with 1-4 audio channels at packet times of 1ms |
| BX | Level B + AX + 1-8 channels at a packet time of 125μs |
| CX | Level C + AX + 1-32 channels at packet times of 125μs |
| Level | To be supported by the Receiver |
|---|---|
|
A (mandatory for AES67 compliance) |
Reception of 48kHz streams with 1-8 audio channels at packet of 1ms |
|
B |
Level A+ 1-8 channels at packet times of 125μs |
|
C |
Level A+
1-64 channels at packet times of 125μs |
|
AX |
Level A (48kHz) + Reception of 96kHz streams with 1-4 audio channels at packet times of 1ms |
|
BX |
Level B + AX + 1-8 channels at a packet time of 125μs |
|
CX |
Level C + AX + 1-32 channels at packet times of 125μs |
Read More
Precision Time Protocol
Click on the button below for more information about Precision Time Protocol (PTP).
Learn More