Abstract: A rounding accuracy of DCT coefficients that are quantized is dynamically varied with a simple structure. As a result, an encoding noise is effectively suppressed and the picture quality is prevented from being deteriorated. DCT coefficients of which a picture signal is transformed by DCT are input to a quantizing circuit 30. The quantizing circuit 30 quantizes the DCT coefficients with a quantizer matrix and supplies the quantized DCT coefficients to a multiplying device 33 through an absolute value circuit 31. A quantizer scale value based on the generated code amount of the entire screen is converted into an invert value thereof and then supplied to a multiplying device 33. In addition, an M value designating circuit 38 designates a value M as a parameter with which a rounding accuracy of DCT coefficients that are quantized is controlled according to a quantizer scale value. An adding device 34 adds the value M to an output of the multiplying device 33.

Abstract: A selector has both a function for creating a header of a sequence layer and a header of a picture layer corresponding to reproduced data of a system area and a function for outputting one of an input stream and a stream of which a created header has been added to the header of the input stream as an output stream. When the mode is not high speed reproducing mode, the selector outputs the header contained in the input stream as a header of the output stream. When the mode is high speed reproducing mode, a header (the header of the sequence layer and the header of the picture layer) is created corresponding to data reproduced from the system area. The selector outputs an output stream of which the created header has been added to the input stream.

Abstract: A residue code amount is calculated. A threshold act_thrsh corresponding to the residue code amount is obtained. A variable mb that designates a macro block is initialized to zero. The variable mb is compared with the total number of macro blocks. When the variable mb matches the total number of macro blocks, the process is completed. Otherwise, the rank of the activity information of the macro block designated by the variable mb is compared with the rank of the threshold act_thrsh. When the rank of the activity information is lower than the rank of the threshold act_thrsh, since there is a possibility of which q_scale can be decreased, q_scale is calculated with the activity information of the macro block mb and min_qq. q_scale of the macro block is subtracted from the total code amount. The subtracted resultant data is stored in a variable tmp. Thereafter, the variable tmp is compared with a target code amount GEN_TGT.

Abstract: MPEG streams of different chroma formats are recorded and reproduced without need to recognize their formats. In an MPEG stream, a header is followed by DCT blocks. Time slots are generated in such a manner that when the chroma format detected from the header is 4:2:2, in all periods of DCT blocks, a process is performed and that when the chroma format detected from the header is 4:2:0, a process is not performed in periods for DCT blocks Cb2 and Cr2 that are not present in the chroma format 4:2:2. The read order of a stream is changed in a memory so as to improve an error resistance. DCT coefficients are rearranged in the order of DC components and AC components from the lowest order component to the highest order component over all DCT blocks. After the stream has been rearranged, time slots are generated in such as manner that when the chroma format is 4:2:0, the process is stopped in the periods for Cb2 and Cr2.

Abstract: The header of the sequence layer of an input sequence is written to a RAM. Information of a typical header is pre-stored to a ROM. The selecting operation of a selector is controlled by an output of a detecting portion. When the input sequence contains the header of the sequence layer, the selector selects as an output stream the stream of which the header has been added to each frame. In contrast, when the stream does not contain the header, the header stored in the RAM or the ROM is added to each frame of the stream. In this case, the header stored in the RAM is added to each frame with higher priority than the header stored in the ROM. The header has been always added to each frame of a stream that is output from the selector.

Abstract: MPEG streams of different chroma formats are recorded and reproduced without need to recognize their formats. In an MPEG stream, a header is followed by DCT blocks. Time slots are generated in such a manner that when the chroma format detected from the header is 4:2:2, in all periods of DCT blocks, a process is performed and that when the chroma format detected from the header is 4:2:0, a process is not performed in periods for DCT blocks Cb2 and Cr2 that are not present in the chroma format 4:2:2. The read order of a stream is changed in a memory so as to improve an error resistance. DCT coefficients are rearranged in the order of DC components and AC components from the lowest order component to the highest order component over all DCT blocks. After the stream has been rearranged, time slots are generated in such as manner that when the chroma format is 4:2:0, the process is stopped in the periods for Cb2 and Cr2.

Abstract: A residue code amount is calculated. A threshold act_thrsh corresponding to the residue code amount is obtained. A variable mb that designates a macro block is initialized to zero. The variable mb is compared with the total number of macro blocks. When the variable mb matches the total number of macro blocks, the process is completed. Otherwise, the rank of the activity information of the macro block designated by the variable mb is compared with the rank of the threshold act_thrsh. When the rank of the activity information is lower than the rank of the threshold act_thrsh, since there is a possibility of which q_scale can be decreased, q_scale is calculated with the activity information of the macro block mb and min_qq. q_scale of the macro block is subtracted from the total code amount. The subtracted resultant data is stored in a variable tmp. Thereafter, the variable tmp is compared with a target code amount GEN_TGT.

Abstract: An apparatus and method for processing a stream compressed and encoded with a variable length code (VLC) in a predetermined unit by detecting an error flag that has been set. The flag corresponds to a position of an error when the error is contained in the stream. Adding information representing an end of the VLC, based on the error flag, to the position corresponding to the error flag in a string of the VLC containing the error flag. Thus, the VLC after the error flag can be discarded. Additionally, an apparatus and method for processing a stream encoded with a VLC by detecting a code symbol that does not match a parameter representing the VLC from the VLC stream. Correcting the stream based on the detected result, and designating the start of the next process after the detected result has been obtained. Thus, even if a stream containing an irregular VLC is input, the apparatus can be operated in a stable mode.

Abstract: A detection circuit detects a slice start code from an input stream. Based on a result of the detection and a frame pulse, a reference macroblock (MB) address generated by a timing generator is sent to an address comparator. The input stream which has been phase-adjusted by a delay circuit is supplied to a variable length decoder (VLD) for decoding a variable length code to detect an MB address. The address comparator compares the reference MB address with the MB address to check the continuity of the MB address. If it is discontinuous, the stream output from the VLD is temporarily interrupted, and a selector selects a replacement data generating circuit in response to a control signal output from the address comparator. The input stream is replaced at a discontinuous macroblock portion with macroblock data which has a correct macroblock address and which is prepared in advance by the replacement data generating circuit.

Abstract: A residue code amount is calculated. A threshold act_thrsh corresponding to the residue code amount is obtained. A variable mb that designates a macro block is initialized to zero. The variable mb is compared with the total number of macro blocks. When the variable mb matches the total number of macro blocks, the process is completed. Otherwise, the rank of the activity information of the macro block designated by the variable mb is compared with the rank of the threshold act_thrsh. When the rank of the activity information is lower than the rank of the threshold act_thrsh, since there is a possibility of which q_scale can be decreased, q_scale is calculated with the activity information of the macro block mb and min_qq. q_scale of the macro block is subtracted from the total code amount. The subtracted resultant data is stored in a variable tmp. Thereafter, the variable tmp is compared with a target code amount GEN_TGT.

Abstract: A residue code amount is calculated. A threshold act_thrsh corresponding to the residue code amount is obtained. A variable mb that designates a macro block is initialized to zero. The variable mb is compared with the total number of macro blocks. When the variable mb matches the total number of macro blocks, the process is completed. Otherwise, the rank of the activity information of the macro block designated by the variable mb is compared with the rank of the threshold act_thrsh. When the rank of the activity information is lower than the rank of the threshold act_thrsh, since there is a possibility of which q_scale can be decreased, q_scale is calculated with the activity information of the macro block mb and min_qq. q_scale of the macro block is subtracted from the total code amount. The subtracted resultant data is stored in a variable tmp. Thereafter, the variable tmp is compared with a target code amount GEN_TGT.

Abstract: A residue code amount is calculated. A threshold act_thrsh corresponding to the residue code amount is obtained. A variable mb that designates a macro block is initialized to zero. The variable mb is compared with the total number of macro blocks. When the variable mb matches the total number of macro blocks, the process is completed. Otherwise, the rank of the activity information of the macro block designated by the variable mb is compared with the rank of the threshold act_thrsh. When the rank of the activity information is lower than the rank of the threshold act_thrsh, since there is a possibility of which q_scale can be decreased, q_scale is calculated with the activity information of the macro block mb and min_qq. q_scale of the macro block is subtracted from the total code amount. The subtracted resultant data is stored in a variable tmp. Thereafter, the variable tmp is compared with a target code amount GEN_TGT.

Abstract: An encoder and an encoding method capable of greatly improving the transfer efficiency in encoding processings. A read control means determines the number of removed bit planes in order that the quantity of generated codes per frame is kept constant when each encoding means performs an encoding processing. A predetermined number of bit planes corresponding to those parts of information that seem relatively small to users are thus removed, and accordingly, the encoder can prevent variation of processing time in a stage before each encoding means performs an encoding processing.

Abstract: In the case that the amount of a code generated in one frame is controlled, when the picture quality is optimized using an adaptive quantization, even if a scene change occurs between two frames, the adaptive quantization can be accurately performed. When data for eight lines that compose a macro block of only a first field of an N-th picture is stored in a buffer, the calculation of activities of macro blocks of the first field is started. Corresponding to the activities of the first field, an average activity is calculated. The average activity of the first field is applied to the first field and the second field of the N-th picture. As a result, a normalized activity of the N-th picture is calculated. Corresponding to the normalized activity, a quantizer scale mqaunt in consideration of a visual characteristic is calculated. Thus, the N-th picture is adaptively quantized.

Abstract: Occurrence of mosquito noise of a macro block that contains even a small plain region is suppressed. One macro block is subdivided into sub blocks each of which is composed of four pixels×four lines. The average value of luminance levels of each sub block is calculated. The absolute values of the difference values between the luminance levels and the average value are obtained for each sub block. The minimum value of the average difference values of the 16 sub blocks of one macro block is selected and decided as an activity of the macro block. Corresponding to the decided activity, a quantizer scale of the macro block is decided. With the decided quantizer scale, the macro block is quantized. According to this method, since the size of each sub block is smaller than the size of a conventional sub block of eight pixels×eight lines, the average difference value of each sub block is more emphasized.

Abstract: A rounding accuracy of DCT coefficients that are quantized is dynamically varied with a simple structure. As a result, an encoding noise is effectively suppressed and the picture quality is prevented from being deteriorated. DCT coefficients of which a picture signal is transformed by DCT are input to a quantizing circuit 30. The quantizing circuit 30 quantizes the DCT coefficients with a quantizer matrix and supplies the quantized DCT coefficients to a multiplying device 33 through an absolute value circuit 31. A quantizer scale value based on the generated code amount of the entire screen is converted into an invert value thereof and then supplied to a multiplying device 33. In addition, an M value designating circuit 38 designates a value M as a parameter with which a rounding accuracy of DCT coefficients that are quantized is controlled according to a quantizer scale value. An adding device 34 adds the value M to an output of the multiplying device 33.

Abstract: In order to obtain a high-quality image when an encoded stream which is encoded using MPEG is played back at variable speed, a stream conversion apparatus is provided which converts an arrangement of DCT coefficients of a source encoded stream into an arrangement suitable for variable-speed playback. Specifically, a header part is separated from an elementary stream of MPEG, and DCT coefficients arranged from a low order of a spatial frequency to a high order are extracted by zigzag scan at intervals of a plurality of DCT blocks which form a macro block. These DCT coefficients are rearranged from a low order to a high order across a plurality of DCT blocks. The DCT coefficients rearranged in this manner are packed into a stream, and the separated header part is added, forming a converted elementary stream. This converted elementary stream is recorded.

Abstract: In the invention, high quality image data can be encoded using encoders, which are originally designed for encoding image data of ordinary image quality. This can be done by intra-encoding Video In signal supplied from input circuit by two encoders when SDI In signal is an HD signal. An entire picture area is divided into a first group and a second group of divisional picture domains, which are distributed over the picture area. The centers of gravity of the respective groups substantially coincide. An encoder encodes image data extracted corresponding to the first group from active video data of Video In signal, while the other encoder encodes image data extracted corresponding to the second group from the active video data of Video In signal. The resultant MPEG signals output from the respective encoders are combined to form a stream.

Abstract: The present invention is a video data recording apparatus, a video data recording method, a video data reproducing apparatus, a video data reproducing method, a video data recording and reproducing apparatus, and a video data recording and reproducing method that can be interfaced using an MPEG2 elementary stream and that allow an input elementary stream to be recorded to a record medium and reproduced therefrom. According to the present invention, a recording side stream converting means is disposed. The recording side stream converting means converts an input elementary stream into a device stream that is a stream suitable for a record medium. A recording means performs a recording process for the converted device stream and records the record data to the record medium. A reproducing means reproduces record data recorded on the record medium as a device stream. According to the present invention, a reproducing side stream converting means is disposed.

Abstract: A residue code amount is calculated. A threshold act_thrsh corresponding to the residue code amount is obtained. A variable mb that designates a macro block is initialized to zero. The variable mb is compared with the total number of macro blocks. When the variable mb matches the total number of macro blocks, the process is completed. Otherwise, the rank of the activity information of the macro block designated by the variable mb is compared with the rank of the threshold act_thrsh. When the rank of the activity information is lower than the rank of the threshold act_thrsh, since there is a possibility of which q_scale can be decreased, q_scale is calculated with the activity information of the macro block mb and min_qq. q_scale of the macro block is subtracted from the total code amount. The subtracted resultant data is stored in a variable tmp. Thereafter, the variable tmp is compared with a target code amount GEN_TGT.