US 6,587,508 B1Granted

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

AssigneesMedia Glue Corporation, Hideyoshi Tominaga

InventorsTsuyoshi Hanamura, Hiroyuki Kasai, Satoshi Nishimura, Hideyoshi Tominaga

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Abstract

An apparatus for transcoding a coded moving picture sequence according to the present invention comprises a rate controller for adapting the scaling factor to perform the rate control over the coded moving picture sequence signal having a desired target bit rate. The rate controller of the apparatus has: a remaining bit computing unit for computing: a remaining number of inputting bits Rin(n) for each of the pictures in the first coded moving picture sequence signal on the basis of the number of real inputting bits Sin(n) of the current picture and the estimated number of inputting bits; and a remaining number of outputting bits Rout(n) for each of the pictures in the second coded moving picture sequence signal on the basis of the number of real outputting bits Sout(n) of the current picture and the estimated number of outputting bits; a target ratio computing unit for computing, for each of the pictures, a target ratio of the remaining number of outputting bits Rout(n) to the remaining number of inputting bits of the picture Rin(n); and a scaling factor computing unit for computing the scaling factor on the basis of the target ratio to control the target bit rate of the second coded moving picture sequence signal.

Claims15

Dependent claims

A method of transcoding a coded moving picture sequence, comprising the steps of:

(a) inputting a first coded moving picture sequence signal at an input bit rate, said first coded moving picture sequence signal consisting of a series of pictures;
(b) computing an estimated number of inputting bits to be input in said inputting step (a) for a predetermined duration on the basis of said input bit rate of said first coded moving picture sequence signal;
(c) decoding said first coded moving picture sequence signal inputted in said inputting step (a) to reconstruct an original picture data, for each of said pictures, having a number of real inputting bits;
(d) computing, for each of said pictures, a remaining number of inputting bits after a previous picture in said first coded moving picture sequence signal is decoded in said decoding step (c) on the basis of said number of real inputting bits of said previous picture and said estimated number of inputting bits obtained in said computing step (b);
(e) transforming, on the basis of a scaling factor, said original picture data reconstructed in said decoding step (c) for each of said pictures into an objective picture data having a number of real outputting bits less than said number of real inputting bits of said original picture data;
(f) encoding said objective picture data obtained in said transforming step (e) to generate a second coded moving picture sequence signal;
(g) outputting said second coded moving picture sequence signal generated in said encoding step (f) at a target bit rate lower than said input bit rate of said first coded moving picture sequence signal;
(h) computing an estimated number of outputting bits to be output in said outputting step (g) for said predetermined duration on the basis of said target bit rate of said second coded moving picture sequence signal;
(i) computing, for each of said pictures, a remaining number of outputting bits after a previous picture in said second coded moving picture sequence signal is encoded in said encoding step (f) on the basis of said number of real outputting bits of said previous picture and said estimated number of outputting bits obtained in said computing step (h);
(j) computing, for each of said pictures, a target ratio of said remaining number of outputting bits computed in said computing step (i) to said remaining number of inputting bits computed in said computing step (d) before the original picture data is transformed in said transforming step (e);
and
(k) computing said scaling factor on the basis of said target ratio computed in said target ratio computing step (j) to control said target bit rate of said second coded moving picture sequence signal.

9 more elements

An apparatus for transcoding a coded moving picture sequence, interposed between a first transmitting path and a second transmitting path, comprising:

inputting means for inputting a first coded moving picture sequence signal through said first transmitting path at an input bit rate, said first coded moving picture sequence signal consisting of a series of pictures;
decoding means for decoding said first coded moving picture sequence signal inputted through said inputting means to reconstruct an original picture data, for each of said pictures, having a number of real inputting bits;
transforming means for transforming, on the basis of a scaling factor, said original picture data reconstructed by said decoding means for each of said pictures into an objective picture data having a number of real outputting bits less than said number of real inputting bits of said original picture data;
encoding means for encoding said objective picture data obtained by said transforming means to generate a second coded moving picture sequence signal;
outputting means for outputting said second coded moving picture sequence signal generated by said encoding means through said second transmitting path at a target bit rate lower than said input bit rate of said first coded moving picture sequence signal;
and
rate controlling means for controlling said target bit rate of said second coded moving picture sequence signal, having:
(a) a remaining bit computing unit for computing:
an estimated number of inputting bits to be input through said inputting means for a predetermined duration on the basis of said input bit rate of said first coded moving picture sequence signal;
a remaining number of inputting bits for each of said pictures in said first coded moving picture sequence signal on the basis of said number of real inputting bits of a current picture and said estimated number of inputting bits;
an estimated number of outputting bits to be output through said outputting means for said predetermined duration on the basis of said target bit rate of said second coded moving picture sequence signal;
and
a remaining number of outputting bits for each of said pictures in said second coded moving picture sequence signal on the basis of said number of real outputting bits of a current picture and said estimated number of outputting bits;
(b) a target ratio computing unit for computing, for each of the pictures, a target ratio of the remaining number of outputting bits computed by the remaining bit computing unit to the remaining number of inputting bits of the picture computed by the remaining bit computing unit;
and
(c) a scaling factor computing unit for computing the scaling factor on the basis of the target ratio computed by the target ratio computing unit to control the target bit rate of the second coded moving picture sequence signal.

13 more elements

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

(a) computer readable program code for inputting a first coded moving picture sequence signal at an input bit rate, said first coded moving picture sequence signal consisting of a series of pictures;
(b) computer readable program code for computing an estimated number of inputting bits to be input by said computer readable program code (a) for a predetermined duration on the basis of said input bit rate of said first coded moving picture sequence signal;
(c) computer readable program code for decoding said first coded moving picture sequence signal inputted by said computer readable program code (a) to reconstruct an original picture data, for each of said pictures, having a number of real inputting bits;
(d) computer readable program code for computing, for each of said pictures, a remaining number of inputting bits after a previous picture in said first coded moving picture sequence signal is decoded by said computer readable program code (c) on the basis of said number of real inputting bits of said previous picture and said estimated number of inputting bits obtained by said computer readable program code (b);
(e) computer readable program code for transforming, on the basis of a scaling factor, said original picture data reconstructed by said computer readable program code (c) for each of said pictures into an objective picture data having a number of real outputting bits less than said number of real inputting bits of said original picture data;
(f) computer readable program code for encoding said objective picture data obtained by said computer readable program code (e) to generate a second coded moving picture sequence signal;
(g) computer readable program code for outputting said second coded moving picture sequence signal generated by said computer readable program code (f) at a target bit rate lower than said input bit rate of said first coded moving picture sequence signal;
(h) computer readable program code for computing an estimated number of outputting bits to be output by said computer readable program code (g) for said predetermined duration on the basis of said target bit rate of said second coded moving picture sequence signal;
(i) computer readable program code for computing, for each of said pictures, a remaining number of outputting bits after a previous picture in said second coded moving picture sequence signal is encoded by said computer readable program code (f) on the basis of said number of real outputting bits of said previous picture and said estimated number of outputting bits obtained by said computer readable program code (h);
(j) computer readable program code for computing, for each of said pictures, a target ratio of said remaining number of outputting bits computed by said computer readable program code (i) to said remaining number of inputting bits computed by said computer readable program code (d) before the original picture data is transformed by said computer readable program code (e);
and
(k) computer readable program code for computing said scaling factor on the basis of said target ratio computed by said computer readable program code (j) to control said target bit rate of said second coded moving picture sequence signal.

9 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/604,973Filed 28 Jun 2000
Priority: JP 11-18645730 Jun 1999
Granted: 1 Jul 2003
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

H04N 19/40
Methods or arrangements for coding, decoding, compressing or decompressing digital video signals: using video transcoding, i.e. partial or full…
H04N 19/124
Characterised by the element, parameter or selection affected or controlled by the adaptive coding: quantisation
H04N 19/149
Data rate or code amount at the encoder output: by estimating the code amount by means of a model, e.g. mathematical model or statistical model
H04N 19/152
Data rate or code amount at the encoder output: by measuring the fullness of the transmission buffer