JPH0823539A - Transcoder in high efficiency encoding - Google Patents

Abstract

PURPOSE:To change a bit rate while preventing quality degradation and to simplify circuit constitution further by providing a specified transcoder for performing output to a second medium device after changing the bit rate of multiplexed and compressed main signals. CONSTITUTION:After separating bit streams transmitted from a first medium device to the main signals and control signals by a separation circuit 2, a part to be changed corresponding to the bit rate of a change destination among the control signals is replaced and the new control signals are generated in a separation/change circuit 4. Then, output signals outputted from the separation circuit 2 are requantized based on the original or new control signals by a requantization circuit 5. Further, the main signals outputted from the requantization circuit 5 and the new control signals outputted from the separation/change circuit 4 are multiplexed and the bit streams to be an output object are generated by a multiplex circuit 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention performs bit rate conversion of compressed digital signals such as moving images, voices and still images between transmission media having different bit rates, storage media, and transmission media and storage media. The present invention relates to a transcoder device.

SUMMARY OF THE INVENTION The present invention is obtained by encoding a video signal by high efficiency encoding, such as a bit stream output from a first media device such as a high efficiency encoding encoder device, and then quantizing it. After receiving the bit stream obtained by multiplexing the compressed video signal and the control signal necessary for expanding the video signal, after changing the bit rate of the video signal multiplexed in the bit stream, Second, such as high-efficiency coding / decoding device
The present invention relates to a transcoder device for high-efficiency encoding for outputting to a media device, wherein a bit stream sent from the first media device is separated into a video signal and a control signal, and then the control signal and the second media. Based on the bit rate that can be accepted by the device side, the video signal must be requantized to a desired bit rate without performing high-efficiency decoding and the control signal must be changed. By replacing the parts and multiplexing the video signal and control signal that have been subjected to these processes into a bit stream, quality deterioration due to repeated encoding / decoding by high efficiency encoding is prevented. However, it is possible to change the bit rate of a digital signal that has been bit-compressed by high-efficiency coding, and The formation simplified in which downsizing of the entire apparatus.

[0003]

2. Description of the Related Art When digitally transmitting a television signal whose bit rate is compressed using high efficiency encoding, the bit rate of the digital signal used at the transmission source and that at the transmission destination may be different.

In such a case, a transcoder device is inserted between the transmission source device and the transmission destination device, and a digital signal (compressed bit) output from the transmission source device by this transcoder device is inserted. Stream)
After decoding and restoring to the original image signal, etc., the image signal etc. is encoded again with high efficiency at the bit rate used in the destination device, compressed, and then transmitted to the destination device. ing.

[0005]

However, in such a conventional transcoder device, since encoding / decoding by high-efficiency encoding is repeatedly performed, the quality of a video signal and the like is remarkably deteriorated and the encoding is performed. However, there is a problem that the circuit configuration becomes complicated and the entire apparatus becomes large because of the encoding / decoding.

In view of the above circumstances, the present invention changes the bit rate of a digital signal bit-compressed by high-efficiency encoding while preventing quality deterioration due to repeated encoding / decoding by high-efficiency encoding. It is an object of the present invention to provide a transcoder device in high efficiency encoding which can realize the above-mentioned structure, further simplify the circuit configuration, and can downsize the entire device.

[0007]

In order to achieve the above-mentioned object, the present invention provides, in claim 1, a compressed main signal obtained by encoding the main signal by high efficiency encoding and then quantizing the main signal. A compression that is connected to a first media device that outputs a bitstream in which a control signal necessary for decompressing this compressed main signal is output, and that inputs the bitstream and is multiplexed in this bitstream. After changing the bit rate of the generated main signal, the bit stream sent from the first media device is separated into the main signal and the control signal in the transcoder device for high efficiency encoding which is output to the second media device. Replace the separation circuit and the part of the control signal output from this separation circuit that must be changed according to the bit rate of the change destination. Demultiplexing / changing circuit that generates a new control signal, and requantization that requantizes the main signal output from the demultiplexing circuit based on the original control signal or a new control signal output from this demultiplexing / change circuit. A circuit and a multiplexing circuit that multiplexes a main signal output from the requantization circuit and a new control signal output from the separation / modification circuit to generate a bitstream to be output. Is characterized by.

According to a second aspect of the present invention, in the transcoder device for high efficiency encoding according to the first aspect, the requantization circuit is an original control signal or a new control signal output from the separation / modification circuit. Based on the above, the main signal output from the separation circuit is inversely quantized, the main signal before being quantized is reproduced, and then the main signal before being quantized is quantized so as to have the bit rate of the change destination. It is characterized by doing.

According to a third aspect of the present invention, in the transcoder device for high efficiency coding according to the first aspect, the requantization circuit is an original control signal or a new control signal output from the separation / modification circuit. On the basis of the above, when the main signal output from the separation circuit is a directly encoded signal or a prediction error signal obtained by interpolation prediction, requantization is performed more coarsely, and the main signal is predictively encoded. When it is a signal, it is characterized by finer requantization.

[0010]

In the above structure, in the claims, the compressed main signal and the main signal output from the first media device, which are obtained by encoding the main signal by high-efficiency coding and then quantizing the main signal, A transformer for high-efficiency coding, which receives a bit stream multiplexed with a control signal necessary for decompression, changes the bit rate of the main signal multiplexed in this bit stream, and then outputs the bit signal to the second media device. In the coder device, the separation circuit separates the bit stream sent from the first media device into a main signal and a control signal, and then the separation / change circuit outputs the control signal of the change destination among the control signals output from the separation circuit. A new control signal is generated by replacing the part that must be changed according to the bit rate, and the requantization circuit The main signal output from the separation circuit is requantized based on the original control signal or the new control signal output from the separation / change circuit, and the main signal output from the requantization circuit by the multiplexing circuit. And a new control signal output from the separation / modification circuit are multiplexed to generate a bit stream to be output, thereby preventing quality deterioration due to repeated encoding / decoding by high-efficiency encoding. However, the bit rate of the digital signal bit-compressed by high-efficiency encoding can be changed, the circuit configuration can be further simplified, and the entire apparatus can be miniaturized.

According to a second aspect of the present invention, in the transcoder device for high efficiency encoding according to the first aspect, the requantization circuit causes the original control signal or the new control signal output from the separation / modification circuit. Based on the above, the main signal output from the separation circuit is inversely quantized, the main signal before being quantized is reproduced, and then the main signal before being quantized is quantized so as to have the bit rate of the change destination. As a result, the bit rate of the digital signal bit-compressed by the high-efficiency encoding is changed while preventing the quality deterioration due to the repetition of the encoding / decoding by the high-efficiency encoding, as in claim 1. Therefore, the circuit configuration is further simplified, and the entire device is miniaturized.

According to a third aspect of the present invention, in the transcoder device for high efficiency encoding according to the first aspect, the requantization circuit outputs the original control signal or a new control signal output from the separation / change circuit. When the main signal output from the separation circuit is a directly encoded signal or a prediction error signal obtained by interpolation prediction,
Repetition of encoding / decoding by high-efficiency encoding, by requantizing more coarsely and requantizing more finely when the main signal is a predictively encoded signal, as in claim 1 and 2. It is possible to change the bit rate of a digital signal bit-compressed by high-efficiency coding while preventing the quality deterioration due to, and further simplify the circuit configuration and downsize the entire apparatus.

[0013]

【Example】

<< Description of High Efficiency Coding >> First, prior to a detailed description of the embodiments, a high efficiency coding system in which the transcoder device according to the present invention is used will be described.

FIG. 4 is a block diagram showing an example of a high efficiency coding system in which the transcoder device according to the present invention is used.

High efficiency coding system 101 shown in this figure.
Includes a high-efficiency encoding encoder device 102 and a high-efficiency encoding decoder device 103. The high-efficiency encoding encoder device 102 takes in a video signal (for example, a television signal) to be transmitted and the like. After compression by a DCT (discrete cosine transform) method with motion compensation to generate a transmission signal (bit stream), the transmission signal is transmitted to a high-efficiency encoding / decoding device 103, and the transmission signal is transmitted by the high-efficiency encoding / decoding device 103. A video signal is reproduced by decompressing with the DCT method with motion compensation.

The high efficiency encoding encoder device 102 is a DC
A T-encoding unit 104, a DCT-decoding unit 105,
And a signal multiplexing unit 106, which takes in a video signal (for example, a television signal) to be transmitted and compresses it by a DCT method with motion compensation into a transmission signal including a control signal. Is transmitted to the high efficiency encoding / decoding device 103.

The DCT encoding unit 104 obtains the difference between the current video signal to be transmitted and the current prediction video signal output by the motion compensation output from the DCT decoding unit 105, and a subtractor 107. Subtractor 107
Compressed mode (Inter / Intra Mode) based on the video difference signal output from
Mode determining circuit 108, a switch circuit 109 for selecting either the current video signal or the video difference signal based on the determination result of the mode determining circuit 108, and the signal selected by the switch circuit 109. D for converting the (current video signal or video difference signal) to a DCT data format video signal by discrete cosine transform
The CT circuit 110 and a quantizing circuit 111 that takes in the video signal output from the DCT circuit 110 and quantizes it with a specified roughness are provided.

Then, the current video signal to be transmitted and the current motion-compensated predicted video signal output from the DCT decoding unit 105 are taken in, and the video difference signal is generated by calculating the difference between them. Either one of the current video signal or the video differential signal is selected, and the selected signal is subjected to discrete cosine transform to a video signal in the DCT data format, and then converted into a control signal output from the signal multiplexing unit 106. A DCT decoding unit 105 that quantizes the video signal in the DCT data format with a roughness according to
It is supplied to the signal multiplexing unit 106.

The DCT decoding unit 105 fetches the quantized DCT data format video signal output from the DCT encoding unit 104, and the roughness based on the control signal output from the signal multiplexing unit 106. A dequantization circuit 112 for dequantizing a quantized video signal in the DCT data format to reproduce a video signal in the DCT data format, and a DC output from the dequantization circuit 112.
Inverse DCT circuit 113 that generates a video signal or a video differential signal by performing an inverse discrete cosine transform on the video signal in the T data format.
And the video differential signal output from the inverse DCT circuit 113, and the video differential signal and the motion-compensated predicted video signal used in the DCT encoding unit 102 are added to add the high-efficiency coding decoder. And an adder circuit 114 for generating a video signal reproduced on the device 103 side.

Further, the DCT decoding unit 105, based on the judgment result of the mode judgment circuit 108, performs the inverse DCT.
Video signal output from the circuit 113 (Intra Mo
When de, a video signal reproduced on the side of the high-efficiency encoding / decoding device 103) or a video signal output from the adding circuit 114 (video when reproduced on the side of the high-efficiency encoding / decoding device 103 in the case of Inter Mode) signal)
Of the video signal selected by the switch circuit 115 and the input video signal of this time are compared with each block (for example, 8 pixels × 8 pixels) of the video signal selected by the switch circuit 115. Motion vector detection circuit 1 for detecting motion vectors of blocks such as pixels)
16 and the video signal selected by the switch circuit 115, and based on the motion vector detected by the motion vector detection circuit 116, motion-compensated prediction is performed on the captured video signal to generate a predicted video signal. However, a motion compensation prediction frame memory circuit 117 for storing this is provided.

Then, the quantized DCT data format video signal output from the DCT encoding unit 104 is fetched and inversely quantized and inverse discrete cosine transformed to reproduce the video signal or the video differential signal, For the video difference signal, the predicted video signal used in the DCT encoding unit 104 is used to convert the video signal into a video signal, and one of the video signals is selected based on the judgment result of the mode judgment circuit 108. The video signal obtained by the operation and the input video signal of this time are compared in block units, and based on the motion vector obtained by this comparison result, motion-compensated prediction is performed to create a predicted video signal. Is delayed by a predetermined period, for example, by one frame, and is supplied to the DCT encoding unit 104.

Further, the signal multiplexing unit 106 takes in the quantized DCT data format video signal output from the DCT encoding unit 104, performs variable length coding by the Huffman coding system, etc., and codes it. A variable length coding circuit 118 for generating a video signal, a coded video signal output from the variable length coding circuit 118 and a motion vector output from the motion vector detection circuit 116,
A multiplexing circuit 119 that multiplexes the determination result of the mode determination circuit 108 with a control signal or the like input to the quantization circuit 111 to generate a transmission signal (bit stream).
Then, the transmission signal output from the multiplexing circuit 119 is taken in and stored, and the stored transmission signal is read out in the FIFO format at a preset transmission rate and is stored in the high-efficiency encoding / decoding device 103. Buffer memory circuit 120 for transmission and this buffer memory circuit 1
A buffer occupancy amount detection circuit 121 for detecting a buffer occupancy amount of a transmission signal in 20 and generating a control signal such as a quantization characteristic switching signal so as to keep the occupancy amount to a constant value and supplying the control signal to the DCT encoding unit 104. I have it.

Then, the quantized DCT data format video signal output from the DCT encoding unit 104 is fetched and variable-length coded to generate a coded video signal. , A motion vector output from the motion vector detection circuit 116, a determination result of the mode determination circuit 108, and a control signal such as a quantization characteristic switching signal input to the quantization circuit 111 are multiplexed to generate a transmission signal. After that, this is temporarily stored in the buffer memory circuit 120, and a control signal such as a quantization characteristic switching signal that causes the buffer occupancy of the buffer memory circuit 120 to fall within a constant value is generated and is used for the DCT encoding. The transmission signal stored in the buffer memory circuit 120 is read while being supplied to the unit 104, and this is read out. Transmitted to the high-efficiency encoding decoder device 103 at a constant transmission rate.

The high-efficiency encoding / decoding device 103 includes a signal separating section 125 and a DCT decoding section 126, which takes in the transmission signal sent from the high-efficiency encoding encoder apparatus 102 and converts it into a video signal. ,
After separating into the control signal, the operation of each part of the apparatus is switched based on the control signal, and the video signal is expanded and reproduced by the DCT method with motion compensation.

The signal separation unit 125 takes in the transmission signal transmitted from the high efficiency encoding encoder device 102,
A buffer memory circuit 127 for temporarily storing this and outputting it in a FIFO format, and a separation circuit 128 for separating the transmission signal output from this buffer memory circuit 127 into a video signal and a control signal are provided. The transmission signal sent from the efficiency encoding encoder device 102 is taken in, this is temporarily stored and read out at a speed according to the processing speed, and separated into a video signal and a control signal,
The DCT decoding unit 12 receives these video signals and control signals.
Supply to 6.

The DCT decoding unit 126 takes in the video signal output from the signal separating unit 125, performs variable length decoding, and reproduces a quantized DCT data format video signal, and a variable length decoding circuit 129. The quantized DCT data format video signal output from the variable length decoding circuit 129 is taken in, and the quantization is performed with the roughness based on the control signal (quantization characteristic switching signal etc.) output from the signal separation unit 125. A dequantization circuit 130 for dequantizing the converted DCT data format video signal to reproduce a DCT data format video signal, and an inverse discrete cosine of the DCT data format video signal output from the dequantization circuit 130. An inverse DCT circuit 131 that converts and generates a video signal or a video differential signal, and captures a video differential signal output from the inverse DCT circuit 131 Together, and an adding circuit 132 for generating a video signal by adding the prediction image signal subjected to input motion compensation and the video difference signal.

Further, the DCT decoding unit 126, based on the control signal (determination result of the mode determining circuit 108) output from the signal separating unit 125, the inverse DCT circuit 13
One of the video signal output from 1 (the video signal in the intra mode) or the video signal output from the adder circuit 132 (the video signal in the inter mode) is selected and used as the reproduced video signal. Switch circuit 133 for outputting and this switch circuit 133
Control signal (motion vector) output from the signal separation unit 125 while capturing the video signal output from
A motion-compensated prediction frame memory circuit 134 which performs motion-compensated prediction on the video signal to generate a predicted video signal, stores the predicted video signal, and delays it for a predetermined period to supply it to the adder circuit 132. ing.

Based on the control signal output from the signal separating unit 125, the video signal output from the signal separating unit 125 is taken in while controlling the operation of each unit of the apparatus, and the image signal is variable with respect to this video signal. Long decoding,
After the video signal or the video differential signal is reproduced by performing the inverse quantization and the inverse discrete cosine transform, the video signal is converted into the video signal by using the predicted video signal obtained by the motion compensation prediction of the previous video signal. While reproducing, the video signal obtained by this selecting operation is selected as one of the video signals based on the judgment result of the mode judging circuit 108, and the reproduced video signal is outputted. With the motion vector detected in step 1, motion-compensated prediction is performed on the video signal to create a predicted video signal, which is used in the next video playback.

Thus, this high efficiency coding system 1
In 01, a high-efficiency encoding encoder device 102 takes in a video signal (for example, a television signal) to be transmitted and compresses it by a DCT method with motion compensation to generate a transmission signal. Since it is transmitted to the encoding / decoding device 103, and the transmission signal is expanded by the DCT method with motion compensation by this high-efficiency encoding / decoding device 103, the video signal is reproduced.
It is possible to transmit a high-quality video signal from the high-efficiency encoding encoder device 102 side to the high-efficiency encoding decoder device 103 side while significantly reducing the bit rate of the transmission signal.

However, in such a high efficiency coding system 101, the high efficiency coding encoder device 102 is used.
If the bit rate of the transmission signal output from the side is the same as the bit rate of the transmission signal that can be reproduced on the high-efficiency encoding / decoding device 103 side, no problem occurs, but these bit rates are When different,
For example, when a plurality of transmission media having different bit rates are interposed between the high-efficiency encoding encoder device 102 and the high-efficiency encoding decoder device 103, the bits of the transmission signal output from the high-efficiency encoding encoder device 102 side. When the rate is high and the bit rate of the transmission signal received by the high efficiency encoding / decoding device 103 is low, the transmitted bit rate cannot correctly reach the high efficiency encoding / decoding device.

Therefore, in such a case, as shown in FIG. 5, the transcoder device 1 in the high efficiency encoding according to the present invention is provided between the high efficiency encoding encoder device 102 and the high efficiency encoding decoder device 103. The transmission signal (first medium) is inserted and the transmission signal (first medium) output from the high-efficiency encoding encoder apparatus 103 side is taken in by the transcoder device 1 in this high-efficiency encoding, and the transmission signal (first 2) and supplies this to the high-efficiency encoding / decoding device 103 to absorb the difference between the bit rate on the high-efficiency encoding / decoding device 102 side and the bit rate on the high-efficiency encoding / decoding device 103 side. Therefore, it is possible to eliminate the inconvenience such as the reproduction failure due to the difference in bit rate.

<< Description of Embodiments >> Next, the transcoder device 1 in the high-efficiency coding according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of a transcoder device in high efficiency coding according to the present invention.

The transcoder device 1 in the high-efficiency coding shown in this figure includes a separation circuit 2 and a variable length decoding circuit 3.
, Separation / change circuit 4, requantization circuit 5, variable length coding circuit 6, multiplexing circuit 7, and buffer memory circuit 8
And a buffer occupancy detection circuit 9, and while controlling the operation of each part of the device based on the control signal in the transmission signal (first medium) sent from the high efficiency encoding encoder device 102, After the video signal in the transmission signal is variable-length decoded and the quantized DCT data format video signal is reproduced, the transmission signal (second medium) that can be input to the high-efficiency encoding / decoding device 103 is transmitted. The quantized D has a roughness corresponding to a bit rate.
The video signal in the CT data format is requantized and variable length coded into a video signal, and the control signal or a control signal obtained by changing a part of the control signal is multiplexed with the video signal and transmitted. After being converted into a signal, the high-efficiency encoding / decoding device 103 is converted at a constant transmission rate.
To transmit.

The separation circuit 2 takes in the transmission signal sent from the high efficiency encoding encoder device 102, separates this transmission signal into a video signal and a control signal, and supplies the video signal to the variable length decoding circuit 3. At the same time, the control signal is supplied to the separation / change circuit 4.

The variable length decoding circuit 3 takes in the video signal output from the separation circuit 2, performs variable length decoding on the video signal, reproduces a quantized video signal in the DCT data format, and requantizes it. Supply to 5.

The separation / change circuit 4 is the separation circuit 2
While taking in the control signal output from, separates the quantization characteristic switching signal etc. included in this control signal,
This is supplied to the requantization circuit 5, and the content of the signal that must be changed by requantization is changed to generate a new control signal, which is supplied to the multiplexing circuit 7.

The requantization circuit 5 is the variable length decoding circuit 3
The video signal of the quantized DCT data format output from the control signal (quantization characteristic switching signal) output from the separation / change circuit 4 and the buffer occupancy detection circuit 9 are output. DCT data quantized by re-quantizing the video signal in the quantized DCT data format with the quantization switching interval based on the control signal (control signal indicating the quantized roughness, etc.) A video signal of the format is generated, and this is generated by the variable length coding circuit 6
Supply to.

In this case, as a requantization procedure, if the video signal is a linearly quantized signal, it is simply output from the variable length decoding circuit 3 with a preset value N. The quotient obtained by dividing the quantized DCT data format video signal is taken as the quantized DCT data format video signal.

However, since the value of N is selected so that the requantized video signal in the DCT data format is included in the quantization table, and the normal quantization characteristic is rounded, N is set to It is desirable to make it an odd number and round it up to an integer when a fraction comes out in the division process.

The variable length coding circuit 6 takes in the quantized DCT data format video signal output from the requantization circuit 5 and performs variable length coding by the Huffman coding method or the like to encode the coded signal. The converted video signal is generated and supplied to the multiplexing circuit 7.

The multiplexing circuit 7 includes a coded video signal output from the variable length coding circuit 6 and a new control signal output from the separation / change circuit 4, that is, a motion vector and the mode determination circuit. As a result of the determination in 108, a new control signal indicating a control signal (quantization characteristic switching signal or the like) input to the requantization circuit 5 is multiplexed to generate a transmission signal, and the transmission signal is generated. Supply to.

The buffer memory circuit 8 is the multiplexing circuit 7
The transmission signal output from the device is fetched and stored, and the stored transmission signal is read out in the FIFO format at a preset transmission rate and transmitted to the high efficiency coding decoder device 103.

Further, the buffer occupancy detection circuit 9 detects the buffer occupancy of the transmission signal in the buffer memory circuit 8 and generates a control signal or the like indicating the quantization roughness or the like so that the buffer occupancy is set to a constant value. Then, this is supplied to the requantization circuit 5.

In this case, the larger the buffer occupancy in the buffer memory circuit 8 is, the larger the value of N used in the requantization circuit 5 is, and when the buffer occupancy is less than the minimum value, N = When set to 1, the requantization process is skipped.

As described above, the transcoder device 1 according to the first embodiment takes in the transmission signal (first medium) sent from the high-efficiency encoding encoder device 102 and does not perform inverse DCT conversion on the transmission signal. Since the transmission signal is requantized to be converted into a transmission signal (second medium) having a reduced bit rate and is transmitted to the high-efficiency encoding / decoding device 102, the high frequency component of the video signal is converted. Due to the fact that high efficiency decoding / high efficiency encoding such as the DCT method that cuts is not performed, quality deterioration due to repetition of encoding / decoding by high efficiency encoding is prevented and high efficiency encoding is performed. The bit rate of the bit-compressed transmission signal can be changed, the circuit configuration can be simplified, and the entire apparatus can be downsized.

FIG. 2 is a block diagram showing a second embodiment of the transcoder device for high efficiency coding according to the present invention. In this figure, the same parts as those in FIG. 1 are designated by the same reference numerals.

The transcoder device 1b shown in this figure is different from the device shown in FIG. 1 in that the requantization circuit 5 is replaced by a requantization circuit 5b, which is transmitted from the high efficiency encoding encoder device 102. Even if the transmission signal (first medium) has a non-linear quantization characteristic or a minute signal, which is obtained by performing dead zone (dead zone) processing, etc., encoding by high efficiency encoding / It is possible to change the bit rate of a transmission signal bit-compressed by high-efficiency encoding while preventing quality deterioration due to repeated decoding.

In this case, the requantization circuit 5b takes in the quantized DCT data format video signal output from the variable length decoding circuit 3 and outputs the control signal (quantization output from the separation / modification circuit 4). And a dequantization circuit 10 for dequantizing the quantized video signal in the DCT data format to reproduce the video signal in the DCT data format, and output from the dequantization circuit 10. Of the DCT data format, the control signal (quantization characteristic switching signal, etc.) output from the separating / changing circuit 4 and the control signal (quantization roughness characteristic The signal of the DCT data format is quantized at a quantization switching interval and a quantization roughness based on the signal shown in FIG. 2) to generate a quantized image signal of the DCT data format. , A quantization circuit 11 which supplies the variable length coding circuit 6 to the variable length coding circuit 6, and takes in the quantized DCT data format video signal output from the variable length decoding circuit 3 and dequantizes it. And reproduces the video signal in the DCT data format, and then outputs the control signal (quantization characteristic switching signal or the like) output from the separation / change circuit 4 and the control signal (quantization output from the buffer occupation amount circuit 9 The DCT data format video signal is quantized with a quantization switching interval based on a signal indicating a roughness characteristic) and a quantization roughness to generate a quantized DCT data format video signal. The variable length coding circuit 6 is supplied.

In this case, before the quantizing circuit 11 quantizes, the quantized DCT data format video signal output from the variable length decoding circuit 3 is dequantized,
Reproduce the video signal in the DCT data format before quantization,
This DCT data format video signal is divided by the value N corresponding to the quantization roughness to obtain the quantized DCT data format video signal. Therefore, the high efficiency coding encoder device 102 sends the video signal. Even if the transmitted signal (first medium) has a non-linear quantization characteristic or a minute signal, which is obtained by performing dead zone (dead zone) processing, etc. Can be converted.

However, the value N used in this embodiment must also be selected so that the quantized DCT data format video signal is included in the quantization table.

As described above, in the transcoder device 1b according to the second embodiment, the transmission signal (first medium) sent from the high-efficiency encoding encoder device 102.
The above-mentioned transmission signal is dequantized and quantized without being subjected to inverse DCT conversion to be converted into a transmission signal (second medium) whose bit rate is lowered, and this is converted into a high-efficiency coding decoder device 103. Therefore, as in the first embodiment described above, the high-efficiency coding / high-efficiency coding such as the DCT method for cutting the high-frequency components of the video signal is not performed. It is possible to change the bit rate of a transmission signal bit-compressed by high-efficiency encoding while simplifying the circuit configuration while preventing quality deterioration due to repeated encoding / decoding due to encoding. Can be miniaturized.

FIG. 3 is a block diagram showing a third embodiment of a transcoder device in high efficiency coding according to the present invention. In this figure, the same parts as those in FIG. 1 are designated by the same reference numerals.

The transcoder device 1c shown in this figure differs from the device shown in FIG. 1 in that the separation / modification circuit 4 is replaced by a separation / modification circuit 4c, which is transmitted from the high-efficiency coding encoder device 102. Transmission signal (first medium)
The control signal of is separated into a signal related to the switching of the quantization characteristic, a signal not related to the switching of the quantization characteristic, but a signal related to the requantization, and a signal not related to the switching of the quantization characteristic. Based on the control of the requantization circuit 5 or the control signal multiplexed by the multiplexing circuit 7,
This is to prevent the shift of the control signal due to the requantization.

In this case, the separation / modification circuit 4c outputs the control signal output from the separation circuit 2 to a signal (for example, a transmission factor signal) related to the switching of the quantization characteristic, but not related to the switching of the quantization characteristic. A signal related to requantization (for example, an Inter / IntraMode signal),
A separation circuit 12 that separates a signal that is not related to the switching of the quantization characteristic (for example, a motion vector signal, a synchronization signal, a time stamp signal, etc.), and a signal that is output from this separation circuit 12 that is related to the switching of the quantization characteristic (quantum And a change circuit 13 for fetching the quantization characteristic switching relation signal and changing the value of the quantization characteristic switching relation signal on the basis of a control signal (such as a signal indicating the quantization roughness) output from the buffer occupancy circuit 9. , The control signal output from the separation circuit 12 is taken in, and the change circuit 1 among the control signals
And a replacement circuit 14 for replacing the control signal corresponding to the control signal changed in 3.

Then, the control signal output from the separation circuit 2 is taken in, and it is requantized with a signal related to the switching of the quantization characteristic (for example, a transmission factor signal) and a signal not related to the switching of the quantization characteristic. A signal related to the conversion (for example, an Inter / IntraMode signal),
A signal that is not related to quantization characteristic switching (for example, a motion vector signal, a synchronization signal, a time stamp signal, etc.) but is not related to quantization characteristic switching, but is related to requantization is requantized. To the re-quantization circuit by directly changing the value of the quantization characteristic switching relation signal based on a control signal (such as a signal indicating the quantization roughness) output from the buffer occupancy circuit 9. 5 to control the requantization process, and further, among the control signals output from the separation circuit 12, based on the changed control signal, change the corresponding control signal and supply it to the multiplexing circuit 7. .

As a result, the ITU is added to the control signal of the transmission signal transmitted from the high-efficiency encoding encoder device 102.
-R (formerly CCIR) Like the transmission factor of Recommendation 723, the value is determined by the buffer occupancy of the high-efficiency encoding encoder device 102, such as the signal related to the switching of the quantization characteristic, and the horizontal television scanning. Even if there is a signal transmitted at a transmission interval of every 8 lines,
Signals of the same nature as defined by the EG standard, eg 1
Slice Quantiz transmitted at 6 line intervals
er Scale signal, Macro-Block transmitted at intervals of microblocks (16 pixels x 16 pixels)
Even if there is a Quantizer Scale signal or the like, the signal relating to the switching of the quantization characteristic can be replaced and multiplexed with the video signal.

The high-efficiency coding encoder device 102
Since it is not necessary to replace control signals other than the signals related to the switching of the quantization characteristics among the control signals of the transmission signal sent from the device, the values are multiplexed with the video signals as they are.

Further, as a signal for controlling requantization,
The coding mode signal is given. Looking at the configurations of the high-efficiency coding encoder device 102 and the high-efficiency coding decoder device 103 shown in FIG.
There is a Mode signal, and this Inter / Intra
When the Intra Mode is designated by the Mode signal, the loop of the prediction signal is broken and becomes an open loop, and error accumulation due to requantization does not occur.

Therefore, in the case of the Intra Mode, no problem occurs, but the Inter Mode
, The prediction signal loop is closed,
Since addition integration is performed and error accumulation occurs due to requantization, the value of the prediction signal used in the high-efficiency coding encoder device 103 and the high-efficiency coding decoder device 10
The value of the prediction signal used in 2 must match.

Therefore, in such a high efficiency encoding system 101, the Intra Mo is set at a predetermined interval.
By using de, the refresh process is performed so that the value of the prediction signal used in the high-efficiency coding encoder device matches the value of the prediction signal used in the high-efficiency coding decoder device.

However, in such a high-efficiency coding system 101, a high-efficiency coding encoder device 102 is used.
When the transcoder device 1, 1b, 1c according to the present invention is inserted between the high efficiency coding decoder device 103 and the high efficiency coding decoder device 103, if the refresh interval is short, no problem occurs, but when the refresh interval is long. The value of the prediction signal used in the high-efficiency coding encoder device 102 and the value of the prediction signal used in the high-efficiency coding decoder device 103 not only deviate from each other, but also on the high-efficiency coding decoder device 103 side. The error may be enlarged by the integration function.

Therefore, the separation / change circuit 4 of the third embodiment is
In c, when Inter Mode is specified by the Inter / IntraMode signal, Int
Finer requantization is performed than in the case of ra Mode to reduce error accumulation due to requantization or skip requantization so that the error itself due to requantization does not become large.

In addition to Inter / Intra, MPE is a mode for encoding a prediction error obtained from interpolation prediction.
G (Moving Picture Image Co)
ing Experts Group: International Conference on Digital Code Compression Systems), which is referred to as B picture in MPEG. In the case of interpolation prediction, as in the case of Intra Mode, since the quantization error does not increase, the quantization characteristic can be made rough.

As described above, in the transcoder device 1c according to the third embodiment, the transmission signal (first medium) sent from the high-efficiency encoding encoder device 102.
The transmission signal is re-quantized and converted into a transmission signal (second medium) having a reduced bit rate without inverse DCT conversion, and this is transmitted to the high-efficiency encoding / decoding device 103. As a result, as in the first and second embodiments described above, the high efficiency decoding / high efficiency encoding such as the DCT method for cutting the high frequency component of the video signal is not performed, so that the high efficiency encoding is performed. Encoding /
While preventing quality deterioration due to repeated decoding,
The bit rate of the digital signal bit-compressed by the high-efficiency encoding can be changed, the circuit configuration can be simplified, and the entire apparatus can be downsized.

Furthermore, in the third embodiment, the control signal included in the transmission signal is not related to the signal related to the switching of the quantization characteristic (for example, the transmission factor signal) and the switching of the quantization characteristic. Is a signal related to requantization (for example, Inter / Intra Mode signal)
And a signal not related to the switching of the quantization characteristic (for example, a motion vector signal, a synchronization signal, a time stamp signal, etc.) and these are processed respectively.
The ITU-R (former CCIR) Recommendation 7 is included in the control signal of the transmission signal transmitted from the high-efficiency encoding encoder device 102.
Like the signal relating to the switching of the quantization characteristics, such as the transmission factor of 23, the value is determined by the buffer occupancy of the high-efficiency encoding encoder device 102, and the transmission interval for every 8 lines of the horizontal scanning of the television. Signal having the same property as defined by the ISO MPEG standard, for example, Slice Quantizer Scale signal transmitted at 16 line intervals,
Macro-Block QuantizerSc transmitted at intervals of microblocks (16 pixels x 16 pixels)
Even if there is an ale signal or the like, the signal related to the switching of the quantization characteristic can be replaced and multiplexed with the video signal.

In addition, in the third embodiment, Int
er / Intra Mode signal by Intra
When Mode is specified, the video signal is roughly requantized, and when Inter Mode is specified,
Since fine requantization is performed or requantization processing is skipped as compared with Intra Mode, it is possible to prevent an error due to requantization from accumulating.

<< Description of Other Embodiments >> Also, the above-mentioned first embodiment
In the third embodiment, like the high-efficiency coding system 101 shown in FIG. 4, a predictive video signal in which a motion vector is detected and motion compensation is performed based on the current video signal and the previous video signal. Although the transcoder device 1, 1b, 1c according to the present invention has been described by taking a system using as an example, a high efficiency coding system other than the system using such a predicted video signal, for example, ISO-MPEG.
B picture, etc., an interpolative prediction mode using a past signal and a future signal, that is, a high prediction for performing a motion-compensated forward-predicted video signal and a motion-compensated backward-predicted video signal. The transcoder device 1, 1b, 1c according to the present invention may be applied to the efficiency coding system.

In this case, in such a high-efficiency coding system, a loop of the prediction signal is not formed when performing the interpolative prediction, so that the high-efficiency coding encoder device and the high-efficiency coding decoder device are connected. However, no matter what requantization is performed, the error does not expand due to the integration function of the high-efficiency coding / decoding device side. Therefore, in the separation / modification circuits 4 and 4c, the intermode signal Even if specified, I
Even if the ntra Mode is specified, it is possible to prevent the error due to the requantization from being accumulated by only the coarse requantization. << Explanation of Another Application Example of the Present Invention >> Further, in each of the above-described embodiments, in the high efficiency encoding system 101 and the like using the high efficiency encoding encoder device 102 and the high efficiency encoding decoder device 103, Although the transcoders 1, 1b, 1c according to the present invention are used, the bit rate compression is performed on the television by using the high efficiency coding method, and when the television is transmitted on the digital line, the bit rate is mutually transmitted. When a transmission signal is transmitted using a plurality of different transmission lines, the transcoder device 1, 1b, 1c according to the present invention is used to change the bit rate of the transmission signal for each transmission line. May be.

Further, the transcoder device 1, 1b, 1c according to the present invention may be used for bit rate conversion between media other than the transmission media, for example, the media described below.

Interconnection of transmission media with different bit rates Storage media with different bit rates (including VTR)
Interconnection (dubbing) of-Transmission media of different bit rates and storage media-Connection of high efficiency coding encoder devices of different bit rates and decoder device having the same algorithm In cases other than bit rate compression by high efficiency encoding, for example, for high efficiency encoding of audio signals and still images, the transcoder device 1 according to the present invention,
You may make it use 1b, 1c.

[0072]

As described above, according to the present invention, in claims 1, 2 and 3, high efficiency coding is performed while preventing quality deterioration due to repetition of encoding / decoding by high efficiency coding. It is possible to change the bit rate of the bit-compressed digital signal by the optimization, further simplify the circuit configuration, and downsize the entire apparatus.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of a transcoder device in high efficiency encoding according to the present invention.

FIG. 2 is a block diagram showing a second embodiment of a transcoder device in high efficiency encoding according to the present invention.

FIG. 3 is a block diagram showing a third embodiment of a transcoder device in high efficiency encoding according to the present invention.

FIG. 4 is a block diagram showing an example of a high efficiency coding system in which the transcoder device according to the present invention is used.

5 is a block diagram showing a system configuration example when a transcoder device according to the present invention is used for the high-efficiency coding system shown in FIG.

[Description of Codes] 1, 1b, 1c Transcoder device in high efficiency coding 2 Separation circuit 3 Variable length decoding circuit 4, 4c Separation / change circuit 5, 5b Requantization circuit 6 Variable length coding circuit 7 Multiplexing Circuit 8 Buffer memory circuit 9 Buffer occupancy detection circuit 10 Inverse quantization circuit 11 Quantization circuit 12 Separation circuit 13 Change circuit 14 Replacement circuit 101 High-efficiency coding system 102 High-efficiency coding encoder device (first media device) 103 High efficiency encoding / decoding device (second media device)

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display area H04N 7/32

Claims (3)

[Claims] 1. A bit in which a compressed main signal obtained by encoding the main signal by high-efficiency coding and then quantized, and a control signal necessary for decompressing the compressed main signal are multiplexed. A high efficiency, which is connected to a first media device for outputting a stream, inputs the bit stream, changes a bit rate of a compressed main signal multiplexed in the bit stream, and then outputs the second main media device. In a transcoder device for encoding, a separation circuit that separates a bit stream sent from the first media device into a main signal and a control signal, and a bit rate to be changed among control signals output from the separation circuit The separation / change circuit that generates a new control signal by replacing the parts that must be changed according to A requantization circuit that requantizes the main signal output from the separation circuit based on the original control signal or the new control signal output, and the main signal output from the requantization circuit and the separation A transcoder device in high-efficiency coding, comprising: a multiplexing circuit that multiplexes a new control signal output from the changing circuit to generate a bitstream to be output. 2. The transcoder device for high efficiency coding according to claim 1, wherein the requantization circuit is based on an original control signal or a new control signal output from the separation / modification circuit. The main signal output from the circuit is inversely quantized, the main signal before being quantized is reproduced, and then the main signal before being quantized is quantized so as to have a bit rate of a change destination. Transcoder device for high efficiency coding. 3. The transcoder device for high efficiency coding according to claim 1, wherein the requantization circuit is based on an original control signal or a new control signal output from the separation / change circuit, When the main signal output from the circuit is a directly encoded signal or a prediction error signal obtained by interpolation prediction,
A transcoder device in high-efficiency coding, characterized in that requantization is performed more coarsely and finer requantization is performed when the main signal is a predictively coded signal.