JP3788431B2 - Image coding method and editing apparatus - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an image encoding method for band-compressing an image signal based on the MPEG standard, and an editing apparatus for editing a band-compressed bit stream.
[0002]
[Prior art]
In recent years, image coding methods for moving images have reached a practical range with improved image quality. However, when a video signal is band-compressed, a video portion having a large amount of information is greatly deteriorated in image quality at the time of decompression.
[0003]
In the field of digital signal processing such as video discs and the field of digital broadcasting, video software and devices are being scaled down by encoding video signals with high efficiency, and the MPEG standard has been established.
[0004]
A conventional image encoding method for band-compressing an input image signal will be described below.
[0005]
FIG. 7 is a block diagram of this conventional image encoding method, and FIG. 8 is a schematic diagram of a bit stream band-compressed by the conventional image encoding method. In FIG. 7, reference numeral 41 denotes format conversion means, 42 denotes frame rearrangement means, 43 denotes motion compensation means, 44 denotes two-dimensional orthogonal transform (hereinafter abbreviated as DCT) means, 45 denotes quantization means, and 46 denotes variable length coding. Means 47, signal multiplexing means, 48 buffer means, 49 rate control means, 50 inverse quantization means, 51 inverse DCT means, and 52 frame accumulation and prediction means.
[0006]
The operation of the conventional image encoding method configured as described above will be described below.
[0007]
First, the input NTSC video signal is converted into a SIF (Source Input Format) format video signal by the format conversion means 41, and after the frame order is rearranged in the order in which it is processed by the frame rearrangement means 42, the motion is changed. It is sent to compensation means 43 for motion compensation processing. The video signal subjected to motion compensation processing is subjected to DCT processing by the DCT means 44 to reduce spatial redundancy, and the processed DCT coefficients are given by the quantization means 45 to further reduce the amount of information. The nonlinear quantization process is performed with the quantization width, and the variable length encoding unit 46 receives the variable length encoding process. The variable-length encoded video signal is multiplexed with the motion information obtained by the motion compensation unit 43 by the signal multiplexing unit 47, sent to the buffer unit 48, and output as a bit stream at a predetermined rate. At this time, the rate control means 49 for monitoring the filling rate of the buffer means 48 controls the quantization width given to the quantization means 45 so that the buffer means 48 does not overflow or become empty.
[0008]
On the other hand, the video signal output from the quantizing unit 45 is subjected to inverse quantization processing by the inverse quantization unit 50 and is subjected to inverse DCT processing by the inverse DCT unit 51 to be restored to a restored prediction video signal. The restored video signal is sent to the frame accumulation and prediction means 52 and used for motion compensation processing and quantization noise reduction processing. According to such a procedure, the encoded video signal is output as a bit stream of a predetermined rate.
[0009]
As shown in FIG. 8, the output bit stream is a set of a series of image groups that are predictively encoded based on one sequence header and an image frame that is intra-image-predictively encoded, called GOP. The vbv_delay value is unlikely to be the same value as vbv_delay (1), vbv_delay (2), and vbv_delay (3). When a degraded image is recognized by the image evaluator when the output bitstream is decoded, various parameters associated with the encoding are changed, and the encoding process is performed again from the beginning.
[0010]
[Problems to be solved by the invention]
However, in the above-described conventional configuration, an image with a large amount of information is encoded and a deteriorated image is output at the time of decoding. Therefore, encoding is performed again so as to be within the image evaluation allowable range of the image evaluator. Further, within the image evaluation allowable range, an appropriate decoded image is compromised and a deteriorated image must be output. Or, there is a problem that the overall image quality is inevitably lowered.
[0011]
The present invention solves the above-mentioned conventional problems, and performs band compression with the same value for the vbv_delay value at the beginning of each unit in a predetermined complete unit at the time of band compression. It is another object of the present invention to provide an image encoding method for performing re-band compression in a unit in which band compression of an image having a large amount of information is completed, and an editing apparatus for editing a bit stream.
[0012]
[Means for Solving the Problems]
In order to achieve this object, the image coding apparatus according to the present invention is an image code that performs band compression on an input image signal at a predetermined rate by using both intra-image prediction coding and inter-image prediction coding based on the MPEG standard. An encoding device for band-compressing an input image signal; a recording unit for holding a bitstream band-compressed by the encoding unit; and a decoding for decompressing the bitstream recorded in the recording unit And the encoding means performs band compression by setting the initial vbv_delay value of each sequence of the plurality of sequences to the same value.
[0013]
The image encoding apparatus according to claim 2, in the image coding apparatus according to claim 1, encoding the initial vbv_delay value of constructed and each GOP sequence in multiple complete set of GOP in the same value Process.
[0018]
[Action]
According to the first aspect of the present invention, the input image signal is encoded with a plurality of sequences and the initial vbv_delay value is encoded with the same value so that the bit stream can be edited. It becomes.
[0019]
Further, according to the second aspect of the present invention, by the above-described configuration, the sequence is a plurality of completed GOP structures so that the bitstream can be edited, and the initial vbv_delay value is encoded with the same value, so that editing in units of GOP can be performed. It becomes possible.
[0024]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0025]
FIG. 1 is a schematic diagram of a bitstream created by the image coding method according to the first embodiment of the present invention. FIG. 3 is a block diagram of an editing apparatus for editing a bitstream according to the third embodiment of the present invention. It is shown. In FIG. 3, 10 is encoding means, 11 is recording means, 12 is instruction means, 13 is information extracting means, 14 is encoding means, 15 is recording means, 16 is editing means, 17 is control means, and 18 is decoding. Means 19 is a display means.
[0026]
The operation of the image coding method of the present embodiment configured as described above and the editing apparatus that edits the bitstream created by the image coding method will be described below.
[0027]
A screen called a sequence header at the beginning of each sequence by outputting the input image signal as a bit stream of a plurality of sequences as shown in FIG. 1 and performing image coding with the first vbv_delay value of each sequence being the same value Various parameters such as an image size, a bit rate, a VBV buffer size, a picture rate, etc. are defined, and reproduction from the middle can be made possible. Furthermore, the encoder of the first picture layer of each sequence sets the same value for the vbv_delay value indicating the value of the virtual input buffer of the decoder in the time of 90 KHz clock, thereby completing one sequence. The bit stream created in this way is edited as follows.
[0028]
The input video signal is recorded in the recording unit 11 as a bit stream band-compressed by the encoding unit 10 which is the image encoding method of the first embodiment. The recorded bit stream is decompressed by the decoding means 18 and displayed by the display means 19. At this time, when the image evaluator recognizes the deteriorated image, the time code is output by the instructing unit 12, the sequence of the position instructed by the information extracting unit 13 or the calculation of the head position of the completed GOP, the head vbv_delay value The second bit is calculated by calculating the length of the bit stream to be read and replaced, and changing the parameter associated with the encoding for the length of the bit stream to be replaced from the indicated position, and band-compressed by the encoding means 14 The stream is recorded in the recording means 15. The recorded second bit stream is expanded by the encoding means 17 and displayed on the display means 18, and various parameters are changed and the encoding process is repeated until a good bit stream is created. Under the control of the control means 17, the editing means 16 changes the first bit stream of the recording means 11 and the second bit stream of the recording means 15 that replaces the sequence in the first bit stream based on the information of the information extracting means 13. Edit in sequence units and output one good bitstream.
[0029]
As described above, according to the present embodiment, in order to edit a bit stream band-compressed at a predetermined rate using both intra-picture prediction encoding and inter-picture prediction encoding based on the MPEG standard, Encoding means 10 for compressing the bandwidth by setting the initial vbv_delay value of each sequence to the same value, information extraction means 13 for calculating the replacement position, bit stream length, vbv_delay value, information of the information extraction means 13 and various parameters It is possible to create a good bit stream with little deterioration by providing an encoding unit 14 that changes the bandwidth and compresses the band and an editing unit 16 that performs editing in sequence units.
[0030]
FIG. 2 is a schematic diagram of a bitstream created by the image coding method according to the second embodiment of the present invention, which is the method described in the first embodiment of the present invention, and further a plurality of sequences are completed. By providing an encoding means for performing band compression by setting the initial vbv_delay value of each GOP of the GOP to the same value, editing can be performed in units of GOP.
[0031]
As described above, according to the present embodiment, in order to edit a bitstream band-compressed at a predetermined rate using both intra-picture prediction encoding and inter-picture prediction encoding based on the MPEG standard, a plurality of sequences are used. Encoding means 10 for compressing the bandwidth by setting the initial vbv_delay value of each GOP of the completed GOP to the same value, information extracting means 13 for calculating the replacement position, the length of the bit stream, and the vbv_delay value, and information extracting means 13 By providing the encoding means 14 for changing the information and various parameters and performing band compression again, and the editing means 16 for editing in GOP units, it is possible to create a good bit stream with little deterioration.
[0032]
The configuration of the first embodiment and the configuration of the second embodiment are the same, and the control means 17 switches between the first embodiment and the second embodiment to operate.
[0033]
FIG. 6 is a block diagram of an editing apparatus for editing a bitstream according to the fourth embodiment of the present invention. In the figure, 10 is encoding means, 11 is recording means, 12 is instruction means, 13 is information extracting means, 14 is encoding means, 15 is recording means, 16 is editing means, 17 is control means, and 18 is decoding. , 19 is a display means, and the above is the same as that shown in FIG. The difference from FIG. 3 is that an information amount determining means 20 and an information amount determining means 21 for determining the information amount of the band-compressed bit stream are provided. FIG. 5 is a schematic diagram showing a re-encoding process procedure in sequence units by the encoding means 10 and the encoding means 14. FIG. 6 is a schematic diagram showing a re-encoding process procedure for each GOP by the encoding unit 10 and the encoding unit 14.
[0034]
The operation of the editing apparatus for editing the bit stream configured as described above will be described below.
[0035]
The input video signal is band-compressed by the encoding means 10 which is the image encoding method of the first and second embodiments. The information amount is determined by the information amount determination means 20, and a predetermined amount of information is detected. Then, as shown in FIG. 4, the band compression of encoding 1 for the sequence is performed from the head of the detected sequence. Further, when a predetermined amount of information is detected, band compression of encoding 2 is performed. Further, when a predetermined amount of information is detected, band compression of encoding 3 is performed. Further, when a predetermined amount of information is detected, band compression of encoding n is performed. The first bit stream output as a result is recorded in the recording means 11. The recorded first bit stream is expanded by the decoding unit 18 and displayed by the display unit 19. At this time, when the image evaluator recognizes the deteriorated image, the time code is output by the instructing unit 12, the sequence of the position instructed by the information extracting unit 13 or the calculation of the head position of the completed GOP, the head vbv_delay value The length of the bit stream to be read out and replaced is calculated, the length of the bit stream to be replaced from the instructed position is changed again, the parameters associated with the encoding are changed, and the second band compressed by the encoding means 14 is compressed. When the information amount of the bit stream is determined by the information amount determination means 21 and a predetermined amount of information is detected, the band compression of encoding 1 for the sequence from the beginning of the detected sequence is performed as shown in FIG. Further, when a predetermined amount of information is detected, band compression of encoding 2 is performed. Further, when a predetermined amount of information is detected, band compression of encoding 3 is performed. Further, when a predetermined amount of information is detected, band compression of encoding n is performed. The second bit stream output as a result is recorded in the recording means 15. The recorded second bit stream is expanded by the encoding means 17 and displayed on the display means 18, and various parameters are changed and the encoding process is repeated until a good bit stream is created. Under the control of the control means 17, the editing means 16 changes the first bit stream of the recording means 11 and the second bit stream of the recording means 15 that replaces the sequence in the first bit stream based on the information of the information extracting means 13. Edit in sequence units and output one good bitstream.
[0036]
As described above, according to the present embodiment, as shown in FIG. 6, the bit stream that may become a degraded image is encoded by the encoding means 10, the information amount determining means 20 for determining the information amount, and the information amount determining means 21. By providing it, a good bit stream with little deterioration can be created.
[0037]
When the bit stream is output by the encoding means 10 as shown in FIG. 5, the difference from the description in the fourth embodiment of the present invention is that editing in sequence units becomes editing in GOP units, and further finely. A good bit stream with little deterioration can be created.
[0038]
【The invention's effect】
As described above, according to the present invention, the encoding unit that performs band compression in a complete unit and the head of the completed unit at the position detected when a predetermined amount of information is detected from the band-compressed first bit stream. Then, various parameters are changed for the unit and band compression is performed again. Furthermore, when a predetermined amount of information is detected, a plurality of completed units are changed to various parameters and band compression is performed again, so that more information is used for images with a large amount of information and less for other images. Band compression with information. Furthermore, it is possible to provide an editing apparatus capable of replacing the second bit stream obtained by band-compressing the image to be replaced with the replacement portion of the first bit stream.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an image encoding method according to a first embodiment of the present invention. FIG. 2 is a schematic diagram of an image encoding method according to a second embodiment of the present invention. FIG. 4 is a schematic diagram of an image encoding method according to a fourth embodiment of the present invention. FIG. 5 is a schematic diagram of an image encoding method according to the fourth embodiment of the present invention. 6 is a block diagram of an editing apparatus according to a fourth embodiment of the present invention. FIG. 7 is a block diagram of a conventional image encoding method. FIG. 8 is a schematic diagram of a conventional image encoding method.
10, 14 Encoding means 11, 15 Recording means 12 Instruction means 13 Information extraction means 16 Editing means 17 Control means 18 Decoding means 19 Display means 20, 21 Information amount judgment means

Claims (4)

An image encoding device that compresses an input image signal to a predetermined rate by using both intra-image prediction encoding and inter-image prediction encoding based on the MPEG (Moving Picture Experts Group) standard,
Encoding means for band-compressing an input image signal;
Recording means for holding the bit stream band-compressed by the encoding means;
Decoding means for decompressing the bitstream recorded in the recording means,
The image encoding device, wherein the encoding means performs band compression by setting an initial vbv_delay value of each sequence of a plurality of sequences to the same value. The image encoding apparatus according to claim 1 , wherein the encoding means performs band compression by setting the initial vbv_delay value of each GOP of a plurality of completed GOPs (Group of Pictures) to the same value . An image encoding method for compressing a band of an input image signal to a predetermined rate based on MPEG (Moving Picture Experts Group) standard by using both intra-image prediction encoding and inter-image prediction encoding,
The input image signal is band-compressed and encoded,
Holds a bit-compressed encoded bitstream;
Decompresses the stored bitstream,
An image encoding method characterized in that, at the time of encoding, band compression is performed by setting an initial vbv_delay value of each sequence of a plurality of sequences to the same value. 4. The image encoding method according to claim 3, wherein, at the time of encoding, band compression is performed by setting the initial vbv_delay value of each GOP of a plurality of completed GOPs (Group of Pictures) to the same value.

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