Moving image encoding apparatus, moving image encoding method, and video device

1. A moving image/picture encoding apparatus configured to transcode an input stream into an output stream, the input stream being a fixed-rate MPEG-2 stream whose bit-rate is controlled to be constant by changing a quantization parameter, the apparatus comprising:

an information acquisition module configured to acquire information on a quantization scale, a num of generated bits and a picture type for each frame from the input stream;

an encoding complexity calculation module configured to calculate, for each of the frames, encoding complexity represented in a form of S X Q gi by using the information acquired in the information acquisition module, where Q denotes an average quantization scale of the frame, S denotes a num of bits of the frame, gi denotes a fixed value determined for each picture type and being independent of image as long as the picture type is same, postfix i of the fixed value gi indicates the picture type, and X denotes a product;

an encoding complexity conversion module configured to convert the encoding complexity calculated by the encoding complexity calculation module into encoding complexity of the output stream by using a linear function prepared for each of the picture types and indicating a relation between the encoding complexity of the input stream and the encoding complexity of the output stream, where the encoding complexity of the input stream is a function of the fixed value gi being independent of the image as long as the picture type is same, and the linear function shows a linearity within a changeable range of the encoding complexity of the input stream; and

a transcode module configured to re-encode the input stream into the output stream by using the encoding complexity of the output stream converted by the encoding complexity conversion module,

wherein the re-encoding by the transcode module is performed for each of the frames by using the linear function prepared for each of the picture types, and

the transcode module includes a num of bits allocation module configured to allocate a num of bits to be used in the re-encoding to each of group of pictures contained in a sequence of the input stream.

2. The apparatus of claim 1 , wherein the transcode module includes a picture num of bits allocation module configured to allocate a bit or bits allocated to the group of pictures to each of I, B, and P pictures in the group of pictures.

3. The apparatus of claim 2 , wherein the transcode module includes a buffer configured to store the calculated encoding complexity, the calculated encoding complexity stored in the buffer being available for a subsequent determination of the quantization scale, and

the bit or bits is/are configured to be allocated to the picture of the I, B, and P pictures, with a condition that past or previous encoding complexity of the output stream for the same picture type is regarded as the present or current encoding complexity of a target frame.

4. The apparatus of claim 3 wherein the transcode module includes

a decoding module configured to decode the input stream,

an encoding module configured to re-encode the stream decoded by the decoding module so as to convert the stream into the output stream, and

a quantization scale determining module configured to determine a quantization scale in the encoding module from the bit or bits allocated to the picture.

5. A moving image/picture encoding method for transcoding an input stream into an output stream, the input stream being a fixed-rate MPEG-2 stream whose bit-rate is controlled to be constant by changing a quantization parameter, the method comprising:

reading, by an information acquisition module, MPEG header information from the input stream to acquire information on a quantization scale, a num of generated bits and a picture type for each frame;

calculating, by an encoding complexity calculation module for each of the frames, encoding complexity represented in a form of S X C gi by using the acquired information, where Q denotes an average quantization scale of the frame, S denotes a num of bits of the frame, gi denotes a fixed value determined for each picture type and being independent of image as long as the picture type is same, postfix i of the fixed value gi indicates the picture type, and X denotes a product;

converting, by an encoding complexity conversion module, the calculated encoding complexity into encoding complexity of the output stream by using a linear function prepared for each of the picture types and indicating a relation between the encoding complexity of the input stream and the encoding complexity of the output stream, where the encoding complexity of the input stream is a function of the fixed value gi being independent of the image as long as the picture type is same, and the linear function shows a linearity within a changeable range of the encoding complexity of the input stream; and

re-encoding, by a transcode module, the input stream into the output stream by using the converted encoding complexity of the output stream, wherein

the re-encoding is performed for each of the frames by using the linear function prepared for each of the picture types, and

a num of bits allocation module is configured to allocate a num of bits to be used in the re-encoding to each of group of pictures contained in a sequence of the input stream.