System and method for seamless switching of compressed audio streams

• US 20030045957A1
• Filed: 07/09/2002
• Published: 03/06/2003
• Est. Priority Date: 07/09/2001
• Status: Active Grant

• Current Assignee: TiVo Corporation (Adeia Inc.)
• Original Assignee: Visible World Incorporated (Comcast Corporation)
• Inventors: Niemeijer, Gerrit, Haberman, Seth, Jansen, Alex, Boltze, Thomas
• Granted Patent: US 7,657,428 B2
• Time in Patent Office: Days
• US Class Current: 700/94
• CPC Class Codes: G11B 2220/213 Read-only discs
• CPC Class Codes: G11B 2220/2545 CDs
• CPC Class Codes: G11B 2220/2562 DVDs [digital versatile discs]; Digital video discs; MMCDs; HDCDs
• CPC Class Codes: G11B 27/034 on discs G11B27/036, G11B27/038 take precedence
• CPC Class Codes: H04H 20/26 Arrangements for switching distribution systems
• CPC Class Codes: H04H 60/06 Arrangements for scheduling broadcast services or broadcast-related services
• CPC Class Codes: H04N 21/23424 involving splicing one content stream with another content stream, e.g. for inserting or substituting an advertisement
• CPC Class Codes: H04N 21/439 Processing of audio elementary streams
• CPC Class Codes: H04N 21/4398 involving reformatting operations of audio signals details of audio signal transcoding G10L19/173
• CPC Class Codes: H04N 21/44016 involving splicing one content stream with another content stream, e.g. for substituting a video clip
• CPC Class Codes: H04N 21/458 Scheduling content for creating a personalised stream, e.g. by combining a locally stored advertisement with an incoming stream; Updating operations, e.g. for OS modules ; time-related management operations arrangements for replacing or switching information during the broadcast or during the distribution H04H20/10
• CPC Class Codes: H04N 21/8541 involving branching, e.g. to different story endings

Abstract

A system and method for seamless switching and concatenation of compressed audio streams in Internet, Digital Radio, Digital Television, DVD, storage, and other applications. The technology allows switching between streams at pre-determined points without the introduction of audible artifacts. It can be used for the personalization messages such as advertisements, news systems and other.

Claims

1. A method of preparing a plurality of digital audio fragments to allow switching between at least one source fragment and at least one target fragment said method comprising:

aligning an end of said at least one source fragment with a beginning of said at least one target fragment, for all possible valid combinations of said at least one source fragment and said at least one target fragment;

wherein said at least one source fragment is aligned to be a length that is an exact multiple of a predetermined number.

2. The method of claim 1 further comprising:

after said step of aligning an end of said at least one source fragment;

moving a sequence of audio samples from a digital audio fragment which was shortened because of said alignment step, to a plurality of digital audio fragments which were lengthened because of said alignment step.

3. The method of claim 2 wherein said moved sequence of audio samples is a length which will result in said at least one source fragment to be a length that is an exact multiple of said predetermined number

4. The method of claim 1 further comprising:

after said step of aligning an end of said at least one source fragment;

moving a sequence of audio samples from said end of said at least one source fragment to said beginning of said at least one target fragment;

wherein said sequence of audio samples is a length which will shorten said at least one source fragment to be a length that is an exact multiple of said predetermined number.

5. The method of claim 1 further comprising:

after said step of aligning an end of said at least one source fragment;

moving a sequence of audio samples from said beginning of said at least one target fragment to said end of said at least one source fragment wherein said sequence of audio samples is a length which will lengthen said at least one source fragment to be a length that is an exact multiple of said predetermined number.

6. The method of claim 5 further including:

moving a second sequence of audio samples from said beginning of said at least one target fragment to said end of said at least one source fragment wherein said second sequence of audio samples is a length equal to said predetermined number.

7. The method of claim 1, wherein the digital audio fragments are compressed as a sequence of frames, wherein each frame comprises a sequence of audio samples;

and wherein a length of said frame is said predetermined number.

8. The method of claim 7, wherein said compression scheme includes encoding a sequence of said frames wherein a subsequent frame encoding is dependent upon an encoding of at least one preceding frame

9. The method of claim 7, wherein ends of a plurality of source fragments are aligned with beginnings of a plurality of associated target fragments by moving identical audio samples from the beginning of said target fragments to the end of said source fragments so that a resulting end of said source fragments aligns at an exact multiple of said predetermined number, and a resulting last frame of said plurality of source fragments is identical.

10. The method of claim 7, wherein ends of a plurality of source fragments are aligned with beginnings of a plurality of associated target fragments by moving identical audio samples from the beginning of said target fragments to the end of said source fragments;

so that the end of said source fragments align at an exact multiple of said predetermined number, and wherein at least one audio sample is identical at the end of all of said source fragments, however the last full frame of audio samples are not identical for all said source fragments.

11. The method of claim 7, wherein the ends of a plurality of source fragments are aligned with beginnings of a plurality of associated target fragments by moving identical audio samples from the end of said source fragments to the beginning of said target fragments;

so that the resulting end of said source fragments aligns at an exact multiple of said predetermined number, wherein at least one more audio sample is identical at the beginning of all of said target fragments, however the first full frame of audio samples is not identical for all said target fragments.

12. The method of claim 7, wherein the ends of a plurality of source fragments are aligned with the beginnings of a plurality of associated target fragments by moving audio samples from the beginning of a first target fragment to the end of said plurality of source fragments;

and removing an identical number of audio samples from the beginning of said remaining plurality of fragments, so that the resulting end of said source fragments aligns at an exact multiple of said predetermined number.

13. The method of claim 7, wherein the ends of a plurality of source fragments are aligned with the beginnings of a plurality of associated target fragments by moving a number of samples from the end of a first source fragment to the beginning of said plurality of target fragments;

and removing an identical number of audio samples from the end of said remaining source fragments, so that the resulting end of said source fragments aligns at an exact multiple of said predetermined number.

14. The method of claim 7, wherein at least one digital audio fragment has an end time that is later than the beginning time of any other digital audio fragments, wherein said at least one digital audio fragment is aligned at an exact multiple of said predetermined number by adding empty audio samples to the end of said at least one audio fragment.

15. The method of claim 8, further including:

copying a last frame of a source fragment to the beginning of at least one target fragment;

compressing said at least one target fragment using said compression scheme;

removing data from the beginning of said compressed at least one target fragment, said data corresponding to a first frame of said at least one target fragment.

16. A system for preparing a plurality of digital audio fragments for transmission to allow a switching device to switch between at least one source fragment and at least one target fragment;

said system comprising;

an audio aligner module, coupled to a source of said plurality of audio fragments, to align beginning and ends of said plurality of audio fragments to selected times based on an exact multiple of a predetermined number;

an audio compression module, coupled to said audio aligner module, to compress said plurality of audio fragments as a sequence of frames, wherein each frame comprises a sequence of audio samples; and

wherein a length of said frame is said predetermined number.

17. The system of claim 16, wherein said plurality of audio fragments are transmitted using a transport mechanism selected from one of MPEG compliant, digital television, dvd broadcast, dvd storage, CD ROM, and internet.

18. The system of claim 16, wherein said plurality of audio fragments are compressed using AC-3

19. The system of claim 16, wherein said plurality of audio fragments are compressed using MPEG Layer II

20. A switching apparatus, to switch between a plurality of audio fragments, wherein said audio fragments are prepared so that so that an end of said at least one source fragment is aligned with a beginning of said at least one target fragment and wherein said least one source fragment is aligned to be a length that is an exact multiple of a predetermined number;

wherein said switch apparatus switches between at least one source fragment and at least one target fragment at said alignment.

21. The switching apparatus of claim 20 wherein said switching apparatus receives said plurality of audio fragments transmitted using a transport mechanism selected from one of MPEG compliant, digital television, dvd broadcast, dvd storage, CD ROM, and internet. a memory module, said memory module to receive at least one target fragment at a time before switching to said at least one target fragment.

22. The switching apparatus of claim 20 wherein said switching apparatus is a receiver for MPEG encoded media streams.

23. The switching apparatus of claim 20 wherein said switching apparatus selected from one of set top box, dvd player, personal computer, digital television set, video server, and video on demand server.