Abstract: In a digital signal recording and playback device, the transmission rate of input transport packets is identified. A recording mode, a rate at which data is to be recorded, is set on the basis of the identified transmission rate. Intra-frame or intra-field coded digital video data is extracted from the transport packets, and the extracted intra-frame or intra-field coded digital video data is reconstructed to generate special playback data. A recording format is generated such that the input transport packets and special playback data will be recorded at predefined positions on a track of a recording medium. The number of repetitions of the special playback data to be recorded on the recording medium or the recording format is varied depending on the recording mode. Because of the improvement in the recording rate of the fast playback data, the playback picture quality during fast playback can be improved.

Abstract: In a magnetic recording/playback apparatus for recording and playing back a digital video signal on a helical track of a magnetic tape using two or more rotary heads, the playback image at the time of high-speed playback is improved by setting the tape travel speed at the time of high-speed playback at an even multiple of a normal playback speed. Further, a tracking phase is offset by one half the track pitch with respect to the tracking during normal speed playback. Alternatively, essential information of the information having been high-efficiency coded is recorded in the central part, and near the ends of the tracks, while high-precision information is recorded in intermediate parts intermediate between the central part and the parts near the ends. Still alternatively, the video data of one of the consecutive fields is recorded in the central part of the tracks and the video data of the other of the consecutive fields is recorded near the ends of the tracks.

Abstract: According to a first aspect of the invention, digital image data are recorded in the form of compressed codewords with check information and flags. The flags indicate codewords containing uncorrected errors. Each time the data are copied, error detection and correction are performed and the flags are updated to indicate any new uncorrectable errors that are detected. The flags can be used for error concealment, to avoid error miscorrection, and to permit the check information to be regenerated each time the data are copied. According to a second aspect of the invention, when image data are copied, the same check information is used to perform error detection and correction twice. Flags identifying uncorrected errors can be transferred from the first error-detecting-and-correcting process to the second.

Abstract: A video signal is divided into blocks, and an orthogonal transform is performed on each block to obtain transformed coefficients. Of the transformed coefficients thus obtained, dominant transformed coefficients are selected from a low-frequency area and a high-frequency area, and based on the dominant transformed coefficients, an evaluation value is calculated, using which value a specific pattern in the video signal is detected. Based on the specific pattern thus detected, an optimum quantization step size is decided, and the transformed coefficients are adaptively quantized, thus preventing image quality degradation.

Abstract: A magnetic recording and reproducing apparatus capable of recording video, audio and other information on a magnetic tape by, for example, the helical scanning method. A rotary head is rotated at an m-fold speed to record intermittent tracks on the magnetic tape so that real-time simultaneous monitoring is performed. By high-speed dubbing due to high-density intermittent recording and by increasing the number of repetition of track scanning, the information is recorded and reproduced simultaneously with a plurality of channels. Any tracking error is detected to form a continuous and uniform track pattern. With this intermittent comb-shaped recording, reciprocating recording and reproducing can be realized.

Abstract: A codeword contains information symbols representing elements of a Galois field, a parity check symbol generated using a certain element of the Galois field, and additional check symbols generated using a polynomial of which this certain element is not a root. The reliability of corrected codewords is assessed by counting the number of symbols found to be in error, or by counting the number of symbols having at least a certain number of bits in error. When a row-column array is decoded, rows of intermediate reliability are not corrected but their error patterns are stored in a memory, and columns of intermediate reliability are corrected if their error patterns match the error information stored in the memory.

Abstract: To reduce the undetected errors without degradation of the burst error correction capability, in error correction decoding of the digital signal with three-dimensional error correction codes appended thereto. For correcting errors by applying error correction codes in three directions of a recording direction, perpendicular direction, and direction of tracks, whether a burst error has occurred is checked, and an error-correction decoding algorithm is switched between one used when a burst error has occurred, and one used when no burst error has occurred.

Abstract: Data separating means extracts intra-frame or intra-field encoded blocks from an intra-frame or intra-field encoded, and inter-frame or inter-field encoded digital video signal, and a digital audio signal contained in an input bit stream. Error correction code appending means appends error correction codes to the extracted intra-encoded blocks. Recording means records the data having the error correction code appended, in special replay data recording areas predefined on the magnetic recording tape. During fast replay or slow replay, error correction is achieved even for the replay signal with a low output level and a poor symbol rate.

Abstract: A digital video tape recorder has interpolation and crossfading circuits and records audio and video signals in independent frames, the audio frames being offset with respect to the video frames. For a four-channel audio signal, the even and odd samples are recorded near different edges of the tape, enabling burst errors near one edge to be recovered efficiently by interpolating the audio signal from the other edge. When audio dubbing is performed, the first and last dubbed frames contain the even samples of the new signal and the odd samples of the old signal, or vice versa, and audio-dubbing flags are recorded in the these frames. When these frames are played back, the old and new signals are regenerated by interpolation and crossfaded to create a smooth transition between them. The same apparatus can also be used to record a two-channel signal, by recording each sample twice.

Abstract: According to a first aspect of the invention, digital image data are recorded in the form of compressed codewords with check information and flags. The flags indicate codewords containing uncorrected errors. Each time the data are copied, error detection and correction are performed and the flags are updated to indicate any new uncorrectable errors that are detected. The flags can be used for error concealment, to avoid error miscorrection, and to permit the check information to be regenerated each time the data are copied. According to a second aspect of the invention, when image data are copied, the same check information is used to perform error detection and correction twice. Flags identifying uncorrected errors can be transferred from the first error-detecting-and-correcting process to the second.

Abstract: Fast speed playback is performed with a reduced error-correcting capability as compared with that for normal speed playback. Information of K symbols is encoded with a first error-correcting code C1 and appended with (N-K) check symbols. After that, m symbols out of the check symbols are punctured, and the information of K symbols is divided into a block of K.sub.1 symbols and a block of K.sub.2 symbols, the block of K.sub.1 symbols being further encoded with a second error-correcting code Cm and appended with m.sub.1 check symbols for error correction. For efficient error-correction coding of auxiliary data which is usually not used but which becomes necessary on occasions, the presence or absence of auxiliary data is written in ID information, and the number of error-correcting check symbols is changed accordingly.

Abstract: When recording HD video signals, twice the number of tracks are used as compared to recording the conventional NTSC video signals, and video signals are recorded in the audio sector. HD video signals are encoded with the same number of checks as the error-correcting code of the present video signals, with the number of information symbols being increased. When recording HD video signals and present video signals, these signals are encoded so that the shortest recording wavelength is the same with either signal.

Abstract: In program retrieval using a magnetic tape in which programs are classified by index signals recorded on the tape, an image at the beginning of each program is displayed in a list on a multi-screen, and a desired program is directly selected using a count value of index signals. In recording, an index signal is recorded at a starting point of recording. When preparing a multi-screen at the time of reproducing, an image reproduced a predetermined time after detection of an index signal is reduced and stored in a memory.

Abstract: An encoding apparatus which structures a band-divided digital image signal into three-dimensional blocks each having a plurality of pixels, discriminates each three-dimensional block between a moving image block and a static image block, and, in the case of a static image block, encodes only the three-dimensional blocks in the lower frequency bands while dropping the three-dimensional blocks in the higher frequency bands. However, of moving image blocks, blocks having a large pixel variance value are encoded as effective image blocks. Also, different size weightings are performed to transform coefficients depending on whether the block is discriminated as a moving image block or a static image block. Furthermore, shuffling is performed on a group of moving image blocks and a group of static image blocks independently of each other, and the transform coefficients for the static image blocks are quantized after quantizing all transform coefficients for the moving image blocks.

Abstract: A variable length coding method designed to assign a different number of coding bits in accordance with the information content a sample holds when an analog signal such as a television signal or the like is converted to a digital signal. An assigning method of coding bits used to a luminance signal is different from that used to a chrominance signal. A variable length coding method is further capable of selecting an optimum assigning method in accordance with contents of an original signal from a plurality of determined assigning methods of coding bits. The data related to the plurality of assigning methods of coding bits is recorded on a medium after it is added to a coded digital signal.

Abstract: Codewords with CDS=0 are mapped in corresponding relationship to datawords, and codewords with CDS>0 and codewords with CDS<0 are paired together and mapped in corresponding relationship to the remaining datawords, and further, codewords with CDS.noteq.0, left unmapped, are mapped in corresponding relationship to the datawords to which the codewords with CDS=0 have been mapped, thus reducing the probability of occurrence of codewords with large DSV in absolute value terms and thereby achieving a further suppression of low-frequency components. Based on the least significant bit of the codeword corresponding to the last dataword and on the current and next datawords, a codeword corresponding to the current dataword is selected, thus realizing high-density recording with good overwrite characteristics.

Abstract: A digital video tape recorder has interpolation and crossfading circuits and records audio and video signals in independent frames, the audio frames being offset with respect to the video frames. For a four-channel audio signal, the even and odd samples are recorded near different edges of the tape, enabling burst errors near one edge to be recovered efficiently by interpolating the audio signal from the other edge. When audio dubbing is performed, the first and last dubbed frames contain the even samples of the new signal and the odd samples of the old signal, or vice versa, and audio-dubbing flags are recorded in the these frames. When these frames are played back, the old and new signals are regenerated by interpolation and crossfaded to create a smooth transition between them. The same apparatus can also be used to record a two-channel signal, by recording each sample twice.

Abstract: In a magnetic recording/playback apparatus for recording and playing back a digital video signal on a helical track of a magnetic tape using two or more rotary heads, the playback image at the time of high-speed playback is improved by setting the tape travel speed at the time of high-speed playback at an even multiple of a normal playback speed. Further a tracking phase is offset by one half the track pitch with respect to the tracking during normal speed playback. Alternatively, essential information of the information having been high-efficiency coded is recorded in the central part, and near the ends of the tracks, while high-precision information is recorded in intermediate parts intermediate between the central part and the parts near the ends. Still alternatively, the video data of one of the consecutive fields is recorded in the central part of the tracks and the video data of the other of the consecutive fields is recorded near the ends of the tracks.

Abstract: In a high-efficiency encoder which performs motion-compensation prediction, an intra-field is set every n fields. The presence of a scene change is detected. When a scene change occurs, a reference picture of motion-compensation prediction is switched, or the field immediately after the scene change is set as an intra-field. In intra encoding mode, a digital video signal is encoded after dividing the digital video signal into subbands, and in predictive encoding mode, the digital video signal is encoded without dividing it into subbands.

Abstract: A coding method and apparatus is for coding a digital video signal of interlaced type. Three-dimensional (horizontal, vertical and temporal directions) blocks are constructed for each of a plurality of picture elements, orthogonal transform is performed to each of the three-dimensional blocks and coefficients are coded. Coefficients non-effected by a pseudo-moving part are weighted with a low rate, and coefficients effected by a pseudo-moving part are weighted with high rate. After the vertical positions of picture elements of odd-number fields and those of even-number fields are coincided with each other by an intra-field picture element operation, the digital video signal is formatted and three-dimensional orthogonal transform is performed.