JPH06253210A - Joint device for compressed video signals - Google Patents

Abstract

PURPOSE:To make picture disturbance at joints of compressed video signals unremarkable. CONSTITUTION:When a switcher 3 is operated, a control signal to read repetitively a frame memory 5 is obtained and the processing is awaited till a selected signal is made stable. Or the switcher 3 has a function of sending only a signal subjected to in-frame processing and a signal subjected to inter-frame processing with respect to the in-frame processing signal till the disturbance of a picture is not caused (or reduced) from a signal switching point. Or in place of the giving of the function to the switcher 3, a decode limit function is provided to a decoder and only a signal subjected to in-frame processing and a signal subjected to inter-frame processing with respect to the in-frame processing signal are decoded and other signals are not decoded till the disturbance of a picture is not caused (or reduced) from a signal switching point.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal connection device, and is particularly effective as a switcher device for selectively deriving a plurality of compressed video signals.

[0002]

2. Description of the Related Art Recently, a system for compressing a video signal to several tenths using an interframe compression technique has been developed. For example, there is a DigiCipher system (“DigiCipher” is a registered trademark of GI Company) which is a proposal of the MPEG standard and the ATV system of the United States. In such a system, a variable length coding method is adopted, and the data length of one frame of the compressed video signal is not fixed but variable.

When editing a plurality of variable length compressed video signals, the conventional editing apparatus method cannot simply edit in arbitrary frame units. This is because there is an inter-frame processed signal and an intra-frame processed signal, and if the first captured signal is the inter-frame processed signal, the entire image cannot be reproduced.
Therefore, each of the plurality of compressed video signals is once decoded, converted into a baseband video signal, synchronized with each baseband video signal, selectively derived by a switcher, edited into one baseband video signal, and connected.
After that, it is compressed by the encoder again and stored in VTR.
It is conceivable that the method of recording in.

[0004]

When the compressed video signals are joined together as described above, if they are simply divided in frame units and joined together, image distortion may occur for a certain period from the joined portion. Further, if a plurality of compressed video signals are decoded / encoded, the system scale and system cost increase, and a simple and inexpensive system cannot be obtained. So this invention
It is an object of the present invention to provide a connecting device for compressed video signals, which can make image distortion in the joints between compressed video signals inconspicuous.

[0005]

SUMMARY OF THE INVENTION
Switching means for supplying the first and second video signals that have been subjected to inter-frame compression processing and intra-frame compression processing, and to bring one of them into a selective derivation state, and decoding means for decoding the output of the switching means, A frame storage unit for storing the output of the decoding unit in a frame; and a frame storage unit provided between the switching unit and the frame storage unit.
When the selected and derived state of the video signal is switched to the selected and derived state of the second video signal, the first stored in the frame storage means until the decoded output of the second video signal becomes a normal image. Control means for continuing to output the decoded output of one video signal.

[0006]

By the above means, the image signal obtained by expanding the first video signal is used until the switched compressed video signal is normally decoded, so that the image disturbance does not continue at the time of switching. .

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1A shows an embodiment of the present invention.
A first compressed video signal and a second compressed video signal are supplied to the input terminal 1 and the input terminal 2, respectively. The switcher 3 selectively derives one of the compressed video signals,
It is supplied to the decoder 4. The decoder 4 decodes the compressed video signal, converts it into a baseband video signal, and supplies this to the frame memory 5. The frame memory 5 is
Normally, it operates as a frame delay device, but when switching the input, the baseband video signal stored for an appropriate period is repeatedly output. The output of the frame memory 5 is input to the monitor 6. A control signal for determining whether the frame memory 5 is repeatedly read or continuously read is given from the switcher 3. Switcher 3
It has a function of extracting control information of the input compressed video signal and determining whether the signal is an intra-frame processed signal or an inter-frame processed signal. The switcher 3 also has a synchronization detecting means for the compressed video signal, and when the first compressed video signal selected state is switched to the second compressed video signal selected state, the second compressed video signal synchronizing portion is automatically operated. It is supposed to switch from. FIG. 2 shows an example of an encoder 20 that produces a compressed video signal and an example of the above decoder 4. The baseband video signal is input to the subtractor 22 via the input terminal 21.
The block is divided before being input to the subtractor 22.

The subtractor 22 subtracts the original frame signal and the preceding frame signal from the baseband video signal to obtain an interframe difference signal (interframe processing). The signal of the previous frame is the motion compensation circuit 3
2 is supplied to the adder 22 via the switch 33. When the intraframe processing is performed, the switch 33 is turned off and the baseband signal is output from the adder 22 as it is.

The output signal of the adder 22 is the DCT circuit 23.
Is input to the input terminal, the discrete cosine is changed (DCT processing), and the output signal is input to the quantization circuit 24 and is quantized. The quantized signal is input to the variable length coding circuit 25, variable length coded, and input to the memory 26. The output of the memory 26 is output as a compressed video signal.

The output of the quantization circuit 24 is the inverse quantization circuit 2
7 is input and inversely quantized, and this output is inverse DC
It is input to the T circuit 28 and subjected to inverse DCT processing, and this output is input to the adder 29. The output of the motion compensation circuit 32 is input to the adder 29 via the switch 34, the inter-frame difference signal is added to the signal of the previous frame, and the original frame signal (previous to the input signal of the adder 22 is input. (Becomes a frame signal) is created and input to the frame memory 30. If the signal input from the inverse DCT circuit 28 to the adder 29 is an in-frame signal, the switch 3
4 is turned off, and the in-frame signal is directly input to the frame memory 30. The signal output from the frame memory 30 is the entire baseband video signal of the previous frame with respect to the signal input to the adder 22, and is input to the motion compensation circuit 32 to be motion-compensated. Motion compensation circuit 32
Corrects the image based on the motion vector from the motion evaluation circuit 31. The motion evaluation circuit 31 uses the frame memory 3
The output of 0 is compared with the signal input to the adder 22,
The amount of motion of the image of the original frame is detected with respect to the image of the previous frame, and the signal of the motion compensation circuit 32 is modified so that the image position of the previous frame approaches the image position of the original frame. Thus, for example, when still images are continuously input, there is almost no difference signal from the subtractor 22, which is effective in reducing transmission information. However, when transmitting the intra-frame signal, all the data within the frame is transmitted.

The compressed video signal is input to and accumulated in the memory 31. When the frame length on transmission is collected and data is discriminated, it is input to the decoding circuit 32 and the variable length coded signal is decoded. The decoded signal is input to the inverse quantization circuit 33 and inversely quantized, and further the inverse DCT circuit 3
4 is subjected to inverse DCT processing, converted into an interframe difference signal of the baseband video signal or an intraframe signal, and input to the adder 35. In the adder 35,
The signal one frame before from the motion compensation circuit 37 is added to the inter-frame difference signal via the switch 36. As a result, the reproduced baseband video signal of the original frame is obtained from the adder 35. If the signal output from the inverse DCT circuit 34 is a signal that has undergone intraframe processing, this signal has all the data for one frame, so the switch 38 is turned off and the adder 35 remains unchanged.
Derived from. The baseband signal is input to the frame memory 36 and then input to the motion compensation circuit 37 delayed by one frame for addition to the next inter-frame difference signal.

The motion compensation circuit 37 receives the transmitted motion vector of the image of the next frame and compensates the image of the previous frame to match the difference information of the original frame. The switch 38 is turned on / off based on the control information reproduced from the compressed video signal, depending on whether the original signal is an interframe difference signal or an intraframe signal. When the original signal is processed within the frame, the signal arrives when the image movement is extremely large, and there may have been panning, but the refresh period is set under a certain rule, and this period is It is constructed to be an in-frame processed signal. The motion compensation circuit 3
The motion control information used in 7 is also included in the control information reproduced from the compressed video signal, and these control information are given from the system control unit (not shown).

According to the above-described embodiment, as shown in FIG. 3B, for a while from the switching point (until the second compressed video signal passes the refresh signal section and becomes stable).
A baseband video signal obtained by decoding the first compressed video signal is repeatedly output from the frame memory 5 (a still image is displayed during this period). Therefore, the image is displayed on the monitor screen without being disturbed. Figure 3 (a) shows
The figure shows a case where the first compressed video signal selection state is simply switched to the second compressed video signal selection state. In this case, a period in which an image is disturbed occurs.

The present invention is not limited to the above embodiment. FIG. 1B shows another embodiment. Figure 1
In the embodiment of (A), the control signal for repeatedly reading the frame memory 5 from the switcher 3 is obtained.
In the example of (B), the switcher 3 eliminates (or reduces) the image disturbance from the signal switching point.
Up to this point, only the signals processed in the frame are supplied to the decoder 4. In this way, FIG.
As shown in (c), although some image disturbance occurs during the switching period, compared to the case where simple switching is performed,
The image quality is good enough. Alternatively, instead of the switcher 3 supplying only the intra-frame processed signal to the decoder 4 until the image is not distorted from the signal switching point, the decoder 4 may not decode any signals other than the intra-frame processed signal. good.

Further, in the present invention, the control signal for repeatedly reading the stored contents of the frame memory 5 is obtained from the switcher 3 in FIG. 1A, but in the embodiment of FIG. Only the intra-frame processed signal and the inter-frame processed signal related to this signal are supplied to the decoder 4 from the switching point to the time when the image disturbance is eliminated (or the disturbance is reduced). Alternatively, the decoder 4 may be controlled not to decode any signals other than the intra-frame processed signal and the inter-frame processed signal related to this signal.

The present invention can also be applied to the case of monitoring or editing the compressed video signal reproduced from the magnetic recording / reproducing apparatus. It can also be applied to the case where the expanded video signal is compressed again and recorded. In such a case, as described above, the other embodiments are very effective when the second compressed video signal is specially reproduced (intermittent reproduction or the like). For this purpose, the switcher 13 needs to have a function of decoding the additional information (control information) of the input compressed video signal and controlling the decoder 4.

[0018]

As described above, according to the present invention,
It is possible to make the image distortion of the joint between the compressed video signals inconspicuous.

[Brief description of drawings]

FIG. 1 is a diagram showing first and second embodiments of the present invention.

FIG. 2 is a diagram showing an image compression decoder and an encoder.

FIG. 3 is a diagram for explaining the operation of the device of the present invention.

[Explanation of symbols]

3 ... switcher, 4 ... decoder, 5 ... frame memory, 6 ... monitor.

Claims (3)

[Claims] 1. A switching means for supplying first and second video signals which have been subjected to inter-frame compression processing and intra-frame compression processing, respectively, and one of which is in a selective derivation state, and an output of the switching means. Is provided between the switching means and the frame storage means, and is provided between the switching means and the frame storage means. Control means for continuing to output the decoded output of the first video signal stored in the frame storage means until the decoded output of the second video signal becomes a normal image when switched to the selective derivation state. A device for connecting compressed video signals, comprising: 2. Switching means for respectively supplying the first and second video signals which have been subjected to inter-frame compression processing and intra-frame compression processing and which puts one of them into a selective derivation state, and the output of the switching means. And a switching means for decoding the second video signal, the second video signal being compressed between frames when the selection and derivation state of the first video signal is switched to the selection and derivation state of the second video signal. In the case where the second video signal is a decoded signal, a control for inputting only the intra-frame processed signal of the second video signal to the decoding means for a certain period until the decoded output of the second video signal becomes a normal image. And a means for connecting compressed video signals, comprising: 3. Switching means for respectively supplying the first and second video signals which have been subjected to inter-frame compression processing and intra-frame compression processing, and which puts one of them into a selective derivation state, and the output of the switching means. And a switching means for decoding the second video signal, the second video signal being compressed between frames when the selection and derivation state of the first video signal is switched to the selection and derivation state of the second video signal. If it is a signal that has been processed, the intra-frame processed signal of the second video signal is supplied to the decoding means as it is for a certain period until the decoded output of the second video signal becomes a normal image, The inter-frame compressed signal has a control means for outputting only a signal corresponding to the intra-frame processed signal to the decoding means. Connecting device of the compressed video signal to.