MPEG-4 Book, The

12.1. Synthetic-Natural Hybrid Coding of Audio

The SNHC of audio is enabled by MPEG-4 Systems through the AudioBIFS architecture and can be used to combine sound streams that are decoded with different (synthetic or natural) audio decoders, as depicted in Figure 12.2. In this figure, it can be seen that at the BIFS level the decoded sounds are processed in a similar way, regardless of the decoder used. The hierarchical AudioBIFS subtree mixes the decoder outputs, and these mixed sounds are associated with the rest of the scene with the aid of the topmost nodes of the AudioBIFS graphs. In Figure 12.2, the topmost node is Sound, which can be given a 3D spatial location and a simple, directive sound radiation pattern. Thus, the AudioBIFS graph describes ...