JPS6257384A - Picture encoder - Google Patents

Abstract

PURPOSE:To encode a meaningless difference signal between frames and to prevent a picture from being disturbed by detecting that an input picture signal is changed over and a synchronous signal is disturbed by a fluctuation detecting means and by stopping an operation of a quantizing encoder. CONSTITUTION:Immediately after a camera 1 is changed over by a change over device 2, an output video signal is disconnected. When that a phase of a synchronous signal is badly shifted is detected by a detector 11, a quantizing encoder 6a stops an encoding of a picture and prevents the picture from being disturbed. At the same time, a change over device 12 is changed over so as to output a raw picture signal and a change over device 13 is changed over in such a manner that an output of a frame memory 8 is not applied to an adder 9, respectively. When a device completes a re-leading of the synchronous signal, an output of the detector 11 is deleted and th quantizing encoder 6a starts the encoding of the raw picture signal. At this time, in the frame memory 8, an output of a quantizing decoder 7 is directly written. When the frame of the encoding of the raw picture signal is completed, the change over devices 12, 13 are reset, an encoding of an original difference signal between frames is started.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an image encoding device using an inter-frame differential method, and particularly to an image encoding device in which image signals from a plurality of input sources (cameras, etc.) are switched as appropriate. This relates to an image encoding device that receives input data.

[Conventional technology]

FIG. 2 shows an image encoding device according to the prior art.

In the figure, 1 is a plurality of cameras for inputting images, and 2 is a switch for switching a plurality of image signals. 3~
Reference numeral 9 constitutes an image encoding device 10 that is a subject of the present invention, and reference numeral 3 indicates an A/D converter for A/D converting an input image signal.
A D converter, 4 is a preprocessing unit that preprocesses the digitized image signal for encoding, 8 is a frame memory for storing the image signal of one frame before, and 5 is the output of the preprocessing unit 4. 6 is a quantization encoder that quantizes and encodes the inter-frame difference signal; 7 is a quantization encoder that performs the opposite process to that of the quantization encoder 6; Summer naturalizer, 9 is an adder.

Now, among the image signals output from the plurality of cameras 1, only one type is selected by the switch 2 and output. When this output signal is input to the image encoding device 10,
After being A/D converted by the A/D converter 3 and subjected to preprocessing for encoding by the preprocessing section 4, it is input to the subtracter 5 to obtain an interframe difference signal. This inter-frame difference signal is quantized and encoded by a quantization encoder 6 and output to the outside, and at the same time is quantized and encoded by a quantization 1 naturalizer 7 and added for processing the next frame. After being added to the output of the frame memory 8 via the unit 9, the output signal is stored in the frame memory 8.

[Problem that the invention seeks to solve]

Here, when considering the actual use of the image encoding device, for example, a video conference can be mentioned. In a video conference, a plurality of cameras are often used, and the signals thereof are often switched and used as appropriate. Therefore, considering the operation when switch 2 is switched, immediately after switching, switch 2
The output image signal becomes discontinuous and the synchronization signal etc. are greatly disturbed.As a result, a meaningless inter-frame difference signal is encoded until the synchronization is completed, causing a problem in the encoded image. . In order to eliminate disturbances in the synchronization signal, a method of synchronously coupling a plurality of cameras 1 can be considered, but there is a problem in that synchronously coupling cameras is generally possible only with expensive cameras.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to minimize image disturbance even when inputting signals from multiple cameras that are not synchronously combined as appropriate. The purpose of the present invention is to provide an encoding device.

Another object of the present invention is to provide an image encoding device that can minimize image disturbance as described above and quickly restore the original image. - [Means for solving the problem] The image encoding device according to the present invention includes a fluctuation detection means for detecting temporal fluctuation of a synchronization signal included in an input image signal, and also includes a quantization encoder. The operation is configured to open and stop when fluctuation is detected, based on the output of the fluctuation detection means.

Further, an image encoding device according to another aspect of the present invention includes a fluctuation detection means for detecting temporal fluctuation of a synchronization signal included in an input image signal, and a quantization encoder based on the output of the fluctuation detection means. and signal switching means for switching the input from the inter-frame difference signal to the input image signal, and the operation of the quantization encoder is configured to open and stop when fluctuation is detected based on the output of the fluctuation detection means. and the signal switching means is configured to switch from the input image signal to the inter-frame difference signal with a delay of one frame of the input image signal after the fluctuation is no longer detected.

[Effect]

In the present invention, the fluctuation detection means detects when the input image signal is switched and the synchronization signal is disturbed, and the operation of the quantization encoder is stopped. This prevents the image from being distorted by encoding meaningless inter-frame difference signals.

Further, in another aspect of the present invention, the raw image signal is encoded instead of the inter-frame difference signal only immediately after the fluctuation detection means no longer detects the synchronization signal disturbance and the quantization encoder starts operating. Ru.

Then, since the frame memory is rewritten with the decoded image, the original image can be restored more quickly.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention shown in the drawings will be described. 1st
The figure is a configuration diagram of an image encoding device showing an embodiment of the present invention. In the figure, 1 is a plurality of cameras for inputting images, and 2 is a switch for switching a plurality of image signals. 3
- 13 constitute an image encoding device 20 according to the present invention, and 3 is an A/D converting the input image signal.
Converter, 4 is a preprocessing unit that preprocesses the digitized image signal for encoding, 8 is a frame memory that stores the image signal of the previous frame, 5 is the output of the preprocessing unit 4 and the frame 6a is a quantization encoder that can be controlled in 0N10FF by an external signal; 7 is a quantization 41i encoder that performs the opposite process to the quantization encoder 6a. , 9 is an adder; 11 is a detector that separates a synchronization signal from an input image signal, detects its temporal fluctuation, and controls the quantization encoder 6a and switching means described later; 12 is the detector a switch 1 that switches between the output of the preprocessor 4 and the output of the subtracter 5 according to the output of the detector 11;
Reference numeral 3 designates a switch which similarly switches the output of the frame memory 8 input to the adder 9 according to the output of the detector 11 to 0N10FF, and each of the switches 12 and 13 switches the image signal 1 after the output of the detector 11 disappears. It is set to return to the original state with a delay of one frame. here,
The detector 11 constitutes the fluctuation detection means of the present invention, and the switch 12 constitutes the signal switching means of the present invention.

Next, the effect will be explained.

First, the plurality of cameras 1 are not synchronously coupled, and each independently sends out a video signal to the switch 2. The image signal input to the image encoding device 20 through the switch 2 is A
After being A/D converted by the A/D converter 3, the signal is preprocessed by the preprocessing section 4 and converted into an interframe difference signal, which is input to the switch 12. Both the inter-frame difference signal and the raw image signal are input to this switch 12, but normally the inter-frame difference signal is output as shown. The inter-frame difference signal output from here is quantized and encoded by a quantization encoder 6a and outputted to the outside, while being quantized and encoded by a quantization decoder 7. On the other hand, since the switch 13 normally outputs the output of the frame memory 8 as it is as shown in the figure, the adder 9 uses the quantized value output from the quantization decoder 7 between frames. The difference signal and the frame memory output from the switch 13 are added and written into the frame memory 8 in preparation for processing the next frame.

Now, let us consider the operation when the switch 2 that switches the camera l is switched. Immediately after switching, the output video signal becomes discontinuous, so the detector 11 detects that the phase of the synchronization signal has shifted significantly. The quantization encoder 6a stops encoding the image when the detector 11 detects a phase shift to prevent the image from being distorted. at the same time,
The input switch 12 of the quantization encoder 6a is switched to output the raw image signal, and the input switch 1 of the adder 9 is switched to output the raw image signal.
3 is switched so that the output of the frame memory 8 is not given to the adder 9. Then, when the device completes re-acquiring the synchronization signal, the output of the detector 11 disappears and the quantization encoder 6a starts encoding the raw image signal. At this time, the output of the quantization decoder 7 is written into the frame memory 8 as is. When the encoding of the raw image signal for one frame is completed, the switch 12, 13 returns to the normal state and starts encoding the original interframe difference signal.

Comparing the above operations with those of the conventional device, (i) Immediately after switching the switch 2, temporal fluctuations in the synchronization signal are detected and the operation of the quantization encoder 6a is stopped;
This eliminates the possibility of encoding meaningless inter-frame difference signals and causing image disturbances.

(ii) Since the completion of synchronization signal re-drawing is detected and the raw image signal is encoded only immediately after that, instead of the interframe difference signal, the original image is It's too early to return to. That is, in the conventional device, when the switch 2 is switched, the image is distorted and it takes a long time to recover, but in the device of the present invention, the image becomes static immediately after switching, and the image recovers in a short time.

It has excellent effects such as

〔Effect of the invention〕

As explained above, according to the present invention, the fluctuation detection means for detecting the temporal fluctuation of the synchronization signal included in the input image signal is provided, and the operation of the quantization encoder is controlled by the fluctuation detection means. By configuring the system to open and stop when fluctuations are detected based on the output, image disturbances can be kept to a minimum even when image signals from multiple cameras that are not synchronously combined are switched and input. This has the advantage that an image encoding device that can encode images can be obtained.

Further, according to another invention of the present invention, there is provided a fluctuation detection means for detecting temporal fluctuation of a synchronization signal included in an input image signal, and an input to a quantization encoder based on the output of the fluctuation detection means. signal switching means for switching from the inter-frame difference signal to the input image signal, and the operation of the quantization encoder is configured to open and stop when fluctuation is detected based on the output of the fluctuation detection means,
and the signal switching means causes a delay of one frame of the input image signal after the fluctuation is no longer detected,
By configuring the input image signal to be switched to the frame-to-frame difference signal, the same effect as described above can be obtained, and an image encoding device that can return to the original image in a short time can be obtained. be.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an image encoding device according to the present invention, and FIG. 2 is a configuration diagram of a conventional image encoding device. In the figure, 1 is a camera, 2 is a switch, 3 is an A/D converter, 4 is a preprocessor, 5 is a subtracter, 6a is a quantization encoder, 7 is a quantization encoder, and 8 is a frame memory , 9 is an adder, 11
1 is a synchronizing signal fluctuation detector (fluctuation detection means), 12 is a switch (signal switching means), 13 is a switch, and 20 is an image encoding device. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Masuo Oiwa (and 2 others) Figure 1 Figure 2

Claims (2)

[Claims] (1) The inter-frame difference signal between the input image signal and the image signal of the previous frame is quantized and encoded by a quantization encoder and output, and this output is quantized and decoded by a quantization decoder. The image encoding device rewrites the frame memory using the input image signal.
An image encoding device characterized in that it is configured to stop operation while fluctuation is detected based on the output of the fluctuation detection means. (2) The inter-frame difference signal between the input image signal and the previous frame image signal is quantized and encoded by a quantization encoder and output, and this output is quantized and decoded by a quantization decoder. In the image encoding apparatus, the frame memory is rewritten using a fluctuation detection means for detecting temporal fluctuation of a synchronization signal included in the input image signal, and the quantization encoding is performed based on the output of the fluctuation detection means. and signal switching means for switching the input to the device from the inter-frame difference signal to the input image signal, and the quantization encoder stops operating while fluctuation is detected based on the output of the fluctuation detection means. and the signal switching means operates to switch from the input image signal to the inter-frame difference signal with a delay of one frame of the input image signal after the fluctuation is no longer detected. An image encoding device characterized by: