Coded data generation or conversion – Analog to or from digital conversion – Digital to analog conversion
Reexamination Certificate
2002-07-26
2003-11-04
Jeanpierre, Peguy (Department: 2819)
Coded data generation or conversion
Analog to or from digital conversion
Digital to analog conversion
C700S094000, C381S119000
Reexamination Certificate
active
06642876
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a coder/decoder(“codec”), and, more particularly, to providing and operating a codec in a particular operational mode. More specifically, the present invention relates to operating a codec in a digital centric mode.
2. Description of Related Art
A coder/decoder(“codec”) is considered to be any technology that encodes or decodes a signal. For example, telephone companies use codecs to convert binary signals transmitted on their digital networks to analog signals converted on their analog networks.
Also, an exemplary type of audio codec is the audio codec (“AC”) '97, which Intel Corporation has published in various revisions of the specification entitled
Audio Codec '
97 (“
AC '
97) (e.g., revision 2.2 in September 2000; revision 2.1 in May 22, 1998; revision 2.0 in Sep. 29, 1997; revision 1.03 in Sep. 15, 1996). The AC '97 specification and its various revisions are hereby incorporated by reference.
The AC '97 specification, revision 1.03 comprehensively defines a serial codec device that is designed to be used in systems in which audio signal processing and audio analog-to-digital (A/D) and digital-to-analog (D/A) conversions are performed in separate devices. The AC '97 specification, revision 2.0 is a follow-up revision to revision 1.03 and further defines the interface for a combined audio/telephony codec. Revision 2.0 also includes definitions for modem sample rate control, tagged data exchange using different sampling rates, general purpose input/output definitions, and extended AC-link definitions for multiple devices and power management event handling. Revision 2.1 updates revisions 1.03 and 2.0 by including some electrical and power management updates. Revision 2.2 provides further updates to revision 2.1 by adding optional S/PDIF support, standardized slot re-mapping, and updated electrical specification for better riser support.
An AC '97 codec typically processes signals by first mixing the digital signals. The mixed digital output signal is then converted into a converted analog signal. The converted analog signal is then mixed with other analog signals. The AC '97 codec provides a mixed analog output signal. However, in some applications, the AC '97 receives and processes digital signals that otherwise are unavailable as analog signals unless further conversions are performed.
For example, the AC '97 codec may be utilized in an audio card of a notebook computer. The AC '97 codec may receive digital signals from a docking station in which the digital signals were originally converted from analog signals of analog sources at the docking station. The digital signals are generally unavailable as analog signals to the AC '97 codec unless further conversions are otherwise performed. If conversions are performed, then digital-to-analog converters (DACs) must be additionally utilized. The use of additional DACs adds to the overall size and cost of the audio circuit, and the DACs further processing the signals may add to the overall noise and distortion of the processed signals. Also, the opportunity for the AC '97 codec to in effect add any digital effects to the analog signals that otherwise would not have digital effects is lost since the process steps for the AC '97 codec is to initially mix the digital signals, convert the mixed digital signal into an analog signal, and then mix the analog signals.
As another example, the AC '97 codec may be utilized in a set-top box for processing audio signals. The set-top box has a circuit in which a portion of the circuit only handles, processes, and/or generates digital audio signals. If the AC '97 codec were to receive the digital audio signals, then additional DACs need to be utilized to convert the digital signals to analog signals. Otherwise, the digital signals are unavailable as analog signals to the AC '97 codec unless further conversions are performed. Again, DACs add to the overall size and cost of the audio circuit for the set-top box and add to the overall noise and distortion of the processed signals. Also, the opportunity for the AC '97 codec to in effect add any digital effects to the analog signals that otherwise do not have the digital effects is lost since the process steps for the AC '97 codec is to initially mix the digital signals, convert the mixed digital signal into an analog signal, and then mix the analog signals.
According to the current method as to how an audio codec processes signals, the audio codec cannot in effect add digital effects to the analog signals. Since the digital effects are missing from the analog signals, then the output of the audio codec does not entirely reflect what is being recorded or played back when digital effects have been added to the digital signals and, in effect, to the analog signals as well.
The present invention recognizes the desire and need for a codec to receive and process digital signals, which relate to the audio source signals without having to perform any additional conversions. The present invention further recognizes the desire and need to avoid the use of additional DACs, which would otherwise add to the overall size, cost, noise and distortion of an audio circuit. The present invention also recognizes the desire and need for the codec to be able to add digital effects to the analog signals that would otherwise not have the digital effects so that the output reflects what is being recorded or played back when digital effects have been added to the digital signals and, in effect, to the analog signals as well. The present invention overcomes the problems and disadvantages that have been encountered with the prior art.
SUMMARY OF THE INVENTION
A system and method of operating a codec in an operational mode are disclosed. The codec is operated in a digital centric mode. Operation in the digital centric mode involves the following: An analog mixer of the codes first mixes analog signals, if any, to produce a mixed analog signal. An analog-to-digital converter converts the mixed analog signal into a converted digital signal. A digital mixer mixes the converted digital signal with digital signals that are otherwise generally unavailable as analog signals to the codec unless further conversions are performed to produce a mixed digital signal. A digital-to-analog converter converts the mixed digital signal into a mixed analog signal. A digital processor may perform digital effects processing on the mixed digital signal to add digital effects to the mixed digital signal. The codec is still able to alternatively operate in an analog centric mode, a host processing mode, or a multi-channel mode.
The above as well as additional objects, features, and advantages of the present invention will become apparent in the following detailed written description.
REFERENCES:
patent: 4694343 (1987-09-01), Flora
patent: 4694344 (1987-09-01), Flora
patent: 5546466 (1996-08-01), Ishiguro et al.
patent: 6218971 (2001-04-01), Sugihara
patent: 6259957 (2001-07-01), Alexander et al.
patent: 6350943 (2002-02-01), Suruga et al.
Puchert Jens
Straup Brian K.
Subramoniam Krishnan
Cirrus Logic Inc.
Jeanpierre Peguy
Lin, Esq. Steven
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