MPEG-4 SLS (scalable lossless coding) was published more than 20 years ago. In the meantime several tools to improve coding efficiency; flexibilities have been invented. Currently, in MPEG WG6 (audio coding) there are two standardization activities on lossless audio coding: Audio Coding for Machines (ACoM); Biomedical; general waveform signal coding (BWC). ACoM phase 1 originally was targeted only towards lossless storage formats for training of machine listening schemes, but additional uses cases like “user generated content analysis”, “live stream content analysis”,; “artistic creation” have been added. The focus was extended to the transmission of audio data from microphone (arrays) to central processing units. BWC is a joint activity with TU-R SG21. While ACoM started with a large number of use cases; includes the specification of a rich set of metadata BWC started with a focus on medical data like electroencephalogram (EEG); electrocardiogram (ECG). However, BWC can be used for audio signals, too; medical data coding are on the list of use cases for ACoM. The call for proposals (CfP) for ACoM was completed in January 2025. Two proposals, both outperforming MPEG-4 SLS, had been submitted. Both proposals reused; optimized core codecs from BWC. Currently, MPEG audio investigates how the ACoM proposals can be merged into BWC. This merge process must be completed end of April 2026. The presentation will give details about ACoM use cases, the ACoM CfP process, the results of the CfP; results from the merge process.
