US 8,014,447 B2Granted

Process and arrangement for encoding video pictures

AssigneeThomson Licensing

InventorsTobias Hinz, Heiko Schwarz, Thomas Wiegand

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Abstract

Today's video codecs require the intelligent choice between many coding options. This choice can efficiently be done using Lagrangian coder control. But Lagrangian coder control only provides results given a particular Lagrange parameter, which correspond to some unknown transmission rate. On the other hand, rate control algorithms provide coding results at a given bitrate but without the optimization performance of Lagrangian coder control. The combination of rate control and Lagrangian optimization for hybrid video coding is investigated. A new approach is suggested to incorporate these two known methods into the video coder control using macroblock mode decision and quantizer adaptation. The rate-distortion performance of the proposed approach is validated and analyzed via experimental results. It is shown that for most bit-rates the combined rate control and Lagrangian optimization producing a constant number of bits per picture achieves similar rate distortion performance as the constant slope case only using Lagrangian optimization.

Claims12

Dependent claims

Process for encoding video pictures in a video coder,

wherein
a pre-analysis of pictures is carried out, wherein for at least a part of macroblocks at least one control-parameter which assists the encoding process is determined based on at least one estimated parameter,
in a second step the picture is encoded on macroblock level with encoding-parameters calculated based on the control-parameters determined in the pre-analysis step, wherein the macroblock encoding process comprises the following steps given a target quantization parameter QPi*:
calculating Lagrangian multipliers used for motion estimation and mode decision of a macroblock i according to:
(λmotion,i)2=λmode,i=0.85·QPi*2 for H.263,MPEG-4, or
(λmotion,i)2=λmode,i=0.85·2^((QP*i−12)/3)for H.264/AVC,
for all motion-compensated macroblock/block modes determining associated motion vectors mi and a reference index ri by minimizing a Lagrangian functional
[
m
i
,
r
i
]
=
arg
⁢
⁢
min
m
⁢
∈
⁢
M
,
r
⁢
∈
⁢
R
⁢
{
D
DFD
⁡
(
i
,
m
,
r
)
+
λ
motion
,
i
·
R
MV
⁡
(
i
,
m
,
r
)
}
,
with a distortion term being given as
D
DFD
⁡
(
i
,
m
,
r
)
=
∑
(
x
,
y
)
∈
⁢
B
i
⁢
⁢

s
⁡
(
x
,
y
,
t
)
-
s
′
⁡
(
x
-
m
x
,
y
-
m
y
,
t
r
)

,
where s( . . . , t) and s′( . . . , tr) represent an array of luminance samples of an original picture and a decoded reference picture given by a reference index r, respectively,
R denotes a set of reference pictures stored in the decoded picture buffer,
M specifies a motion vectors search range inside a reference picture,
tr is a sampling time of a reference picture referred by the reference index r,
B is the area of a corresponding block or macroblock, and
RMV(i,m,r) specifies a number of bits needed to transmit all components of a motion vector m=[mx,my]T as well as the reference index r;
determining macroblock/block encoding modes pi of a macroblock i by minimizing a Lagrangian cost function
p
i
=
arg
⁢
⁢
min
p
⁢
∈
⁢
S
mod
⁢
⁢
e
⁢
{
D
REC
⁡
(
i
,
p
❘
QP
i
*
)
+
λ
mod
⁢
⁢
e
·
R
all
⁡
(
i
,
p
❘
QP
i
*
)
}
where DREC(i,p|QPi*) is defined as
D
REC
⁡
(
i
,
p
❘
QP
i
*
)
=
∑
(
x
,
y
)
⁢
∈
⁢
B
⁢
⁢
(
s
⁡
(
x
,
y
)
-
s
′
⁡
(
x
,
y
❘
p
,
QP
i
*
)
)
2
s( . . . ) and s′( . . . ) represent an array of original macroblock samples and their reconstruction, respectively,
B specifies a set of corresponding macroblock/block samples,
Rall(i,p|QPi*) is a number of bits associated with choosing a mode p and quantization parameter QPi*, including bits for the macroblock/block modes, motion vectors and reference indices as well as quantized transform coefficients of all luminance and chrominance blocks, and
Smode is a given set of possible macroblock/block modes.

223 more elements

Arrangement with at least one chip and/or processor that is (are) installed in such a manner, that a process for encoding video pictures can be executed in a manner so that a pre-analysis of pictures is carried out, wherein for at least a part of macroblocks at least one control-parameter which assists the encoding process is determined based on at least one estimated parameter,

in a second step the picture is encoded with encoding-parameters calculated based on the control-parameters determined in the pre-analysis step wherein the macroblock encoding process comprises the following steps given a target quantization parameter QPi*:
calculating Lagrangian multipliers used for motion estimation and mode decision of a macroblock i according to:
(λmotion,i)2=λmode,i=0.85·QPi*2 for H.263,MPEG-4, or
(λmotion,i)2=λmode,i=0.85·2^((QP*i−12)/3)for H.264/AVC,
for all motion-compensated macroblock/block modes determining associated motion vectors mi and a reference index ri by minimizing a Lagrangian functional
[
m
i
,
r
i
]
=
arg
⁢
⁢
min
m
∈
M
,
r
∈
R
⁢
{
D
DFD
⁡
(
i
,
m
,
r
)
+
λ
motion
,
i
·
R
MV
⁡
(
i
,
m
,
r
)
}
,
with a distortion term being given as
D
DFD
⁡
(
i
,
m
,
r
)
=
∑
(
x
,
y
)
∈
B
i
⁢
⁢

s
⁡
(
x
,
y
,
t
)
-
s
′
⁡
(
x
-
m
x
,
y
-
m
y
,
t
r
)

,
where s( . . . , t) and s′( . . . , tr) an array of luminance samples of an original picture and a decoded reference picture given by a reference index r, respectively,
R denotes a set of reference pictures stored in the decoded picture buffer,
M specifies a motion vectors search range inside a reference picture,
tr is a sampling time of a reference picture referred by the reference index r,
B is the area of a corresponding block or macroblock, and
RMV(i,m,r) specifies a number of bits needed to transmit all components of a motion vector m=[mx,my]T as well as the reference index r;
determining macroblock/block encoding modes pi of a macroblock i by minimizing a Lagrangian cost function
p
i
=
arg
⁢
⁢
min
p
∈
S
mod
⁢
⁢
e
⁢
{
D
REC
⁡
(
i
,
p
|
QP
i
*
)
+
λ
mod
⁢
⁢
e
·
R
all
⁡
(
i
,
p
|
QP
i
*
)
}
where DREC(i,p|QPi*) is defined as
D
REC
⁡
(
i
,
p
|
QP
i
*
)
=
∑
(
x
,
y
)
∈
B
⁢
⁢
(
s
⁡
(
x
,
y
)
-
s
′
⁡
(
x
,
y
|
p
,
QP
i
*
)
)
2
s( . . . ) and s′( . . . ) represent an array of original macroblock samples and their reconstruction, respectively,
B specifies a set of corresponding macroblock/block samples,
Rall(i,p|QPi*) is a number of bits associated with choosing a mode p and quantization parameter QPi*, including bits for the macroblock/block modes, motion vectors and reference indices as well as quantized transform coefficients of all luminance and chrominance blocks, and
Smode is a given set of possible macroblock/block modes.

212 more elements

Computer program embodied on a non-transitory computer readable storage medium within a computer that enables the computer to run a process for encoding video pictures, where a pre-analysis of pictures is carried out, wherein for at least a part of macroblocks at least one control-parameter which assists the encoding process is determined based on at least one estimated parameter,

in a second step the picture is encoded with encoding-parameters calculated based on the control-parameters determined in the pre-analysis step wherein the macroblock encoding process comprises the following steps given a target quantization parameter QPi*:
calculating Lagrangian multipliers used for motion estimation and mode decision of a macroblock i according to:
(λmotion,i)2=λmode,i=0.85·QPi*2 for H.263,MPEG-4, or
(λmotion,i)2=λmode,i=0.85·2^((QP*i−12)/3)for H.264/AVC,
for all motion-compensated macroblock/block modes determining associated motion vectors mi and a reference index ri by minimizing a Lagrangian functional
[
m
i
,
r
i
]
=
arg
⁢
⁢
min
m
⁢
∈
⁢
M
,
r
⁢
∈
⁢
R
⁢
{
D
DFD
⁡
(
i
,
m
,
r
)
+
λ
motion
,
i
·
R
MV
⁡
(
i
,
m
,
r
)
}
,
with a distortion term being given as
D
DFD
⁡
(
i
,
m
,
r
)
=
∑
(
x
,
y
)
⁢
∈
⁢
B
i
⁢
⁢

s
⁡
(
x
,
y
,
t
)
-
s
′
⁡
(
x
-
m
x
,
y
-
m
y
,
t
r
)

,
where s( . . . , t) and s′( . . . , tr)represent an array of luminance samples of an original picture and a decoded reference picture given by a reference index r, respectively,
R denotes a set of reference pictures stored in the decoded picture buffer,
M specifies a motion vectors search range inside a reference picture,
tr is a sampling time of a reference picture referred by the reference index r,
B is the area of a corresponding block or macroblock, and
RMV(i,m,r) specifies a number of bits needed to transmit all components of a motion vector m=[mx,my]T as well as the reference index r;
determining macroblock/block encoding modes pi of a macroblock i by minimizing a Lagrangian cost function
p
i
=
arg
⁢
⁢
min
p
⁢
∈
⁢
S
mod
⁢
⁢
e
⁢
{
D
REC
⁡
(
i
,
p
❘
QP
i
*
)
+
λ
mod
⁢
⁢
e
·
R
all
⁡
(
i
,
p
❘
QP
i
*
)
}
where DREC(i,p|QPi*) is defined as
D
REC
⁡
(
i
,
p
❘
QP
i
*
)
=
∑
(
x
,
y
)
∈
⁢
B
⁢
⁢
(
s
⁡
(
x
,
y
)
-
s
′
⁡
(
x
,
y
❘
p
,
QP
i
*
)
)
2
s( . . . ) and s′( . . . ) represent an array of original macroblock samples and their reconstruction, respectively,
B specifies a set of corresponding macroblock/block samples,
Rall(i,p|QPi*) is a number of bits associated with choosing a mode p and quantization parameter QPi*, including bits for the macroblock/block modes, motion vectors and reference indices as well as quantized transform coefficients of all luminance and chrominance blocks, and
Smode is a given set of possible macroblock/block modes.

221 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/570,092Filed 23 Aug 2004
Priority: EP 030902823 Sep 2003
Published: US 2008/0298464 A14 Dec 2008
Granted: 6 Sep 2011
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

H04N 19/19
Characterised by the adaptation method, adaptation tool or adaptation type used for the adaptive coding: using optimisation based on Lagrange…
H04N 19/103
Characterised by the element, parameter or selection affected or controlled by the adaptive coding: selection of coding mode or of prediction mode
H04N 19/126
Quantisation: details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers
H04N 19/147
Data rate or code amount at the encoder output: according to rate distortion criteria