Apparatus and method for object based rate control in a coding system

Claim 9

Apparatus for encoding each frame of an image sequence, said frame having at least one object, said apparatus comprising: a motion compensator for generating a predicted image of a current frame; a transform module for applying a transformation to a difference signal between the current frame and said predicted image, where said transformation produces a plurality of coefficients; a quantizer for quantizing said plurality of coefficients with at least one quantizer scale; and a controller for selectively adjusting said at least one quantizer scale for a current frame in response to a target object bit rate for the at least one object, wherein said target object bit rate for the at least one object is selected in accordance with a mean absolute differences (Mad) of said object in accordance with: ##EQU8## where Mad i is a mean absolute difference (Mad) of an object i, n is a number of said objects in the frame, T frame is said target frame bit rate and V i is said target object bit rate for object i.

Claim 10

Apparatus for encoding each frame of an image sequence, said frame having at least one object, said apparatus comprising: a motion compensator for generating a predicted image of a current frame; a transform module for applying a transformation to a difference signal between the current frame and said predicted image, where said transformation produces a plurality of coefficients; a quantizer for quantizing said plurality of coefficients with at least one quantizer scale; and a controller for selectively adjusting said at least one quantizer scale for a current frame in response to a target object bit rate for the at least one object, wherein said target object bit rate for the at least one object is selected in accordance with a mean absolute differences (Mad) of said object in accordance with: ##EQU8## where Mad i is a mean absolute difference (Mad) of an object i, n is a number of said objects in the frame, T frame is said target frame bit rate and V i is said target object bit rate for object i.

Claim 11

The apparatus of claim 5, wherein said target object bit rate is adjusted in accordance with a measure of a buffer fullness.

Claim 12

The apparatus of claim 6, wherein said target object bit rate is adjusted in accordance with: if (buffer.sub.-- fullness+V.sub.i >margin) then V.sub.i =Max(R.sub.s /30/number.sub.-- of.sub.-- objects, margin-buffer.sub.-- fullness) where "margin" is defined as: margin=ceil((1.0-SAFETY.sub.-- MARGIN)×buffer.sub.-- fullness) where buffer -- fullness is a current buffer fullness of a buffer, where SAFTETY -- MARGIN is a constant, where R s is a bit rate, where V i is said target object bit rate for object i and where number -- of -- objects is a number of objects in the image.

Claim 13

The apparatus of claim 6, wherein said target object bit rate is adjusted in accordance with: if (buffer.sub.-- fullness-B.sub.pp +V.sub.i ≦SAFETY.sub.-- MARGIN×buffer.sub.-- size) then V.sub.i =B.sub.pp -V.sub.i -buffer.sub.-- fullness+SAFETY.sub.-- MARGIN×buffer.sub.-- size, where buffer -- fullness is a current buffer fullness of a buffer, where SAFTETY -- MARGIN is a constant, where buffer -- size is a size of said buffer, where V i is said target object bit rate for object i and B pp is a channel output rate.

Claim 14

Apparatus for encoding each frame of an image sequence, said frame having at least one object, said apparatus comprising: a motion compensator for generating a predicted image of a current frame; a transform module for applying a transformation to a difference signal between the current frame and said predicted image, where said transformation produces a plurality of coefficients; a quantizer for quantizing said plurality of coefficients with at least one quantizer scale; and a controller for selectively adjusting said at least one quantizer scale for a current frame in response to a target object bit rate for the at least one object, wherein said target object bit rate is derived from a target frame bit rate, wherein said target frame bit rate, T frame , is derived in accordance with: ##EQU9## where R is a remaining number of bits for a sequence of frames, Nf is a number of remaining frames in the sequence, T previous frame is a number of bits used for encoding a previous frame, and past -- percent is a constant.

Claim 15

Apparatus for encoding each frame of an image sequence, said frame having at least one object, said apparatus comprising: a motion compensator for generating a predicted image of a current frame; a transform module for applying a transformation to a difference signal between the current frame and said predicted image, where said transformation produces a plurality of coefficients; a quantizer for quantizing said plurality of coefficients with at least one quantizer scale; and a controller for selectively adjusting said at least one quantizer scale for a current frame in response to a target object bit rate for the at least one object, wherein said target object bit rate is derived from a target frame bit rate, wherein said target frame bit rate, T frame , is derived in accordance with: ##EQU9## where R is a remaining number of bits for a sequence of frames, Nf is a number of remaining frames in the sequence, T previous frame is a number of bits used for encoding a previous frame, and past -- percent is a constant.

Claim 16

A computer-readable medium having stored thereon a plurality of instructions, the plurality of instructions including instructions which, when executed by a processor, cause the processor to perform the steps comprising of: (a) determining a target frame bit rate for the frame; and (b) allocating said target frame bit rate among the at least one object, wherein said allocating step comprises the step of allocating said target frame bit rate in accordance with a target object bit rate for the at least one object, wherein said target object bit rate for the at least one object is selected in accordance with a mean absolute differences (Mad) of said object in accordance with: ##EQU10## where Mad i is the mean absolute difference (Mad) of an object i, n is a number of said objects in the frame, T frame is said target frame bit rate and V i is said target object bit rate for object i.

Claim 17

A computer-readable medium having stored thereon a plurality of instructions, the plurality of instructions including instructions which, when executed by a processor, cause the processor to perform the steps comprising of: (a) determining a target frame bit rate for the frame; and (b) allocating said target frame bit rate among the at least one object, wherein said allocating step comprises the step of allocating said target frame bit rate in accordance with a target object bit rate for the at least one object, wherein said target object bit rate for the at least one object is selected in accordance with a mean absolute differences (Mad) of said object in accordance with: ##EQU10## where Mad i is the mean absolute difference (Mad) of an object i, n is a number of said objects in the frame, T frame is said target frame bit rate and V i is said target object bit rate for object i.

Claim 18

A computer-readable medium having stored thereon a plurality of instructions, the plurality of instructions including instructions which, when executed by a processor, cause the processor to perform the steps comprising of: (a) determining a target frame bit rate for the frame; and (b) allocating said target frame bit rate among the at least one object, wherein said allocating step comprises the step of allocating said target frame bit rate in accordance with a target object bit rate for the at least one object, wherein said target object bit rate is adjusted in accordance with a measure of a buffer fullness in accordance with: if (buffer.sub.-- fullness+V.sub.i >margin) then V.sub.i =Max(R.sub.s /30/number.sub.-- of.sub.-- objects, margin-buffer.sub.-- fullness) where "margin" is defined as: margin=ceil((1.0-SAFETY.sub.-- MARGIN)×buffer.sub.-- fullness) where buffer fullness is a current buffer fullness of a buffer, where SAFTETY -- MARGIN is a constant, where R s is a bit rate, where V i is said target object bit rate for object i and where number of objects is a number of objects in the input image.

Claim 19

A computer-readable medium having stored thereon a plurality of instructions, the plurality of instructions including instructions which, when executed by a processor, cause the processor to perform the steps comprising of: (a) determining a target frame bit rate for the frame; and (b) allocating said target frame bit rate among the at least one object, wherein said allocating step comprises the step of allocating said target frame bit rate in accordance with a target object bit rate for the at least one object, wherein said target object bit rate is adjusted in accordance with a measure of a buffer fullness in accordance with: if (buffer.sub.-- fullness+V.sub.i >margin) then V.sub.i =Max(R.sub.s /30/number.sub.-- of.sub.-- objects, margin-buffer.sub.-- fullness) where "margin" is defined as: margin=ceil((1.0-SAFETY.sub.-- MARGIN)×buffer.sub.-- fullness) where buffer fullness is a current buffer fullness of a buffer, where SAFTETY -- MARGIN is a constant, where R s is a bit rate, where V i is said target object bit rate for object i and where number of objects is a number of objects in the input image.

Claim 20

A computer-readable medium having stored thereon a plurality of instructions, the plurality of instructions including instructions which, when executed by a processor, cause the processor to perform the steps comprising of: (a) determining a target frame bit rate for the frame; and (b) allocating said target frame bit rate among the at least one object, wherein said allocating step comprises the step of allocating said target frame bit rate in accordance with a target object bit rate for the at least one object, wherein said target object bit rate is adjusted in accordance with a measure of a buffer fullness in accordance with: if (buffer.sub.-- fullness-B.sub.pp +V.sub.i ≦SAFETY.sub.-- MARGIN×buffer.sub.-- size) then V.sub.i =B.sub.pp -V.sub.i -buffer.sub.-- fullness+SAFETY.sub.-- MARGIN×buffer.sub.-- size, where buffer fullness is a current buffer fullness of a buffer, where SAFTETY -- MARGIN is a constant, where buffer size is a size of said buffer, where V i is said target object bit rate for object i and B pp is a channel output rate.

Claim 21

A computer-readable medium having stored thereon a plurality of instructions, the plurality of instructions including instructions which, when executed by a processor, cause the processor to perform the steps comprising of: (a) determining a target frame bit rate for the frame; and (b) allocating said target frame bit rate among the at least one object, wherein said allocating step comprises the step of allocating said target frame bit rate in accordance with a target object bit rate for the at least one object, wherein said target object bit rate is adjusted in accordance with a measure of a buffer fullness in accordance with: if (buffer.sub.-- fullness-B.sub.pp +V.sub.i ≦SAFETY.sub.-- MARGIN×buffer.sub.-- size) then V.sub.i =B.sub.pp -V.sub.i -buffer.sub.-- fullness+SAFETY.sub.-- MARGIN×buffer.sub.-- size, where buffer fullness is a current buffer fullness of a buffer, where SAFTETY -- MARGIN is a constant, where buffer size is a size of said buffer, where V i is said target object bit rate for object i and B pp is a channel output rate.

Claim 22

A computer-readable medium having stored thereon a plurality of instructions, the plurality of instructions including instructions which, when executed by a processor, cause the processor to perform the steps comprising of: (a) determining a target frame bit rate for the frame, wherein said target frame bit rate T frame , is derived in accordance with: ##EQU11## where R is a remaining number of bits for the image sequence, Nf is a number of remaining frames in the image sequence, T previous frame is a number of bits used for encoding a previous frame, and past percent is a constant; and (b) allocating said target frame bit rate among the at least one object.

Claim 23

A computer-readable medium having stored thereon a plurality of instructions, the plurality of instructions including instructions which, when executed by a processor, cause the processor to perform the steps comprising of: (a) determining a target frame bit rate for the frame, wherein said target frame bit rate T frame , is derived in accordance with: ##EQU11## where R is a remaining number of bits for the image sequence, Nf is a number of remaining frames in the image sequence, T previous frame is a number of bits used for encoding a previous frame, and past percent is a constant; and (b) allocating said target frame bit rate among the at least one object.