Picture coding method, picture coding equipment and image repeating equipment

Abstract

The invention relates to a picture coding device, a picture coding method and image repeater facility used for recoding digit compressed picture signals to obtain digit picture signals with the compressed format which is the same to or different from the compressed format of the digit compressed picture signals to be recoded. A picture coding apparatus contains a rate control unit, an image buffer, an orthogonal transformation unit, a quantizing unit, a variable length coding unit, a motion predicting unit, a coding unit, and an output buffer. The rate control unit allocates a target code amount to each of pictures, and transfers a quantizing value which is determined by a code amount to the quantizing unit. This target code amount is calculated by adding a reference target code amount to a correction value. The correction value is calculated based on a difference between a predetermined target value and an actual value of a remaining coding picture amount of the output buffer.

Description

technical field [0001] The present invention relates to a picture encoding device and a picture encoding method for re-encoding a digitally compressed picture signal to obtain a digital picture signal having the same or different compression format as that of the digitally compressed picture signal. More particularly, the present invention relates to the ability to increase the bit usage when a digitally compressed picture signal is re-encoded as an input picture signal to reduce the number of frame skip operations in the case where the total number of frames of the digitally compressed picture signal per unit time is varied. Efficient picture encoding device and picture encoding method. Background technique [0002] A video conferencing system using a narrowband ISDN is generally used practically. Such a video conferencing system can be implemented by a picture compression technology capable of compressing digitized meeting pictures to obtain a pre...

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Problems solved by technology

results, such as Figure 12 As explained in the transcoding device shown, when no picture can be input at the coded frame rate suitable for the setting, an efficient total code allocation cannot be achieved

[0045] Second, when the encoding frame rate is set to a large encoding frame rate to solve the above problem, there is another problem that the frame skipping operation occurs multiple times

In this case, the (moving) picture to be output may become a (moving) picture lacking in smoothness compared to the input (moving) picture

Moreover, the total amount of code associated with the originally coded picture becomes useless and the image quality will deteriorate

[0047] As previously described, when a conventional rate control system is implemented in a system switching device, the following problems may occur: namely, (1) since the frame rate of an input picture is unknown and varies, an appropriate amount of code cannot be set, and Inefficient use of this amount of code that can be used raw makes image quality worse

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