JP2000354242A - Coding converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively apply re-coding to a moving picture signal coded by a prescribed coding system at a coding efficiency in response to source transmission, relay transmission and terminal station transmission. SOLUTION: A coding buffer 10 stores a coded signal coded by a 1st coding system. A decoding circuit 20 decodes codes stored in a code buffer 10 into a digital component signal. A changeover circuit 30 is switched on purpose and supplies the decoded signal to a 1st coding circuit 40 or a 2nd coding circuit 50 and a code including a motion vector from the code buffer 10 is given to its input of the 1st coding circuit 40 when the 1st coding circuit 40 is selected. The 1st coding circuit 40 extracts a motion vector code from the 1st coded signal and uses the motion vector to re-encodes the decoded signal by using the motion vector. The 2nd coding circuit 50 detects a 2-way motion vector from the decoded signal and applies re-encoding to a signal whose noise is reduced on the basis of the detection of the motion vector.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coding conversion apparatus, and more particularly, to a coding conversion apparatus suitable for use in an image transmission system such as a relay apparatus for changing the coding efficiency of a moving image signal according to a transmission destination and transmitting the moving image signal. The present invention relates to a simple coding conversion device.

[0002]

2. Description of the Related Art In recent years, for example, when a moving image signal such as a television signal is transmitted or recorded, MPEG (mo
2. Description of the Related Art Encoding apparatuses that compress and encode an image using a high-efficiency encoding method such as a ving picture coding experts group and transmit or record the image are known. Ideally, high-efficiency coding has high coding efficiency and little deterioration in image quality. However, actually, there is a trade-off between the deterioration of the image quality and the coding efficiency, and if the image quality is prioritized, the coding efficiency is lowered, and if the coding efficiency is prioritized, the image quality is deteriorated.
In the image transmission system, image quality is prioritized and transmission is performed with low coding efficiency; relay stations are transmitted in which transmission errors and noise are removed at each relay station; There are three types of transmission schemes in the case where transmission is performed with higher encoding efficiency prior to higher encoding efficiency.

Conventionally, in such an image transmission system,
There are a transmission device of a material transmission system that prioritizes image quality, a transmission device of a relay transmission system, and a transmission device of a terminal transmission system. In these transmission devices, for example, when a moving image signal coded by a predetermined coding method by the above-described coding device is input, the coded signal is temporarily converted to a digital image before coding. A decoder for decoding the digital image signal into an analog component signal,
If necessary, a playback device including a DA converter and a video signal encoder that reproduces an analog composite signal similar to the original television signal, and converts the reproduced analog video signal back to a digital component signal
A converter including an AD converter and a video signal decoder;
And an encoder for re-encoding the digital component signal by an encoding method having a predetermined encoding efficiency.

As a result, in a transmission apparatus of a material transmission system,
By returning a moving image signal encoded by a predetermined encoding method to an original component signal or a composite signal, a high-quality image is reproduced, and the moving image signal is re-encoded with a low encoding efficiency. In this case, the data is encoded and transmitted by the encoding method having a higher priority.

[0005] In a transmission device of a relay transmission system, when reproducing a moving image signal encoded and transmitted by a predetermined encoding method into an original component signal or a composite signal, a code error or noise is removed. Then, by re-encoding again with a predetermined encoding method, the encoded signal is reproduced and transmitted as a coded signal free from code errors and noise.

[0006] In a transmission device of a terminal transmission system, a moving image signal coded and transmitted by a predetermined coding method is temporarily returned to an original component signal or composite signal in order to increase the coding efficiency. In addition, the reproduced moving image signal is encoded by an encoding method having a high encoding efficiency and transmitted, so that the transmission efficiency is enhanced and the video signal is effectively distributed to each home.

[0007]

However, in the above-mentioned conventional technique, the coded signal is converted into the original analog component signal or the composite signal in order to convert the coding efficiency or to eliminate transmission errors or noise. Converting a digital signal to an analog signal causes image quality degradation due to repeated AD / DA conversion.When converting to a composite signal, the component is converted from the composite signal to a component signal. When returning to a signal, there is a problem that deterioration is further caused by Y / C separation and conversion by a decoder. Further, in the relay system, decoding and encoding are repeated many times, and a DCT (discrete cosine transform) is used.
However, the irreversible coding method such as that described above has a problem that the image quality deteriorates each time coding and decoding are repeated.

In the above-described conventional techniques, transmission apparatuses corresponding to material transmission, relay transmission, and terminal transmission must be prepared according to their respective applications, and can be commonly used for these. The development of a coding conversion device has been desired.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a coding conversion apparatus capable of effectively obtaining coding efficiency according to a partner with little image quality deterioration.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a coding conversion apparatus according to the present invention receives a moving picture signal coded by a first coding method and receives a first coded video signal. Encoding apparatus for re-encoding to a code having an encoding efficiency different from the encoding efficiency of the encoding scheme and outputting the same,
Storage means for sequentially accumulating codes of the first coding method, decoding means for decoding the codes of the first coding method supplied via the storage means into digital moving picture signals, and digital decoding by the decoding means. Encoding means for encoding the moving image signal of the first encoding method by a second encoding method having an encoding efficiency higher than that of the first encoding method, and outputting the encoded digital signal decoded by the decoding means. A second encoding unit that encodes and outputs the moving image signal using a third encoding system having an encoding efficiency at least lower than the encoding efficiency of the first encoding system, and re-encodes an output of the decoding unit Switching means for switching to the input of the first encoding means or the second encoding means in accordance with the encoding efficiency to be performed.

In this case, the first encoding means uses a motion vector extraction means for extracting a motion vector code from the codes of the first encoding method, and a motion vector extracted by the motion vector extraction means. Encoding means for encoding the video signal decoded from the decoding means by the second encoding method.

The second encoding means includes a motion vector detecting means for obtaining a motion vector of the moving picture signal decoded by the decoding means, and a moving picture from the decoding means based on the motion vector from the motion vector detecting means. It is preferable to include a noise reduction unit that reduces noise of a signal, and an encoding unit that encodes a moving image signal from the noise reduction unit using a third encoding method.

In these cases, it is advantageous that the encoding conversion apparatus according to the present invention includes monitoring means for displaying a locally decoded signal of the moving picture signal decoded by the decoding means on a predetermined display device and monitoring the same.

Further, it is further advantageous to include a monitor means for displaying a locally decoded signal of the moving picture signal encoded by the first encoding means or the second encoding means on a predetermined display device for monitoring. .

Further, by switching between a locally decoded signal of a moving image signal from the decoding means and a locally decoded signal of a moving image signal encoded by the first encoding means or the second encoding means, a predetermined Monitor means for displaying and monitoring on a display device may be included.

[0016]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a code conversion apparatus according to the present invention; FIG.
FIG. 1 shows an embodiment of a coding conversion apparatus according to the present invention. The encoding conversion device according to the present embodiment is, for example,
When transmitting or relaying a moving picture signal coded by a coding method such as MPEG (moving picture coding experts group), the transmission system changes its coding efficiency depending on the destination, for example, to a transmission system. This is a transmission device to which the present invention is applied, and is a coding conversion device that converts and outputs the coding method according to a case where coding efficiency is prioritized and a case where image quality is prioritized.

In particular, in this embodiment, when the moving picture signal decoded in the case of encoding with priority on the encoding efficiency is re-encoded by the encoding method with high encoding efficiency, the original encoding method is used. A first encoding circuit 40 for re-encoding using a motion vector included in the code, and a video signal decoded in a case where encoding is performed with priority on image quality, the noise is reduced, and then the original encoding method is applied. And a second encoding circuit 50 for re-encoding with a coding scheme with low encoding efficiency or equivalent encoding efficiency. When re-encoding with these encoding circuits 40 and 50, an analog image signal The main feature is that the digital signal is processed as it is without being reproduced.

More specifically, as shown in FIG. 1, the encoding conversion apparatus according to the present embodiment comprises a buffer memory 10 and a decoding circuit.
20, a switching circuit 30, a first encoding circuit 40, a second encoding circuit 50, a frame memory 60, and a monitor interface 70. The buffer memory 10 is a storage circuit for sequentially storing codes of moving image signals coded by the first coding method, and the stored codes are sequentially read in accordance with the decoding timing in the decoding circuit 20. In the present embodiment, the moving image signal is, for example, a first component obtained by converting an NTSC television signal into a digital component signal and encoding the digital image by, for example, MPEG encoding.
Are supplied as encoded signals.

The decoding circuit 20 is a decoder for decoding the first encoded signal read from the buffer memory 10, and includes, for example, a first circuit including circuits such as an inverse orthogonal transform circuit, an inverse quantization circuit, and a motion compensation memory. Is a decoder corresponding to the encoded signal of. In this embodiment, the locally decoded signal is supplied to the frame memory 60 for monitoring and maintenance, and the digital component signal decoded to the original image is supplied to the switching circuit.
30 through the first encoding circuit 40 or the second encoding circuit
Supplied to 50.

The switching circuit 30 has a first switch 30a for switching the digital component signal decoded by the decoding circuit 20 to the first encoding circuit 40 or the second encoding circuit 50 according to the purpose. This is a switch circuit. In the present embodiment, when switching to the first encoding circuit 40, the second encoding circuit supplies the code of the first encoded signal from the buffer memory 10 to the first encoding circuit 40. Includes switch 30b.

The first encoding circuit 40 converts the digital component signal obtained by decoding the first encoded signal supplied from the decoding circuit 20 supplied via the switching circuit 30 into the encoding efficiency of the first encoding method. This is a re-encoding circuit that re-encodes at a higher encoding efficiency. In this embodiment, a re-encoding circuit uses a motion vector at the time of encoding by the first encoding method included in the first encoded signal. An encoding circuit for re-encoding.

More specifically, for example, as shown in FIG. 2, the first encoding circuit 40 of this embodiment includes a subtractor 400,
Orthogonal transformation circuit 402, quantization circuit 404, and inverse quantization circuit
406, an inverse orthogonal transformation circuit 408, an adder 410, an image buffer 412, a motion correction circuit 414, a motion vector code extraction circuit 416, and a code output circuit 418, and perform orthogonal transformation and quantization. An encoder in which the image compression ratio is set higher than that of the first encoding method is advantageously used. To explain each part, the orthogonal transform circuit 402 converts the image data supplied via the subtractor 400 into a DCT (discrete cosine transform).
) Is an encoding circuit that performs compression encoding by orthogonal transformation such as. The quantization circuit 404 is a quantizer that quantizes the orthogonally transformed code with a predetermined quantization coefficient.

The inverse quantization circuit 406 is a circuit for inversely transforming the quantized code to the original transform coefficient. Inverse orthogonal transform circuit
Reference numeral 408 denotes an inverse transform circuit for returning the transform coefficient from the inverse quantization circuit 406 to the original signal. The inverse quantization circuit 406 and the inverse orthogonal transform circuit 408 form a local decoding circuit.
The image buffer 412 is a frame memory for sequentially storing the inversely converted image signals supplied via the adder 410. The motion correction circuit 414 is a correction circuit that performs motion correction on the image signal of the previous frame from the image buffer 412 using the motion vector between the current frame and the current frame, and supplies the result to the subtractor 400.
In this embodiment, the image buffer 41 is used by using the motion vector of the first encoded signal from the motion vector code extraction circuit 416.
Motion-correct the image of the previous frame from 2.

The motion vector code extraction circuit 416 extracts a motion vector code from the code of the first coded signal supplied through the second switch 30b in the switching circuit 30. The extracted motion vector code of the current frame is supplied to the code output circuit 418 as it is, and the decoded motion vector is sequentially supplied to the motion correction circuit 414. The code output circuit 418 is an output circuit that adds the motion vector code from the motion vector extraction circuit 416 to the code of the coded image signal and outputs it as a second coded signal formed into a predetermined stream. .

Returning to FIG. 1, the second encoding circuit 50 converts the digital component signal obtained by decoding the first encoded signal supplied from the decoding circuit 20 supplied via the switching circuit 30 into a first encoded signal. Is a re-encoding circuit that re-encodes at an encoding efficiency lower than or equal to the encoding efficiency of the encoding method. In the present embodiment, the noise of the digital component signal obtained by decoding the first encoded signal is reduced. This is an encoding circuit that performs re-encoding by reducing the image quality and improving the image quality.

More specifically, the second encoding circuit 50 of the present embodiment includes, for example, a motion vector detecting unit 52, a noise reducing unit 54, and a re-encoding unit 56, as shown in FIG. . To explain each unit, the motion vector detection unit 52 is a unit that detects a high-precision motion vector from a decoded digital image signal. In the present embodiment, a delay circuit 522, a vector detection circuit 524, and a vector selection circuit 526. The delay circuit 522 is a frame memory that stores the decoded image signal for each frame and delays the decoded image signal by at least one frame.

The vector detection circuit 524 calculates the direction and magnitude of the motion of the image between the previous frame image signal delayed by one frame from the delay circuit 522 and the current frame image signal directly from the decoding circuit 20. This is a detection circuit for detecting a motion vector representing the motion vector. In the present embodiment, both the motion vector based on the previous frame and the motion vector based on the current frame are obtained. In this embodiment,
For example, as a motion vector detection method, a deviation amount of an image corresponding to a pixel unit or a block unit of a predetermined number of pixels is repeatedly calculated based on a gradient value and a difference value of the pixel or the block. An iterative gradient method or the like is effectively applied.

The vector selection circuit 526 is a circuit for selecting a motion vector suitable for the image of the current frame from the two types of motion vectors detected by the vector detection circuit 524. The image signal from the delay circuit 522 is displaced by the motion vector from the vector detection circuit 524, and a motion vector is selected using the difference value as a parameter. The selected motion vector is
The signals are supplied to the noise reduction unit 54 and the re-encoding unit 56, respectively.
The difference value obtained as a parameter is supplied to the noise reduction unit 54.

The noise reduction unit 54 is a unit for reducing the noise of the decoded digital image signal and improving the image quality. In the present embodiment, the first multiplier 542 and the second multiplier 542
A first-order recursive filter including 544, an adder 546, a coefficient generating circuit 548, and a motion correcting circuit 550 is formed to reduce noise. The first multiplier 542 is a multiplying circuit that multiplies sequentially input image signals by a coefficient α of a first-order recursive filter. The second multiplier 544 is a multiplication circuit that multiplies the image signal of the previous frame subjected to the motion correction by the coefficient (1-α) of the first-order recursive filter.

The adder 546 includes a first multiplier 54 and a second multiplier 54.
This is an addition circuit that adds the image signals from 2,544 to obtain an output with reduced noise. The coefficient generation circuit 548 includes first and second multipliers 542, 542, based on the parameter from the vector selection circuit 526, that is, the above-described difference value representing the motion accuracy.
544 and the coefficients α and (1-
α) respectively.

The motion compensating circuit 550 performs motion compensation on the noise-reduced image signal from the adder 546 using the motion vector from the vector selecting circuit 526, and outputs the result to a second multiplier.
The circuit supplies the signal of the previous frame to the signal of the current frame. In other words, the first-order recursive filter reduces noise by adding the weight of the pixel value of the current frame and the pixel value obtained by motion-correcting the previous frame to the current frame. The image signal resulting from the noise reduction from the adder 546 is sequentially supplied to the re-encoding unit 56.

The re-encoding unit 56 encodes the image signal whose noise has been reduced by the noise reduction unit 54 at an encoding efficiency lower than or equal to the encoding efficiency of the first encoding method. In this embodiment, the local encoding circuit 562, the code buffer 564, the local decoding circuit 566, and the motion correcting circuit 56
8 and a differential encoding circuit 570. Local coding circuit 56
Reference numeral 2 denotes an encoder for intra-frame encoding of the image signal from the noise reduction unit 54. In the present embodiment, the first encoding circuit 20
Similarly to the above, an orthogonal transformation circuit and a quantization circuit are included.
The code buffer 564 is a storage circuit that stores the code from the local coding circuit 562 for one frame, and is a delay circuit that outputs the signal of the previous frame delayed by one frame.

The local decoding circuit 566 is a decoder for decoding the code from the code buffer 564 into the original image signal.
As with the encoding circuit 20 of, an inverse quantization circuit and an inverse orthogonal transform circuit are included. The motion compensation circuit 568 includes a noise reduction unit.
This is a circuit that performs motion correction on the image signal from the motion vector using the motion vector detected by the vector detection unit 52 and outputs the result. The difference encoding circuit 570 is an encoder that encodes, for each block, a difference value between the motion-compensated image signal of the current frame and the image signal of the previous frame from the local decoding circuit 566, and is similar to the local encoding circuit 562. Includes an orthogonal transformation circuit and a quantization circuit. The re-coded video signal is output as a third coded signal.

Returning again to FIG. 1, the frame memory 60
This is a storage circuit for sequentially storing image signals decoded by the decoding circuit 20. In the present embodiment, a block-line for storing at least one frame of a locally decoded image signal for each block and outputting for each line Including conversion function.

The monitor interface 70 is an interface for converting the decoded image from the frame memory 60 so that it can be displayed on a predetermined display device and outputting the converted image. For example, when displaying an image of the NTSC system, an AD (analog to digital)
It may include a converter, a low-pass filter, a synchronization signal mixing circuit, an NTSC encoder, and the like. Of course, when displaying an image on a monitor capable of displaying component signals, it is preferable to supply the signal as it is from the frame memory 60.

The operation of the coding conversion apparatus according to the present embodiment in the above-described configuration will be described. First, when priority is given to image quality, coding efficiency is prioritized, or relay is performed, The switching circuit 30 is connected to the first encoding circuit 40 or the second encoding circuit 50 depending on the purpose of
Switch to one of At that time, the first switch
When 30a is switched to the first encoding circuit 40, the second switch 30b is connected to the other input of the first encoding circuit 40, and when the first switch 30a is switched to the second encoding circuit 50, The second switch 30b is disconnected.

In such a state, when a moving image signal encoded by the first encoding method is supplied to the input, the first encoded signal is sequentially accumulated in the buffer memory 10, and Further, they are read out at the decoding timing in the decoding circuit 20 and are sequentially supplied to the decoding circuit 20. At this time, if the second switch 30b is connected to the first encoding circuit 40,
The code including the motion vector read from the code buffer 10 is sent to the first encoding circuit 40 via the second switch 30b.
Is also supplied.

Next, the first coded signal supplied to the decoding circuit 20 is locally decoded for each code, further subjected to motion correction and the like, and decoded into a digital component signal before coding. Is done. At this time, the locally decoded video signal is supplied to the frame memory 60, subjected to block-line conversion for each frame, supplied to the monitor interface 70, and further converted to a displayable video signal. Is displayed on a predetermined display device. This allows the monitoring or maintenance person to look at the image display and
It is possible to monitor whether the transmission of a desired image or the operation of the apparatus is normally performed.

Next, the digital component signal decoded by the decoding circuit 20 is sequentially supplied to the first encoding circuit 40 or the second encoding circuit 50 via the switching circuit 30, and the encoding is performed. Re-encoded according to efficiency. For example, the first encoding circuit 40 may give priority to encoding efficiency over image quality.
In the case of re-encoding, the orthogonal transformation circuit 402 and the quantization circuit with a higher compression ratio set than the first encoding method
At 404, the component signals sequentially input are compression-encoded for each block. The compression-encoded image signal is locally decoded by an inverse quantization circuit 406 and an inverse orthogonal transform circuit 408, and is stored in an image buffer 412.

On the other hand, in the motion vector extracting circuit 416, the first signal supplied via the second switch 30b of the switching circuit 30 is used.
The code of the motion vector of each image is extracted from the codes of the coded signal of. The extracted motion vector is decoded and supplied to the motion correction circuit 414, and the signal of the previous frame from the image buffer 412 which has been motion-corrected by the motion vector is supplied to the subtractor 400 and the adder 410.

As a result, the difference between the respective images of the previous frame and the current frame is supplied to the orthogonal transformation circuit 402 via the subtractor 400, and the result is sequentially encoded with a high encoding efficiency. It is supplied to a sign output circuit 418. Similarly, the digital component signals from the decoding circuit 20 which are sequentially input are inter-frame coded between the digital image and the previous frame which has been motion-corrected based on the motion vector extracted by the motion vector extraction circuit 416. Is output.

Next, the signal coded with high coding efficiency receives the motion vector code of the image from the motion vector code extraction circuit 416 at a code output circuit 418 and forms them into a predetermined bit stream. And outputs it as a second encoded signal.

On the other hand, the image quality is prioritized over the coding efficiency and the second
When re-encoding is performed by the encoding circuit 50, the decoding circuit 20
The decoded digital component signal from
The signals are sequentially supplied to the vector detection unit 52 and the noise reduction unit 54. In the vector detecting section 52, the image signal of the current frame sequentially inputted and the delay circuit 522 are inputted to the vector detecting circuit 524.
Then, the motion vector of each image is bidirectionally detected from the image signal of the previous frame delayed by and the result is supplied to the vector selection circuit 526. Vector selection circuit 526
Then, a difference value between the image signal of the current frame and the image signal of the previous frame which has been motion-corrected by each motion vector is obtained, and a true motion vector is selected using the value as a parameter. The selected motion vector is supplied to the noise reduction unit 54 and the re-encoding unit 56, respectively, and the parameters at the time of vector selection are supplied to the noise reduction unit 54 as motion accuracy information.

Next, the noise reduction unit 54 which has received the motion accuracy information and the motion vector reduces the noise of the sequentially input digital component signals by the action of the primary recursive filter. In this case, first, in the coefficient generation circuit 548, the coefficients α, (1
−α) to obtain a first multiplier 542 and a second multiplier 542, respectively.
To the multiplier 544. On the other hand, the motion correction circuit 550 performs motion correction on the image signal supplied via the adder 546 using the motion vector from the vector detection unit 52, and supplies the result to the second multiplier 544.

As a result, the first multiplier 542 multiplies the sequentially input signal of the current frame by the coefficient α, and supplies the result to an adder 546. The second multiplier 544 provides a motion compensation circuit 550. Is multiplied by a coefficient (1−α) from the signal of the previous frame subjected to the motion correction and supplied to the adder 546. As a result, the signal from the first multiplier 542 and the second
, And the result is sequentially supplied to the re-encoding unit 56 as a noise-reduced signal of the current frame.

Next, the re-encoding unit 56 that has received the noise-reduced component signal performs re-encoding at a lower encoding efficiency than the first encoding method in the case of material transmission, and performs re-encoding in the case of relay transmission. Re-encoding is performed with the same encoding efficiency as that of the first encoding method. In this case, the local encoding circuit 562 and the differential encoding circuit 570 are preset with a compression ratio and a quantization coefficient according to the encoding efficiency.

In this state, first, the image signal of the current frame in which the noise has been reduced is sequentially supplied to the local encoding circuit 562 and the motion correction circuit 568, respectively. This allows
In the local encoding circuit 562, the image signal of the current frame is intra-coded for each block, and the result is sequentially supplied to the code buffer 564. After the code stored in the code buffer 564 is delayed by one frame, the code is decoded by the local decoding circuit 566 and supplied to the differential coding circuit 570.

On the other hand, the motion correction circuit 568 sequentially receives the motion vectors from the vector detection unit 52, performs motion correction on the noise-reduced image signal sequentially input with the motion vectors, and outputs the result as a differential encoding circuit. 570. As a result, the difference encoding circuit 570 encodes the difference value between the signal of the current frame from the motion compensation circuit 568 and the signal of the previous frame from the local decoding circuit 566 at a predetermined compression ratio, and outputs the result to the third compression unit. As an encoded signal.

Similarly, in the second encoding circuit 50, a new high-precision motion vector is newly detected from the digital component signal decoded by the decoding circuit 20, and the noise of the image signal is detected based on the detected vector. And further re-encodes at a coding efficiency lower than or equal to the first coding method depending on the other party, and the result is converted to a third coded signal. Output as

As described above, according to the coding conversion apparatus of the present embodiment, the coding efficiency of a moving picture signal coded by the first coding method is converted according to the destination or purpose. In the case of transmission, the digital component signal decoded by the decoding circuit 20 is switched by the switching circuit 30 and supplied to the first encoding circuit 40 or the second encoding circuit 50, thereby achieving a desired encoding efficiency. Can be transmitted as an encoded signal.

In this case, the first encoding circuit 40 performs re-encoding based on the motion vector included in the first encoded signal when re-encoding, so that the original analog component signal or composite Without returning to the signal
The digital component signal can be re-encoded at a desired encoding efficiency without changing the digital signal. Therefore, image quality degradation due to AD / DA conversion and
It is possible to transmit a moving image signal without Y / C separation and deterioration due to a video signal decoder or the like.

At this time, by using a motion vector of the first encoding method which has higher accuracy than a motion vector detected by an encoding method having a higher encoding efficiency, the encoding efficiency at the time of encoding is further improved. Can be improved. Also,
By using the motion vector of the first coding scheme,
The operation time of motion vector detection, which takes the longest time during encoding, can be omitted, and the encoding speed can be increased. Therefore, it is possible to reduce the delay due to re-encoding, obtain a coded signal with high coding efficiency, and transmit the terminal station to each home where priority is given to efficiency such as transmission speed and transmission capacity over image quality. In this case, it is possible to effectively distribute the contents at high speed and with high efficiency.

On the other hand, at the time of re-encoding, the second encoding circuit 50 reduces the noise of the moving image signal decoded into a digital component signal as a digital signal using a first-order recursive filter, and performs re-encoding. Therefore, the digital component signal can be re-encoded at a desired encoding efficiency without returning to the original analog component signal or composite signal without changing the digital component signal. Therefore, as in the above case, AD /
It is possible to transmit a moving image signal without deterioration of image quality due to DA conversion, Y / C separation, and deterioration due to a video signal decoder.

At this time, a motion vector is detected bidirectionally with higher accuracy than the first encoding method, and noise is reduced based on the motion accuracy information used in the detection of the motion vector. Since re-encoding is performed by removing generated noise or deterioration of image quality caused by decoding or the like, effective image transmission according to material transmission or relay transmission giving priority to image quality can be realized.

Further, in the present embodiment, when decoding and re-encoding, the original analog component signal or composite signal is not converted. After conversion, the result is converted by the monitor interface 70,
It can be displayed on a predetermined display device. Therefore, the display can effectively cope with monitoring and maintenance.

In the above embodiment, the first encoding circuit
Although the output of the code buffer 10 is received via the second switch 30b at 40 and the motion vector code is extracted therefrom, in the present invention, for example, as shown in FIG. The motion vector at the time of the motion vector decoding of the circuit 20 may be received via the second switch 30b.

In this case, the motion vector code extraction circuit 416
It is preferable to include an extraction circuit that extracts a motion vector responding to the motion correction and supplies the extracted motion vector to the motion correction circuit 414 as it is, and an encoding circuit that encodes the motion vector and supplies it to the code output circuit 418.

Further, in the above embodiment, only the locally decoded signal of the decoding circuit 20 is converted by the frame memory 60 and the monitor interface 70 to display the image. In the present invention, for example, FIG. As shown in
The images processed by the first encoding circuit 40 and the second encoding circuit 50 may be monitored.

In this case, before the frame memory 60, the signal from the decoding circuit 20, the signal from the first encoding circuit 40, and the signal from the second encoding circuit 50 are received and necessary. It is preferable to provide a selection circuit 80 for selecting any one of the signals in response. The signal from the first encoding circuit 40 is a local decoded signal. In the example shown in FIG. 2, the signal is the output of the adder 410 that adds the inversely quantized and inversely orthogonal signal and the motion compensated signal. Similarly, the signal from the second encoding circuit 40 is a locally decoded signal, and is an output of the local decoding circuit 566 in the example shown in FIG.

In the example shown in FIG. 4, the selection circuit 80 is provided to select and monitor each local decoded signal. However, in the present invention, circuits similar to the memory 60 and the monitor interface 70 are respectively provided. , And each image may be monitored separately.

Further, in the above embodiment, the first encoded signal was described as an encoded signal by MPEG encoding. However, in the present invention, for example, motion JPEG (joint ph)
A coded signal of another coding method such as an otographic image coding experts group may be applied. Also, MPEG2
Corresponding to the type such as level, profile, etc.
Assuming that the first encoded signal is a signal of a main profile,
It may be applied to the case where the encoding of the first encoding circuit 40 is converted into a signal of a lower level or profile, and the encoding of the second encoding circuit 50 is converted into a signal of an upper level or profile. . Of course, the first encoded signal may be a signal of another level or profile.

In these cases, the decoding circuit 20 is not limited to the internal configuration described in the above embodiment, and the first circuit supplied is
It is preferable to apply a decoding circuit for effectively decoding the coded signal corresponding to the above coded signal. Similarly, in the first encoding circuit 40, the re-encoding portion excluding the portion using the motion vector of the first encoded signal is not limited to the internal configuration of the encoding circuit shown in FIG. It is good to apply the thing of the encoding system which obtains the 2nd encoded signal of encoding efficiency of. Further, in the second encoding circuit 50, the re-encoding unit 56 shown in FIG. 3 may be replaced with a circuit of a desired encoding method. If necessary, a resolution conversion circuit may be provided before the first encoding circuit 40 and the second encoding circuit 50 to convert and supply the resolution of the decoded digital component signal.

[0063]

As described above, according to the coding conversion apparatus of the present invention, a moving picture signal coded by a predetermined coding method is decoded into a digital component signal by a decoding means. The decoded signal is switched and supplied to the first encoding means or the second encoding means by the switching means in accordance with the encoding efficiency of transmitting the decoded signal. In this case, the encoding is performed at the desired encoding efficiency by the encoding means of (2). Therefore, when the image quality is prioritized over the encoding efficiency or when the encoding efficiency is prioritized over the image quality and re-encoded and transmitted, the image quality and the signal Can be effectively re-encoded and transmitted according to each purpose without deteriorating.

In particular, in the first encoding means, when the encoding efficiency is prioritized, re-encoding is performed using the motion vector included in the original encoded signal, so that re-encoding can be performed in a short time. In addition to high-efficiency coding, the present invention can be effectively applied to a terminal transmission system to each home where transmission efficiency and the like are prioritized. Also, the second encoding means detects a motion vector with higher accuracy than the original encoding method, reduces the noise with the motion vector and re-encodes the signal. It can be effectively applied to systems or relay transmission systems.

Therefore, by switching the decoded signal from the decoding means to the first encoding means or the second encoding means by the switching means, it is possible to adapt to the terminal station transmission system, the relay transmission system and the material transmission system. There is an excellent effect that the encoding conversion can be effectively realized.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing an embodiment of a coding conversion apparatus according to the present invention.

FIG. 2 is a functional block diagram illustrating a configuration example of a first encoding circuit of the encoding conversion device according to the embodiment of FIG. 1;

3 is a functional block diagram illustrating a configuration example of a second encoding circuit of the encoding conversion device according to the embodiment in FIG. 1;

FIG. 4 is a functional block diagram showing another embodiment of the coding conversion apparatus according to the present invention.

[Explanation of symbols]

 10 Buffer memory 20 Decoding circuit 30 Switching circuit 40 First encoding circuit 50 Second encoding circuit 60 Frame memory 70 Monitor interface

Claims (6)

[Claims] 1. Receiving a moving image signal encoded by a predetermined first encoding method, re-encoding a code of the first encoding method by an encoding method having a different encoding efficiency. A coding conversion device for outputting, the device comprising: storage means for sequentially accumulating a code of a first coding method to be input; and a code of the first coding method supplied via the storage means. Decoding means for decoding a digital moving image signal into a digital moving image signal;
A first encoding unit that encodes and outputs a digital moving image signal decoded by the decoding unit according to a first encoding method, wherein the first encoding unit encodes and outputs the digital moving image signal according to the first encoding method. The second encoding method which encodes with the third encoding method whose encoding efficiency is lower than or equal to the encoding efficiency of
And switching means for switching to the input of the first encoding means or the input of the second encoding means in accordance with the encoding efficiency for re-encoding the output of the decoding means. Encoding conversion device. 2. The encoding conversion apparatus according to claim 1, wherein the first encoding unit extracts a motion vector code from a code of a first encoding method, Encoding means for encoding the decoded video signal from the decoding means by a second encoding method using the motion vector extracted by the motion vector extraction means. Conversion device. 3. The coding conversion apparatus according to claim 1, wherein said second coding means comprises: a motion vector detection means for obtaining a motion vector of a video signal decoded by said decoding means; Noise reduction means for reducing the noise of the video signal from the decoding means based on the motion vector from the detection means, and coding for coding the video signal from the noise reduction means in a third coding scheme Coding conversion apparatus characterized by including means. 4. The encoding conversion apparatus according to claim 1, wherein the apparatus displays a locally decoded signal of the moving image signal decoded by the decoding means on a predetermined display device. A coding conversion device characterized by including a monitor means for monitoring. 5. The coding conversion apparatus according to claim 1, wherein said coding conversion apparatus includes a moving picture encoded by said first encoding means or said second encoding means. An encoding / conversion device comprising a monitor for displaying a locally decoded signal of the signal on a predetermined display device and monitoring the signal. 6. The coding conversion apparatus according to claim 1, wherein said coding conversion apparatus includes: a local decoding signal of a moving image signal from said decoding means; A coding conversion apparatus comprising a monitoring means for switching between a video signal coded by the second coding means and a locally decoded signal, and displaying and monitoring on a predetermined display device.