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    3.
    发明专利
    未知

    公开(公告)号：DE69808146T2

    公开(公告)日：2003-05-15

    申请号：DE69808146

    申请日：1998-01-12

    Applicant: ST MICROELECTRONICS ASIA

    Inventor： ABSAR JAVED ,  GEORGE SAPNA ,  ALVAREZ-TINOCO MARIO

    IPC: H03M7/00 ,  H04B1/66

    Abstract: A method and apparatus for coding audio data in a frequency transform digital audio coder employing differential frequency coefficient exponent coding. Differential coding of exponents places constraints on possible values an exponent can take, which can lead to distortion in the decoded and reconstructed audio signal. The method and apparatus herein can overcome this restriction by mapping the input exponent set to a new set of values which satisfy the differential constraint as well as reducing information loss, thereby minimizing overall signal distortion due to coding restrictions.

    4.
    发明专利
    未知

    公开(公告)号：DE69711102T2

    公开(公告)日：2002-11-07

    申请号：DE69711102

    申请日：1997-12-27

    Applicant: ST MICROELECTRONICS ASIA

    Inventor： ABSAR JAVED ,  GEORGE SAPNA ,  ALVAREZ-TINOCO MARIO

    IPC: H04B1/66 ,  H04S1/00

    Abstract: A method and apparatus for determining parameters for coupling of channels in a digital audio encoder. A frequency range of two audio channels is coupled together in a coupling channel, and a systematic method of determining optimum coupling parameters is employed. Sub-bands of the channels are processed individually, and a measure of the power of each sub-band is used to determine a coupling coefficient generation scheme for each individual sub-band. Adjacent ones of the sub-bands using the same coupling scheme are combined to form bands in the coupling channel, which dictate the generation of the coupling coordinates for the audio channels. The arrangement of the sub-bands in bands also facilitates the generation of phase flags for each band, on the basis of the coupling scheme used in the band.

    5.
    发明专利
    未知

    公开(公告)号：DE69813912T2

    公开(公告)日：2004-05-06

    申请号：DE69813912

    申请日：1998-10-26

    Applicant: ST MICROELECTRONICS ASIA

    Inventor： ABSAR JAVED ,  GEORGE SAPNA ,  ALVAREZ-TINOCO MARIO

    IPC: G10L19/02 ,  G10L19/14 ,  G10L19/16 ,  G06F19/00

    Abstract: AC-3 is a high quality audio compression format widely used in feature films and, more recently, on Digital Versatile Disks (DVD). For consumer applications the algorithm is usually coded into the firmware of a DSP Processor, which due to cost considerations may be capable of only fixed point arithmetic. It is generally assumed that 16-bit processing is incapable of delivering the high fidelity audio, expected from the AC-3 technology. Double precision computation can be utilized on such processors to provide the high quality; but the computational burden of such implementation will be beyond the capacity of the processor to enable real-time operation. Through extensive simulation study of a high quality AC-3 encoder implementation, a multi-precision technique for each processing block is presented whereby the quality of the encoder on a 16-bit processor matches the single precision 24-bit implementation very closely without excessive additional computational complexity.

    7.
    发明专利
    未知

    公开(公告)号：DE69722973D1

    公开(公告)日：2003-07-24

    申请号：DE69722973

    申请日：1997-12-19

    Applicant: ST MICROELECTRONICS ASIA

    Inventor： ABSAR JAVED ,  GEORGE SAPNA ,  ALVAREZ-TINOCO MARIO

    IPC: H04B1/66 ,  H04S1/00

    Abstract: A method and apparatus for subband phase flag determination for coupling of channels in a dual channel audio encoder is based on a psychoacoustic model of the human auditory system. The method and apparatus are applicable to audio encoders which utilize a coupling channel to combine certain frequency components of the input audio signals. The method ensures a least square error between the original channel frequency coefficients at the encoder and the estimated coefficients at the decoder by determining the sign of the dot product of the coefficients for one of the channels and the coupling coefficients. No restriction is placed on the strategy utilized for generating the coupling channel coefficients or the coupling coordinates.

    8.
    发明专利
    未知

    公开(公告)号：DE69813912D1

    公开(公告)日：2003-05-28

    申请号：DE69813912

    申请日：1998-10-26

    Applicant: ST MICROELECTRONICS ASIA

    Inventor： ABSAR JAVED ,  GEORGE SAPNA ,  ALVAREZ-TINOCO MARIO

    IPC: G10L19/02 ,  G10L19/14 ,  G10L19/16 ,  G06F19/00

    Abstract: AC-3 is a high quality audio compression format widely used in feature films and, more recently, on Digital Versatile Disks (DVD). For consumer applications the algorithm is usually coded into the firmware of a DSP Processor, which due to cost considerations may be capable of only fixed point arithmetic. It is generally assumed that 16-bit processing is incapable of delivering the high fidelity audio, expected from the AC-3 technology. Double precision computation can be utilized on such processors to provide the high quality; but the computational burden of such implementation will be beyond the capacity of the processor to enable real-time operation. Through extensive simulation study of a high quality AC-3 encoder implementation, a multi-precision technique for each processing block is presented whereby the quality of the encoder on a 16-bit processor matches the single precision 24-bit implementation very closely without excessive additional computational complexity.

    9.
    发明专利
    未知

    公开(公告)号：DE69711102D1

    公开(公告)日：2002-04-18

    申请号：DE69711102

    申请日：1997-12-27

    Applicant: ST MICROELECTRONICS ASIA

    Inventor： ABSAR JAVED ,  GEORGE SAPNA ,  ALVAREZ-TINOCO MARIO

    IPC: H04B1/66 ,  H04S1/00

    Abstract: A method and apparatus for determining parameters for coupling of channels in a digital audio encoder. A frequency range of two audio channels is coupled together in a coupling channel, and a systematic method of determining optimum coupling parameters is employed. Sub-bands of the channels are processed individually, and a measure of the power of each sub-band is used to determine a coupling coefficient generation scheme for each individual sub-band. Adjacent ones of the sub-bands using the same coupling scheme are combined to form bands in the coupling channel, which dictate the generation of the coupling coordinates for the audio channels. The arrangement of the sub-bands in bands also facilitates the generation of phase flags for each band, on the basis of the coupling scheme used in the band.

    10.
    发明专利
    未知

    公开(公告)号：DE60121632D1

    公开(公告)日：2006-08-31

    申请号：DE60121632

    申请日：2001-05-17

    Applicant: ST MICROELECTRONICS ASIA

    Inventor： TIAN WEN SHUN ,  ALVAREZ-TINOCO MARIO

    IPC: H04B3/23 ,  H04M9/08

    Abstract: In a communications system having incoming communications signals and outgoing communications signals the outgoing communications signals may undesirably include an echo signal derived from the incoming communications signals. Accordingly, echo cancellation techniques may be applied in the communications system, including generating weighting filter coefficients based on linear prodictive coding coefficients calculated from a block comprising a plurality of sequential samples of the incoming communications signals. The incoming communications signals are filtered through a weighting filter utilising the weighting filter coefficients to produce a weighted incoming communications signals. Estimated echo signals are generated by filtering the incoming communications signals through an adaptive transversal filter, the adaptive transversal filter using adaptive filter coefficients. Then, the estimated echo signals can be subtracted from the outgoing communications signals to produce error signals. Advantageously, the adaptive filter coefficients are determined for each sample in said block on the basis of the weighted incoming communications signals and the error signals.

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