Video encoding method and video encoding apparatus

Abstract

An video encoding method and a video encoding apparatus wherein an input video signal is divided into a plurality of temporally continuous scenes each including at least one frame, statistical feature amounts are calculated for each of the scenes, encoded parameters are generated for each of the scenes based on said statistical feature amounts, and the input image signal is encoded using the encoded parameters.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to a video compression and encoding technology such as an MPEG scheme utilized in a video transmission system and a video database system through the Internet or the like. The present invention particularly relates to a video encoding method and a video encoding apparatus capable of providing a unified decoded video for each scene, which is easy to see without increasing data size, by encoding data in accordance with encoded parameters based on the content of scenes. [0002] The MPEG scheme, which is an international standard for video encoding, is a technique for compressing a video by a combination of motion compensation prediction, discrete cosine transformation and variable length coding, as is well known. The MPEG scheme is described in detail in, for example, Reference 1: “MPEG”, The Institute of Television Engineers edition, Ohmsha, Ltd.). [0003] In a conventional video encoding apparatus based on the MPEG scheme...

AI Technical Summary

Benefits of technology

[0015] In this way, according to the present invention, the encoded parameters used for encoding the input video signal are generated for each scene based on the statistical feature amounts calculated for each scene of the input video signal, thereby making it possible to prevent the frame rate from decreasing when the motion of the object or that of the camera is active and the visual quality of a decoded video from deteriorating.

[0016] Further, the video feature amounts based on the motion of the object in the video, the motion of the camera and the like are reflected on the encoded parameters, based on which the frame rate is changed or the quantization width is changed for each macro-block, thereby making it possible to obtain a good decoded video unified for each scene even with the same number of generated bits.

[0018] As can be seen, the encoded parameters generated as stated above are corrected while always monitoring the number of generated bits, and encoding is repeated twice or more, whereby it is possible to realize encoding capable of obtaining a good decoded video with data size not more than the target number of bits.

Problems solved by technology

With this method, however, if the number of coded bits generated in a previous frame is large, frame skipping is conducted until the buffer capacity becomes not more than the frame skip threshold.

Due to this, the distance between the frame and the next frame becomes too wide, with the result that video disadvantageously becomes unnatural.

For that reason, frame rate become too low on a scene in the video on which an object moves actively and the motion of the object becomes unnatural.

Besides, due to the inappropriate quantization width, the picture may be distorted to thereby disadvantageously find it difficult to visually recognize the picture.

The two-pass encoding, however, has the same problems as those described above since encoding parameters are conventionally, basically set irrespectively of the contents of a video.

Due to this, the frame rate suddenly decreases on a scene in the video on which an object moves actively and the motion of the object becomes unnatural.

Also, due to the inappropriate quantization width, the video may be distorted.

Thus, the conventional video encoding apparatus has a disadvantage in that the deterioration of picture quality tends to be conspicuous.

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