Bluetooth SIG Has Not Ratified LC3plus As An LE Audio Codec

03 November 2026

Fraunhofer’s LC3plus codec is being positioned as a high-resolution option for Bluetooth LE Audio, but the available specifications describe it as a vendor-specific codec rather than being officially ratified by the Bluetooth SIG.

The Fraunhofer IIS has characterized LC3plus as “a single audio codec supporting speech, music, gaming and high-resolution audio — and now lossless up to 192 kHz,” according to their product sheet. The company says LC3plus supports Bluetooth LE Audio.

However, a July 2025 Fraunhofer specification for LC3plus High Resolution over Bluetooth LE Audio states that this use of the codec is "not part of any Bluetooth SIG specification" and is not compliant with current Bluetooth specifications. Instead, the specification describes how to expose, negotiate, and transport LC3plus High Resolution as a vendor-specific codec over Bluetooth LE Audio.

The LC3plus specification, in its current form, does not represent a ratification of LC3plus as an LE Audio codec by the Bluetooth SIG. But it is an illustration of how the codec can be used in a proprietary way over LE Audio connections.

What LC3plus Is

LC3plus is a codec developed by the Fraunhofer IIS, building on their earlier work on the LC3 codec, which is a key part of Bluetooth LE Audio.

Fraunhofer describes LC3plus as a comprehensive codec that can handle all manner of audio content, from speech to high-resolution lossless audio up to 192 kHz. They say it offers minimal latency and maximal robustness.

Around since 2021, the codec is being positioned as a superset of LC3 with additional high-resolution support, along with lower latency and more robust error correction features. With its full feature set, Fraunhofer says, it can be used for high-resolution music streaming and other demanding wireless audio applications.

What Bluetooth LE Audio Requires

When the Bluetooth Special Interest Group (Bluetooth SIG) released LE Audio, they made LC3 the mandatory codec for the format. But they also included provisions for optional and custom codecs to promote flexibility and innovation.

The current Bluetooth SIG FAQ on LE Audio explains that:

LC3, the new low complexity communication codec (LC3), is the mandatory codec for all Bluetooth LE Audio products. In addition to LC3, manufacturers can support other optional codecs and implement custom codecs for applications that have specific audio quality, bandwidth, or power consumption requirements.

Media and system reports on the new codec option have expressed it as "ratification".

What Is Actually New

The actual state of play is better described by the July 2025 Fraunhofer LC3plus High-Resolution Service Specification for Bluetooth LE Audio. This document, version 1.0.0, spells out how to expose, negotiate, and transport LC3plus High Resolution as a "vendor-specific codec" over Bluetooth LE Audio.

The specification is an initial release from July 2025, and it covers enabling LC3plus High Resolution in LE Audio as a proprietary feature, rather than a ratified feature of the Bluetooth standard.

As noted above, the document emphasizes that this implementation is "not part of any Bluetooth SIG specification" and is not compliant with the current state of the published Bluetooth specifications.

What that means in practice is that this use of LC3plus is a vendor-specific way of using the codec over Bluetooth LE Audio, rather than a feature of the standard that all Bluetooth LE Audio devices can interoperate via.

Technical Capabilities

The new specifications are based on the core ability of the LC3plus codec, which is to transmit high-resolution audio over Bluetooth LE Audio, including:

* 48 kHz and 96 kHz sample rates

* 10 ms, 7.5 ms, 5 ms and 2.5 ms frame durations

* 24-bit signed integer or 32-bit IEEE floating point sample depths

These high-resolution options are selected in conjunction with an LC3plus service specification extra field, which carries the codec information and negotiating parameters.

The codec transmits frames using Bluetooth Audio Distribution Profile (A2DP) streams, and uses multicast retransmission to overcome potential packet loss.

By adopting LC3plus High Resolution, Bluetooth LE Audio projects can use higher-fidelity codecs over wireless connections — albeit with the caveat that this feature relies on proprietary support in devices, and is not yet part of the core Bluetooth standard.