Apparatus, method and computer program product for transcoding a coded multiplexed sound and moving picture sequence

The method as set forth in claim 7 or claim 9, wherein said transforming step (c72) comprises the steps of:

• (c91) computing a target number of outputting bits of said output video elementary streams on the basis of outputting bits of said second coded signal able to be outputted at said predetermined time interval;
• (c92) computing a reference ratio of outputting bits to inputting bits on the basis of said target number of outputting bits of said output video elementary streams computed in said computing step (c91) and said number of real inputting bits of said video elementary streams reconstructed in said decoding step (c71);
• and
• (c93) computing a quantization scaling factor required for transforming said video elementary streams to generate said output video elementary streams, on the basis of said reference ratio of outputting bits to inputting bits computed in said computing step (c92).

An apparatus of transcoding a coded multiplexed sound and moving picture sequence, comprising:

• inputting means for inputting a first coded signal through a first transmitting path at an input bit rate;
• demultiplexing means for demultiplexing said first coded signal inputted by said inputting means into one or more first data strings, one or more second data strings, and one or more third data strings, said one or more first data strings each having a number of real inputting bits;
• transforming means for transforming said one or more first data strings demultiplexed by said demultiplexing means into one or more first data strings having a number of real outputting bits less than said number of real inputting bits of said one or more first data strings, respectively;
• multiplexing means for multiplexing said one or more transformed first data strings transformed by said transforming means, said one or more second data strings demultiplexed by said demultiplexing means, and one or more corrected third data strings to generate a second coded signal;
• correcting means for-correcting said one or more third data strings demultiplexed by said demultiplexing means, on the basis of said first coded signal, in accordance with a change of said second coded signal to generate said one or more corrected third data strings having a number of real inputting bits when said one or more transformed first data strings, said one or more second data, and said one or more corrected third data strings are multiplexed by said multiplexing means;
• and
• outputting means for outputting said second coded signal through a second transmitting path at a target bit rate lower than said input bit rate of said first coded signal.

A computer program product comprising a computer usable storage medium having computer readable code embodied therein for transcoding a coded multiplexed sound and moving picture sequence, comprising:

• (a) computer readable program code for inputting a first coded signal through a first transmitting path at an input bit rate;
• (b) computer readable program code for demultiplexing said first coded signal inputted by said computer readable program code (a) into one or more first data strings, one or more second data strings, and one or more third data strings, said one or more first data strings each having a number of real inputting bits;
• (c) computer readable program code for transforming said one or more first data strings demultiplexed by said computer readable program code (b) into one or more first data strings having a number of real outputting bits less than said number of real inputting bits of said one or more first data strings, respectively;
• (d) computer readable program code for multiplexing said one or more transformed first data strings transformed by said computer readable program code (c), said one or more second data strings demultiplexed by said computer readable program code (b), and one or more corrected third data strings to generate a second coded signal;
• (e) computer readable program code for correcting said one or more third data strings demultiplexed by said computer readable program code (b), on the basis of said first coded signal, in accordance with a change of said second coded signal to generate said one or more corrected third data strings having a number of real inputting bits when said one or more transformed first data strings, said one or more second data, and said one or more corrected third data strings are multiplexed by said computer readable program code (d);
• and
• (f) computer readable program code for outputting said second coded signal through a second transmitting path at a target bit rate lower than said input bit rate of said first coded signal.