# US 2018/0322889 A1 · Decoding audio bitstreams with enhanced spectral band replication metadata in at least one fill element > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0322889 A1 - Document ID: US20180322889A1 - Status: Published application - Kind: A1 - Application number: 16/040,243 - Filed: 2018-07-19 - Published: 2018-11-08 - Earliest claimed: 2015-03-13 - Assignees: Dolby International AB - Applicants: Dolby International AB - Inventors: Lars Villemoes; Heiko Purnhagen; Per Ekstrand - Web page: https://patentgrep.com/patent/US20180322889A1 ## CPC - G10L 19/167: {Audio streaming, i.e. formatting and decoding of an encoded audio signal representation into a data stream for transmission or storage purposes} - G10L 19/035: Scalar quantisation - G10L 19/24: Variable rate codecs, e.g. for generating different qualities using a scalable representation such as hierarchical encoding or layered encoding - G10L 21/038: using band spreading techniques - G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING ## Abstract Embodiments relate to an audio processing unit that includes a buffer, bitstream payload deformatter, and a decoding subsystem. The buffer stores at least one block of an encoded audio bitstream. The block includes a fill element that begins with an identifier followed by fill data. The fill data includes at least one flag identifying whether enhanced spectral band replication (eSBR) processing is to be performed on audio content of the block. A corresponding method for decoding an encoded audio bitstream is also provided. ## Claims ### Claim 1 An audio processing unit comprising: a bitstream payload deformatter configured to demultiplex a block of an encoded audio bitstream; and a decoding subsystem coupled to the bitstream payload deformatter and configured to decode at least a portion of the block of the encoded audio bitstream, wherein the block of the encoded audio bitstream includes: a fill element with an identifier indicating a start of the fill element and fill data after the identifier, wherein the fill data includes: at least one flag identifying whether a base form of spectral band replication or an enhanced form of spectral band replication is to be performed on audio content of the block of the encoded audio bitstream, wherein the base form of spectral band replication includes spectral patching, the enhanced form of spectral band replication includes harmonic transposition, one value of the flag indicates that said enhanced form of spectral band replication should be performed on the audio content, and another value of the flag indicates that said base form of spectral band replication but not said harmonic transposition should be performed on the audio content, wherein the audio processing unit is an audio decoder, and the identifier is a three bit unsigned integer transmitted most significant bit first and having a value of 0x6. ### Claim 2 (depends on 1) The audio processing unit of claim 1, wherein the fill data includes an extension payload, the extension payload includes spectral band replication extension data, and the extension payload is identified with a four bit unsigned integer transmitted most significant bit first and having a value of ‘1101’ or ‘1110’. ### Claim 3 (depends on 1) The audio processing unit of claim 1, wherein the block of the encoded audio bitstream includes a first fill element and a second fill element, and spectral band replication data is included in the first fill element and the first flag, but not spectral band replication data, is included in the second fill element. ### Claim 4 (depends on 1) The audio processing unit of claim 1, wherein the enhanced form of spectral band replication processing includes harmonic transposition, the base form of spectral band replication processing includes spectral patching, one value of the first flag indicates that said enhanced form spectral band replication processing should be performed on audio content of the block of the encoded audio bitstream, and another value of the first flag indicates that spectral patching but not said harmonic transposition should be performed on audio content of the block of the encoded audio bitstream. ### Claim 5 (depends on 4) The audio processing unit of claim 4, wherein the spectral band replication extension element includes enhanced spectral band replication metadata other than the first flag and wherein the enhanced spectral band replication metadata includes a parameter indicating whether to perform pre-flattening. ### Claim 6 (depends on 4) The audio processing unit of claim 4, wherein the spectral band replication extension element includes enhanced spectral band replication metadata other than the first flag and the second flag and wherein the enhanced spectral band replication metadata includes a parameter indicating whether to perform inter-subband sample temporal envelope shaping. ### Claim 7 (depends on 1) The audio processing unit of claim 1 further comprising an enhanced spectral band replication processing subsystem configured to perform enhanced spectral band replication processing using the first flag, wherein the enhanced spectral band replication includes harmonic transposition. ### Claim 8 (depends on 1) The audio processing unit of claim 1 wherein if the at least one flag identifies the enhanced form of spectral band replication processing a second flag identifying whether signal adaptive frequency domain oversampling is enabled or disabled. ### Claim 9 A method for decoding an encoded audio bitstream, the method comprising: receiving a block of an encoded audio bitstream; demultiplexing at least a portion of the block of the encoded audio bitstream; and decoding at least a portion of the block of the encoded audio bitstream, wherein the block of the encoded audio bitstream includes: a fill element with an identifier indicating a start of the fill element and fill data after the identifier, wherein the fill data includes: at least one flag identifying whether a base form of spectral band replication or an enhanced form of spectral band replication is to be performed on audio content of the block of the encoded audio bitstream, wherein the base form of spectral band replication includes spectral patching, the enhanced form of spectral band replication includes harmonic transposition, one value of the flag indicates that said enhanced form of spectral band replication should be performed on the audio content, and another value of the flag indicates that said base form of spectral band replication but not said harmonic transposition should be performed on the audio content. ### Claim 10 (depends on 9) The method of any one of claim 9, wherein the fill data includes an extension payload, the extension payload includes spectral band replication extension data, and the extension payload is identified with a four bit unsigned integer transmitted most significant bit first and having a value of ‘1101’ or ‘1110’. ### Claim 11 (depends on 9) The method of any one of claim 9, wherein the enhanced form of spectral band replication processing is harmonic transposition, the base form of spectral band replication processing is spectral patching, one value of the first flag indicates that said enhanced form spectral band replication processing should be performed on audio content of the block of the encoded audio bitstream, and another value of the first flag indicates that spectral patching but not said harmonic transposition should be performed on audio content of the block of the encoded audio bitstream. ### Claim 12 (depends on 11) The method of claim 11, wherein the spectral band replication extension element includes enhanced spectral band replication metadata other than the first flag and wherein the enhanced spectral band replication metadata includes a parameter indicating whether to perform pre-flattening, or wherein the spectral band replication extension element includes enhanced spectral band replication metadata other than the first flag and wherein the enhanced spectral band replication metadata includes a parameter indicating whether to perform inter-subband sample temporal envelope shaping. ### Claim 13 (depends on 9) The method of claim 9 further comprising performing enhanced spectral band replication processing using the first flag and the second flag, wherein the enhanced spectral band replication includes harmonic transposition. ### Claim 14 (depends on 9) The method of claim 9 wherein the encoded audio bitstream is an MPEG-4 AAC bitstream. ### Claim 15 (depends on 9) A non-transitory computer readable medium containing instructions that when executed by a processor perform the method of claim 9.