JPS6338379A - Moving picture compressing device of picture quality switching type - Google Patents

Abstract

PURPOSE:To secure selection of the picture quality in response to the purpose and application of a user at a fixed circuit transmission speed, by providing a picture quality changeover switch to perform the time lapse and subsampling to a time lapse/subsampling circuit with selection of screens. CONSTITUTION:A user selects previously an image resolution-based screen or a smooth movement-based screen via a picture quality changeover switch 18. A time lapse/subsampling circuit 13 decided (512 lines X 768 picture elements X4 frames/sec) in a selection mode of an image resolution-based screen and then (256 lines X 384 picture elements X 16 frames/sec) in a selection mode of a smooth movement-based screen, for example, with selection of screens carried out by the switch 18. In such a way, the number of picture elements is increased within a single frame and the number of frames is decreased per second in the case of an image resolution-based screen. While the number of picture elements is decreased within a single frame and the number of frames is increased per second in the case of a smooth movement-based picture. In such a way, a time lapse/subsampling action is carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION The field of industrial application relates to an image quality switching type reduction lock for use in video conference systems, surveillance systems, etc.

2. Prior Art Conventionally, a moving image compression device for this scale has one compression ratio, one dino changeover switch, one λ'CJ, and three changeover switches. Therefore, it is possible to obtain a good video image with little deterioration in image quality.
”Yip'r Goni + J, l::Toeho 1.544Hb
pswo, if you want to obtain a high IF reduction ratio even if you allow the deterioration of the original image 74i, you should select the 64 Kbps range. FIG. 2 shows a schematic block diagram of the configuration of a conventional moving image compression device. In FIG. 2, 1 is a to/D converter.
(''' is present, and is connected to the FP degree/color signal (Y/C) splitting circuit 2.
The prediction formula 7 output circuit 4 extracts the main error on the child side, and is inputted to the transmission buffer 6 through the entropy encoding circuit 5 and the compression ratio changeover switch. 8'C-decision) It is sent to the line 7 at the transmission line speed [α]. 73, the one-door control circuit 9 is designated by the symbol 'I]
A circuit C' that performs code control, a transmission buffer r'6, L[
It is connected to J, which receives the output of the reduction ratio changeover switch 8, and outputs a control signal to the frame drop reprinting circuit 3 and the prediction method X extraction circuit 4.

Next, the dynamic f1 of the above conventional example will be explained. In FIG. 2, the user selects the desired compression rate (line transmission speed) in advance using the compression rate l and lI changeover switch 8, and then
In order to prevent the A-bar slowdown from occurring when the line transmission speed rα is set to 1, the occupancy level according to the line transmission speed of 6 is set to 1 (): Congratulations, frame drop rib ring ring circuit. 3. Send a control signal to the prediction error calculation circuit 4 to perform frame dropping control. - input analog N 1S CJ In A/D converter 1, A at 14fSC (fSC: leaf kitsj' frequency)
/D converted, Y, /C min-1 J to circuit 2,
Separated into Yf degrees and color temperature (component signals).

The above-mentioned component signal Y] is encoded in the frame drop refring ring circuit 3, and is subjected to frame drop/1 knob → non-pulling as necessary according to the one-dot system ti+1 circuit 9J and sent out system 611 signal 5J. In the circuit 1, the encoding mode is predicted according to the control signal transmitted by the output circuit 9J, and 9 times the P71111 error with respect to the true value is output. What is the above prediction error? 1 jj conversion circuit 5 converts it into 1 tropy 7413, and transfers it to the transmission buffer 7.
・After the time is stored in 6, the transmission line 7
is fed at a constant speed [αC 1j.

This J, Uni-1: Select the compression rate (line transmission speed) in the conventional pressure M11 rate switching type video compression device.
You can select the image quality by selecting the

Problems that the invention seeks to solveHowever, - [-] Conventional compression rate switching method video compression devices do not allow switching the compression rate (line transmission speed) to achieve the desired image quality. , depending on the image quality you select, you will always need a small amount of line capacity, and if you select J, the line capacity will be small and the required line capacity will vary depending on the selected image quality. There was a problem.

The present invention solves these conventional problems by providing excellent image quality switching that allows the user to select the image quality according to his or her wishes at the same compression rate (line transmission speed) and d3. The first image compression system is 4? It is something that covers offering as a [] target.

Measures to Solve the Problems In order to solve the above problems, this section describes how to perform frame drop/subsampling by screen selection for the frame drop subsampling circuit.
An image quality changeover switch that performs non-pulling is provided, and the image quality can be switched between a resolution-oriented screen and a motion smoothness medium-phase screen at the same n-reduction ratio (line transmission speed + u).

Operation With the above configuration, the user can select
! If you select the 1' image resolution screen, the number of frames per second will be reduced and the number of images in 1 frame will be increased, and if you select the motion slide 1 vertical phase screen, the number of images in 1 frame will be reduced. It is τ' to reduce the number of frames and increase the number of frames per second, which makes it possible to select and switch the image quality according to the purpose, as in F-1, with the same compression rate (line transmission speed 1α). -Monkey.

Example Hereinafter, one embodiment of the wood Rime will be explained based on the drawings.

FIG. 1 shows a schematic diagram of the configuration of an embodiment of the present invention. In Fig. 1, J3 is shown, and 11 is an A/D converter.
The output (component signal) of the Y/C separation circuit 12 is connected to the IRF degree/color (m number (Y/C) separation circuit 12. It is temporarily stored in a transmission buffer 7716 through a prediction error extraction circuit 14 that extracts errors and an entropy encoding circuit 15 that performs entropy encoding, and is sent to a transmission line 17 at a predetermined constant speed.Image quality switching The switch 18 is connected to the frame dropping] knob 4 and the non-bringing circuit 13, and the encoding mode control circuit 19 receives the output of the transmission buffer 6 and controls the frame dropping and non-bringing circuit 13 and the prediction error output circuit 14. It is connected to J, which outputs the signal.

Next, the operation of the above embodiment will be explained. In the above embodiment, the user presses the image quality selector switch 18 in advance to select either the resolution-oriented screen or the motion smoothness screen.
Rir. ”-Selected Song is a piece drop sublimp ring circuit 1
3 can be conveyed. Now, the input NTSC (
The A/D converter 11 performs rimbling at a frequency of 4 fsc (fsc:→knob key ↑・rear frequency) and converts it into a digital signal. This digital signal is sent to the Y/C separation circuit 12 as a luminance/color signal (component signal) 3)
Minute H is done. In the frame dropping sublimbling circuit 13, for example, 512 lines x
768 pixels x 4 frames/sec, or when selecting a screen that emphasizes motion clarity, for example, 25G lines x 384 pixels x 16 frames/sec, and for a screen that emphasizes resolution, increasing the number of pixels in one frame to 1 Decrease the number of frames per second, and in the case of a screen that emphasizes sensitivity, reduce the number of pixels in one frame and increase the number of frames per second. Perform sampling. After this, the encoding mode control circuit 1
Frame dropping and rebringing are performed as necessary according to the control (i? 13) sent from 9. Control 11 output from
The prediction is made according to the number, and the prediction error from the true value is shown. The output of the prediction error detection circuit 14 is input to the encoder circuit 15 through the encoder 15, and this output is temporarily stored in the transmission buffer '16 and output to the transmission line 17 at a predetermined speed. Furthermore, the encoding mode control circuit 19 performs frame dropping/ribling control on the frame dropping/librbling circuit 13 to prevent the transmission buffer 16 from overflowing in accordance with the occupancy of the transmission buffer 16, and performs prediction. The error extraction circuit 14 is controlled to determine a prediction function.

In this way, the above embodiment has the advantage that the line transmission speed remains constant, and the user can select between a screen that emphasizes resolution and a screen that emphasizes smoothness depending on the user's purpose and application. Ru. Furthermore, as in the above embodiment, the number of pixels per second (512 x 768 x 4-1572864 pixels) when using an Iff'ff type viewing screen and the number of pixels per second when using a screen that emphasizes smooth motion (2
56x 384x 16-= 1b72864 pixels)
By writing them as the same, even if the screen is different, the 14 intervals allowed for processing one pixel is significant, and r'If
sc→non-pulling 3oノ[norm/'! , (!c is very long < t, r (636r + 5ec
) for whichever screen is selected for the piece? A [
The advantage is that the dynamic speed of the Birdow core below 7 Lee-I limp ring circuit 13 is constant, and that high-speed processing is not required for /Ifsc limp ring.

Effects of the North Gate According to Benmei Ki, the advantage is that the user can select the image quality according to the user's purpose and application while maintaining a fixed line transmission speed. Furthermore, by making the total number of pixels to be encoded in one second the same for each image quality, which image quality is selected and 1) corrected per pixel]
If the J5 interval is constant, it can take much longer than the 1fSc limping ring of 30 frames/sec.

[Brief explanation of drawings]

Fig. 1 shows an example of this embodiment of the present invention, and Fig. 2 shows an outline of a conventional 11 reduction rate switching type moving image compressor. It is a diagram.

Claims (1)

[Claims] 1. A frame dropping sub-sampling circuit is provided to control frame dropping and sub-sampling so that the transmission buffer output to the transmission line does not overflow depending on the occupancy at a constant line transmission speed. This is a video quality switching type video compression device that is equipped with an image quality changeover switch that performs frame dropping and subsampling by selecting a screen for the sampling circuit.