JPH05227513A - Video signal transmitter - Google Patents

Abstract

PURPOSE:To improve a transmitted picture by controlling a band limiting characteristic based on a band limitation distortion generated at the time of limiting the pass band of a video signal, and an encoded distortion generated at the time of quantizing the video signal. CONSTITUTION:In an encoded distortion detecting circuit 22, the encoded distortion at a quantizing circuit 8 is searched, and supplied to a control circuit 23 as encoded distortion data S34. The control circuit 23 searches the distortion amount generated at the time of transmitting a pre-field from the upper bits of band limitation distortion data S23 and encoded distortion data S34, outputs band limitation data S35 to a pre-filter circuit, so that both the distortion data can be a prescribed ratio set in order to minimize the deterioration of the picture quality of transmitted output data S8. Thus, the danger of the visibility of the block-shaped distortion due to the rapid increase of the encoded distortion of the output data S8 outputted through a transmission buffer memory 10 to a transmission path 11, or the danger of the blur of the outline of the picture due to the rapid increase of the band limitation distortion, can be effectively avoided.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. Industrial Application Conventional Technology (FIGS. 3 to 6) Problems to be Solved by the Invention (FIGS. 3 to 6) Means for Solving the Problems (FIGS. 1 and 2) Action Example (FIGS. 1 and 2) (FIG. 2) (1) First embodiment (FIG. 1) (2) Second embodiment (FIG. 2) (3) Other embodiments Effect of the invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal transmission apparatus, and is suitable for application to a video signal transmission apparatus for transmitting high-quality video in a one-to-many transmission mode such as transmission in a broadcasting station.

[0003]

2. Description of the Related Art Conventionally, in a so-called video signal transmission system for transmitting a video signal composed of a moving image to a remote place such as a video conference system and a video telephone system, in order to efficiently use a transmission line, The video signal is coded by utilizing the inter-frame correlation of (1) to improve the transmission efficiency of significant information.

[0004] For example intraframe coding processing, as shown in FIG. 3, to be transmitted each image PC1, PC2, PC3 and ...... constituting a moving at time _{t = t 1, t 2,} t 3 ...... In this case, the image data to be transmitted is one-dimensionally encoded and transmitted within the same scanning line. In addition, the inter-frame encoding process uses the autocorrelation of the video signal with respect to the time axis to sequentially adjoin the images PC1, PC2, and PC2.
, And the image data PC12, PC23 ... Which are the difference in pixel data between PC3.

As a result, the video signal transmission system high-efficiency-codes the images PC1, PC2, PC3, ... It can be sent to.

That is, as shown in FIG. 4, the image data transmission apparatus 1 converts an input video signal VD into a luminance signal and a color difference signal through a pre-processing circuit 2 and then uses an analog digital conversion circuit to output an 8-bit digital signal. And output as input image data S1. The pre-processing circuit 2 includes a pre-filter circuit 2A (not shown), and controls the transmission band according to the amount of generated information of the video signal to be transmitted.

The image data sequentially sent as the input image data S1 is extracted from the frame image data FRM by the method shown in FIG. One frame image data FRM is divided into 2 (horizontal direction) × 6 (vertical direction) block groups GOB as shown in FIG. 5A, and each block group GOB is shown in FIG. 5B. As shown, 11 macroblocks (horizontal direction) × 3 macroblocks MB (vertical direction) are included in each macroblock M.
As shown in FIG. 5C, B includes color difference signal data C _b and C _r which are color difference signal data corresponding to all pixel data of luminance signal data Y _{1 to} Y ₄ for 8 × 8 pixels.

At this time, the arrangement of the image data in the block group GOB is such that the image data is continuous in units of macro blocks MB, and in the macro block MB, the image data is continuous in units of minute blocks in the order of raster scanning. It is designed to do.

Here, the macroblock MB uses image data (Y _{1 to} Y ₄ ) of 16 × 16 pixels continuous in the horizontal and vertical scanning directions as one unit with respect to the luminance signal. In the two color difference signals corresponding to, the amount of data is reduced and then time-axis multiplexed, and data of 16 × 16 pixels is assigned to each of the minute blocks C _r and C _b .

The difference data generation circuit 3 receives the input image data S
When the previous frame data S2 of the previous frame stored in the previous frame memory 4 is input together with 1, the difference between the previous frame data S2 and the input image data S1 is obtained to generate interframe encoded data (hereinafter referred to as interframe encoding mode). ), The difference data S3 is output to the discrete cosine transform (DCT) circuit 6 and the switching control circuit 7 via the switching circuit 5.

The switching circuit 5 is controlled by the control signal S4 output from the switching control circuit 7. If the intra-field-encoded data can be transmitted with a smaller amount of data, the switching circuit 5 outputs the input image data S1 as it is. Further, if the inter-frame coded data can be transmitted with a smaller amount of data, the differential data S3 is output. The discreet cosine conversion circuit 6 outputs the video signal 2
Using the dimensional correlation, the input image data S1 or the difference data S3 is subjected to discrete cosine transform in the unit of a small block, and the resulting transformed data S5 is converted into a quantization circuit 8
It is designed to output to.

The quantization circuit 8 is a block group GOB.
The converted data S5 is quantized by a quantization step size determined for each, and the quantized data S6 obtained at the output end is supplied to a variable length coding circuit VLC (variable length code) 9 and an inverse quantization circuit 12. Here, the variable length coding circuit 9 performs variable length coding processing on the quantized data S6 and supplies it to the transmission buffer memory BM10 as transmission data S7.

The transmission buffer memory 10 stores the transmission data S
7 is once stored in the memory, then extracted as output data S8 in a predetermined order and output to the transmission line 11, and the quantization control signal S9 in block group GOB unit is output according to the residual data amount remaining in the memory. The quantization circuit 8 is fed back to control the quantization step size. As a result, the transmission buffer memory 10
Adjusts the amount of data generated as the output data S8 and maintains a proper amount of data (the amount of data that does not cause overflow or underflow) in the memory.

Further, the transmission buffer memory 10 supplies the quantization control signal S9 to the preprocessing circuit 2 and controls the transmission band characteristic of the prefilter circuit 2A according to the amount of residual data remaining in the memory. .. By the way, if the remaining amount of data in the transmission buffer memory 10 increases to the allowable upper limit,
The transmission buffer memory 10 sends the quantization step size STPS (FIG. 6) of the quantization circuit 8 according to the quantization control signal S9.
By increasing the step size of, the data amount of the quantized data S6 is reduced.

On the contrary, the transmission buffer memory 10
When the remaining amount of data is reduced to the allowable lower limit value, the transmission buffer memory 10 reduces the step size of the quantization step size STPS of the quantization circuit 8 in accordance with the quantization control signal S9, so that the data amount of the quantized data S6. Increase. The inverse quantization circuit 12 inversely quantizes the quantized data S6 sent from the quantization circuit 8 into a representative value and converts the quantized data S6 into inverse quantized data S10. And inversely quantized data S10 to inverse discrete cosine inverse transform IDCT
(Inverse discrete cosine transform) circuit 13 is supplied.

Discrete cosine inverse conversion circuit 13
Is the inverse quantized data S1 decoded by the inverse quantization circuit 12.
0 is converted into decoded image data S11 by a conversion process reverse to that of the discrete cosine inverse conversion circuit 6, and is output to the previous frame data generation circuit 14 and the switching circuit 15. As a result, the discrete cosine inverse conversion circuit 13 outputs the input image data S1 or the difference data S before the conversion by the discrete cosine conversion circuit 6 of the output data S8 output through the transmission line 11 and reproduced on the receiving side.
3 can be decoded on the transmission side.

That is, the discrete cosine inverse conversion circuit 13 reproduces the input image data S1 when the video signal VD is intrafield encoded and transmitted, while the video signal VD is interframe encoded. When the data is transmitted after being transmitted, the difference data S3 is reproduced. The previous frame data generation circuit 14 adds the previous frame data S2 fed back from the previous frame memory 4 and the decoded image data S11 to output data S8.
By reproducing the image data of the previous frame output as, and outputting it to the previous frame memory 4 via the switching circuit 15, the images transmitted to the receiving side are sequentially reproduced and stored in the previous frame memory 4. Has been done.

Here, the switching circuit 15 is controlled to be switched by the control signal S4 which is delayed by the time required from the discrete cosine conversion of the video signal to the inverse discrete cosine conversion of the video signal through the delay circuit 16. Has been done.

[0019]

By the way, in the image data transmission apparatus 1 for transmitting the discrete cosine conversion of the video signal VD as in the prior art, a large amount of information is transmitted and accumulated in the transmission buffer memory 10. When the amount of accumulated data increases, the pass band of the pre-filter circuit 2A is suppressed so as to block the passage of high-frequency components in an oblique direction, the resolution is lowered, and the amount of generated information is suppressed. ..

However, as described above, the front filter circuit 2A is
When the pass band characteristic of 1 is controlled by the quantized control signal S9 to suppress the information amount, the control parameter follows the accumulated amount, and thus the generated information amount fluctuates alternately, making it difficult to control the generated information amount. Therefore, the output signal S8 transmitted through the transmission line 11 has a problem that the image quality is visually deteriorated.

The present invention has been made in consideration of the above points, and is based on the band-limiting distortion that occurs when the pass band of the video signal is limited and the actual coding distortion that occurs when the video signal is quantized. By controlling the band limiting characteristic, it is possible to further improve the image quality of the transmitted image for transmission.

[0022]

In order to solve such a problem, in the first invention, the video signal VD is band-limited through the band limiting circuit 2A, and the video signal S after the band limiting is performed.
In the video signal transmission devices 20 and 40 which perform high-efficiency encoding processing to convert 1 into high-efficiency encoded data S5, and quantize the high-efficiency encoded data S5 into transmission data S6, quantization information S9 is obtained. Based on the high efficiency coded data S5
Decoding means 12, 13, 14, 15 for decoding the video signal S1, the band-limited video signal S1 via the band limiting circuit 2A, and the decoded data S decoded by the decoding means 12, 13, 14, 15
The difference data detecting means 30 for obtaining the difference with respect to 31 and the actual encoding distortion detecting means 3 for obtaining the actual encoding distortion S34 based on the difference S32 obtained by the difference data detecting means 30.
2, 33 and the control means 23 for controlling the band limiting characteristic of the band limiting circuit 2A based on the actual coding distortion S34.

In the second invention, the video signal VD
Is band-limited via the band limiting circuit 2A, the video signal VD after the band limiting is subjected to high-efficiency encoding processing to be converted into high-efficiency encoded data S5, and the high-efficiency encoded data S5 is quantized and transmitted. Video signal transmission device 2 for converting to data S6
At 0, the difference S21 between the first video signal VD input to the band limiting circuit 2A and the second video signal S1 output from the band limiting circuit 2A is obtained, and the band limiting distortion S23 is obtained from the difference S21. Limiting strain detection means 25, 2
6, 27 and the decoding means 12, 13, 14, 15 for decoding the high-efficiency coded data S5 based on the quantization information S9.
And the second video signal S1 and the decoding means 12, 13, 14,
Difference data detecting means 30 for obtaining a difference S32 from the decoded data S31 decoded in 15, and difference data detecting means 3
Based on the difference S32 obtained by 0, the actual encoding distortion S3
4 and the band-limited distortion S obtained by the band-limited distortion detectors 25, 26, and 27.
23 and the control means 23 for controlling the band limiting characteristic of the band limiting circuit 2A based on the real coding distortion S34 obtained by the real coding distortion detecting means 32 and 33.

Further, in the third invention, the video signal V
Band limiting of D is performed via the band limiting circuit 2A, the video signal VD after the band limiting is subjected to high efficiency encoding processing to be converted into high efficiency encoded data S5, and the high efficiency encoded data S5 is quantized. In the video signal transmission device 40 for converting into the transmission data S6, the video signal VD is delayed for a predetermined period and supplied to the band limitation circuit 2A, and based on the video signal of the previous reference frame output from the delay means 43. The image data prediction unit 44 that predicts the video signal of the current reference frame input to the delay unit 43, and the difference S42 between the predicted image data S41 output from the image data prediction unit 44 and the video signal VD of the current reference frame. Find the difference S
Prediction distortion detection means 45, 4 for obtaining the prediction distortion S43 from 42
6 and the high-efficiency encoded data S based on the quantization information S9.
5, decoding means 12, 13, 14, 15 and a difference S32 between the video signal S1 band-limited by the band limiting circuit 2A and the decoded data S31 decoded by the decoding means 12, 13, 14, 15. Difference data detecting means 30 for obtaining
And the actual encoding distortion detecting means 32 and 33 for obtaining the actual encoding distortion S34 based on the difference S32 obtained by the difference data detecting means 30, and the prediction distortion S43 and the actual distortion obtained by the predictive distortion detecting means 45 and 46. The band limiting circuit 2 is based on the actual coding distortion S34 obtained by the coding distortion detecting means 32 and 33.
And a control means 23 for controlling the band limiting characteristic of A.

[0025]

According to the first aspect of the invention, the band limiting characteristic of the band limiting circuit 2A is controlled on the basis of the actual coding distortion S34 that occurs when the video signal VD is quantized and actually transmitted, so that the video signal VD is actually transmitted. The control can be performed according to the image quality of the transmitted image, and the video signal can be transmitted with higher image quality.

In the second invention, the actual coding distortion S
In addition to S.34, by controlling the band limiting characteristic of the band limiting circuit 2A based on the band limiting distortion S23 generated when passing through the band limiting circuit 2A, the block distortion and the band limiting due to the increase of the actual coding distortion S34. Blurring of the contour portion due to the increase of the distortion S23 can be suppressed, and the visual image quality of the transmission image can be further improved.

Further, in the third invention, the predicted image data S predicted based on the video signal of the previous reference frame.
41 and the difference between the video signal VD of the current reference frame,
By controlling the band limiting characteristic of the band control circuit 2A based on the prediction distortion S43 and the actual encoding distortion S34, it is possible to suppress the block distortion and the blurring of the contour portion which are visible in the transmission image, and also due to the scene change. It is possible to effectively avoid the deterioration of the image quality and further improve the visual quality of the transmitted image.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings.

(1) First Embodiment In FIG. 1 in which parts corresponding to those in FIG. 4 are designated by the same reference numerals, the image data transmission device 20 causes distortion that occurs when the pass band is limited by the preprocessing circuit 2. The band limitation characteristic of the preprocessing circuit 2 is detected based on the output data of the resolution deterioration detection circuit system 21 to be detected, the coding distortion detection circuit system 22 generated when the quantization circuit 8 quantizes, and both detection circuit systems 21 and 22. It has the same configuration except that it has a control circuit 23 for controlling.

The resolution deterioration detection circuit system 21 supplies the input video signal VD to the pre-processing circuit 2 and the subtraction circuit 25 via the delay circuit 24. Here, the delay circuit 24
Is configured to delay the input video signal VD by the time required for the front filter circuit 2A to band-limit the high frequency component and supply the delayed input video signal VD to the subtraction circuit 25.

The subtraction circuit 25 obtains the difference between the band-limited input image data S1 and the input video signal VD to obtain the deterioration of the resolution due to the transmission of no high frequency component as the difference data S21, and the distortion amount detection. Supply to the circuit 26. The distortion amount detection circuit 26 obtains the square value of the difference data S21, and takes this as the square value data S22, and the integration circuit 27.
Output to. The integrator circuit 27 uses 1 of the squared value data S22.
By obtaining the sum of the fields, the band limiting distortion that occurs when the input video signal VD passes through the pre-filter circuit 2A is obtained by one field, and is output to the control circuit 23 as 4-bit band limiting distortion data S23. Has been done.

On the other hand, the coding distortion detection circuit system 22 is
The locally decoded data S31 reproduced by the previous frame data generation circuit 14 is input to the subtraction circuit 30, and the input image data S1 is input via the delay circuit 31. Thereby, the subtraction circuit 30 obtains the difference between the locally decoded data S31 corresponding to the same position of the input image data S1 and the input image data S1, and the distortion caused by the encoding is obtained as the difference data S3.
It is designed to output as 2.

After obtaining the square value of the difference data S32, the actual distortion detecting circuit 32 supplies it to the integrating circuit 33 as the square value data S33 and obtains the total of one field. The integrating circuit 33 controls the quantization accuracy of the quantizing circuit 8 controlled by the amount of data stored in the transmission buffer memory 10 and the pre-filter circuit 2.
By calculating the sum of the squared value data S33 that varies depending on the pattern of the transmitted image of the input image data S1 output from A within one field, the average value of the distortion actually generated at the time of encoding is calculated. The control circuit 23 outputs the 4-bit real encoded distortion data S34.

The control circuit 23 outputs the 4-bit band limiting data S35 to the pre-filter circuit 2A of the pre-processing circuit 2 to control the band limiting characteristic of the pre-filter circuit 2A. Here, the control circuit 23 is a ROM (read only memor
y) configuration, the pre-field band limitation data S36 at the pre-field input after being delayed by one field through the delay circuit 35, the resolution deterioration detection circuit system 2
Band-limited distortion data S2 input from the integration circuit 27 of 1
3 and the actual encoded distortion data S34 input from the integration circuit 33 of the encoded distortion detection circuit system 22 are weighted according to the priority order and output as band limited data S35.

Incidentally, the control circuit 23 obtains the first-order derivative of the band-limited data S34 by way of the delay circuit 35, and obtains the increase / decrease of the band-limited data S35 outputted for each field.

In the above structure, when the image data transmission device 20 inputs the video signal VD to the prefilter circuit 2A of the preprocessing circuit 2, the video signal VD of the video signal VD is supplied based on the band limiting data S35 supplied from the control circuit 23. The band is limited according to the amount of generated information, and is output to the difference data generation circuit 3 as the input image data S1. At this time, the resolution deterioration detection circuit system 21 limits the band of the original video signal VD and the original video signal VD, and thereby the input image data S whose resolution is deteriorated.
After obtaining the difference from 1, the sum of the square values of the difference data S21 is obtained for one field period, and the distortion amount caused by the band limitation is supplied to the control circuit 23.

At this time, the coding distortion detection circuit system 22 is
Quantized data S6 obtained by quantizing the input image data S1 through the discrete cosine transform circuit 6 and the quantizer circuit 8 is locally decoded and input to the subtractor circuit 30 as locally decoded data S31. The difference with respect to the band-limited input image data S1 is obtained via the filter circuit 2A. After this, the encoding distortion detection circuit system 22
When the actual encoding distortion generated during the encoding in the quantizing circuit 8 is obtained through the actual distortion detecting circuit 32 and the integrating circuit 33, is supplied to the control circuit 23 as the actual encoding distortion data S34.

Here, the control circuit 23 obtains the amount of distortion actually generated when the preceding field is transmitted from the upper bits of the band-limited distortion data S23 and the actual encoded distortion data S34, and the band-limited data S34 is stored in the pre-filter circuit. It is controlled so that both distortion data are output at a predetermined ratio set so that the deterioration of the image quality of the output data S8 which is output to 2A and transmitted is visually minimized.

As a result, the control circuit 23 outputs the output data S output to the transmission line 11 via the transmission buffer memory 10.
It is possible to effectively avoid the possibility that the real coding distortion increases sharply and the block-shaped distortion is visually recognized, or the band limitation distortion increases sharply and the contour of the image is blurred, and the image quality can be further improved.

According to the above configuration, both the band-limiting distortion generated when the video signal VD passes through the front filter 2A and the actual coding distortion generated when the video signal VD is quantized through the quantizing circuit 8 are generated. By controlling to a predetermined ratio and controlling the band limiting characteristics of the video signal VD so that the distortion that is visually perceived is minimized,
It is possible to further improve the image quality of the transmission image viewed on the receiving side as compared with the conventional case.

(2) Second Embodiment In FIG. 2 in which parts corresponding to those in FIG. 1 are designated by the same reference numerals, the image data transmission device 40 uses a prediction error between the predicted image of the current field and the image of the current field. It has the same configuration except that it has a prediction error discrimination circuit system 41 for discriminating the amount. The prediction error identification circuit system 41 supplies the input video signal VD to the subtraction circuit 42, and also supplies it to the preprocessing circuit 2 and the interpolation filter 44 via the delay circuit 43.

When the interpolation filter 44 receives the video signal VD delayed for a predetermined time through the delay circuit 43, the pixel data of the next field is obtained by weighting a plurality of pixels of the previous field, and the pixel after the weighting is calculated. The data is output to the subtraction circuit 42 as the predicted video signal S41 of the current field. Prediction error detection circuit 42
Calculates the difference by comparing the predicted video signal S41, which is a predicted value, with the input video signal VD as the original image.

At this time, the difference data S42 output from the subtraction circuit 42 is such that the finer the input image and the more vigorous the image movement (that is, it is difficult to improve the coding efficiency in the quantization circuit 8 and the coding distortion). The more likely the input is, the larger it becomes. When the difference data S42 is input from the subtraction circuit 42, the prediction error detection circuit 45 obtains the square value of the difference data S42 and supplies the square value to the integration circuit 46 to obtain the total distortion generated in the current field, and the control circuit 23 in the current field. The prediction error data S43 is supplied.

The control circuit 23 has a ROM configuration, and based on the actual encoded distortion data S34 and the current field prediction error data S43 input at 6 bits, the band limiting data S44 of 4 bits is stored in the preprocessing circuit 2. It is adapted to be supplied to the pre-filter circuit 2A to control the band limiting characteristic of the pre-filter circuit 2A.

That is, the control circuit 23 receives a video of a fine image or a video signal with a lot of movement as the video signal VD to increase the band limitation distortion, which may cause blurring of the contour or quantization of the converted data S5. The actual coding distortion increases,
The control is performed by balancing both strains so as to avoid the possibility that blocky strains are visually recognized.

In the above structure, the image data transmission device 40 supplies the sequentially input video signal VD to the prediction error discriminating circuit system 41, and the preprocessing circuit 2, the discrete cosine transform circuit 6, and the quantizing circuit 8. The data is sequentially coded, variable-length coded, and output to the transmission path 11. At this time, the coding distortion detection circuit system 22 receives the input image data S1.
A discrete cosine transform circuit 6 and a quantization circuit 8
The quantized data S6 quantized via the local decoding is input to the subtraction circuit 30 as the local decoded data S31, and the subtraction circuit 30 subtracts the difference from the band-limited input image data S1 via the pre-filter circuit 2A. Ask for.

After this, the coding distortion detection circuit system 22 obtains the coding distortion generated in the front field at the time of coding in the quantization circuit 8 via the actual distortion detection circuit 32 and the integration circuit 33,
The actual encoded distortion data S34 is supplied to the control circuit 23. Here, when the scene signal is present in the video signal VD of the current field, the subtraction circuit 42 causes the prediction error detection circuit 4
5. The current field prediction error data S43 output to the control circuit 23 via the integration circuit 46 increases at the scene change.

On the other hand, the actual encoded distortion data S34 is a small value which is substantially equal to or less than a constant value because it is the actual encoded distortion with respect to the previous field before scene change occurs. At this time, in the control circuit 23, the current field prediction error data S43 input from the prediction error identification circuit system 41 has a large value, while the actual coding distortion data S34 input from the coding distortion detection circuit system 22 is small. Determines that the scene change has occurred.

Here, the control circuit 23 controls the band limiting data S
When 44 is output to the prefilter circuit 2A of the preprocessing circuit 2, the video signal VD of the current field is output via the delay circuit 43.
When passing through the front filter circuit 2A, the amount of high-frequency components passing is suppressed with respect to the previous field to reduce the amount of information in the edge portion of the current field image, and even if the resolution is slightly reduced, the quantization circuit 8 Quantized quantized data S6
Reduce the occurrence of block distortion of the image transmitted by
As a result, the possibility that the image quality is visually deteriorated is avoided.

According to the above configuration, the current field prediction error data S43 and the quantizing circuit 8 indicating whether or not the video signal VD to be transmitted at present is an image which easily causes coding distortion.
By controlling the band limiting characteristic of the pre-filter circuit 2A based on the actual encoding distortion S34 that occurs when the image is quantized via, the distortion visually perceived in the transmitted image can be reduced, and The image quality can be stabilized.

(3) Other Embodiments In the above-described embodiments, the case where the pass band characteristic of the input video signal VD is controlled for each field has been described, but the present invention is not limited to this, and for each frame. The present invention can be widely applied to the case where the pass band characteristic is controlled in a unit of a predetermined field, such as the case of controlling the frequency.

In the above embodiment, the control circuit 2
Although the case where 3 is composed of a ROM has been described, the present invention is not limited to this and may be controlled using another arithmetic processing unit.

Further, in the above-mentioned first embodiment, the control circuit 23 obtains the first-order derivative of the band limiting data S35 by passing the band limiting data S35 through the delay circuit 35, and obtains it as the preceding field band limiting data S36. The case where the band-limited data S34 is set based on the band-limited distortion data S23 and the actual encoded distortion data S34 has been described, but the present invention is not limited to this, and the band-limited distortion data S23 and / or the actual encoded distortion data S34 can be used. The band limitation data S35 may be set based on the above.

Further, in the above-described second embodiment, the control circuit 23 uses the current field prediction error data S43 and the actual encoded distortion data S34 to set the band limiting data S4.
However, the present invention is not limited to this, and the band limitation data S35 may be set based on the current field prediction error data S43 or the actual encoded distortion data S34.

Further, in the above-described first embodiment, the case where the square value of the difference data S21 and S32 is obtained by the distortion amount detection circuit 26 and the actual distortion detection circuit 32 respectively has been described, but the present invention is not limited to this. Alternatively, the absolute value of each difference data S21 and S32 or a non-linearly weighted value may be obtained.

Further, in the above-described second embodiment, the case where the prediction error detection circuit 43 obtains the square value of the difference data S42 has been described, but the present invention is not limited to this, and the absolute value of the difference data S42 or A non-linearly weighted value may be obtained.

Further, in the above-described first embodiment, the control circuit 23 controls the band limiting data S23 so that the band limiting distortion data S23 and the actual encoded distortion data S34 have a predetermined ratio.
However, the present invention is not limited to this, and the ratio of the band-limited distortion data S23 is not limited to this when the deterioration of the image quality is more difficult to be visually recognized when the band-limited distortion is larger than the coding distortion. It may be controlled to be higher, or if the deterioration of the image quality is more difficult to be visually recognized when the coding distortion is larger than the band-limiting distortion, the ratio of the coding distortion data S34 may be controlled to be higher.

Further, in the above-mentioned second embodiment, the case where the interpolation filter 44 obtains the interpolation data by weighting a plurality of pixels of the previous field has been described. However, the shape of the filter, each weight, and the performance are hardware. Various interpolation filters may be applied depending on

[0059]

As described above, according to the present invention, the band limiting characteristic of the band limiting circuit is controlled based on the actual coding distortion generated when the high efficiency coded data is quantized by the quantizing means. The generation of distortion visually perceived in the transmitted image can be further reduced compared to the conventional case, and the image quality of the transmitted image on the receiving side can be further improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of an image data transmission device according to the present invention.

FIG. 2 is a block diagram showing a second embodiment of the image data transmission device according to the present invention.

FIG. 3 is a schematic diagram for explaining intraframe / interframe encoding processing.

FIG. 4 is a block diagram for explaining a conventional image data transmission device.

FIG. 5 is a schematic diagram showing a configuration of frame image data.

FIG. 6 is a schematic diagram for explaining a quantization step.

[Explanation of symbols]

20, 40 ... Image data transmission device, 21 ... Resolution deterioration detection circuit system, 22 ... Encoding distortion detection circuit system, 23 ...
Control circuit, 25, 30, 42 ... Subtraction circuit, 26 ... Distortion amount detection circuit, 27, 33, 46 ... Integration circuit, 32 ...
Real distortion detection circuit, 41 ... Prediction error identification circuit system, 44 ...
Interpolation filter 45 ... Prediction error detection circuit.

[Procedure amendment]

[Submission date] August 17, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 2

[Correction method] Change

[Correction content]

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 3

[Correction method] Change

[Correction content]

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal transmission device, and more particularly to a video signal transmission device for transmitting a high quality image in a one-to-many transmission mode such as broadcasting by orthogonal transformation such as Discrete Cosine Transform. It is suitable for application.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

[0003]

2. Description of the Related Art Conventionally, in a so-called video signal transmission system for transmitting a video signal composed of a moving image to a remote place such as a video conference system and a video telephone system, in order to efficiently use a transmission line, The video signal is coded by utilizing the correlation of (1) to improve the transmission efficiency of significant information.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

That is, as shown in FIG. 4, the image data transmission apparatus 1 performs band limitation, transmission order conversion and the like on the digitized input video signal VD by the preprocessing circuit 2 and outputs it as input image data S1. To do. Preprocessing circuit 2
Includes a front filter circuit 2A (not shown), and controls the transmission band in accordance with the amount of generated information of the transmitted video signal.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

The difference data generation circuit 3 receives the input image data S
When the previous frame data S2 of the previous frame stored in the previous frame memory 4 is input together with 1, the difference between the previous frame data S2 and the input image data S1 is obtained to generate interframe encoded data (hereinafter referred to as interframe encoding mode). ) And the discrete cosine transform (DCT) of the difference data S3 via the switching circuit 5.
The output circuit 6 and the switching control circuit 7 are output together with the input image data S1.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

The switching circuit 5 is controlled by the control signal S4 output from the switching control circuit 7, and when it is judged that there is a high possibility that a smaller amount of data can be transmitted by intra-field coding and transmission, The difference data S3 is output when it is determined that the input image data S1 is output as it is, and that the possibility of transmission with a small amount of data is high when the data is encoded and transmitted between frames.
The discreet cosine transform circuit 6 utilizes the two-dimensional correlation of video signals to input image data S1 or difference data S
3 is subjected to discrete cosine transform in units of a minute block, and coefficient data S5 obtained as a result is output to the quantizing circuit 8.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction content]

On the contrary, the transmission buffer memory 10
When the remaining amount of data is reduced to the allowable lower limit value, the transmission buffer memory 10 reduces the step size of the quantization step size STPS of the quantization circuit 8 in accordance with the quantization control signal S9, so that the data amount of the quantized data S6. Increase. The inverse quantization circuit 12 inversely quantizes the quantized data S6 sent from the quantization circuit 8 into a representative value, converts the quantized data S6 into inverse quantized data S10, and performs inverse discrete cosine transform (IDCT).
The circuit is supplied to the cosine transform circuit 13.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

Discrete cosine inverse conversion circuit 13
Is the inverse quantized data S1 decoded by the inverse quantization circuit 12.
0 is converted into decoded image data S11 by a conversion process reverse to that of the discrete cosine inverse conversion circuit 6, and is output to the previous frame data generation circuit 14 and the switching circuit 15. As a result, the discrete cosine inverse conversion circuit 13 outputs the input image data S1 or the difference data S1 before the conversion of the output data S8 output via the transmission line 11 and restored on the receiving side in the discrete cosine conversion circuit 6.
3 can be decoded on the transmission side.

[Procedure Amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

That is, the discrete cosine inverse conversion circuit 13 restores the input image data S1 when the video signal VD is subjected to intra-field coding processing and then transmitted, while the video signal VD is subjected to inter-frame coding processing. When the data is transmitted after being transmitted, the difference data S3 is restored. The previous frame data generation circuit 14 adds the previous frame data S2 fed back from the previous frame memory 4 and the decoded image data S11 to output data S8.
By reproducing the image data of the previous frame output as, and outputting it to the previous frame memory 4 via the switching circuit 15, the images transmitted to the receiving side are sequentially reproduced and stored in the previous frame memory 4. Has been done.

[Procedure Amendment 12]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

The present invention has been made in consideration of the above points, and the band is based on the band-limiting distortion that occurs when the pass band of the video signal is limited and the coding distortion that occurs when the video signal is quantized. By controlling the limiting characteristic, it is possible to further improve the image quality of the transmission image and transmit the image.

[Procedure Amendment 13]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

[0022]

In order to solve such a problem, in the first invention, the video signal VD is band-limited through the band limiting circuit 2A, and the video signal S after the band limiting is performed.
In the video signal transmission devices 20 and 40 that perform the orthogonal transform processing of 1 to coefficient data S5, quantize the coefficient data S5 and convert it to quantized data S6, the quantized information S9
Decoding means 12 for decoding the quantized data S6 based on
13, 14, 15 and the video signal S1 band-limited by the band limiting circuit 2A and the decoding means 12, 13, 14, 1
Difference data detecting means 30 for obtaining a difference from the decoded data S31 decoded in 5, and coding distortion detecting means 32, 33 for obtaining a coding distortion S34 based on the difference S32 obtained by the difference data detecting means 30. , And a control means 23 for controlling the band limiting characteristic of the band limiting circuit 2A based on the encoding distortion S34.

[Procedure Amendment 14]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

In the second invention, the video signal VD
Is band-limited through the band-limiting circuit 2A, the band-limited video signal VD is orthogonally transformed to coefficient data S5, and the coefficient data S5 is quantized to be quantized data S6.
In the video signal transmission device 20 for converting into a video signal, the difference S21 between the first video signal VD input to the band limiting circuit 2A and the second video signal S1 output from the band limiting circuit 2A.
And the band-limited distortion detecting means 25, 26, 27 for obtaining the band-limited distortion S23 from the difference S21 and the quantization information S.
Decoding means 1 for decoding the quantized data S6 based on 9
2, 13, 14, 15 and the second video signal S1 and the decoded data S3 decoded by the decoding means 12, 13, 14, 15.
A difference data detecting means 30 for obtaining a difference S32 from 1.
A coding distortion detecting means 32 for calculating a coding distortion S34 based on the difference S32 calculated by the difference data detecting means 30,
33, band limiting distortion S23 and coding distortion detecting means 32, 33 obtained by the band limiting distortion detecting means 25, 26, 27.
The control means 23 for controlling the band limiting characteristic of the band limiting circuit 2A on the basis of the coding distortion S34 obtained by

[Procedure Amendment 15]

[Document name to be amended] Statement

[Correction target item name] 0024

[Correction method] Change

[Correction content]

Further, in the third invention, the video signal V
D is band-limited via the band limiting circuit 2A, the band-limited video signal VD is orthogonally transformed to coefficient data S5, and the coefficient data S5 is quantized to quantize data S5.
In the video signal transmission device 40 for converting to 6, the video signal VD is delayed for a predetermined period and delayed based on the delay means 43 supplied to the band limiting circuit 2A and the video signal of the previous reference frame output from the delay means 43. An image data prediction unit 44 for predicting a video signal of the current reference frame input to the unit 43, and a difference S42 between the predicted image data S41 output from the image data prediction unit 44 and the video signal VD of the current reference frame, Predictive distortion detecting means 45, 46 for obtaining the predictive distortion S43 from the difference S42, and decoding means 12, 1 for decoding the quantized data S6 based on the quantized information S9.
3, 14, 15 and the band-limited video signal S1 via the band limiting circuit 2A and the decoding means 12, 13, 14, 15
Difference data detecting means 30 for obtaining a difference S32 from the decoded data S31 decoded in step 3, and coding distortion detecting means 32, 33 for obtaining a coding distortion S34 based on the difference S32 obtained by the difference data detecting means 30. , Predictive distortion detection means 4
5 and 46, based on the prediction distortion S43 and the encoding distortion S34 obtained by the encoding distortion detecting means 32 and 33,
Control means 2 for controlling the band limiting characteristic of the band limiting circuit 2A
3 and 3.

[Procedure 16]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction content]

[0025]

In the first aspect of the present invention, the video signal VD is actually transmitted by controlling the band limiting characteristic of the band limiting circuit 2A based on the coding distortion S34 that occurs when the video signal VD is quantized and actually transmitted. It is possible to control according to the image quality of the transmitted image, and it is possible to transmit the video signal with higher image quality.

[Procedure Amendment 17]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

In the second invention, the coding distortion S3 is used.
In addition to 4, the block distortion and the band limiting distortion due to the increase of the coding distortion S34 are controlled by controlling the band limiting characteristic of the band limiting circuit 2A based on the band limiting distortion S23 generated when passing through the band limiting circuit 2A. Blurring of the contour portion due to the increase in S23 can be suppressed, and the visual image quality of the transmission image can be further improved.

[Procedure 18]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

Further, in the third invention, the predicted image data S predicted based on the video signal of the previous reference frame.
41 and the difference between the video signal VD of the current reference frame,
By controlling the band limiting characteristic of the band control circuit 2A based on the prediction distortion S43 and the encoding distortion S34, it is possible to suppress the block distortion and the blurring of the contour portion which are visible in the transmission image, and the image quality due to scene change is suppressed. Can be effectively avoided, and the visual quality of the transmitted image can be further improved.

[Procedure Amendment 19]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction content]

After obtaining the square value of the difference data S32, the actual distortion detecting circuit 32 supplies it to the integrating circuit 33 as the square value data S33 and obtains the total of one field. The integrating circuit 33 controls the quantization accuracy of the quantizing circuit 8 controlled by the amount of data stored in the transmission buffer memory 10 and the pre-filter circuit 2.
By calculating the sum of the squared value data S33 that varies depending on the pattern of the transmitted image of the input image data S1 output from A within one field, the average value of the distortion actually generated at the time of encoding is calculated. The control circuit 23 outputs the 4-bit encoded distortion data S34.

[Procedure amendment 20]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction content]

The control circuit 23 outputs the 4-bit band limiting data S35 to the pre-filter circuit 2A of the pre-processing circuit 2 to control the band limiting characteristic of the pre-filter circuit 2A. Here, the control circuit 23 uses a ROM (read only)
y memory), the front field band limitation data S36 in the previous field, which is delayed by one field by the delay circuit 35, and the band limitation input from the integration circuit 27 of the resolution deterioration detection circuit system 21. The distortion data S23 and the encoded distortion data S34 input from the integration circuit 33 of the encoded distortion detection circuit system 22 are weighted according to the priority order and output as band-limited data S35.

[Procedure correction 21]

[Document name to be amended] Statement

[Name of item to be corrected] 0037

[Correction method] Change

[Correction content]

At this time, the coding distortion detection circuit system 22 is
Quantized data S6 obtained by quantizing the input image data S1 through the discrete cosine transform circuit 6 and the quantizer circuit 8 is locally decoded and input to the subtractor circuit 30 as locally decoded data S31. The difference with respect to the band-limited input image data S1 is obtained via the filter circuit 2A. After this, the encoding distortion detection circuit system 22
When the coding distortion generated at the time of coding in the quantizing circuit 8 is obtained through the distortion detecting circuit 32 and the integrating circuit 33, is supplied to the control circuit 23 as coding distortion data S34.

[Procedure correction 22]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction content]

Here, the control circuit 23 obtains the amount of distortion actually generated when the preceding field is transmitted from the upper bits of the band-limited distortion data S23 and the encoded distortion data S34, and the band-limited data S34 is stored in the pre-filter circuit 2A. It is controlled so that both distortion data have a predetermined ratio that is set so that the deterioration of the image quality of the output data S8 that is output and transmitted is visually minimized.

[Procedure amendment 23]

[Document name to be amended] Statement

[Correction target item name] 0039

[Correction method] Change

[Correction content]

As a result, the control circuit 23 outputs the output data S output to the transmission line 11 via the transmission buffer memory 10.
It is possible to effectively avoid the possibility that a block-shaped distortion is visually recognized due to a sharp increase in the coding distortion in 8 and a blur of the image contour due to a sharp increase in the band-limited distortion, and the image quality can be further improved.

[Procedure amendment 24]

[Document name to be amended] Statement

[Item name to be corrected] 0040

[Correction method] Change

[Correction content]

According to the above configuration, both the band limiting distortion generated when the video signal VD passes through the front filter 2A and the coding distortion generated when the video signal VD is quantized through the quantization circuit 8 are predetermined. By controlling the ratio and controlling the band limiting characteristic of the video signal VD so that the visible distortion is minimized, the image quality of the transmission image viewed on the receiving side can be further improved as compared with the conventional case. ..

[Procedure Amendment 25]

[Document name to be amended] Statement

[Correction target item name] 0044

[Correction method] Change

[Correction content]

The control circuit 23 has a ROM configuration, and based on the encoded distortion data S34 and the current field prediction error data S43 input at 6 bits respectively, the band limiting data S44 consisting of 4 bits is supplied to the pre-processing circuit 2 in advance. It is adapted to be supplied to the pre-filter circuit 2A to control the band limiting characteristic of the pre-filter circuit 2A.

[Procedure Amendment 26]

[Document name to be amended] Statement

[Name of item to be corrected] 0045

[Correction method] Change

[Correction content]

That is, the control circuit 23 receives the image of a fine image as the image signal VD or the image signal with a lot of movement and the band limitation distortion increases, which may occur when the contour is blurred or the coefficient data S5 is quantized. The coding distortion is increased and the distortion is balanced and controlled so as to avoid the possibility that the block-shaped distortion is visually recognized.

[Procedure Amendment 27]

[Document name to be amended] Statement

[Correction target item name] 0047

[Correction method] Change

[Correction content]

Thereafter, the coding distortion detecting circuit system 22 obtains the coding distortion generated in the previous field at the time of coding in the quantizing circuit 8 via the distortion detecting circuit 32 and the integrating circuit 33 to obtain the coding distortion data. It is supplied to the control circuit 23 as S34. If there is scene change in the video signal VD of the current field, the current field prediction error data S43 output from the subtraction circuit 42 to the control circuit 23 via the prediction error detection circuit 45 and the integration circuit 46 is the boundary of the scene change. Increase to.

[Procedure correction 28]

[Document name to be amended] Statement

[Correction target item name] 0048

[Correction method] Change

[Correction content]

On the other hand, the coded distortion data S34 is a small value which is almost equal to or less than a fixed value because it is the code distortion for the previous field before scene change occurs. At this time, the control circuit 23 determines that the current field prediction error data S43 input from the prediction error identification circuit system 41 has a large value.
Since the encoded distortion data S34 input from the encoding distortion detection circuit system 22 is small, it is determined that a scene change has occurred.

[Procedure correction 29]

[Document name to be amended] Statement

[Correction target item name] 0053

[Correction method] Change

[Correction content]

Further, in the above-mentioned first embodiment, the control circuit 23 obtains the first-order derivative of the band limiting data S35 by passing the band limiting data S35 through the delay circuit 35, and obtains it as the preceding field band limiting data S36. The case where the band-limited data S34 is set based on the band-limited strain data S23 and the encoded strain data S34 has been described.
The present invention is not limited to this, and based on the band-limited distortion data S23 and / or the encoded distortion data S34, the band-limited data S3 is generated.
5 may be set.

[Procedure amendment 30]

[Document name to be amended] Statement

[Correction target item name] 0054

[Correction method] Change

[Correction content]

Further, in the above-mentioned second embodiment, the control circuit 23 uses the current field prediction error data S43 and the encoded distortion data S34 to limit the band limitation data S44.
However, the present invention is not limited to this, and the band limitation data S35 may be set based on the current field prediction error data S43 or the encoded distortion data S34.

[Procedure 31]

[Document name to be amended] Statement

[Correction target item name] 0057

[Correction method] Change

[Correction content]

Further, in the above-described first embodiment, the control circuit 23 controls the band-limited distortion data S3 so that the band-limited distortion data S23 and the encoded distortion data S34 have a predetermined ratio.
However, the present invention is not limited to this, and the band-limited distortion data S can be used when the deterioration of the image quality is less visible when the band-limited distortion is larger than the coding distortion.
The ratio of the coded distortion data S34 is controlled so that the ratio of the coded distortion data S34 is increased when the coding distortion is larger than the band-limited distortion and the deterioration of the image quality is less visible. May be.

[Procedure correction 32]

[Document name to be amended] Statement

[Correction target item name] 0059

[Correction method] Change

[Correction content]

[0059]

As described above, according to the present invention, the transmission image is controlled by controlling the band limiting characteristic of the band limiting circuit based on the actual coding distortion generated when the coefficient data is quantized by the quantizing means. It is possible to further reduce the occurrence of distortion visually recognized, and to further improve the image quality of a transmission image on the receiving side.

[Procedure amendment 33]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

[Procedure amendment 34]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

[Procedure amendment 35]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

[Figure 4] ─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] April 15, 1993

[Procedure amendment 33]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

Claims (3)

[Claims] 1. A video signal is band-limited through a band-limiting circuit, and the band-limited video signal is subjected to high-efficiency coding processing to be converted into high-efficiency coded data. In a video signal transmission device for quantizing and converting into transmission data, a decoding means for decoding the high-efficiency encoded data based on quantization information, the video signal band-limited by the band-limiting circuit, and the decoding Difference data detecting means for obtaining a difference from the decoded data decoded by the means, real encoding distortion detecting means for obtaining an actual encoding distortion based on the difference obtained by the difference data detecting means, and the real code A video signal transmission device, comprising: a control unit that controls the band limiting characteristic of the band limiting circuit based on the distortion. 2. A video signal is band-limited through a band-limiting circuit, the band-limited video signal is subjected to high-efficiency encoding processing to be converted into high-efficiency encoded data, and the high-efficiency encoded data is converted into the high-efficiency encoded data. In a video signal transmission device for quantizing and converting into transmission data, a difference between the first video signal input to the band limiting circuit and the second video signal output from the band limiting circuit is calculated, Band limiting distortion detecting means for obtaining a band limiting distortion from a difference; decoding means for decoding the high-efficiency coded data based on quantization information; and the second video signal and decoded data decoded by the decoding means. On the basis of the difference data detecting means for obtaining the difference between the difference data detecting means, the actual encoding distortion detecting means for obtaining the actual encoding distortion based on the difference obtained by the difference data detecting means, and the band limiting distortion detecting means. Based on the actual coding distortion obtained by the band limiting the distortion and the actual coding distortion detecting means, a video signal transmission apparatus characterized by comprising a control means for controlling the band limitation characteristic for the band limiting circuit. 3. A video signal is band-limited through a band limiting circuit, the band-limited video signal is subjected to high-efficiency encoding processing to be converted into high-efficiency encoded data, and the high-efficiency encoded data is converted into high-efficiency encoded data. In a video signal transmission device for quantizing and converting into transmission data, delay means for delaying the video signal for a predetermined period and supplying it to the band limiting circuit, and based on the video signal of the previous reference frame output from the delay means. Then, the image data prediction means for predicting the video signal of the current reference frame input to the delay means, the difference between the predicted image data output from the image data prediction means and the video signal of the current reference frame are calculated. Seeking,
Predictive distortion detecting means for obtaining predictive distortion from the difference, decoding means for decoding the high-efficiency encoded data based on quantization information, the video signal band-limited through the band-limiting circuit, and the decoding means Difference data detecting means for obtaining a difference from the decoded data decoded by, the actual encoding distortion detecting means for obtaining an actual encoding distortion based on the difference obtained by the difference data detecting means, and the prediction distortion detecting means. And a control means for controlling the band limiting characteristic of the band limiting circuit based on the predictive distortion obtained by the means and the actual encoding distortion obtained by the actual encoding distortion detecting means. Signal transmission equipment.