A video decoder compliant with the Advanced Television Systems Standard (ATSC) includes circuitry which decodes an ATSC encoded image and employs a downconversion process to produce a standard definition video signal. The video decoder includes a frequency-domain filter to reduce the resolution of the ATSC encoded signal. The video decoder downconversion system also includes a formatting section having vertical and horizontal filters, as well as resampling processing, to format the decoded and downconverted video image for a particular display and aspect ratio. The decoder senses the display format of the encoded video signal and changes the processing provided by the decoder to produce a standard definition output signal regardless of the display format of the encoded input signal. The system also includes a format converter which may be programmed to use a plurality of methods to convert the aspect ratio of the input signal for display on a display device having a different aspect ratio. In one mode, the system sequences through the possible methods to allow the user to select one method.

Hdtv downconversion system

A signal processing system comprises inputs for an analog audio signal and a digital data signal. The digital data signal is modulated to an analog data signal in an inaudible frequency band. Filters are used to ensure that the audio signal is restricted to audible frequencies and that the analog data signal is restricted to inaudible frequencies. The two analog signals are then combined into a composite analog signal. The composite signal is stored on a medium such as a compact disc. Filters are used to extract and separate the two analog signals from the composite signal stored on the medium. The analog data signal is demodulated to retrieve the original digital data signal.

System for carrying transparent digital data within an audio signal

A high-definition television receiver includes circuitry to decode a received high-definition television signal to produce a digital data stream representing the corresponding high-definition television image. In addition, the receiver includes circuitry which generates a signal representing a reduced resolution image from the decoded data stream. The receiver provides both the high-definition television signal and the reduced resolution signal at an output port. A video tape recorder (VTR) receives the two signals, segments them and formats them onto the tape in a manner which allows a majority of the reduced resolution segments to be recovered and displayed in at least one of the VTR's trick-play modes. The reduced resolution image may be from the same channel or from a different channel and may also be displayed as an inset picture (PIX-IN-PIX) in the main high-definition image.

Digital high definition television receiver with features that facilitate trick-play modes on a digital vcr

Provided is a video coding method and a video decoding method increasing the resolution and quality of images while suppressing an amount of data required for increasing the resolution. A video coding apparatus includes a first orthogonal transformation unit performing discrete cosine transform on an input picture signal, a low-pass filter performing low-pass filtering on the input picture signal, a downsampling unit downsampling the resolution of a low-frequency image signal, a coding unit compressing and coding a reduced image signal, a local decoding unit decoding a coded bit stream, a second orthogonal transformation unit performing discrete cosine transform on a decoded image signal, and a modification information generation unit generating, based on input image DCT coefficients and decoded image DCT coefficients, coefficient modification information used for modifying orthogonal transformation coefficients obtained by performing orthogonal transformation on a decoded video signal obtained from a coded bit stream.

Video encoding method and video decoding method

The present invention relates to an encoding apparatus, an encoding method, an encoding program, a decoding apparatus, a decoding method and a decoding program for adaptively controlling an encoding bit rate. Coefficient data obtained using wavelet transform is quantized, and segmented into bit planes. The coefficient data is entropy encoded from the bit plane of the MSB in a direction from an upper bit position to a lower bit position. Entropy encoding is stopped at a bit position where an amount of code has reached a target amount. On the bit plane, the coefficient data is entropy encoded from a lower frequency region to a higher frequency region. Data greatly affecting subjective image quality of a decoded image is selectively output while the amount of code is easily controlled.

Encoding device, encoding method, encoding program, decoding device, decoding method, and decoding program

A digital signal magnetic recording/reproducing apparatus converts a digital signal into multi-value digital signals and performs recording/reproducing of a multi-value quadrature amplitude-modulated signal. By using the multi-value quadrature amplitude modulation, it is possible to remove the DC component in the recording signal and improve the utilization efficiency of the recording frequency band. Further, using a system to memorize the frequency characteristic of the magnetic recording/reproducing unit and effect Viterbi decoding regarding the intersymbol interference caused by the frequency as a convolutional coding, it is possible to detect the level without necessitating frequency equalization. Accordingly, there arises no deterioration of the S/N ratio by frequency equalization. Furthermore, by providing an encoder for error control coding by increasing the number of multi-values and a corresponding decoder, the error rate can be improved against the deterioration of the S/N ratio. Further, by bias recording the multi-value quadrature amplitude modulated signal, non-linearity of the electromagnetic conversion system is relaxed, and deterioration of the S/N ratio by distortion is improved.

Digital signal magnetic recording/reproducing apparatus using multi-level QAM modulation and maximum likelihood decoding

A digital signal magnetic recording/reproducing apparatus converts a digital signal into a multi-value digital signal, followed by recording/reproducing the quadrature biphase modulated multi-value quadrature amplitude modulated signal. By using a multi-value quadrature amplitude modulation, a direct current component in the recorded signal can be eliminated, and the utilization efficiency of the recording frequency band of the digital signal magnetic recording/reproducing apparatus can be improved. Also, with respect to the amplitude non-linear characteristic which occurs in the magnetic recording/reproducing process, by providing a compensating circuit during the mapping before recording or after reproducing and demodulating, the deterioration of the S/N ratio of the reproduced and demodulated signal can be reduced to decrease the errors in the decoded data. Furthermore by bias-recording the multi-value quadrature amplitude modulation signal, the non-linearity of the electromagnetic conversion system is alleviated to decrease the deterioration of the S/N ratio due to distortion, thereby making the application of the modulation scheme more reliable.

Digital signal magnetic recording/reproducing apparatus

A disclosed time base corrector comprises a clock generater for generating a clock signal whose period is fixed, an analog-to-digital converter for sampling amplitude values of an input analog signal having a time base error at sampling points given by the clock signal, an adaptive interpolation filter for interpolating a correct amplitude value at a resampling indicated by a resampling position signal, a resampling position signal producing circuit for detecting the time base error and producing from the detected error the resampling position signal, and a digital-to-analog converter for converting the interpolated amplitude values to an analog signal which has no time base errors. The time base correction is implemented by pure digital signal processing without any analog signal processing. The time base corrector does not use such a clock signal that has time base fluctuations.

Time base corrector

An encoding and decoding apparatus for a video signal and a high-definition television signal is disclosed. For the picture A having the horizontal to vertical screen frame ratio of 4:3, the picture B having the horizontal to vertical screen frame ratio of 16:9 and the picture C having the horizontal to vertical screen frame ratio of 16:9 and having a larger number of vertical pixels than that of the picture A and picture B, the apparatus limits the band of the picture C to obtain the picture D having the same numbers of horizontal and vertical pixels respectively as those of the picture B, and high-efficiency encodes the picture A, picture B or picture D in the same method. The apparatus obtains the additional picture E which is a difference between the picture D and the picture C, or a difference between the picture D' which is a result of decoding a signal that has been obtained by high-efficiency encoding the picture D and the picture C, and then high-efficiency encodes the additional picture E obtained.

Video signal encoding and decoding apparatus

When a standard TV signal of digital format is a first video signal and another digitized TV signal having a bandwidth wider than that of the first video signal is a second video signal, every two frames of the second video signal are calculated to produce a pixel value sum of the two frames and a pixel value difference between the same and either a resultant interframe calculated output or the first video signal is compressed through two-dimensional orthogonal transformation for ease of storage.

Toyohiko Matsuta

Papers

Digital signal magnetic recording/reproducing apparatus using multi-level QAM modulation and maximum likelihood decoding

Digital signal magnetic recording/reproducing apparatus

Time base corrector

Video signal encoding and decoding apparatus

Video signals recorder and player including interframe calculating means