WO1995021503A1 - Video motion estimation - Google Patents
Video motion estimation Download PDFInfo
- Publication number
- WO1995021503A1 WO1995021503A1 PCT/GB1995/000207 GB9500207W WO9521503A1 WO 1995021503 A1 WO1995021503 A1 WO 1995021503A1 GB 9500207 W GB9500207 W GB 9500207W WO 9521503 A1 WO9521503 A1 WO 9521503A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- motion
- motion vectors
- field
- vectors
- sequence
- Prior art date
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
- H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
- H04N19/503—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving temporal prediction
- H04N19/51—Motion estimation or motion compensation
- H04N19/577—Motion compensation with bidirectional frame interpolation, i.e. using B-pictures
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/14—Picture signal circuitry for video frequency region
- H04N5/144—Movement detection
- H04N5/145—Movement estimation
Definitions
- This invention relates to video motion estimation of the type which can be used in a video coder for reducing the bit rate of a digital video signal such as may be required for storage on digital storage media or for broadcast.
- MPEG-l is now an international standard and is specified in ISO/IEC document IS 11172 parts 1,2 and 3.
- ISO/IEC document IS 11172 parts 1,2 and 3 A description of the MPEG-l video compression algorithm can be found in Communications of the ACM April 1991, Vol.34, No. 4 MPEG-2 is a substantial extension of MPEG-l and is due for publication as an international standard in 1995.
- Intra pictures are coded without reference to other pictures. They serve as access points to the coded video sequence where decoding can begin.
- Predicted pictures are coded with reference to a motion compensated prediction derived from a previous I or P picture. Coding of P pictures is more efficient than for I pictures.
- Bi-directionally predicted pictures are coded with reference to a forward motion compensated prediction from a previous I or P picture and a backward motion compensated prediction from a future I or P picture and provide the greatest degree of compression.
- FIG. 1 A typical sequence of I, P and B pictures is illustrated in Figure 1.
- frame II is an I picture
- frames P4 and P7 are P pictures
- frames B2, B3, B5, B6, B8 and B9 are B pictures.
- Frame P4 is coded with reference to a forward prediction derived from frame II.
- Frame P7 is coded with reference to a forward prediction derived from frame P4.
- Frames B2 and B3 are coded with reference to a forward prediction derived from frame 11 and a backward prediction derived from frame P4.
- Frames B5 and B6 are coded with reference to a forward prediction derived from frame P4 and a backward prediction derived from frame P7.
- Frames B8 and B9 are coded with reference to a forward prediction derived from frame P7 and a backward prediction derived from frame 110.
- a video coder When a video coder is implemented in hardware, a large part of its circuitry is devoted to the measurement of motion vectors in order to generate the required motion compensated predictions.
- B pictures two simultaneous motion measurements are required in order to generate both the forward and backward predictions.
- MPEG-2 algorithm twice as many motion measurements are required as both 'frame' and 'field' versions of each motion vector are needed.
- FIG. 1 shows the sequence of I, B, and P frames described above,-
- Figure 2 shows a conventional motion estimator arrangement required to produce vectors defining the sequence of frames shown in Figure 1; and Figure 3 shows a motion estimator embodying the inventio
- the sequence may be split into "triples" of ⁇ BBP ⁇ or (less often) ⁇ BBl ⁇ , i.e. two interpolated and one reference picture.
- a coder's motion estimator For each ⁇ BBP ⁇ triple, a coder's motion estimator must generate five motion vectors. For example, in the case of the triple ⁇ B12, B13, P14 ⁇ the five required motion vectors are:
- a coder's motion estimator For each ⁇ BBl ⁇ triple a coder's motion estimator must generate four motion vectors. For example, in the case of the triple ⁇ B15, B16, 117 ⁇ the four required motion vectors are:
- the architecture which is generally proposed to generate these motion vectors is based around two motion estimators as shown in Figure 2. This comprises a forward motion estimator 2 receiving a previous reference picture and the current picture and producing forward motion vectors and a backward motion vector estimator 4 receiving a future reference picture and the current picture and producing backward motion vectors . These are the vectors referred to above.
- Table 1 shown below describes the passage of the sequence, B12, B13 , P14, B15, B16, 117, through the motion estimators. It will be seen that the sequence of the pictures is re-ordered to P14, B12, B13 , 117, B15, B16, prior to input to the motion estimators in accordance with the MPEG algorithm.
- Each column of the table represents an instant in time. For example, the first column means, "when P14 is on the current picture input, Pll is applied to the previous reference picture input and the forward motion vector output generates the motion vector Pll to P14".
- the table demonstrates how the two motion estimators of Figure 1 can together generate the required five motion vectors for each ⁇ BBP ⁇ triple and the required four motion vectors for each ⁇ BBl ⁇ triple.
- the required motion vectors for the ⁇ BBP ⁇ triple are (Pll to P14) , (Pll to B12) , (Pll to B13), (P14 to B12) and (P14 to B13) .
- the motion estimator has generated the first three of these.
- the missing two motion vectors may be calculated using additional vector processing as follows :
- the required motion vectors for the (BBl) triple are (P14 to B15), (P14 to B16) , (117 to B15) and (117 to B16) .
- the motion estimator has generated the first two of these as well as the vector (P17 to 117) .
- the missing two motions vectors may be calculated as follows :
- the forward motion estimator may identify a number of motion vectors that will yield equally good predictions even though they need not represent the actual motion of the object. If the forward motion vector is incorrect, the derived backward motion vector may yield a poor prediction. (It should be noted that if a prediction resulting from a backward motion vector is poor, the coder will simply choose some other prediction mode for that particular macroblock and the erroneous backward motion vector will go unnoticed) .
- the additional vector processing required to generate all forward and backward vectors using a single vector estimator could be implemented in hardware using vector adders and/or subtractors and some suitable storage and switching arrangement to supply the vectors to the adders at the correct times. Alternatively the processing could be carried out in software.
- the current MPEG-2 test model details a further improved bit-rate reduction standard comprising field and frame motion vectors.
- the idea is as follows.
- MPEG-2 defines a macroblock as covering an area of picture 16 pixels by 16 frame lines, 8 lines originating from the odd field and the other 8 lines originating from the even field.
- the job of a coder's prediction generator stage is to generate "predictions" of the macroblocks comprising the current frame. If the image is moving then these predictions will generally be realised by motion compensating (i.e. assigning one or more motion vectors to each macroblock of a reference frame.
- the motion estimators (of the type referred to above) generate both 'field' and 'frame' motion vectors in order to derive two predictions of each macroblock in the current frame:- one based on the field motion vectors, the other based on the frame motion vector.
- the coder chooses the prediction which most closely matches the actual macroblock of the current frame.
- a macroblock is treated as a single 16 x 16 block of a frame.
- a single "frame" motion vector is assigned to describe how a prediction of the macroblock may be generated by motion compensating a 16 x 16 pixel area of a reference frame.
- two "field" motion vectors are used to independently generate predictions of the odd field and even field components of a macroblock. i.e. One field motion vector is used to predict the 8 odd lines of the macroblock from the odd field of a reference picture and the other field motion vector is used to predict the 8 even field lines from the even field of a reference picture.
- the motion vectors are used to generate two predictions of a macroblock from the current picture, one generated using the frame motion vector, the other generated using the two field motion vectors. It is then the job of the coder's "decision module" to decide which is the better prediction.
- a frame motion vector may be derived instead by averaging the two field motion vectors. If the two field motion vectors match, then the frame motion vector will have the same value resulting in similar frame and field based predictions, however, if the two field motion vectors are different, the frame motion vector is likely to be incorrect and the field based prediction is likely to be best.
- the vector generation is explained in more detail below.
- Motion occurring in the odd and even fields of a previous frame is independently measured and used to generate predictions of the add and even fields of a future frame, i.e. the odd field of the future frame is predicted from the odd field of the previous frame and correspondingly with the even field. This one prediction of a single future frame comprising odd and even fields has been generated.
- the vectors measured in the odd field are averaged with those in the even field to give a set of frame motion vectors.
- a further prediction of the future frame may now be generated by motion compensating the previous frame with the set of frame motion vectors.
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- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Compression Or Coding Systems Of Tv Signals (AREA)
- Image Analysis (AREA)
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP7520453A JPH09509799A (en) | 1994-02-02 | 1995-02-02 | Video motion estimation |
GB9616294A GB2301255B (en) | 1994-02-02 | 1995-02-02 | Video motion estimation |
EP95907091A EP0742983A1 (en) | 1994-02-02 | 1995-02-02 | Video motion estimation |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9401989A GB9401989D0 (en) | 1994-02-02 | 1994-02-02 | Video motion estimation |
GB9401989.0 | 1994-02-02 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1995021503A1 true WO1995021503A1 (en) | 1995-08-10 |
Family
ID=10749737
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB1995/000207 WO1995021503A1 (en) | 1994-02-02 | 1995-02-02 | Video motion estimation |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0742983A1 (en) |
JP (1) | JPH09509799A (en) |
GB (2) | GB9401989D0 (en) |
WO (1) | WO1995021503A1 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2809572A1 (en) * | 2000-05-29 | 2001-11-30 | Cit Alcatel | VIDEO SOURCE CODING WITH MOTION PREDICTION AND BLOCK EFFECT FILTERING |
DE10225434A1 (en) * | 2002-06-07 | 2004-01-08 | Siemens Ag | Video coding method and apparatus |
EP1490982A2 (en) * | 2002-03-29 | 2004-12-29 | SONY ELECTRONICS INC. (a Delaware corporation) | Method of estimating backward motion vectors within a video sequence |
WO2005027520A1 (en) * | 2003-09-12 | 2005-03-24 | Institute Of Computing Technology Chinese Academy Of Sciences | Bi-directional predicting method for video coding/decoding |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0424026A2 (en) * | 1989-10-14 | 1991-04-24 | Sony Corporation | Video signal transmitting system |
US5049991A (en) * | 1989-02-20 | 1991-09-17 | Victor Company Of Japan, Ltd. | Movement compensation predictive coding/decoding method |
EP0534350A2 (en) * | 1991-09-23 | 1993-03-31 | Matsushita Electric Industrial Co., Ltd. | Derivation and use of motion vectors in a differential pulse code modulation system |
EP0541389A2 (en) * | 1991-11-08 | 1993-05-12 | Matsushita Electric Industrial Co., Ltd. | Method for predicting move compensation |
-
1994
- 1994-02-02 GB GB9401989A patent/GB9401989D0/en active Pending
-
1995
- 1995-02-02 EP EP95907091A patent/EP0742983A1/en not_active Ceased
- 1995-02-02 JP JP7520453A patent/JPH09509799A/en active Pending
- 1995-02-02 WO PCT/GB1995/000207 patent/WO1995021503A1/en not_active Application Discontinuation
- 1995-02-02 GB GB9616294A patent/GB2301255B/en not_active Expired - Fee Related
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5049991A (en) * | 1989-02-20 | 1991-09-17 | Victor Company Of Japan, Ltd. | Movement compensation predictive coding/decoding method |
EP0424026A2 (en) * | 1989-10-14 | 1991-04-24 | Sony Corporation | Video signal transmitting system |
EP0534350A2 (en) * | 1991-09-23 | 1993-03-31 | Matsushita Electric Industrial Co., Ltd. | Derivation and use of motion vectors in a differential pulse code modulation system |
EP0541389A2 (en) * | 1991-11-08 | 1993-05-12 | Matsushita Electric Industrial Co., Ltd. | Method for predicting move compensation |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2809572A1 (en) * | 2000-05-29 | 2001-11-30 | Cit Alcatel | VIDEO SOURCE CODING WITH MOTION PREDICTION AND BLOCK EFFECT FILTERING |
EP1161101A1 (en) * | 2000-05-29 | 2001-12-05 | Alcatel | Videocoding using motion prediction and filtering for block effect reduction |
EP1490982A2 (en) * | 2002-03-29 | 2004-12-29 | SONY ELECTRONICS INC. (a Delaware corporation) | Method of estimating backward motion vectors within a video sequence |
EP1490982A4 (en) * | 2002-03-29 | 2010-12-22 | Sony Electronics Inc | Method of estimating backward motion vectors within a video sequence |
DE10225434A1 (en) * | 2002-06-07 | 2004-01-08 | Siemens Ag | Video coding method and apparatus |
DE10225434B4 (en) * | 2002-06-07 | 2004-12-30 | Siemens Ag | Video coding method and apparatus |
US7580458B2 (en) | 2002-06-07 | 2009-08-25 | Siemens Aktiengesellschaft | Method and apparatus for video coding |
US8111748B2 (en) | 2002-06-07 | 2012-02-07 | Siemens Aktiengesellschaft | Method and apparatus for video coding |
WO2005027520A1 (en) * | 2003-09-12 | 2005-03-24 | Institute Of Computing Technology Chinese Academy Of Sciences | Bi-directional predicting method for video coding/decoding |
Also Published As
Publication number | Publication date |
---|---|
GB2301255B (en) | 1998-08-26 |
GB9401989D0 (en) | 1994-03-30 |
JPH09509799A (en) | 1997-09-30 |
GB2301255A (en) | 1996-11-27 |
GB9616294D0 (en) | 1996-09-11 |
EP0742983A1 (en) | 1996-11-20 |
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