Data processing: generic control systems or specific application – Specific application – apparatus or process – Digital audio data processing system
Reexamination Certificate
2000-03-13
2004-03-30
Nguyen, Duc (Department: 2643)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Digital audio data processing system
C725S131000
Reexamination Certificate
active
06714826
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application contains subject matter which is related to the subject matter of the following applications, each of which is assigned to the same assignee as this application and each of which is hereby incorporated herein by reference in its entirety:
“Method To Play Audio And Video Clips Through MPEG Decoders,” Ser. No. 09/046,283, filed Mar. 23, 1998; and
“System And Method For Merging Multiple Audio Streams,” Ser. No. 09/273,919, filed Mar. 22, 1999.
TECHNICAL FIELD
The present invention relates generally to digital data decoding systems, and more particularly, to a processing facility capable of receiving multiple concurrent streams of digital audio data and simultaneously outputting therefrom both a mixed digital audio signal and an unmixed digital audio signal.
BACKGROUND OF THE INVENTION
Full motion video and audio displays based on digital signals have become widely available. While these displays have many advantages, they also often require a massive amount of raw digital data. Because the storage and transmission of digital video and audio signals is central to many applications, and because an uncompressed representation of a video and audio signal requires a large amount of storage, the use of digital compression techniques is vital to this advancing art.
Several international standards for the compression of digital video and audio signals have emerged over the past decade, with more currently under development. These standards apply to algorithms for the transmission and storage of compressed digital data in a variety of applications, including: video-telephony and teleconferencing; high quality digital television transmission on coaxial and fiberoptic networks; as well as broadcast terrestrially and other direct broadcast satellites; and in interactive multimedia products on CD-ROM, digital audio tape, and Winchester disk drives.
Several of these standards involve algorithms based on a common core of compression techniques, e.g., the CCITT (Consultative Committee on International Telegraphy and Telephony) Recommendation H.120, the CCITT Recommendation H.261, and the ISO/IEC MPEG-1 and MPEG-2 Standards. The MPEG algorithms have been developed by the Moving Picture Experts Group (MPEG), part of a joint technical committee of the International Standards Organization (ISO) and the International Electro-technical Commission (IEC). The MPEG Committee has been developing standards for the multiplex, compressed representation of video and associated audio signals.
Briefly summarized, the MPEG-2 standard describes an encoding method that results in substantial bandwidth reduction by a subjective lossy compression followed by a lossless compression. The encoded, compressed digital data is subsequently decompressed and decoded in an MPEG-2 compliant decoder.
Video and audio decoding in accordance with the MPEG-2 standard is described in greater detail in commonly assigned U.S. Pat. No. 5,576,765, entitled “Video Decoder”, which is hereby incorporated herein in its entirety, as well as the above-incorporated, commonly assigned pending application Ser. No. 09/046,283, entitled “Method To Play Audio And Video Clips Through MPEG Decoders”.
Audio/video decoders are typically embodied as general or special purpose processors and memory. Decoders that are used with television sets are often referred to in the industry as set-top box (STB) systems.
Stand-alone audio/video decoders currently used in STB systems generally utilize a dedicated interface to a specific transport chip and/or network interface module (NIM). As the required utility of these STB systems expands, it is becoming desirable to adopt input from various sources in addition to the base network (e.g., cable/satellite) connection.
For example, in addition to a main audio stream, such as a soundtrack for a movie, it may be desirable for the transport stream carrying the program to also contain a secondary audio stream or channel that provides, e.g., additional narrative for disabled viewers who are unable to hear subtle sounds in the original soundtrack. Alternatively, it may be desirable to allow a user to run other functions in the background and request audio queues when certain events have occurred, such as receiving mail, etc. Further, it may be desirable to allow an internet browser or other interactive application to run in the foreground, with primary audio and video programming (e.g., a movie) running in a window on the display. In such cases, it is desirable that the secondary or supplementary audio sound be mixed with the original audio stream so that both can be heard at a single time through a common set of speakers, as opposed to mixing the two streams where only one or the other is heard.
As an additional consideration, in order to accomplish decoding of multiple audio streams, the base audio decoder would conventionally be replicated for as many digital audio streams as output is desired. However, this could be costly and unnecessary in many potential audio mixing applications such as those noted above.
Therefore, in order to establish commercial advantage, there is a need for an integrated device capable of decoding and merging multiple independent digital audio streams using a single audio decode facility. The present invention is directed to meeting this need, as well as others described herein.
DISCLOSURE OF THE INVENTION
In set top boxes, there is an increasing need to be able to play multiple audio streams concurrently by mixing two streams together to a single composite output. As a further example, message overlays can be used when web browsing, while simultaneously watching either a program or listening to other audio content. Service providers are requiring this support for their designs.
Existing solutions have focused on combining the audio streams in the analog domain after decoding and digital to analog conversion. One technique for analog mixing is described in the above-referenced patent application entitled “System And Method For Merging Multiple Audio Streams.” However, recognized herein is a need for a facility for digitally processing multiple streams of audio data, and for simultaneously outputting of both a mixed digital audio signal and an unmixed digital audio signal, for example, for simultaneous listening and taping, respectively.
Briefly summarized, therefore, the present invention meets these needs by providing a method for processing digital audio data which includes: receiving a first stream of digital audio data and a second stream of digital audio data; outputting the first stream of digital audio data as an unmixed digital audio signal; and digitally mixing the first stream of digital audio data and the second stream of digital audio data and outputting based thereon a mixed digital audio signal, wherein the mixed digital audio signal is output concurrent with output of the unmixed digital audio signal.
In enhanced aspects, the method includes concurrently receiving into an audio decoder the first and second streams of digital audio data through dedicated real time interfaces, wherein the audio decoder decodes at least one of the first stream of digital audio data and the second stream of digital audio data. Further, if digitized at different rates, resampling of the second stream of audio data can occur based on a sample frequency of the first stream of digital audio data. Also, n additional streams of digital audio data, wherein n≧1, can be received and digitally mixed for output as the mixed digital audio signal.
Systems, articles of manufacture and program storage devices corresponding to the above-summarized processing facilities are also described and claimed herein.
Advantageously, in one embodiment the present invention provides an ability to send a second stream of digital audio data to an audio decoder for processing by its internal digital signal processor, e.g., using a second “clip mode” type interface such as that described in the above-incorporated application entitled “Method To Play Audio And Video Clips
Curley Lawrence D.
Driftmyer James F.
Foster Eric M.
Heslin Rothenberg Farley & & Mesiti P.C.
International Business Machines - Corporation
Lao Lun-See
Nguyen Duc
Radigan, Esq. Kevin P.
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