JPH07203456A - Coder, decoder and video recording device - Google Patents

Abstract

PURPOSE:To suppress image quality deterioration in space by setting an upper limit of a quantization step to obtain the image quality allowable visually so as to suppress the step to be less than the upper limit. CONSTITUTION:A quantization step upper limit setting section 109 is msed to set an upper limit of a quantization step so as to obtain i,age quality allowed visually through quantization to a frame arrangement setting section 101. At first a 0-th frame is inputted to a video input section 100 and it is fed to a DCT section 105 applying orthogonal transformation to a difference between a processing object frame and a prediction frame by using a frame processing order revision section. Thus, a DCT section 105 transforms the frequency area for each block, and a quantization section 106 adds weighting for each frequency band to implement quantization and a quantized coefficient is subject to entropy coding by a coding section 107 and the result is outputted from a coding data output section 113. When a qtuantization step from the coding section 107 exceeds an upper limit, the quantization step set to a setting section 109 is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encoding device and a decoding device for performing moving image encoding suitable for a moving image encoding / recording / reproducing device, and a video recording device to which the encoding method is applied.

[0002]

2. Description of the Related Art As a moving image encoding method, a method of compressing by utilizing correlation in the time axis direction is known. The encoding method is a method that uses the correlation between frames and between frames. In general, the coding using inter-frame correlation can improve the compression rate compared to the intra-frame coding, but when an error etc. occurs, it is propagated in the time axis direction, so the intra-frame coding is performed at a predetermined cycle. Refresh is needed.

FIG. 2 shows a relationship between a predicted frame and a frame to be processed in a method of compressing a moving image by utilizing the correlation in the time axis direction. In FIG. 2, I is an intra-frame coding processing frame, P is an inter-frame coding processing frame whose previous frame is a prediction frame, and B is a preceding and following frame and an interpolation frame generated from the preceding and following frames is a prediction frame. This represents a frame interpolation coding processing frame. I is a frame that is compressed using only the correlation within the frame, and is used as a predicted frame in the subsequent P and B frame processing.

The P frame refers to the previous I frame or the previous P frame as a prediction frame. The B frame refers to the preceding and following I and P frames and the interpolated image generated from the I and P frames as a prediction frame. Also, the numbers represent the display order in the same sequence,
For example, P-3 is an inter-frame coding processing frame, and indicates that the display order is the third.

FIG. 3 shows how the frames shown in FIG. 2 are rearranged in the processing order. As the encoding process, first, the I-0 frame is intra-frame encoded. Next processed I-
P-3 frame is inter-coded with 0 frame as a prediction frame. Next processed I-0 frame,
The P-3 frame and the interpolated image generated from the I-0 and P-3 frames are B-1 frames as prediction frames.
The frame B-2 is frame-interpolated. Next, the P-6 frame is interframe-coded with the processed P-3 frame as a prediction frame. Next, the processed P
-3 frame, P-6 frame and interpolated image generated from P-3 and P-6 frame as a prediction frame B
-4 frames and B-5 frames are subjected to frame interpolation coding. The processing order of each frame is determined by the type of encoding processed in this way.

FIG. 4 shows an outline of the generated code amount of each frame when each frame is encoded in the order of FIG. Generally, when obtaining the same image quality in each frame as in FIG. 4, the code amount of each frame increases in the order of B frame, P frame, and I frame.

Further, in the case of a system that handles moving images, the compression rate (rate) of encoded data must be suppressed below the data transfer rate of the recording medium. In this case, a buffer is provided in the output stage, and the quantization step is controlled by the untransmitted code amount in the buffer to control the code amount. Further, a virtual buffer having a different capacity is assumed depending on the type of encoding method in each frame, and the code amount is controlled by the virtual buffer. As shown in FIG. 4, when the same image quality is generally obtained, the generated code amount increases in the order of B frame, P frame, and I frame. This is a method of changing the virtual buffer capacity every time and controlling so that the buffer does not overflow or underflow as a whole.

FIG. 20 shows a block diagram of a conventional moving picture coding apparatus. In FIG. 20, reference numeral 2000 denotes an image input unit, 2
Reference numeral 001 denotes an intra-frame coding processing frame that is coded by intra-frame processing, an inter-frame coding processing frame that uses the previous frame as a prediction frame, a preceding frame and a preceding frame, and an interpolating frame that is generated from the preceding and following frames. A frame arrangement setting unit that sets the arrangement of frame interpolation coding processing frames to be set, 2002 is a frame processing order changing unit that changes the frame order to be processed according to the frame arrangement information set by the frame arrangement setting unit 2001, and 2003 is a process A motion vector detection unit that detects a motion vector between a target frame and an already-processed frame, which is a prediction frame of the processing target frame, in block units. 2004 indicates a difference value for each block between the processing target frame and the prediction frame. A subtraction unit for obtaining, 2005 is an orthogonal transformation with respect to the difference value. DCT subjected to is one of DCT
, 2006 is a quantizer that quantizes the transform coefficient obtained by the DCT unit 2005, and 2007 is the coefficient that is quantized by the quantizer 2006 (for example, Huffman coding).
An encoding unit 2008 is an encoding method for each frame set in the frame arrangement setting unit 2001, and an encoding unit 20.
A code amount control unit that controls the quantization step according to the generated code amount from 07, 2009 is an inverse quantization unit, and 2010 is an inverse D
The CT unit, 2011 is a frame memory unit that temporarily stores the processed frames, and 2012 is the encoded data output unit.

The detailed operation of FIG. 20 when encoding with the frame arrangement shown in FIG. 2 will be described below. First,
The frame processing order changing unit 2002 sets the I-0 frame to D
Send to the CT unit 2005. Here, since the I-0 frame is intra-frame encoded, the motion vector detection unit 200
3, the subtraction unit 2004 does not perform processing, and the DCT unit 20
At 05, DCT processing is performed for each block (for example, 8 × 8) to transform into the frequency domain. In the quantizer 2006,
Quantization is performed using a quantization table weighted for each frequency band as shown in FIG. In general, since the image has a strong correlation between adjacent pixels, energy concentrates on low frequency components.

Therefore, as shown in FIG. 21, the low frequency components are weighted so that the quantization step is small and the high frequency components are large. The quantized coefficient is entropy coded by the coding unit 2007,
It is output from the code data output unit 2012. In addition, the code amount control unit 2008 controls the quantization step based on the information that it is intra-frame encoding and the generated code amount of the encoding unit 2007, and gives it to the quantization unit 2006. The quantization unit 2006 calculates a new quantization step based on the quantization table of FIG. 21 and the quantization step given by the code amount control unit 2008, and performs quantization for each block. FIG. 22 shows a quantization table newly calculated by the quantization unit 2006 when the quantization step output from the code amount control unit 2008 is “2”.

Further, the data quantized by the quantizer 2006,
The coefficient of each block is inversely quantized by the inverse quantization unit 2009,
The inverse DCT unit 2010 performs the inverse DCT process, and is temporarily stored in the frame memory unit 2011. The frame is referred to as a prediction frame in the subsequent processing.

Next, the P-3 frame is read by the frame processing order changing unit 2002. Since the P-3 frame is an inter-frame coded frame in which the I-0 frame is the prediction frame, the I-0 frame is read from the frame memory unit 2011 and the block unit ( For example, a 16 × 16) motion vector is detected. The subtraction unit 2004 uses the motion vector calculated for each block to calculate the difference value between the blocks. In the DCT unit 2005, the DCT for each block
Then, the encoding unit 2007 performs entropy encoding. The code amount control unit 2008 controls the quantization step based on the information indicating that it is interframe coding and the generated code amount of the encoding unit 2007, and gives it to the quantization unit 2006.

Further, the data quantized by the quantizer 2006,
The coefficient of each block is inversely quantized by the inverse quantization unit 2009,
The inverse DCT unit 2010 performs the inverse DCT process, refers to the motion vector information for the previous I-0 frame, adds them in block units, and temporarily stores them in the frame memory unit 2011.
The frame is referred to as a prediction frame in the subsequent processing. In this way, the frame placement setting unit 20
It encodes according to the information of 01.

The image is composed of a plurality of scenes, and the amount of information contained in the image varies in each scene. Generally, an image with less motion and a flat image can be compressed at a lower rate. 5, FIG. 6, FIG. 7, and FIG. 8, the average quantization step of each frame and the transfer buffer in the transfer buffer when changing from a scene with little motion and a lot of low frequency components to a scene with a lot of motion and a lot of high frequency components Shows the variation of the data. FIG. 5 shows allocation of processing frames.

In FIG. 5, the 0th frame to the 8th frame are scenes with little motion and a lot of low frequency components, and the 9th and subsequent frames are scenes with a lot of motion and a lot of high frequency components. FIG. 6 shows how the frames in FIG. 5 are arranged in the processing order. FIG. 7 shows an average quantization step when each frame is processed in the processing order of FIG. Figure 7
As described above, the average quantization step is suppressed low in a scene with little motion and a lot of low frequency components, but the average quantization step of each frame is large in a scene with a lot of motion and a lot of high frequency components.

The reason why the average quantization step of B-7 and B-8 frames is large even though the scene has little motion and many low frequency components is that the untransmitted data in the transmission buffer in the processing of I-9 frame is not transmitted. Since the amount of data has increased, the quantization step has become large. FIG. 8 shows the amount of untransferred data in the transmission buffer when each frame is processed in the processing order of FIG. As shown in FIG. 8, fixed-rate coding is performed by controlling the quantization step so that the transmission buffer does not overflow or underflow.

[0017]

However, the above-mentioned conventional coding device has the following problems. (1) The upper limit of the code amount depends on the data transfer rate of the recording medium. Therefore, in order to suppress the compression rate (rate) of the encoded data (prevent an increase in the generated code amount) in a scene with a lot of movement, The quantity control unit 2008 controls to increase the quantization step width. However, if the quantization step width is too large, the image quality will be degraded. (2) When the video is recorded on the recording medium, the recordable time is uniquely determined with respect to the recordable capacity. Therefore, if the recording target video time is slightly longer than the recordable time, the recording failure occurs. If possible, or even if recorded, part of the recording target video is not recorded.

In view of the above points, the present invention (1) can suppress image quality deterioration when the compressed image is visually deteriorated remarkably depending on the type of the image, and (2) can be recorded within the recordable capacity. It is an object of the present invention to provide a moving image recording device capable of recording video.

[0019]

[Means for Solving the Problems] To achieve the above object,
The encoding device of the present invention comprises means for setting an upper limit value of a quantization step that can obtain a visually acceptable image quality,
And a means for calculating a quantization step based on the set upper limit value of the quantization step, the amount of untransmitted codes in the transmission buffer, and means for controlling to thin out the next processing frame when the transmission buffer overflows. It is a composition.

Information indicating that there is a thinning frame is added to the processing frame immediately before the thinning frame, and information indicating the display order in the frame group as header information of the thinning frame and the thinning frame In this configuration, information indicating that is added.

When the decoding device of the present invention detects additional information indicating that the next processing frame is a thinned frame during reproduction, it controls so as to reduce the reading speed of the code data from the reception buffer, and Based on the information indicating the display order of the thinned frames in the frame group and the information indicating that the frame is a thinned frame, at the time of playback display, control is performed to redisplay the frame immediately before the thinned frame in the display order, Alternatively, the configuration is such that interpolation reproduction is performed from the previous and next display frames.

The first video recording apparatus of the present invention comprises means for calculating the recording rate of the video based on the recordable capacity information of the recording medium and the total time information of the video to be stored, and the recording rate below the calculated recording rate. An encoding unit for compressing an image is provided, and an image for a designated time is recorded below the recordable capacity of the recording medium.

Further, the second video recording apparatus of the present invention comprises a recording rate calculation means for calculating the recording rate of the video based on the recordable capacity information of the recording medium and the total time information of the video to be recorded, and the input video. For the frame thinning,
Frame rate conversion means for outputting the encoded video, frame rate calculation means for determining the frame rate of the encoded video based on the recording rate calculated by the recording rate calculation means, and the calculated recording Encoding means for encoding the encoded video at a rate, and when the calculated recording rate is smaller than a fixed value as compared with the pixel rate of the input video, the frame rate converting means is configured to transmit the frame. The configuration is such that frame thinning processing is performed based on the frame rate calculated by the rate calculation means.

Further, the third video recording apparatus of the present invention comprises a recording rate calculating means for calculating the recording rate of the video based on the recordable capacity information of the recording medium and the total time information of the video to be recorded, and the input video. On the other hand, based on the pixel rate conversion means for thinning out the pixels in the frame and outputting the encoded video, and the recording rate calculated by the recording rate calculation means, the in-frame pixel rate of the encoded video is determined. In-frame pixel rate calculation means for
An encoding unit that encodes the encoded video at the calculated recording rate, and if the calculated recording rate is smaller than a fixed value as compared with the pixel rate of the input video, the pixel rate conversion The means is configured to perform thinning processing of pixels in the frame based on the pixel rate in the frame calculated by the pixel rate calculating means in the frame.

Further, the fourth video recording apparatus of the present invention comprises a recording rate calculating means for calculating the recording rate of the video based on the recordable capacity information of the recording medium and the total time information of the video to be recorded, and the input video. On the other hand, the frame of the encoded video is subjected to frame thinning and pixel thinning in the frame to output the encoded video and the pixel rate conversion means, and the frame of the encoded video based on the recording rate calculated by the recording rate calculation means. A frame and pixel rate calculating means for determining a rate and an in-frame pixel rate; and an encoding means for encoding the encoded video at the calculated recording rate, wherein the calculated recording rate is the input video. If it is smaller than a fixed value compared to the pixel rate of It is configured to perform frame decimation processing decimation and frame pixel based on the frame rate and frame pixel rate calculated by the arm and pixel rate calculation means.

[0026]

With the above structure, the encoding apparatus of the present invention is
By setting the upper limit value of the quantization step that can obtain a visually acceptable image quality, and suppressing the quantization step below the upper limit value, the deterioration of the image quality in space is suppressed, and if the transmission buffer overflows, The buffer overflow is avoided by thinning out the next processing frame.

The first and second video recording apparatuses of the present invention slow down the reading speed of the code data from the reception buffer if the additional information indicating that the next processing frame is a thinned frame is detected during reproduction. To control
During reproduction display, control is performed to redisplay the frame immediately preceding the thinned frame in the display order based on the information indicating the display order of the thinned frames in the frame group and the information indicating that the frame is the thinned frame. Thus, underflow of the receiving buffer can be avoided and interpolation reproduction of thinned frames can be easily realized.

The first video recording apparatus of the present invention can record video for a designated time in the recordable capacity of the recording medium, and can manage by time.

In the second video recording apparatus of the present invention, when the recorded video is remarkably deteriorated by the encoding, the frame rate of the input video is lowered so that the video whose visual deterioration is suppressed for the designated time is recorded on the recording medium. It is possible to record within the recordable capacity of.

In the third video recording apparatus of the present invention, when the recorded video is remarkably deteriorated due to the encoding, the pixel rate in the frame of the input video is lowered to reduce the visual deterioration of the video for a designated time. The data can be recorded within the recordable capacity of the recording medium.

In the fourth image recording apparatus of the present invention, when the recorded image is remarkably deteriorated by the encoding, the frame rate of the input image and the pixel rate in the frame are reduced to produce an image in which the visual deterioration is suppressed. It is possible to record for a designated time within the recordable capacity of the recording medium.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An encoding apparatus according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an encoding device according to an embodiment of the present invention.

In FIG. 1, 100 is an image input unit and 10 is an image input unit.
Reference numeral 1 denotes an intra-frame coding processing frame that is coded by intra-frame processing, an inter-frame coding processing frame that uses a previous frame as a prediction frame, a preceding frame and a preceding frame, and an interpolation frame generated from the preceding and following frames as a prediction frame. A frame arrangement setting unit that sets the arrangement of the frame interpolation coding processing frames to be processed, 102 is a frame processing order changing unit that changes the order of frames to be processed according to the frame arrangement information of the frame arrangement setting unit 101, and 103 is a processing target frame, It is a motion vector detection unit that detects, in block units, a motion vector with respect to a frame that has been processed, in which the frame to be processed is a prediction frame.

Reference numeral 104 is a subtraction unit for obtaining a difference value for each block between the frame to be processed and the prediction frame, and 105 is a DCT which performs DCT which is one of orthogonal transforms on the difference value.
, 106 is a quantizer for quantizing the transform coefficient obtained by the DCT unit 105, 107 is a coding unit for coding the coefficient quantized by the quantizing unit 106 (for example, Huffman coding), and 109 is a quantum. It is a quantization step upper limit value setting unit that sets an upper limit value of the quantization step.

Reference numeral 108 denotes an encoding method for each frame set in the frame arrangement setting unit 101, and an encoding unit 107.
Depending on the amount of code generated from, the code amount control unit for controlling the quantization step with the quantization step set in the quantization step upper limit value setting unit 109 as the upper limit value, 110 is an inverse quantization unit, 111 is an inverse DCT unit. , 112 is a frame memory unit for temporarily storing the processed frames, and 113 is an encoded data output unit.

Hereinafter, FIG. 5, FIG. 7, FIG. 9, FIG. 11, and FIG.
The operation of the block of FIG. 1 will be described in detail with reference to FIG. First, in the frame arrangement setting unit 101, the quantization step upper limit value setting unit 109 sets the upper limit value of the quantization step that can obtain a visually acceptable image quality by quantization of the encoding processing type of each frame shown in FIG. Set to. This set value is set based on some experience value.

First, the 0th frame is input from the video input unit 100. Since the 0th frame is an intra-frame encoding processing frame, the frame processing order changing unit 102
−0 frame is sent to the DCT unit 105. Where I-0
Since the frame is intra-frame encoded, the motion vector detection unit 103 and the subtraction unit 104 do not perform processing, and the DC
In the T unit 105, DCT processing is performed for each block (for example, 8 × 8) to transform into the frequency domain.

The quantizer 106 performs quantization using a quantization table weighted for each frequency band as shown in FIG. In general, since the image has a strong correlation between adjacent pixels, energy concentrates on low frequency components. Therefore, as shown in FIG. 21, the low-frequency component is weighted so that the quantization step is small and the high-frequency component is large.

The quantized coefficient is entropy coded by the coding unit 107 and output from the coded data output unit 113. Further, in the code amount control unit 108, information indicating that the coding is intraframe, the generated code amount of the coding unit 107, and the quantization step upper limit value setting unit 109 are set.
The quantization step is controlled by the upper limit value of the quantization step and given to the quantization unit 106.

When the quantization step calculated by the amount of codes generated by the encoding unit 107 exceeds the quantization step upper limit value, the quantization step is set to the quantization step upper limit value 109. The quantization unit 106 calculates a new quantization step using the quantization table of FIG. 21 and the quantization step given by the code amount control unit 108, and performs quantization for each block.

FIG. 22 shows a quantization table newly calculated by the quantization unit 106 when the quantization step output from the code amount control unit 108 is "2". In addition, FIG.
12 shows the average quantization step of each frame, and FIG. 12 shows the amount of untransmitted data in the transmission buffer. As shown in FIGS. 11 and 12, in the case of the I-0 frame, the average quantization step is equal to or less than the upper limit value set in the quantization step upper limit value setting unit 109, and the transmission buffer does not overflow or underflow. Controlled.

The coefficients of each block quantized by the quantizer 106 are inversely quantized by the inverse quantizer 110 and inverse D
Inverse DCT processing is performed in the CT unit 111, and the frame memory unit 1
It is temporarily stored in 12. The stored frame is referred to as a prediction frame in the subsequent processing.

Next, the frame processing order changing unit 102 reads the P-3 frame. Since the P-3 frame is an inter-frame coded frame in which the I-0 frame is the prediction frame, the I-0 frame is read from the frame memory unit 112 and the block unit ( For example, a 16 × 16) motion vector is detected. The subtraction unit 104 uses the motion vector calculated for each block to calculate the difference value between the blocks. The DCT unit 105 performs DCT on each block.

In the code amount control unit 108, information indicating that inter-frame coding is performed, the generated code amount of the coding unit 107 and the quantization step upper limit value setting unit 109 are set.
The quantization step is controlled by the upper limit value of the quantization step and given to the quantization unit 106. When the quantization step calculated by the generated code amount of the encoding unit 107 exceeds the quantization step upper limit value, the quantization step is set to the quantization step upper limit value 109.

As shown in the average quantization step of each frame of FIG. 11 and the amount of untransmitted data in the transmission buffer of FIG. 12, in the case of P-3 frame, the average quantization step is the quantization step upper limit value. The transmission buffer is controlled so as not to exceed the upper limit value set in the setting unit 109 and the transmission buffer does not overflow or underflow.

As described above, the quantization is performed by the quantization unit 106.
The coefficient of each block quantized by
Inverse quantization is performed by 0, inverse DCT processing is performed by the inverse DCT unit 111,
The motion vector information for the previous I-0 frame is referred to, added in block units, and temporarily stored in the frame memory unit 112. The stored frame is referred to as a prediction frame in the subsequent processing. In this way, encoding is performed according to the information of the frame arrangement setting unit 101.

In the image as shown in FIG. 5, the average quantization step does not exceed the upper limit set in the quantization step upper limit setting unit 109 in the processing up to I-9 frame as shown in FIG. Similar processing is performed. I-9
If a frame is processed in the same manner as described above, a transmission buffer overflows. Therefore, the B-7 frame to be processed next to the I-9 frame is thinned out. In the same process, when the code amount control unit 108 detects that the transmission buffer overflows, the read rate of the code data from the encoding unit 107 is halved, and the frame processing order changing unit 102 Instruct to skip B-7 frame.

As described above, when the transmission buffer overflows by suppressing the quantization step to the upper limit value or less, the next processing frame is thinned out to avoid the overflow of the transmission buffer as shown in FIG. . Thereafter, similar processing is performed, and quantization is performed in each frame at a quantization step equal to or less than the quantization step upper limit value. FIG. 9 shows the thinned state.

FIG. 13 shows a state of data when encoded by the encoding device of FIG. As shown in FIG. 13, as additional information of each frame, information on presence / absence of thinning processing of the next frame, information on whether the frame is a thinned frame, and information indicating the display order in the frame group are added. Figure 1
FIG. 3 is a diagram showing a state of encoded data when a thinning frame occurs as shown in FIG. 9, and in the I-9 frame, the next processing frame (B-7) is a thinning frame. , The next frame thinning information is "O
N ", since the thinning out of this frame is not performed," OFF "is added to the thinning out information of this frame, and" 9 "is added to the display order in the frame group. After the additional information, the actual I-
Stores 9 frames of code data.

In the next B-7 frame, the next processing frame (B-8) is not a thinned frame, so "OF".
F ", thinning out of this frame is being performed, so" O "
N "," 7 "is added to the display order within the frame group.
Since 7 frames are thinned-out frames, there is no actual code data.

Next, a decoding apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 14 is a block diagram of a decoding device for reproducing a moving image according to the embodiment of the present invention.

In FIG. 14, 1400 is obtained by the encoded data input unit, 1401 is an input buffer for temporarily storing the encoded data, 1402 is a decoding unit for decoding the encoded data, and 1403 is a decoding unit 1402. An inverse quantizer for inverse quantizing the transform coefficient, 1404 inverse DC for the transform coefficient
An inverse DCT unit for T, 1405 is a frame memory unit for temporarily storing reproduced video, 1406 is an adding unit, and 1407 is a frame order changing unit for outputting in a display order.

Next, the operation of FIG. 14 when reproducing the encoded data shown in FIG. 13 will be described. The encoded data is input from 1400 at a constant rate, and the input buffer 14
01 is temporarily stored. In the case of FIG. 13, first, the I-9 data is input. The decoding unit 1402 first analyzes the header information. In the frame, since the next frame thinning information is "ON", the decoding unit 1402
Controls the reading rate of data from the input buffer 1401 to 1/2. Further, the thinning information “OFF” for this frame and the display order information “# 9” in the frame group are given to the frame order changing unit 1407. After that, the I-9 code data is sequentially read from the input buffer 1401, decoded by the decoding unit 1402, and the obtained transform coefficient is given to the dequantization unit 1403.

Inverse quantization section 1403 performs inverse quantization,
The inverse DCT unit 1404 performs inverse DCT and writes it in the frame memory unit 1405. Next, B-7 data is input. The decoding unit 1402 analyzes the header information. In the frame, thinning information "O"
N "and the display order information"# 7 "in the frame group are given to the frame order changing unit 1407. Next, the header information of B-8 is read. In the frame, the thinning information" OFF "of the next frame and the current frame. , Frame group display order information ”#
8 ″ is given to the frame order changing unit 1407.

After that, the code data of B-8 is sequentially read from the input buffer 1401, decoded by the decoding unit 1402, and the obtained transform coefficient is given to the dequantization unit 1403. Inverse quantization section 1403 performs inverse quantization and performs inverse DCT.
Inverse DCT is performed in the unit 1404, addition with the reference frame is performed in the addition unit 1406, and the result is the frame memory unit 140.
Write to 5.

The frame order changing unit 1407 sequentially displays as shown in FIG. Since the seventh frame is a thinned frame, control is performed such that the previous frame is displayed again according to the thinned frame information. In this case, the P-6 frame is displayed again. Next, B-8,
It is displayed in the order of I-9 according to the display order information in the frame group. At this time, P is displayed in the thinned 7th frame display.
An interpolated frame may be generated and displayed from the −6 frame and the B-8 frame.

Next, a video recording apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 15 shows a block diagram of a video recording apparatus in the first embodiment of the present invention.

In FIG. 15, 1500 is the recordable capacity information of the recording medium, 1501 is the time information of the video to be recorded, and 1502 is the recording rate for calculating the recording rate from the recordable capacity information 1500 and the recorded video time information 1501. A calculation unit, 1503 is a video input unit, 1504 is an encoding unit for encoding at a recording rate calculated by the recording rate calculation unit 1502 or less, and 1505 is an encoding unit 1504.
It is a recording medium for recording code data coded in. The operation of the recording rate calculation unit 1502 will be described below. If the recordable capacity is N bits and the recorded video time is S seconds, the recording rate (R) is calculated by the following equation (1).

R = N / S (1) For example, if the storable capacity is 100 megabytes and the recording video time is 400 seconds, the recording rate (R) is 2 megabits / second according to the equation (1). Becomes Therefore, the encoding unit 1504 performs the encoding process while controlling the recording rate to 2 megabits / second or less.

As described above, the video recording apparatus of this embodiment is
It is possible to record video for a designated time within the recordable capacity of the recording medium, and to manage by time.

However, in an image having a high pixel rate of the input image, a sufficient image quality cannot be obtained by the encoding process at the above recording rate. For example, a typical television image has a rate of about 160 megabits / second. Therefore, it must be compressed to about 1/80. However, the deterioration limit is usually 20 to 1/40. Therefore, 2 megabits /
If it is encoded in seconds, the image quality of each frame will be significantly degraded and it will not be usable.

Next, a video recording apparatus of the second embodiment of the present invention for preventing the above-mentioned image quality deterioration will be described with reference to the drawings. FIG. 16 is a block diagram of a video recording apparatus according to the second embodiment of the present invention.

In FIG. 16, 1600 is the recordable capacity information of the recording medium, 1601 is the time information of the video to be recorded, 1602 is the recording for calculating the recording rate from the recordable capacity information 1600 and the recorded video time information 1601. Rate calculation unit 1603 is input video rate information, 160
Reference numeral 4 denotes a frame rate calculation unit that calculates the frame rate of the input video from the input video rate information 1603 and the recording rate calculated by the recording rate calculation unit 1602.
Reference numeral 606 denotes a frame rate conversion unit that converts the frame rate of the input video according to the frame rate calculated by the frame rate calculation unit 1604. Reference numeral 1607 denotes the video obtained by the frame rate conversion unit 1606 in the recording rate calculation unit 1602. An encoding unit that encodes at a recording rate equal to or lower than the calculated recording rate, and 1608 is a recording medium that records the code data encoded by the encoding unit 1607.

The operations of the frame rate calculating section 1604 and the frame rate converting section 1606 will be described below with reference to FIG. FIG. 19 is a diagram showing the relationship between the recording rate and the pixel rate of the input video. In FIG. 19, the shaded area is an area where a visually permissible image quality can be obtained.

For example, in FIG. 19, the recording rate is "
If "A", the pixel rate needs to be suppressed to "B" or less. In FIG. 19, the recording rate (A) is 2 megabits / second, and the pixel rate (B) is 80 megabits. 16 and the input video rate in FIG. 16 is 160 megabits / second (frame rate is 30 frames / second), the frame rate calculation unit 1604 sets the frame rate to 15 frames / second, which is an odd number or an even number. Decide whether to thin out the frame of
It is given to the frame rate conversion unit 1606. In the frame rate conversion unit 1606, the frame rate calculation unit 1604
Frame thinning according to the information of
07, in this case, compression is performed while controlling the rate to be 2 megabits / second or less.

As described above, according to the present embodiment, even if the recorded image is significantly deteriorated by the encoding, the frame rate of the input image is reduced to reduce the visual deterioration of the image for the designated time. Minutes, within the recordable capacity of the recording medium,
Can be recorded.

The third embodiment will be described below with reference to the drawings. In the video recording apparatus of the third embodiment shown in FIG. 17, the configuration is provided with an in-frame pixel rate calculation unit 1704 for calculating the pixel rate in the frame and a pixel rate conversion unit 1706 for converting the pixel rate. Video rate conversion is realized by thinning out pixels in the frame.

As described above, according to the present embodiment, even if the recorded image is significantly deteriorated due to the encoding, the pixel rate in the frame of the input image is reduced, so that the image with the visual deterioration suppressed can be obtained. It is possible to record for a designated time within the recordable capacity of the recording medium.

The fourth embodiment will be described below with reference to the drawings. The video recording apparatus according to the fourth embodiment shown in FIG. 18 includes a frame / pixel rate calculation unit 1804 for calculating a frame / pixel rate and a frame / pixel rate conversion unit 1806 for converting a frame / pixel rate. Thus, as the rate conversion of the input video, the frame rate conversion and the pixel thinning in the frame are used together.

As described above, according to the present embodiment, even if the recorded image is significantly deteriorated due to the encoding, the frame rate of the input image and the pixel rate within the frame are reduced to suppress the visual deterioration. The recorded image can be recorded for a designated time within the recordable capacity of the recording medium.

In FIGS. 17 and 18, the same parts as those in FIG. 16 are designated by the same reference numerals. Further, although the description of the recording means on the recording medium is omitted, it goes without saying that an appropriate recording means may be used according to the type of medium.

[0072]

As described above, according to the present invention, the following excellent effects can be exhibited.

(1) By suppressing the quantization step below the set upper limit value of the quantization step, it is possible to suppress deterioration in image quality in the space, and when the transmission buffer overflows, the next processing frame is processed. You can avoid buffer overflow by thinning out
It is possible to realize an encoding device that suppresses deterioration in space, which is noticeable in terms of visual characteristics.

(2) When additional information indicating that the next processing frame is a thinned frame is detected during reproduction, control is performed so as to reduce the reading speed of the code data from the reception buffer, and the frame group in the thinned frame is controlled. Underflow of the reception buffer by controlling to redisplay the frame immediately before the frame thinned out in the display order during the reproduction display by the information indicating the display order in and the information indicating that the frame is a thinned frame. It is possible to realize a decoding device that can avoid the above and can easily realize interpolation reproduction of thinned frames.

(3) It is possible to record video for a designated time within the storable capacity of the storage medium.

(4) When the recorded image is significantly deteriorated by the encoding, by reducing the frame rate of the input image,
It is possible to realize a video recording device capable of recording a video with suppressed visual deterioration in a storable capacity of a storage medium for a designated time.

(5) When the recorded image is significantly deteriorated due to the encoding, the pixel rate in the frame of the input image is reduced to suppress the visually deteriorated image for a specified time.
A video recording device capable of recording within the storable capacity of a storage medium can be realized.

(6) When the recorded image is significantly deteriorated due to the encoding, the frame rate of the input image and the pixel rate in the frame are reduced to store the image in the storage medium for a designated time period while suppressing the visual deterioration. It is possible to realize a video recording device capable of recording within the available capacity.

[Brief description of drawings]

FIG. 1 is a block diagram of an encoding device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between prediction frames in encoding using interframe prediction.

FIG. 3 is a diagram showing a state in which frames are arranged in encoding order.

FIG. 4 is a diagram showing a generated code amount of each frame when each frame is encoded in the order of FIG.

FIG. 5 is a diagram showing a relationship between prediction frames in encoding using interframe prediction.

FIG. 6 is a diagram showing a state in which frames are arranged in encoding order.

FIG. 7 is a diagram showing an average quantization step of each frame.

FIG. 8 is a diagram showing a data amount in a buffer of each frame.

FIG. 9 is a diagram showing a state in which frames are thinned out.

FIG. 10 is a diagram showing a state in which thinned frames are interpolated and displayed.

FIG. 11 is a diagram showing an average quantization step of each frame.

FIG. 12 is a diagram showing the amount of data in the buffer of each frame.

FIG. 13 is a diagram showing coded data.

FIG. 14 is a block diagram of a decoding device according to an embodiment of the present invention.

FIG. 15 is a block diagram of a video recording apparatus according to the first embodiment of the present invention.

FIG. 16 is a block diagram of a video recording apparatus according to a second embodiment of the present invention.

FIG. 17 is a block diagram of a video recording device according to a third embodiment of the present invention.

FIG. 18 is a block diagram of a video recording device according to a fourth embodiment of the present invention.

FIG. 19 is a diagram showing a relationship between a recording rate and an input pixel rate according to this embodiment.

FIG. 20 is a block diagram of a conventional encoding device.

FIG. 21 is a diagram showing an example of a quantization table according to the present embodiment.

FIG. 22 is a diagram showing another example of the quantization table according to the present embodiment.

[Explanation of symbols]

 100 image input unit 101 frame arrangement setting unit 102 frame processing order changing unit 103 motion vector detection unit 104 subtraction unit 105 DCT unit 106 quantization unit 107 encoding unit 108 code amount control unit 109 quantization step upper limit value setting unit 110 inverse quantum Conversion unit 111 inverse DCT unit 112 frame memory unit 113 coded data output unit

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical indication H04N 7/13 Z

Claims (7)

[Claims] 1. Intra-frame coding for coding a moving image by intra-frame processing, inter-frame coding for using a previous frame as a prediction frame, and prediction of preceding and following frames and interpolated frames generated from preceding and following frames. In a coding method that combines frame interpolation coding to form a frame, each frame is divided into at least one or more processing blocks, and an untransmitted code in a transmission buffer for moving image data of each processing block. An encoding device for controlling a quantization step according to an amount, comprising: means for setting an upper limit value of the quantization step, the set quantization step upper limit value, and a quantization step depending on an untransmitted code amount in a transmission buffer. And a means for controlling to thin out the next processing frame when the transmission buffer overflows. An encoding device characterized by: 2. The processing frame immediately before the thinning frame,
In addition to adding information indicating that there is a thinning frame, information indicating a display order in the frame group and information indicating that the frame is a thinning frame are added as header information of the thinning frame. The encoding device according to claim 1. 3. When reproducing, when additional information indicating that the next processing frame is a thinning frame is detected, the reading speed of the code data from the receiving buffer is controlled so as to be slowed down, and the frame group in the thinning frame is controlled. Depending on the information indicating the display order and the information indicating that the frame is a thinned frame, during playback display, control is performed to redisplay the frame immediately before the frame thinned in the display order, or interpolation display from the previous and next display frames. A decoding device characterized by controlling to perform. 4. A recording means for calculating the recording rate of the video based on the recordable capacity information of the recording medium and the total time information of the video to be stored, and an encoding means for compressing the video below the calculated recording rate. A video recording apparatus having the above-mentioned recording medium and recording video for a designated time within a recordable capacity of the recording medium. 5. A recording rate calculation means for calculating the recording rate of the video based on the recordable capacity information of the recording medium and the total time information of the video to be recorded, and frame thinning of the input video to perform coding. Frame rate conversion means for outputting a video; frame rate calculation means for determining a frame rate of the encoded video based on the recording rate calculated by the recording rate calculation means; An encoding unit for encoding the encoded video, wherein the frame rate converting unit is the frame rate calculating unit when the calculated recording rate is smaller than a fixed value as compared with the pixel rate of the input image. A video recording apparatus, wherein frame thinning processing is performed based on the frame rate calculated by. 6. A recording rate calculation means for calculating a recording rate of the image based on the recordable capacity information of the recording medium and total time information of the image to be recorded, and pixel thinning in a frame is performed on the input image to reduce the pixel Pixel rate conversion means for outputting encoded video, in-frame pixel rate calculation means for determining the in-frame pixel rate of the encoded video based on the recording rate calculated by the recording rate calculation means, and the calculation An encoding unit that encodes the encoded video at a recorded rate, and if the calculated recording rate is smaller than a fixed value as compared with the pixel rate of the input image, the pixel rate conversion unit , Thinning processing of pixels in a frame is performed based on the pixel rate in the frame calculated by the pixel rate calculating unit in the frame. A video recording device characterized by the following features. 7. A recording rate calculation means for calculating the recording rate of the video based on the recordable capacity information of the recording medium and the total time information of the video to be recorded, and frame thinning and pixel thinning in frame for the input video. A frame for outputting the encoded video and a pixel rate conversion means, and a frame for determining the frame rate and the in-frame pixel rate of the encoded video based on the recording rate calculated by the recording rate calculation means, It has a pixel rate calculation unit and an encoding unit that encodes the encoded video at the calculated recording rate, and the calculated recording rate is smaller than a certain value as compared with the pixel rate of the input video. In this case, the frame and pixel rate conversion means is the frame and pixel rate calculation means. A video recording apparatus, which performs frame thinning-out and pixel in-frame thinning-out processing based on the calculated frame rate and intra-frame pixel rate.