# US 2018/0025735 A1 · Systems and methods for implementing efficient cross-fading between compressed audio streams > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0025735 A1 - Document ID: US20180025735A1 - Status: Published application - Kind: A1 - Application number: 15/722,240 - Filed: 2017-10-02 - Published: 2018-01-25 - Earliest claimed: 2011-11-18 - Assignees: Sirius XM Radio Inc. - Applicants: Sirius XM Radio Inc. - Inventors: Raymond Lowe; Mark Kalman; Deepen Sinha; Christopher Ward - Web page: https://patentgrep.com/patent/US20180025735A1 ## CPC - G10L 19/00: Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis (in musical instruments G10H) - G11B 27/031: Electronic editing of digitised analogue information signals, e.g. audio or video signals - G11B 27/038: Cross-faders therefor - H04H 20/38: Arrangements for distribution where lower stations, e.g. receivers, interact with the broadcast - H04H 60/04: Studio equipment; Interconnection of studios - G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) - H04H: BROADCAST COMMUNICATION (multiplex communication H04J; pictorial communication aspects of broadcast systems H04N) ## Abstract Systems and methods are presented for efficient cross-fading (or other multiple clip processing) of compressed domain information streams on a user or client device, such as a telephone, tablet, computer or MP3 player, or any consumer device with audio playback. Exemplary implementation systems may provide cross-fade between AAC/Enhanced AAC Plus (EAACPlus) information streams or between MP3 information streams or even between information streams of unmatched formats (e.g. AAC to MP3 or MP3 to AAC). Furthermore, these systems are distinguished by the fact that cross-fade is directly applied to the compressed bitstreams so that a single decode operation may be performed on the resulting bitstream. Moreover, using the described methods, similar cross fade in the compressed domain between information streams utilizing other formats of compression, such as, for example, MP2, AC-3, PAC, etc. can also be advantageously implemented. Thus, in exemplary embodiments of the present invention a set of frames from each input stream associated with the time interval in which a cross fade is decoded, and combined and recoded with a cross fade or other effect now in the compressed bitstream. Once sent through the client device's decoder, the user hears the transitional effect. The only input data that is decoded and processed is that associated with the portion of each stream used in the crossfade, blend or other interstitial, and thus the vast majority of the input streams are left compressed. ## Claims ### Claim at position 1 1-28. (canceled) ### Claim 29 A computer-implemented method for implementing cross-fading between compressed audio streams, comprising: time aligning compressed packets of a first audio stream with compressed packets of a second audio stream; decomposing data in each time aligned compressed packet of the first audio stream and the second audio stream into subcomponents; deriving composite compressed packets by combining each subcomponent of each time aligned compressed packet of the first audio stream with a corresponding subcomponent of a time aligned compressed packet of the second audio stream; and decoding the composite compressed packets during a cross-fade between the first audio stream and the second audio stream. ### Claim 30 (depends on 29) The method of claim 29, further comprising presenting the composite compressed packets to an audio decoder. ### Claim 31 (depends on 30) The method of claim 30, wherein the presenting the composite compressed packets to the audio decoder includes multiplexing the first audio stream, the second audio stream, and the derived composite compressed packets according to a time index. ### Claim 32 (depends on 29) The method of claim 29, wherein at least one of the first audio stream and the second audio stream is encoded in AAC format. ### Claim 33 (depends on 29) The method of claim 29, wherein at least one of the first audio stream and the second audio stream is encoded in EAAC Plus format. ### Claim 34 (depends on 29) The method of claim 29, wherein at least one of the first audio stream and the second audio stream is encoded in MP3 format. ### Claim 35 (depends on 29) The method of claim 29, wherein the subcomponents include at least one AAC Core component. ### Claim 36 (depends on 29) The method of claim 29, wherein the subcomponents include at least one Spectral Band Replication (“SBR”) component. ### Claim 37 (depends on 29) The method of claim 29, wherein the subcomponents include at least one Parametric Stereo (“PS”) component. ### Claim 38 (depends on 29) The method of claim 29, wherein the time aligning is performed using data included in a header of at least one of the first audio stream and the second audio stream. ### Claim 39 (depends on 29) The method of claim 29, wherein the decomposing includes at least partially demultiplexing the data into the subcomponents of the data. ### Claim 40 (depends on 29) The method of claim 29, wherein the time aligning includes identifying a first frame from at least one of the first audio stream and the second audio stream based at least in part on a sampling frequency. ### Claim 41 (depends on 29) The method of claim 29, wherein the time aligning includes identifying a first frame from at least one of the first audio stream and the second audio stream based at least in part on a number of raw data blocks per frame in the at least one of the first audio stream and the second audio stream. ### Claim 42 An audio playback device, comprising: a processor; and a memory containing instructions that, when executed by the processor, cause the device to: time align compressed packets of a first audio stream with compressed packets of a second audio stream; decompose data in each time aligned compressed packet of the first audio stream and the second audio stream into subcomponents; derive composite compressed packets by combining each subcomponent of each time aligned compressed packet of the first audio stream with a corresponding subcomponent of a time aligned compressed packet of the second audio stream; and decode the composite compressed packets during a cross-fade between the first audio stream and the second audio stream. ### Claim 43 (depends on 42) The audio playback device of claim 42, wherein at least one of the first audio stream and the second audio stream is encoded in AAC format. ### Claim 44 (depends on 42) The audio playback device of claim 42, wherein at least one of the first audio stream and the second audio stream is encoded in EAAC Plus format. ### Claim 45 (depends on 42) The audio playback device of claim 42, wherein the subcomponents include at least one AAC Core component. ### Claim 46 (depends on 42) The audio playback device of claim 42, wherein the subcomponents include at least one SBR component. ### Claim 47 (depends on 42) The audio playback device of claim 42, wherein the subcomponents include at least one PS component. ### Claim 48 A computer-implemented method for implementing efficient cross-fading between compressed audio streams, comprising: time aligning compressed packets from each stream of N streams that are involved in a cross-fade; synthesizing composite compressed packets containing information derived from the N streams; and presenting the composite compressed packets to an audio decoder during a cross-fade phase.