MPEG-H 3D Audio – WG11 (MPEG) promotes Baseline Profile for 3D Audio to the final stage
At its 131st meeting, WG11 (MPEG) announces the completion of the new ISO/IEC 23008-3:2019, Amendment 2, "3D Audio Baseline profile, Corrections and Improvements," which has been promoted to Final Draft Amendment (FDAM) status. This amendment introduces a new profile called Baseline profile addressing industry demands. Tailored for broadcast, streaming, and high-quality immersive music delivery use cases, the 3D Audio Baseline profile supports channel and object signals and is a subset of the existing Low Complexity profile. The 3D Audio Baseline profile can be signaled in a backwards compatible fashion, enabling interoperability with existing devices implementing the 3D Audio Low Complexity profile. In addition to its advanced loudness and Dynamic Range Control (DRC), interactivity and accessibility features, the Baseline profile enables the usage of up to 24 audio objects in Level 3 for high quality immersive music delivery.
At the same time, MPEG initiates New Editions at Committee Draft (CD) status for MPEG-H 3D Audio Reference Software and Conformance which incorporate the 3D Audio Baseline profile functionality.
In addition to finalizing the Amendment, WG11 made available the “MPEG-H 3D Audio Baseline Profile Verification Test Report”. This reports on the results of five subjective listening tests assessing the performance of the 3D Audio Baseline profile. Covering a wide range of bit rates and immersive audio use cases, the tests were conducted in nine different test sites with a total of 341 listeners.
Analysis of the test data resulted in the following conclusions:
- Test 1 measured performance for the “Ultra-HD Broadcast” use case, in which highly immersive audio material was coded at 768 kb/s and presented using 22.2 or 7.1+4H channel loudspeaker layouts. The test showed that at the bit rate of 768 kb/s, the 3D Audio Baseline Profile easily achieves “ITU-R High-Quality Emission” quality, as needed in broadcast applications.
- Test 2 measured performance for the “HD Broadcast” or “A/V Streaming” use case, in which immersive audio material was coded at three bit rates: 512 kb/s, 384 kb/s and 256 kb/s and presented using 7.1+4H or 5.1+2H channel loudspeaker layouts. The test showed that for all bit rates, the 3D Audio Baseline Profile achieved a quality of “Excellent” on the MUSHRA subjective quality scale.
- Test 3 measured performance for the “High Efficiency Broadcast” use case, in which audio material was coded at three bit rates, with specific bit rates depending on the number of channels in the material. Bitrates ranged from 256 kb/s (5.1+2H) to 48 kb/s (stereo). The test showed that for all bit rates, the 3D Audio Baseline Profile achieved a quality of “Excellent” on the MUSHRA subjective quality scale.
- Test 4 measured performance for the “Mobile” use case, in which immersive audio material was coded at 384 kb/s, and presented via headphones. The 3D Audio FD binaural renderer was used to render a virtual, immersive audio sound stage for the headphone presentation. The test showed that at 384 kb/s, the 3D Audio Baseline Profile with binaural rendering achieved a quality of “Excellent” on the MUSHRA subjective quality scale.
- Test 5 measured performance for the "High Quality Immersive Music Delivery" use case in which object based immersive music is delivered to the receiver with up to 24 objects at high per object bit rates. This test used 11.1 (as 7.1+4H) as presentation format, with material coded at a rate of 1536 kb/s. The test showed that at that bit rate, the 3D Audio Baseline Profile easily achieves "ITU-R High-Quality Emission" quality, as needed in high quality music delivery applications.
