Systems and methods for implementing efficient cross-fading between compressed audio streams

Patent metadata

Field	Value
Publication number	US-10366694-B2
Application number	US-201715722240-A
Country	US
Kind code	B2
Filing date	Oct 2, 2017
Priority date	Nov 18, 2011
Publication date	Jul 30, 2019
Grant date	Jul 30, 2019

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.

First claim

What is claimed:

1. 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.

2. The method of claim 1 , further comprising presenting the composite compressed packets to an audio decoder.

3. The method of claim 2 , 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.

4. The method of claim 1 , wherein at least one of the first audio stream and the second audio stream is encoded in AAC format.

5. The method of claim 1 , wherein at least one of the first audio stream and the second audio stream is encoded in EAAC Plus format.

6. The method of claim 1 , wherein at least one of the first audio stream and the second audio stream is encoded in MP3 format.

7. The method of claim 1 , wherein the subcomponents include at least one AAC Core component.

8. The method of claim 1 , wherein the subcomponents include at least one Spectral Band Replication (“SBR”) component.

9. The method of claim 1 , wherein the subcomponents include at least one Parametric Stereo (“PS”) component.

10. The method of claim 1 , 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.

11. The method of claim 1 , wherein the decomposing includes at least partially demultiplexing the data into the subcomponents of the data.

12. The method of claim 1 , 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.

13. The method of claim 1 , 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.

14. 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.

15. The audio playback device of claim 14 , wherein at least one of the first audio stream and the second audio stream is encoded in AAC format.

16. The audio playback device of claim 14 , wherein at least one of the first audio stream and the second audio stream is encoded in EAAC Plus format.

17. The audio playback device of claim 14 , wherein the subcomponents include at least one AAC Core component.

18. The audio playback device of claim 14 , wherein the subcomponents include at least one SBR component.

19. The audio playback device of claim 14 , wherein the subcomponents include at least one PS component.

20. A computer-implemented method for implementing efficient cross-fading between compressed audio streams, comprising:
generating a sequence of paired-packets based on time aligning compressed packets from at least two streams of N streams that are involved in a cross-fade;
synthesizing composite compressed packets from the at least two streams based at least in part on combining each of the paired-packets of the sequence and relative weights corresponding to the at least two streams, wherein the relative weights are indicative of a dominant stream from the at least two streams;
re-encoding the composite compressed packets with a cross fade effect; and
presenting the re-encoded composite compressed packets to an audio decoder during a cross-fade phase.

Assignees

• Sirius Xm Radio Inc

Inventors

• Lowe Raymond
• Kalman Mark
• Sinha Deepen
• Ward Christopher

Classifications

• G10L19/00 Primary

  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) · CPC title

• G11B27/038

  Cross-faders therefor · CPC title

• H04H60/04 Primary

  Studio equipment; Interconnection of studios · CPC title

• G11B27/031

  Electronic editing of digitised analogue information signals, e.g. audio or video signals · CPC title

• H04H20/38

  Arrangements for distribution where lower stations, e.g. receivers, interact with the broadcast · CPC title