Abstract:
An improved method for generating non-linear multimedia effects by employing two or more tweens. Specifically, a second tween mapping is chained to a first tween mapping. A first time signal is received. The first tween is employed to map the first time signal into a second time signal. The second tween mapping is employed to map the second time signal into an output that varies in a non-linear fashion with respect to the first time signal.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates generally to the creation, integration, and publication of digital media and more particularly to an improved method to generate non-linear effects, such as acceleration of an object and the fading in and out of a volume level, by chaining two or more tweens.  
           [0003]    2. Description of the Related Art  
           [0004]    The assignee of the present invention has developed Quicktime™, an award-winning industry-standard software architecture that allows developers to create, integrate, and publish all types of digital media. As applications increase in sophistication, and consumers demand increased realism in multi-media products, developers are increasingly turning to generate non-linear effects to create added realism.  
           [0005]    In addition, many human perceptions and senses, such as the auditory perception of sound and the visual perception of object motion (e.g., acceleration) can only be described mathematically as a non-linear function. Unfortunately, these non-linear mathematical functions are typically very difficult to describe, mathematically or otherwise. The versions of Quicktime™ up through release 2.5 do not allow a developer to specify a custom specific non-linear effect. For example, although a developer can use a predetermined fade-in or fade-out of a volume level, the Quicktime™ architecture does not allow developers to customize or specify other fade-in or fade-out relationships or functions besides the predetermined relationships, supported by the Quicktime™ architecture.  
           [0006]    As a result, developers were left to one of two undesirable choices. The first choice is to attempt to describe a non-linear mapping by employing a mathematical function. However, as stated previously, many of the non-linear functions are difficult, if not impossible, to describe mathematically. The second choice is to employ a table that is, at best, an estimate of the non-linear performance or behavior of a particular parameter such as volume level or an object&#39;s speed. The second choice suffers from the disadvantage that the table typically approximates to a first order the mathematical function, but is not the same as the mathematical function. Accordingly, a loss of realism occurs. Moreover, different developers develop their own tables, resulting in non-uniformity in the industry. For example, different software products can describe non-linear effects, such as acceleration of an object or the fading in and out of a volume level in very different ways. Furthermore, because there is no consistent way to describe non-linear effects, developers cannot build enhancements to their existing models or other developer&#39;s models. Nor can developers share or port the models to others.  
           [0007]    Accordingly, there remains a need in the industry for an improved method to provide multimedia non-linear effects that overcomes the disadvantages set forth previously.  
         SUMMARY OF THE INVENTION  
         [0008]    An improved method for generating multimedia non-linear effects by chaining two or more tweens. The present invention can employ a second tween mapping that maps a first time signal into a second time signal, and a first tween mapping that maps the second time signal to an output value. The first tween is employed to map the first time signal into a second time signal in either a linear or non-linear fashion. The second tween mapping maps the second time signal into an output that varies in a linear or non-linear fashion with respect to the first time signal. Additional tweens can be chained to the first and second tween to provide other multimedia effects, such as moving an object forward and back across a path numerous times.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 shows one example of a conventional computer system in which the present invention can be implemented.  
         [0010]    [0010]FIG. 2 shows an example of a computer readable storage medium incorporating one embodiment of the present invention in which two tweens are chained or linked.  
         [0011]    [0011]FIG. 3 illustrates an exemplary multimedia application of a planet orbiting a sun in which the present invention can be employed to provide non-linear effects.  
         [0012]    [0012]FIG. 4 illustrates a path-to-point tween that defines the path for the planet of FIG. 3.  
         [0013]    [0013]FIG. 5 illustrates a time versus time interpolation curve, which when employed in conjunction with the tween described in FIG. 4, provides non-linear multimedia effects to the planet.  
         [0014]    [0014]FIG. 6 illustrates a time versus time interpolation curve which when employed in conjunction with the tween described in FIG. 4 and the tween described in FIG. 5 provide for counterclockwise movement of the planet around the sun.  
         [0015]    [0015]FIG. 7 illustrates a time versus time interpolation curve which when employed in conjunction with the tween, described in FIG. 4, and the tween, described in FIG. 5, provide for clockwise full orbit at double speed and then counterclockwise full orbit at double speed.  
         [0016]    [0016]FIG. 8 shows an example of a computer readable storage medium incorporating an alternative embodiment of the present invention, in which three tweens are chained or linked.  
         [0017]    [0017]FIG. 9 shows an example of a computer readable storage medium incorporating yet another embodiment of the present invention, in which n tweens are chained or linked so as to form a chain of n tweens.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]    In the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be obvious to one skilled in the art that the present invention may be practiced without these specific details. In other instances, well known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the present invention.  
         [0019]    Some portions of the detailed description which follow are presented in terms of algorithms and symbolic representations of operations on data bits within a computer memory. These algorithmic descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. An algorithm is here, and generally, conceived to be a self-consistent sequence of steps leading to a desired result. The steps are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like.  
         [0020]    It should be noted, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise, it should be noted that throughout the description of the present invention, terms such as “processing” or “computing” or “calculating” or “determining” or “displaying” or the like, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical (electronic) quantities within the computer system&#39;s register and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices.  
         [0021]    The present invention also relates to an apparatus for performing the processing steps of the present invention. This apparatus may be specially constructed for the required purposes, or it may comprise a general purpose computer selectively activated or reconfigured by a computer program. The algorithms and displays presented herein are not inherently related to any particular computer or other apparatus. Various general purpose machines may be used with programs in accordance with the teachings herein, or it may prove convenient to construct more specialized apparatus to perform the required method steps. The required structure for a variety of these machines will become apparent from the description below. In addition, the present invention is not described with reference to any particular programming language. It will be appreciated that a variety of programming languages may be used to implement the teachings of the invention as described herein.  
         [0022]    Referring to the figures, exemplary embodiments of the invention will now be described. The exemplary embodiments are provided to illustrate aspects of the invention and should not be construed as limiting the scope of the invention. The exemplary embodiments are primarily described with reference to block diagrams and flow charts. As to the flow charts, each block within the flow charts represents both a method step and an apparatus element for performing the method step. Depending upon the implementation, the corresponding apparatus element may be configured in hardware, software, firmware or combinations thereof.  
         [0023]    Computer System  
         [0024]    [0024]FIG. 1 shows one example of a conventional computer system  151  in which the present invention can be implemented. The computer system  151  interfaces to external systems through a modem or network interface  169 . It will be appreciated that the modem or network interface  169  may be considered part of the computer system  151 . This interface  169  may be an analog modem, an ISDN modem, a cable modem, a token ring interface, a satellite transmission interface (e.g., “Direct “PC”), or other interferences for coupling a digital processing system to other digital processing systems.  
         [0025]    The computer system  151  includes a processor  153  which may be a conventional microprocessor, such as a Motorola PowerPC microprocessor or an Intel Pentium microprocessor. Memory  155  is coupled to the processor  153  by the bus  157 . Memory  155  may be dynamic random access memory (DRAM) and may also include static RAM (SRAM). The bus  157  couples the processor  153  to the memory  155  and also to mass memory  163  and to display controller  159  and to the I/O (input/output) controller  165 . Display controller  159  controls in the conventional manner a display on the display device  161  which may be a CRT or a liquid crystal display device. The input/output devices  169  may include a keyboard, disk drives, printers, a scanner, a digital camera, and other input and output devices, including a mouse or other pointing devices.  
         [0026]    The display controller  159  and the I/O controller  165  may be implemented with conventional well known technology. The mass memory  163  is often a magnetic hard disk, an optical disk, or another form of storage for large amounts of data. Some of this data is often written, by a direct memory access process, into memory  155  during execution of software in the computer system  151 .  
         [0027]    It will be appreciated that the computer system  151  is one example of many possible computer systems which have different architectures. For example, Macintosh or Wintel systems often have multiple busses, one of which may be considered to be a peripheral bus. Network computers may also be considered to be a computer system which may be used with the present invention. Network computers may not include a hard disk or other mass storage, and the executable programs are loaded from a network connection into the memory  151  for execution by the processor  153 . A Web TV system, which is known in the art, may be considered to be a computer system according to the present invention, but it may not include certain features shown in FIG. 1, such as certain input or output devices. A cell phone having a suitable display and a processor and memory may also be considered to be a digital processing system or a computer system which may be used with the present invention.  
         [0028]    A typical computer system will usually include at least a processor, memory and a bus coupling the memory to the processor. It will also be appreciated that the computer system  151  is typically controlled by an operating system software which includes a file management system, such as a disk operating system, which is part of the operating system software.  
         [0029]    Tween Definition  
         [0030]    Tweens (also referred to herein as “tween mapping”) are functions that generate an output value based upon an input, such as a percentage, and a relationship between the input and static data. This relationship can be described in a table which provides a mapping, or a mathematical function, which also provides a mapping. The Quicktime™ software architecture provides for tweens or tween-mappings.  
         [0031]    Interpolation Tweens  
         [0032]    One example of a tween is a Quicktime™ interpolation tween which receives the following inputs: 1) a starting number, 2) an ending number, and 3) input percentage. Based on these inputs, the tween mapping generates an interpolated number. In this case, the percentage specifies the distance from the starting number to the requested number divided by the distance between the start number and the end number. Path to X( ) and Path to Y( ) tweens are examples of non-linear interpolation tweens. The Path to X( ) and Path to Y( ) are described in greater detail in Appendix I.  
         [0033]    A Quicktime™ interpolation tween can be employed, for example, to fade-in a volume level of a multimedia application, such as a sound track to a movie, over a certain duration of time.  
         [0034]    OT Atom Tween  
         [0035]    Another Quicktime™ tween can include a list of data items and can return a single item from the list based upon an input percentage. This type of tween can be used to generate a cycle of discrete numbers. These discrete numbers can be employed to direct a sprite as to which image to use to produce animation. Another type of Quicktime™ tween can store a path and return a location and tangent of a point along the path based upon an input percentage. This type of tween can be used to make a sprite follow and rotate along a path. The Quicktime™ software architecture employs tween mappings to produce resolution independent behavior in the time domain.  
         [0036]    Chain of Tweens  
         [0037]    The present invention allows a chain of tween mappings to operate upon a time value and to generate intermediate time values, where the final time value is provided to a root tween mapping that generates an output value based on the final time value. The present invention provides for the reuse of two or more existing Quicktime™ tween mappings (also referred to herein as “tweeners”) in order to build new custom and more complex tweens. A developer can create new tweens to customize certain functions that manipulate time, which is ultimately provided to a root tween mapping. Accordingly, the present invention allows a user/developer to customize and reuse complex and preexisting tweens to generate additional tweens. It will be understood by those of ordinary skill in the art that many different permutations of change of tweens can be derived and developed.  
         [0038]    Chain of Two Tweens  
         [0039]    [0039]FIG. 2 shows an example of a computer readable storage medium incorporating one embodiment of the present invention in which two tweens are chained or linked. The present invention  200  provides a novel method of providing non-linear effects to multimedia by the chaining together of multiple tweens. Specifically, FIG. 2 illustrates the chaining together of a first tween  201  and a second tween  202 . A first time value (t 1 )  204  is provided to the second tween  202 . In response, the second tween  202  generates a second time value (t 2 )  218  in accordance to a particular relationship  224 . For example, the relationship  224  can be represented by the following: f(t 1 )=t 2 . This relationship  224  can vary and be adapted and tailored to a particular application.  
         [0040]    A first tween  201  receives the second time value (t 2 )  218  and responsive thereto, generates an output value  208 . The relationship  240  between the second time value (t 2 )  218  and the output value  208  can be represented by the following expression:  
           f ( t   2 )=output  
         [0041]    This relationship  240  can be varied, adapted and tailored to suit a particular application. Appendix I illustrates several tweens that are provided in Quicktime™ Version 3.0 that are especially adapted to be the second tween  202 . The second tween  202 , or intermediary tween, is also referred to herein as an “interpolator tween” that provides an output, which is in turn used as a time input to another tween that is chained to the interpolator tween.  
         [0042]    Example of Effects Created by Present Invention  
         [0043]    [0043]FIG. 3 illustrates a planet  304  orbiting a sun  302 . The present invention can be employed to provide acceleration effects of planet  304  as it orbits around the sun  302  in the predetermined orbit path  308 .  
         [0044]    [0044]FIG. 4 illustrates a path-to-point tween (i.e., PathToPoint( )) described by Table I. Table I assumes that the orbit path  308  has a total length (L) when measured from starting point A and ending at point A. Further, points A, B, C, D, E, F, G, and H are assumed to be evenly distributed across the path (i.e., that is the distance between each point is the same and is given by the length (L) divided by 8).  
                               TABLE I                                   Time   Point   Tween                           t 1=0×L     A=   PathToPoint(t 1 )           t 2=(1/8)×L     B=   PathToPoint(t 2 )           t 3=(2/8)×L     C=   PathToPoint(t 3 )           t 4=(3/8)×L     D=   PathToPoint(t 4 )           t 5=(4/8)×L     E=   PathToPoint(t 5 )           t 6=(5/8)×L     F=   PathToPoint(t 6 )           t 7=(6/8)×L     G=   PathToPoint(t 7 )           t 8=(7/8)×L     H=   PathToPoint(t 8 )                      
 
         [0045]    [0045]FIG. 5 illustrates a time versus time interpolation curve which when employed in conjunction with the tween of FIG. 4 provides multimedia effects (e.g., acceleration) to the planet  304 .  
         [0046]    [0046]FIGS. 6 and 7 illustrate how a third tween can be chained with a first and second tween to form a chain of three tweens.  
         [0047]    [0047]FIG. 6 illustrates a time versus time interpolation curve which when employed in conjunction with (i.e., “chained”) the tween described in FIG. 4 and the tween described in FIG. 5 provide for counterclockwise movement of the planet around the sun.  
         [0048]    [0048]FIG. 7 illustrates a time versus time interpolation curve which when employed in conjunction with (i.e., “chained”) the tween described in FIG. 4 and the tween described in FIG. 5 provide for clockwise full orbit at double speed and then counterclockwise full orbit at double speed.  
         [0049]    Chain of Three Tweens  
         [0050]    [0050]FIG. 8 shows an example of a computer-readable storage medium incorporating an alternative embodiment of the present invention, in which three tweens are chained or linked. In this embodiment, three tweens are chained together to provide further non-linear multimedia effects. A third tween  322  includes an input for receiving a first time value (t 1 )  324 , and responsive thereto, for generating a second time value (t 2 )  328 . The relationship  326  between the first time value (t 1 )  324  and the second time value (t 2 )  328  can be described by the following:  
           f ( t   1 )= t   2 .  
         [0051]    A second tween  342  is coupled to receive the second time value (t 2 )  328 , and responsive thereto, generates a third time value (t 3 )  348 . The relationship  346  between the second time value (t 2 )  328  and the third time value (t 3 )  348  can be described by the following:  
           f ( t   2 )= t   3 .  
         [0052]    A first tween  352  is coupled to receive the third time value (t 3 )  348 , and responsive thereto, generates an output  358  based on a relationship  356 . This relationship  356  can be described as follows:  
           f ( t   3 )=output.  
         [0053]    Chain of N Tween  
         [0054]    [0054]FIG. 9 shows an example of a computer readable storage medium incorporating of yet another embodiment of the present invention, in which n tweens are chained or linked so as to form a chain of n tweens. In this embodiment, an nth tween  410  is coupled to receive a time value (t)  412  and, in response thereto, generates a second time value (t 2 )  414  based on a relationship  416  (e.g., f(t 1 )=t 2 ). An n−1 tween  420  is linked to the n tween  410  and is coupled to receive the second time value (t 2 )  414 . Responsive thereto, the n−1 tween  420  generates a third time value (t 3 )  424  based on the relationship  426  (e.g., f(t 1 )=t 3 ). A second tween  440  is provided to receive a t (n−1)  value  442 , and in response thereto, to generate t n  value  444  based upon a relationship  446  (e.g., f(t n−1 )=t n ). A first tween  450  is coupled to receive the t n  value  444  and in response thereto, to generate an output  454 , based on a relationship  456  (e.g., f(t n )=output).  
         [0055]    When the tweens described in FIGS. 4 and 5 are chained or linked in accordance with the present invention, a multimedia acceleration effect is provided for an object, in this case, a planet. Before the introduction of the present invention, the speed of the object orbiting the planet is constant. FIG. 5 illustrates a second tween, which maps linear time to a non linear time causing the velocity of the orbiting object to go from a constant one to one with acceleration. The acceleration models the real world acceleration of an orbiting planet. FIG. 6 is a third tween mapping that causes the planet to orbit backwards, which in this example would be counterclockwise instead of clockwise. As can be seen from this example, the present invention provides the flexible use of multiple tween mappings to allow a developer to describe non-linear effects with ease and precision.  
         [0056]    In the foregoing specification, the invention has been described with reference to specific exemplary embodiments thereof. It will however be evident that various modifications and changes made be made thereto without departing from the broader spirit and scope of the invention as set forth in the appended claims. The specification and drawings are accordingly to be regarded as illustrative rather than restrictive.