JPH0313792B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image encoding device that performs band compression encoding of an image signal output from a television camera.

[Prior art]

Conventionally, as a band compression encoding method for image signals,
Transform coding methods such as predictive coding and variable length coding that use intra-frame and inter-frame correlation are known. Data encoded using these encoding methods is once stored in a buffer memory in order to match the transmission bit rate, and then sent out to the transmission line at a constant transmission bit rate. In such a system, when the amount of buffer memory occupied increases, the amount of generated information is suppressed by switching the quantization characteristic to a coarser characteristic, or using subsample encoding, field repeat, or the like.

[Problem that the invention seeks to solve]

However, with this method, it is not possible to deal with cases where the amount of information generated increases rapidly due to scene changes, etc., and in order to prevent buffer memory overflow, if the amount of buffer memory occupied exceeds a certain value, the screen may be But it has become necessary to stop encoding. As a result, a problem arises in that the image on the lower side of the screen is not encoded and the image quality deteriorates.

An object of the present invention is to provide an image encoding device that can eliminate the above-mentioned drawbacks and obtain good images.

[Means for solving problems]

In order to solve the above problem, the image signal encoding device of the present invention provides a switching system for switching the image signal input to the encoder in an image encoding device that performs band compression encoding of an image signal output from a television camera. and an input image switching control circuit that outputs a switching instruction to the switching circuit and outputs switching prediction information to the encoder, and the circuit includes an input image switching control circuit that outputs a switching instruction to the switching circuit and outputs switching prediction information to the encoder. Encoding is controlled so that encoding does not stop in the middle of the screen.

According to the present invention, since it is possible to know in advance the increase in the amount of information generated due to switching of the image signal input to the encoder, it is possible to control the encoding mode of the encoder so as to improve the image that appears visually. .

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

Referring to FIG. 1, an image encoding control device according to an embodiment of the present invention is shown. Input terminal 1
An image signal a given from the input terminal 2, an image signal b given from the input terminal 2, and an image signal c given from the input terminal 3 are each input to the switching circuit 4.
These three signals are provided, for example, by separate television cameras. The switching circuit 4 selects one of these three image signals a, b, and c as an output signal d based on the switching instruction signal e outputted from the input image switching control circuit 5 and supplies it to the encoder 6. . This switching instruction signal e is generated a predetermined time (FIG. 3) after the switching prediction signal f generated in response to switching of the three TV cameras. The encoding parameters in the encoder 6 are determined by the input image switching control circuit 5.
It is controlled by switching prediction information f output from the buffer memory 7 and a signal h indicating the buffer memory content capacity output from the buffer memory 7. The encoded data g from the encoder 6 is temporarily stored in the buffer memory 7, and then read out at a predetermined speed as encoded data i, and sent from the digital output terminal 8 to the transmission line.

Next, a method for controlling the encoding parameters of the encoder 6 will be explained with reference to FIG. 3 which shows the operation timing of the encoder input signal d and the switching prediction information f of FIG. An example of switching from image signal a to image signal b of the second TV camera will be explained. The output signal d of the switching circuit 4 changes from the image signal a to the image signal b at time _T0 according to the switching instruction signal e.
Switch to . Since the encoder 6 has received the switching prediction information f from the input image switching control circuit 5 before the predetermined time _T0 , the encoding mode for the scene change, for example, for several frames,
An encoding mode is executed in which each frame is partially encoded and one screen is sent out. Specifically, for several frames, well-known sub-sample encoding or the like is used to suppress the sudden amount of information generated due to a scene change. Thereafter, until switching prediction information is received again, the encoder 6 performs encoding in the encoding mode determined by the buffer memory content h output from the buffer memory 7.

FIG. 2 is a circuit diagram showing an example of the configuration of the encoder 6 when predictive coding is used. The input video signal d is digitized by an A/D conversion circuit 61, and this digitized signal A is supplied to a color signal processing circuit 62, where time division multiplexing (TDM) of the color signal and noise removal are performed. . The predictive encoder 63 predictively encodes the output signal X of the color signal processing circuit 62 and supplies it as an output signal Y to the variable length encoder 64. On the other hand, the encoding parameter control circuit 65 determines encoding parameters based on the switching prediction information f and the buffer memory content h, and sets the encoding mode M to the predictive encoder 6 for increasing or decreasing the data g output to the transmission path.
3. Supply to variable length encoder 64. As shown in the operation timing in FIG. 3, the switching prediction information f is sent to the encoding parameter control circuit 65 before the input image signal switching time, and the input signal is switched in the encoding parameter control circuit 65 regardless of the buffer memory content h. A predictive encoder 63 receives coding parameters for a new scene change from the beginning of the Watsuta frame.
The signal is supplied to a variable length encoder 64.

〔Effect of the invention〕

As described above, according to the present invention, even if the image signal input to the encoder is switched, the encoding parameters are predetermined and encoded based on the switching prediction information, so the amount of information generated due to scene changes etc. can be suppressed, and a good image with no visually noticeable deterioration can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an image encoding control device according to an embodiment of the present invention, FIG. 2 is a block diagram showing details of the encoder 6 in FIG. 1, and FIG.
It is a diagram showing the timing of input signals of the encoder 6 in the figure. In the figure, a, b, c, d, e, f, g,
h, i, A, X, Y, M are signal lines, 1, 2, 3,
8 is a terminal, 4 is a switching circuit, 5 is an input image switching control circuit, 6 is an encoder, 7 is a buffer memory, 61
is an A/D conversion circuit, 62 is a color signal processing circuit, 63
64 is a predictive encoder, 64 is a variable length encoder, and 65 is a parameter control circuit.

Claims (1)

[Scope of Claims] 1. An image encoding device having an encoder for band compression encoding an image signal output from a television camera, comprising: a switching circuit for switching an image signal input to the encoder; and a switching circuit for switching an image signal input to the encoder; and an input image switching control circuit that outputs a switching instruction and outputs switching prediction information to the encoder to notify the switching before outputting the switching instruction signal, and the switching prediction outputted from the switching control circuit. An image encoding apparatus characterized in that predetermined encoding parameters are set in the encoder so that the encoder can execute an encoding mode in which the amount of information generated is small.