EP1812903A1 - Procede de codage d'images codees par ondelettes a controle de debit, dispositif de codage et programme d'ordinateur correspondants - Google Patents
Procede de codage d'images codees par ondelettes a controle de debit, dispositif de codage et programme d'ordinateur correspondantsInfo
- Publication number
- EP1812903A1 EP1812903A1 EP05801394A EP05801394A EP1812903A1 EP 1812903 A1 EP1812903 A1 EP 1812903A1 EP 05801394 A EP05801394 A EP 05801394A EP 05801394 A EP05801394 A EP 05801394A EP 1812903 A1 EP1812903 A1 EP 1812903A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- rate
- wavelet coefficients
- coding
- mesh
- coefficients
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T9/00—Image coding
- G06T9/007—Transform coding, e.g. discrete cosine transform
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T9/00—Image coding
- G06T9/001—Model-based coding, e.g. wire frame
-
- 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
- H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
- H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
- H04N19/146—Data rate or code amount at the encoder output
- H04N19/147—Data rate or code amount at the encoder output according to rate distortion criteria
Definitions
- the field of the invention is that of the encoding of video sequences, with a view to their transmission, by means of wireless or wireless communication networks, such as the Internet, mobile radio networks or terrestrial television broadcasting networks.
- wireless or wireless communication networks such as the Internet, mobile radio networks or terrestrial television broadcasting networks.
- DVB-T type for example, or from recording media such as DVDs, CD-ROMs, floppy disks, etc.
- the invention also applies to the storage of video sequences on such media, or more generally on data servers.
- the invention relates to controlling the bit rate of such video sequences.
- each image composing the video sequence is represented by a mesh.
- this mesh is decomposed into a second generation wavelet base, making it possible to reduce the visual information into a basic mesh and a series of wavelet coefficients. These coefficients can represent spatial information as well as temporal evolutions.
- the first technique aims to converge accurately to the target rate, and will be used in particular for still images.
- the rate can be adapted, for example depending on the complexity of the image to be processed.
- the invention falls within this framework.
- the object of the invention is to overcome these disadvantages of the prior art, and to propose a method of controlling the rate and distortion well adapted to mesh and wavelet coding.
- Another object of the invention is to provide such a technique, which is simple to implement, and which does not require special adaptation of the prior coding, as described for example in the aforementioned document.
- an object of the invention is to provide a technique for controlling the final flow rate by the user while optimizing the final visual distortion.
- this method implements an encoded data rate control, according to the following steps:
- control of a second data rate representative of wavelet coefficients according to a second flow criterion final optimization of the bit rate of the coded data, by checking quantization characteristics of said selected wavelet coefficients.
- the flow control is performed at a double level (basic mesh and wavelet coefficients, which optimizes the rate-distortion ratio.
- said coded data rate control implements the following steps:
- the ratio between said target bit rate and said intermediate bit rate may be between 10 and 50. It may in particular be worth
- a user can set at least one of the following aspects:
- - coding mode namely constant bit rate coding or variable bit rate coding. This allows the user (coding side and / or decoding side) to choose the processing parameters, according to characteristics related to the needs and / or available resources.
- said quantization step comprises the following substeps:
- the optimization thus relates not only to the bit rate of the wavelet coefficients, but also to their selection, in order to deal in priority with the most significant ones.
- the bit rate of the coded data is variable, as a function of information representative of the complexity of an image to be coded.
- This embodiment is of course intended for image sequences. It is also possible that the final flow is fixed and imposed.
- said final compression coding comprises entropic coding. This technique makes it possible to obtain a strong reduction in the flow rate, for example by a factor of 20.
- the invention also relates to a coding device for at least one fixed or animated image, comprises coded data rate control means comprising, for example grouped together in a processor controlled by a suitable program: means for controlling a first data rate representative of a basic mesh meeting a first flow criterion;
- Such a device can be autonomous, or integrated into a transmission device, a server, a storage device, etc.
- the invention also concerns a computer program product comprising program code instructions recorded on a data medium. usable in or by a computer, controlling coding means, for example integrated in the device presented above.
- a program comprises computer readable programming means for performing: a control of a first data rate representative of a basic mesh meeting a first flow criterion;
- FIG. 1 is a simplified flowchart introducing the essential aspects of the invention
- FIG. 2 is a detailed flowchart of a preferred embodiment of the coding method of the invention
- FIG. 3 schematically shows the data streams used in the method illustrated in FIG. 2;
- FIGS. 4a and 4b illustrate the principle of creating the lower and upper terminals in the method of FIG. 2;
- FIG. 5 presents the different steps of a recursive quantization of the bit planes of the method of FIG. 2;
- FIG. 6 is a block diagram of a device implementing the invention.
- the invention relates to the control of the bit rate of a sequence of images, or of an image, encoded using a mesh and of second generation wavelets.
- the main aspects of this coding technique, known per se, are recalled in the appendix.
- the approach of the invention is to provide a technique for obtaining the best compromise between a desired rate and the final quality returned. It is therefore a "distortion rate" control method for coding still images and video sequences. This process is carried out in two main stages:
- the method of the invention is based on four successive steps:
- step 101 creation of the basic mesh by the known technique, according to the rate requested by the user;
- step 102 creating a lower bound and an upper bound, which will be the interval in which the final output will be; step 103: analysis and creation of the wavelet coefficients, then classification of these coefficients in a SPIHT tree (Set Partitioning In Hierarchical Tree for "partitioning sets into a hierarchical tree”); step 104: coding of the coefficients in bit planes and adaptive quantization of the latter as a function of the interval obtained and the targeted target bit rate.
- SPIHT tree Set Partitioning In Hierarchical Tree for "partitioning sets into a hierarchical tree”
- step 104 coding of the coefficients in bit planes and adaptive quantization of the latter as a function of the interval obtained and the targeted target bit rate.
- FIG. 2 details an algorithm of an embodiment of the invention.
- the target bit rate D is chosen. This target bit rate may be set by the user or may be a function of constraints imposed for example by the terminal or the capacities of a transmission network.
- the mode of coding CBR) or variable (VBR) is also chosen. This choice will influence the processing, since the sequence will not be coded in the same way.
- the CBR mode is the only one possible.
- CBR and VBR modes are possible.
- the VBR mode allows to authorize over-consumption of the bit rate, for scenes or images that are more difficult to encode, and in return for under-consuming when these scenes or images are simpler to code.
- a target algorithm rate D ' is determined, which takes into account the final compression that will be performed, for example by entropy encoding.
- Step 2 of the algorithm is the search for the basic mesh, which is carried out in a manner known per se, for example according to the technique presented in the document already mentioned in the preamble.
- This terminal is of course given as an example, and can be adapted according to the size of the stream.
- step 4 a test is performed on the minimum bit rate of the coded base mesh. If it is lower than the target rate of algorithm D ', go to step 5. Otherwise, loop back to step 2.
- Step 5 is a storing step of the basic mesh, which is kept for subsequent transmission. It constitutes the image reconstruction base as well as the lower limit of the algorithm target rate D '.
- step 6 the refinement of this basic mesh is carried out.
- the basic mesh is refined equally on all the triangles, in order to obtain the maximum of flow, that is to say the upper limit of the frame of D '.
- the subdivision method used is a classical 1 to 4 subdivision at a given level k.
- the refinement is advantageously carried out by the method described in the aforementioned document in the preamble.
- This method is an adaptive hierarchical method: some triangles are subdivided to the maximum, others are subdivided only at an intermediate level, and some of them are not subdivided.
- Step 7 is a test on the final throughput of the subdivided mesh. If this final rate is greater than the target rate of algorithm D ', we proceed to the next step 8. In the opposite case, we return to step 6, to continue the refinement.
- step 8 the mesh thus refined is stored, in order to then be analyzed.
- step 9 the analysis of this refined mesh is carried out by a second generation wavelet transformation, for example according to the method described in the document "Multiresolution Analysis for Surfaces of
- step 10 a series of wavelet coefficients is obtained in step 10 which, without quantification, have a flow rate of between D '- 50% and D' + 50%.
- This classification makes it possible to establish which are the important coefficients and which are the least important coefficients.
- step 12 the wavelet coefficients are coded on bit planes, according to the method proposed by SAID and PEARLMAN. This technique is illustrated in Figure 5, discussed in more detail later. Coefficients are classified in planes, starting from the largest bit plane and going to the least bit plane. At each iteration, the corresponding image is reconstructed and the PSNR (Peak Signal Noise Ratio) of the latter is calculated. Thus, one can also impose a PSNR instead of a target rate, during the control by the user in step 1, one can also combine these two aspects.
- Step 15 is therefore a step of entropy coding of the stream having the target rate of algorithm D 'to obtain a bit rate D. This compression can be performed using a dictionary method, or by a Huffman algorithm .
- bit stream is created, at the target rate D.
- the generation of this stream may for example be performed according to the technique presented in the document cited in the preamble.
- VBR variable rate coding method
- This method has the advantage of offering a more consistent quality when viewing the content.
- the same approach will be used, except that the algorithm will maintain a floating frame of flow rather than converging on it. Quantification of the coefficients will therefore be more flexible in the case of overconsumption, and harder in the case of underconsumption.
- a psycho-visual criterion (for example the PSNR) makes it possible to determine the need to increase or decrease the quantification while remaining in the frame fixed by the algorithm.
- PSNR psycho-visual criterion
- L is the number of images of the processed sequence or group of images.
- Figure 3 illustrates the data flows handled in the context of Figure 2, and the corresponding rates.
- bit rate D ' is obtained, which after entropy coding (CE) has a bit rate D, from which the final bit stream (CB) is created.
- e represents the number of vertices of the basic mesh, c the number of relevant wavelet coefficients, after selection, and c the total number of wavelet coefficients.
- Figures 4a and 4b illustrate the principle of creating the lower and upper bounds A and B.
- a total subdivision 42 of the mesh is carried out at a level k, which makes it possible to obtain a first list of vertices of the mesh 43. This makes it possible to fix the upper bound of the mesh. flow D 44.
- no subdivision 45 of the mesh is made, which makes it possible to obtain a list of vertices 46 which is greatly reduced compared to the summit list 43.
- the lower limit of the flow rate A 47 is deduced therefrom.
- FIG. 5 illustrates the principle of recursive quantization of the bit planes, corresponding to steps 9 to 14 of the method of FIG. 2.
- the wavelet analysis 42 is carried out, delivering a series of coefficients 53 organized in levels 0, 1 and 2. These coefficients are then distributed (54) in an SPIHT tree 55.
- Figure 6 is a block diagram of a coding device embodying the invention. It may in particular be an encoder, implemented in a signal transmission device, in order to reduce the bit rate before transmission, or in a data storage system, in order to reduce the size stored files.
- the device comprises processing means 61, for example in the form of a microprocessor, data storage means 62, for example in the form of a RAM memory, in which are stored the basic mesh and the coefficients d wavelet (especially in steps 5 and 8) and a program 63 controlling the microprocessor 61 to implement the method described above.
- processing means 61 for example in the form of a microprocessor
- data storage means 62 for example in the form of a RAM memory, in which are stored the basic mesh and the coefficients d wavelet (especially in steps 5 and 8) and a program 63 controlling the microprocessor 61 to implement the method described above.
- the processor 61 receives a request 64 representative of the desired bit rate, and the type of coding, and images 65 to be processed. It stores the temporary information in the memory 62, and carries out the processing described above, according to the program instructions 63. It delivers a coded signal 66, at the fixed target rate.
- the wavelets of the second generation constitute a new transformation from the mathematical world.
- These wavelets are constructed from an irregular subdivision of the analysis space, and are based on a weighted and averaged interpolation method.
- the vector product usually used on L 2 (R) becomes a weighted internal vector product.
- These wavelets are particularly well suited for analysis on compact media and intervals. However, they retain the properties of the first-generation wavelets, namely a good time / frequency location and a good calculation speed, because they are built around the lifting method described above.
- the wavelets form a base of Riez on L 2 (R), as well as a "uniform" base for a wide variety of function spaces, such as the spaces of Lebesgue, Lipchitz, Sobolev and Besov. This means that any function of the given spaces can be decomposed on a wavelet basis, and this decomposition will uniformly converge to norm (the norm of the starting space) towards this function.
- norm the norm of the starting space
- P2 The decomposition coefficients on the uniform basis are known (or can be found simply). Either the wavelets are orthogonal or the dual wavelets are known (in the bi-orthogonal case).
- the wavelets as well as their dual, have local properties in space and in frequency. Some wavelets are even compact support (the present invention preferably uses, but not exclusively, such wavelets).
- the frequency localization properties result directly from the wavelet regularity (for high frequencies) and the number of zero polynomial moments (for low frequencies).
- Wavelets can be used in multiresolution analysis.
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Multimedia (AREA)
- Theoretical Computer Science (AREA)
- Discrete Mathematics (AREA)
- Signal Processing (AREA)
- Compression Or Coding Systems Of Tv Signals (AREA)
- Compression Of Band Width Or Redundancy In Fax (AREA)
- Compression, Expansion, Code Conversion, And Decoders (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR0412336A FR2878396A1 (fr) | 2004-11-19 | 2004-11-19 | Procede de codage d'images codees par ondelettes a controle du debit, dispositif de codage et programme d'ordinateur corespondants |
PCT/EP2005/055797 WO2006053842A1 (fr) | 2004-11-19 | 2005-11-07 | Procede de codage d'images codees par ondelettes a controle de debit, dispositif de codage et programme d'ordinateur correspondants |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1812903A1 true EP1812903A1 (fr) | 2007-08-01 |
Family
ID=34951972
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP05801394A Withdrawn EP1812903A1 (fr) | 2004-11-19 | 2005-11-07 | Procede de codage d'images codees par ondelettes a controle de debit, dispositif de codage et programme d'ordinateur correspondants |
Country Status (4)
Country | Link |
---|---|
US (1) | US20080240251A1 (fr) |
EP (1) | EP1812903A1 (fr) |
FR (1) | FR2878396A1 (fr) |
WO (1) | WO2006053842A1 (fr) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN100515021C (zh) * | 2006-12-30 | 2009-07-15 | 中国科学院计算技术研究所 | 基于图像质量和码率约束的jpeg2000码率控制方法 |
JP5284355B2 (ja) * | 2007-07-09 | 2013-09-11 | テレフオンアクチーボラゲット エル エム エリクソン(パブル) | 通信システムにおける適応レート制御 |
EP2910026B1 (fr) * | 2012-10-19 | 2017-11-29 | Visa International Service Association | Procédés de diffusion numérique mettant en uvre des réseaux maillés et des ondelettes sécurisés |
US11871052B1 (en) * | 2018-09-27 | 2024-01-09 | Apple Inc. | Multi-band rate control |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CA2145914A1 (fr) * | 1994-05-27 | 1995-11-28 | Alexandros Eleftheriadis | Codage de sequences video a faibles debits binaires assiste par un modele |
US6144773A (en) * | 1996-02-27 | 2000-11-07 | Interval Research Corporation | Wavelet-based data compression |
US6614428B1 (en) * | 1998-06-08 | 2003-09-02 | Microsoft Corporation | Compression of animated geometry using a hierarchical level of detail coder |
US6879324B1 (en) * | 1998-07-14 | 2005-04-12 | Microsoft Corporation | Regional progressive meshes |
FR2817066B1 (fr) * | 2000-11-21 | 2003-02-07 | France Telecom | Procede de codage par ondelettes d'un maillage representatif d'un objet ou d'une scene en trois dimensions, dispositifs de codage et decodage, systeme et structure de signal correspondants |
AU2002951574A0 (en) * | 2002-09-20 | 2002-10-03 | Unisearch Limited | Method of signalling motion information for efficient scalable video compression |
US20070064099A1 (en) * | 2004-06-18 | 2007-03-22 | Raphaele Balter | Method of representing a sequence of pictures using 3d models, and corresponding devices and signals |
KR100679018B1 (ko) * | 2004-09-07 | 2007-02-05 | 삼성전자주식회사 | 다계층 비디오 코딩 및 디코딩 방법, 비디오 인코더 및디코더 |
-
2004
- 2004-11-19 FR FR0412336A patent/FR2878396A1/fr active Pending
-
2005
- 2005-11-07 US US11/791,134 patent/US20080240251A1/en not_active Abandoned
- 2005-11-07 WO PCT/EP2005/055797 patent/WO2006053842A1/fr active Application Filing
- 2005-11-07 EP EP05801394A patent/EP1812903A1/fr not_active Withdrawn
Non-Patent Citations (1)
Title |
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See references of WO2006053842A1 * |
Also Published As
Publication number | Publication date |
---|---|
WO2006053842A1 (fr) | 2006-05-26 |
FR2878396A1 (fr) | 2006-05-26 |
US20080240251A1 (en) | 2008-10-02 |
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