Encoding and decoding IVAS bitstreams
Encoding/decoding an immersive voice and audio services (IVAS) bitstream comprises: encoding/decoding a coding mode indicator in a common header (CH) section of an IVAS bitstream, encoding/decoding a mode header or tool header in the tool header (TH) section of the bitstream, the TH section following the CH section, encoding/decoding a metadata payload in a metadata payload (MDP) section of the bitstream, the MDP section following the CH section, encoding/decoding an enhanced voice services (EVS) payload in an EVS payload (EP) section of the bitstream, the EP section following the CH section, and on the encoder side, storing or streaming the encoded bitstream, and on the decoder side, controlling an audio decoder based on the coding mode, the tool header, the EVS payload, and the metadata payload or storing a representation of same.
1 . A method of decoding a bitstream of an audio signal, comprising:
determining a frame length of the bitstream;
computing a table row index of an immersive voice and audio services (IVAS) bitrate distribution control table based on the determined frame length;
accessing the IVAS bitrate distribution control table at the table row index to identify a number of channels and a quantization strategy indicator to configure an IVAS decoder;
with the IVAS decoder:
extracting and decoding, using an immersive voice and audio services (IVAS) decoder, a coding mode indicator or coding tool indicator in a common header (CH) section of an IVAS bitstream, the coding mode indicator or coding tool indicator indicating a coding mode or coding tool for the audio signal;
extracting and decoding, using the IVAS decoder, a mode header or tool header in a Tool Header (TH) section of the IVAS bitstream, the TH section including data associated with the IVAS bitrate distribution control table;
extracting and decoding, using the IVAS decoder, a metadata payload from metadata payload (MDP) section of the IVAS bitstream, the metadata payload including spatial metadata;
determining a quantization level from a set of quantization levels based on the quantization level indicator;
unquantizing the spatial metadata according to the determined quantization level;
extracting and decoding, using the IVAS decoder, a payload from a payload section of the IVAS bitstream, the payload including coded bits for each channel or downmix channel of the audio signal; and
reconstructing or rendering the audio signal for playback on a device based on the coding mode or coding tool indicator, the mode header or tool header, the unquantized spatial metadata and the payload.
2 . A system comprising:
one or more processors; and
a non-transitory computer-readable medium storing instructions that, upon execution by the one or more processors, cause the one or more processors to perform operations of the method of claim 1 .
3 . A non-transitory, computer-readable medium storing instructions that, upon execution by one or more processors, cause the one or more processors to perform operations of the method of claim 1 .