Audio stems are generated to contain audio content to be mixed by recipient devices. Multiple sets of mixing instructions for multiple audio channel configurations are determined, for example, based on input of audio producers. Each set of mixing instructions is to be used for mixing the audio stems for rendering in a corresponding audio channel configuration. A bitstream is generated to carry both the audio stems and the sets of mixing instructions. A recipient device receives the bitstream as the input. The recipient device determines a specific audio channel configuration to be used for rendering the plurality of audio stems. Based on that determination, a specific set of mixing instructions is retrieved from the bitstream and used to mix the audio stems.