Aspects of media content rendering

Media content is arranged into a number of sets of video, audio, or data samples, referred to as clips, which are rendered by a media content manager. A playlist, which is handled by a presentation manager, specifies the time-ordered sequence of clips playable to a user. Certain actions are taken during media content play to minimize glitches perceived by the user, including determining a time offset value that is used to decide how far in advance of a scheduled play time to begin pre-rendering an upcoming clip. The time offset value is determined using one or more static characteristics associated with a media source for the upcoming clip, such as the location of the media source, codec parameters, or encryption complexity, and one or more dynamic characteristics of the presentation system, such as retrieval states, (including play speeds) of media clips, processing loads, or clock frequencies.

BACKGROUND

Multimedia players are devices that render combinations of video, audio or data content (“multimedia presentations”) for consumption by users. Multimedia players such as DVD players currently do not provide for much, if any, user interactivity during play of media content—media content play is generally interrupted to receive user inputs other than play speed adjustments. For example, a user of a DVD player must generally stop the movie he is playing to return to a menu that includes options allowing him to select and receive features such as audio commentary, actor biographies, or games.

Interactive multimedia players are devices (such devices may include hardware, software, firmware, or any combination thereof) that render combinations of interactive content concurrently with traditional video, audio or data content (“interactive multimedia presentations”). Interactive content is generally any user-selectable visible or audible object presentable alone or concurrently with other video, audio or data content. Although any type of device may be an interactive multimedia player, devices such as optical media players (for example, DVD players), computers, and other electronic devices are particularly well positioned to enable the creation of, and consumer demand for, commercially valuable interactive multimedia presentations because they provide access to large amounts of relatively inexpensive, portable data storage.

To enhance investment in all types of media content players, particularly interactive multimedia players and interactive multimedia presentations, it is desirable to provide predictable and relatively glitch-free play of video, audio or data content.

It will be appreciated that the claimed subject matter is not limited to implementations that solve any or all of the disadvantages of specific multimedia presentation systems, interactive multimedia presentation systems, or aspects thereof.

SUMMARY

Many types of presentations, such as multimedia presentations and interactive multimedia presentations, include media content. One example of media content is a movie, but media content may be video, audio, data, or any combination thereof. Media content is generally arranged into a number of sets of samples, referred to as clips, which are rendered by a media content manager. One clip is generally receivable from one media source. A playlist, which is handled by a presentation manager, specifies the time-ordered sequence of clips that are presentable to a user. Sometimes, a real-time transition from one clip to another as specified in the playlist is difficult to perform without causing the user to experience glitches (for example, delays, undesirable interruptions, or dropped content) in the play of the media content, especially when presentation systems with limited processing and/or decoding resources are used.

Methods, systems, apparatuses, and articles of manufacture for playing media content that are discussed herein involve pre-rendering at least a portion of an upcoming clip before the clip is scheduled for play, to minimize glitches during play of the media content. Certain actions taken during play of the media content include determining a time offset value, which is used to decide how far in advance of the scheduled play time to begin pre-rendering the upcoming clip. There should be enough time for pre-rendering the clip before the scheduled play time, but the clip should not be pre-rendered so far in advance that pre-rendering activities negatively affect other important activities occurring within the presentation system.

The time offset value is determined using one or more static characteristics associated with the media source for the upcoming clip, and one or more dynamic characteristics of the presentation system. Examples of static characteristics of a particular media source include the location of the media source, codec parameters or settings, or encryption parameters or settings. Examples of dynamic characteristics of the presentation system include retrieval states (including play speeds) of media clips, media or graphics processing loads, or media or graphics clock frequencies. The time offset value may be determined multiple times during play of the media content to account for various dynamic characteristics.

This Summary is provided to introduce a selection of concepts in a simplified form. The concepts are further described in the Detailed Description section. Elements or steps other than those described in this Summary are possible, and no element or step is necessarily required. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended for use as an aid in determining the scope of the claimed subject matter.

DETAILED DESCRIPTION

Turning to the drawings, where like numerals designate like components,FIG. 1is a simplified functional block diagram of an interactive multimedia presentation system (“Presentation System”)100. Presentation System100includes a media content manager102, an interactive content (“IC”) manager104, a presentation manager106, a timing signal management block108, and a mixer/renderer110. In general, design choices dictate how specific functions of Presentation System100are implemented. Such functions may be implemented using hardware, software, or firmware, or combinations thereof.

In operation, Presentation System100handles interactive multimedia presentation content (“Presentation Content”)120. Presentation Content120includes a media content component (“media component”)122and an interactive content component (“IC component”)124. Media component122and IC component124are generally, but need not be, handled as separate data streams, by media content manager102and IC manager104, respectively.

Presentation System100also facilitates presentation of Presentation Content120to a user (not shown) as played presentation127. Played Presentation127represents the visible and/or audible information associated with Presentation Content120that is produced by mixer/renderer110and receivable by the user via devices such as displays or speakers (not shown). For discussion purposes, it is assumed that Presentation Content120and played presentation127represent high-definition DVD movie content, in any format. It will be appreciated, however, that Presentation Content120and Played Presentation127may be any type of presentation of media content now known or later developed.

Media component122represents the traditional video, audio or data components of Presentation Content120. For example, a movie generally has one or more versions (a version for mature audiences, and a version for younger audiences, for example); one or more titles131with one or more chapters (not shown) associated with each title (titles are discussed further below, in connection with presentation manager106); one or more audio tracks (for example, the movie may be played in one or more languages, with or without subtitles); and extra features such as director's commentary, additional footage, trailers, and the like. It will be appreciated that distinctions between titles and chapters are purely logical distinctions. For example, a single perceived media segment could be part of a single title/chapter, or could be made up of multiple titles/chapters. It is up to the content authoring source to determine the applicable logical distinctions. It will also be appreciated that although media component122is referred to as a movie, media component122may in fact be video, audio, data, or any combination thereof.

Sets of media samples (for example, sets of video, audio, or data samples) that form media component122are referred to as clips123(clips123are shown within media component122, media content manager102, and playlist128). Referring to media content manager102, information associated with clips123is handled by one or more media processing pipelines159(two media processing pipelines are shown for exemplary purposes, but any number are possible). Within a particular media processing pipeline159, information associated with clips123is received from a media source160and demultiplexed, decoded, and/or decrypted at a decoder block161.

A particular media source160is any device, location, or data from which video, audio, or data is derived or obtained. Examples of media sources include, but are not limited to, networks, hard drives, optical media, alternate physical disks, and data structures referencing storage locations of specific video, audio, or data. In general, any computer-readable medium may serve as a media source (computer-readable media are discussed further below, in connection withFIG. 7).

Each media source160has one or more media source characteristics162associated therewith. A media source characteristic is a static parameter associated with a particular media source. Examples of such static parameters include, but are not limited to: the location of the media source; encoder-decoder pair (“codec”) parameters or settings (for example, encoding/decoding formats or protocols such as WMV, H.264, MPEG, VC1, group of picture (“GOP”) size settings, compression ratio settings, or quality settings); or encryption parameters or settings (for example, encryption type such as symmetric or asymmetric, encryption complexity, or encryption formats or protocols). It will be appreciated that other static parameters associated with a particular media source may also be defined or recognized.

Decoder blocks161represent any devices, techniques or steps used to retrieve renderable video, audio, or data content from information received from a media source160. Decoder blocks161may include codecs, demultiplexers, or decrypters, for example. Decoder blocks161and components thereof may be implemented using hardware, software, firmware, or any combination thereof. Although a one-to-one relationship between decoders and media sources is shown, it will be appreciated that one decoder may serve multiple media sources, and vice-versa. For example, some commercially available DVD players include only one decoder.

Media content data (“media data”)132is data associated with media component122that has been prepared for rendering by media content manager102and transmitted to mixer/renderer110. Sets (for example, frames) of media data134generally include, for each active clip123, a rendering of a portion of the clip. The exact portion or amount of the clip rendered in a particular set of media data may be based on several factors, such as the characteristics of the video, audio, or data content of the clip, or one or more media source characteristics162. Media content manager102has a dynamic media processing load based on the identity and scheduling of the various clips comprising media component122and/or IC component124(discussed below).

Referring again to Presentation Content120, IC component124includes interactive objects125, which are user-selectable visible or audible objects, optionally presentable concurrently with media component122, along with any instructions (shown as applications155and discussed further below) for presenting the visible or audible objects. Interactive objects125may be static or animated. Examples of interactive objects include, among other things, video samples or clips, audio samples or clips, graphics, text, and combinations thereof.

Interactive objects125originate from one or more sources (not shown). A source is any device, location, or data from which interactive objects are derived or obtained. Examples of sources for interactive objects125include, but are not limited to, networks, hard drives, optical media, alternate physical disks, and data structures referencing storage locations of specific interactive objects. Examples of formats of interactive objects125include, but are not limited to, portable network graphics (“PNG”), joint photographic experts group (“JPEG”), moving picture experts group (“MPEG”), multiple-image network graphics (“MNG”), audio video interleave (“AVI”), extensible markup language (“XML”), hypertext markup language (“HTML”), extensible HTML (“XHTML”), extensible stylesheet language (“XSL”), and WAV.

Applications155provide the mechanism by which Presentation System100presents interactive objects125to a user. Applications155represent any signal processing method or stored instruction(s) that electronically control predetermined operations on data. It is assumed for discussion purposes that IC component124includes three applications155, which are discussed further below in connection withFIGS. 2 and 3. The first application presents, concurrently with visual aspects of the movie, certain interactive objects that provide a menu having multiple user-selectable items; the second application presents one or more interactive objects that provide graphic overlays (such as circles) that may be used to identify and/or follow one or items appearing in the movie (a person, a car, a building, or a product, for example); and the third application presents a media clip such as an animated thumbnail (referred to as a “script clip”).

Interactive content data (“IC data”)134is data associated with IC component124that has been prepared for rendering by IC manager104and transmitted to mixer/renderer110. Each application has an associated queue (not shown), which holds one or more work items (not shown) associated with rendering the application.

Presentation manager106, which is configured for communication with both media content manager104and IC manager102, facilitates handling of Presentation Content120and presentation of played presentation127to the user. Presentation manager106has access to a playlist128. Playlist128includes, among other things, a time-ordered sequence of clips123and applications155(including interactive objects125) that are presentable to a user. The clips123and applications155/interactive objects125may be arranged to form one or more titles131. For exemplary purposes, one title131is discussed herein. Playlist128may be implemented using an extensible markup language (“XML”) document, or another data structure.

Presentation manager106uses playlist128to ascertain a presentation timeline130for title131. Conceptually, presentation timeline130indicates the times within title131when specific clips123and applications155are presentable to a user. A sample presentation timeline130, which illustrates exemplary relationships between presentation of clips123and applications155is shown and discussed in connection withFIG. 2. In certain circumstances, it is also useful to use playlist128and/or presentation timeline130to ascertain a media content timeline (“media timeline”)142(an exemplary media timeline142is discussed further below, in connection withFIG. 6).

Presentation manager106provides information, including but not limited to information about presentation timeline130, to media content manager102and IC manager104. Based on input from presentation manger206, media content manager102prepares media data132for rendering, and IC manager104prepares IC data134for rendering. In one implementation, presentation manager106controls media processing pipelines159.

Timing signal management block108produces various timing signals158, which are used to control the timing for preparation and production of media data132and IC data134by media content manager102and IC manager104, respectively. In particular, timing signals158are used to achieve frame-level synchronization of media data132and IC data134. Details of timing signal management block108and timing signals158are discussed further below, in connection withFIG. 4.

Mixer/renderer renders media data132in a video plane (not shown), and renders IC data134in a graphics plane (not shown), The graphics plane is generally, but not necessarily, overlayed onto the video plane to produce played presentation127for the user.

With continuing reference toFIG. 1,FIG. 2is a graphical illustration of a sample presentation timeline130for title131within playlist128. Time is shown on horizontal axis220. Information about media component122(clips123are illustrated) and IC component124(applications155, which present interactive objects125, are illustrated) is shown on vertical axis225.

Regarding media component122, four clips123are shown: a first media clip (“media clip1”)230, a second media clip (“media clip2”)250, a third media clip (“media clip3”)251, and a fourth media clip (“media clip4”)253. Media clip1230is playable from zero seconds to 10 seconds via media processing pipeline1(shown inFIG. 1), media clip2250is playable from eight seconds to 15 seconds via media processing pipeline2(also shown inFIG. 1), media clip3251is playable from 10 seconds to 20 seconds via media processing pipeline1, and media clip4253is playable from 30 seconds to 40 seconds via media processing pipeline2. No media content is scheduled by playlist128for play between 20 seconds and 30 seconds, although an application155may present script clip255for play via media processing pipeline1between 20 seconds and 30 seconds. Script clip is a media clip, such as an animated thumbnail, which is not generally included in the playlist, but which may be optionally invoked via an application at times (such as when no media content is scheduled for play) within played presentation127.

Regarding IC component124, as mentioned above in connection withFIG. 1, one application is responsible for presenting certain interactive objects that provide user-selectable items (for example, buttons with associated text or graphics) of menu280. Another application is responsible for presenting one or more interactive objects that provide graphic overlay290. As shown, menu280is displayed concurrently with media clips1through4, and graphic overlay290is displayable concurrently with media clip1230and a portion of media clip2. A third application is responsible for presenting script clip255when there is no media content scheduled for presentation (as shown, script clip255is playable between 20 seconds and 30 seconds).

The particular amount of time along horizontal axis220in which title131is presentable to the user is referred to as play duration292of title131. Specific times within play duration292are referred to as title times. Seven title times (“TTs”) are shown on presentation timeline130—TT1293, TT2294, TT3295, TT4296, TT5297, TT6298, and TT7299. Because a title may be played once or may be played more than once (in a looping fashion, for example) play duration292is determined based on one iteration of title131. Play duration292may be determined with respect to any desired reference, including but not limited to a predetermined play speed (for example, normal, or 1×, play speed), a predetermined frame rate, or a predetermined timing signal status. Play speeds, frame rates, and timing signals are discussed further below, in connection withFIG. 4.

It will be appreciated that implementation-specific factors such as display techniques, and specific rules regarding play sequences and timing relationships among clips and interactive objects for each title may impact upon exact values of a title's play duration and title times therein. The terms play duration and title times are intended to encompass all such implementation-specific details.

Although title times at/within which content associated with IC component124is presentable are generally predetermined, it will be appreciated that actions taken when the user interacts with such content may only be determined based on user input while Played Presentation127is playing. For example, the user may select, activate, or deactivate certain applications, interactive objects, and/or additional content associated therewith during play of Played Presentation127.

Other times and/or durations within play duration292are also defined and discussed herein. Media presentation intervals240are defined by beginning and ending times of play duration292between which particular content associated with particular clips123is playable. For example, media clip1230has a presentation interval240defined by beginning title time TT1293and ending TT3295, media clip2250has a presentation interval240defined by beginning title time TT2294and ending title time TT4296, media clip3251has a presentation interval240defined by beginning title time TT3295and ending title time TT5297, media clip4253has a presentation interval240defined by beginning title time TT6298and ending title time TT7299, and script clip255has a presentation interval240defined by beginning title time TT5297and ending title time TT6298.

Pre-rendering times220are title times (or intervals thereof) that precede the title times at which particular clips123are playable based on presentation timeline130by amounts based on variable time offset values (determination of time offset values and pre-rendering times220is discussed below, in connection withFIGS. 5 and 6).

Time intervals associated with applications155(such as application presentation intervals and application play durations) are defined and discussed below, in connection withFIG. 3.

With continuing reference toFIGS. 1 and 2,FIG. 3is a functional block diagram of a single application155. Application155is generally representative of applications responsible for presenting interactive objects280,290, and255(shown inFIG. 2). Application155includes instructions304(discussed further below). Application155has associated therewith an application play duration320and one or more application presentation intervals321.

Application play duration320is a particular amount of time, with reference to an amount (a part or all) of play duration292within which interactive objects125associated with application155are presentable to and/or selectable by a recipient of played presentation127. In the context ofFIG. 2, for example, application155responsible for menu280has an application play duration composed of the amount of time between TT1293and TT7299. The application responsible for graphical overlay290has an application play duration composed of the amount of time between TT1293and TT3295. The application responsible for script clip255has an application play duration composed of the amount of time between TT5297and TT6298.

The intervals defined by beginning and ending title times obtained when an application play duration320associated with a particular application is conceptualized on presentation timeline are referred to as application presentation intervals321. For example, referring toFIG. 2, the application responsible for menu280has an application presentation interval beginning at TT1293and ending at TT7299, the application responsible for graphic overlay290has an application presentation interval beginning at TT1293and ending at TT3295, and the application responsible for script clip255has an application presentation interval beginning at TT5297and ending at TT6298.

In some cases, application155may have more than one page (pages are not shown). A page is a logical grouping of one or more interactive objects that are contemporaneously presentable within a particular application play duration320and/or application presentation interval321. Interactive objects associated with a particular page may be presented concurrently, serially, or a combination thereof. The number of applications and pages associated with a given title, and the interactive objects associated with each application or page, are generally logical distinctions that are matters of design choice. For example, designation of a particular initial page is not necessary, more than one page of an application may be presented concurrently, or an application may be started with no pages (or an initial page that contains nothing). Pages of an application may be loaded and unloaded while keeping the application and script in tact. Multiple pages may be used when it is desirable to manage (for example, limit) the number or amount of resources associated with an application that are loaded into memory during execution of the application.

Instructions304, when executed, perform tasks (among other tasks) related to rendering of interactive objects125associated with application155, based on user input. One type of user input (or a result thereof) is a user event. User events are actions or occurrences initiated by a recipient of played presentation127that relate to IC component124. User events are generally, but not necessarily, asynchronous. Examples of user events include, but are not limited to, user interaction with interactive objects within played presentation127, such as selection of a button within menu280, selection of the circle associated with graphical overlay290, or invocation of script clip255. Such interactions may occur using any type of user input device now known or later developed, including a keyboard, a remote control, a mouse, a stylus, or a voice command. It will be appreciated that application155may respond to events other than user events, such as system events, document object model events, or other types of events.

In one implementation, instructions304are computer-executable instructions encoded in computer-readable media (discussed further below, in connection withFIGS. 8 and 9). In the examples set forth herein, instructions304are implemented using either script308or markup elements303. Although either script or markup elements may be used alone, in general, the combination of script and markup elements enables the creation of a comprehensive set of interactive capabilities for a high-definition DVD movie.

Script308includes instructions304written in a non-declarative programming language, such as an imperative programming language. An imperative programming language describes computation in terms of a sequence of commands to be performed by a processor. In most cases where script308is used, the script is used to respond to user events. Script308is useful in other contexts, however, such as handling issues that are not readily or efficiently implemented using markup elements alone. Examples of such contexts include handling aspects of the presentation of script clip255, system events, state management, and resource management (for example, accessing cached or persistently stored resources). In one implementation, script308is ECMAScript as defined by ECMA International in the ECMA-262 specification. Common scripting programming languages falling under ECMA-262 include JavaScript and JScript. In some settings, it may be desirable to implement308using a subset of ECMAScript262, such as ECMA-327.

Markup elements303represent instructions304written in a declarative programming language, such as Extensible Markup Language (“XML”). In XML, elements are logical units of information defined, using start-tags and end-tags, within XML documents. XML documents are data objects that are made up of storage units called entities (also called containers), which contain either parsed or unparsed data. Parsed data is made up of characters, some of which form character data, and some of which form markup. Markup encodes a description of the document's storage layout and logical structure. There is one root element in an XML document, no part of which appears in the content of any other element. For all other elements, the start-tags and end-tags are within the content of other elements, nested within each other.

An XML schema is a definition of the syntax(es) of a class of XML documents. Some XML schemas are defined by the World Wide Web Consortium (“W3C”). Other XML schemas have been promulgated by the DVD Forum for use with XML documents in compliance with the DVD Specifications for High Definition Video, and for other uses. It will be appreciated that other schemas for high-definition DVD movies, as well as schemas for other interactive multimedia presentations, are possible.

At a high level, an XML schema includes: (1) a global element declaration, which associates an element name with an element type, and (2) a type definition, which defines attributes, sub-elements, and character data for elements of that type. Attributes of an element specify particular properties of the element using a name/value pair, with one attribute specifying a single element property.

With continuing reference toFIGS. 1-3,FIG. 4is a simplified functional block diagram illustrating various components of timing signal management block108and timing signals158in more detail.

Timing signal management block108is responsible for the handling of clocks and/or timing signals that are used to determine specific times or time durations within Presentation System100. As shown, a continuous timing signal401is produced at a predetermined rate by a clock source402. Clock source402may be a clock associated with a processing system, such as a general-purpose computer or a special-purpose electronic device. Timing signal401produced by clock source402generally changes continually as a real-world clock would—within one second of real time, clock source402produces, at a predetermined rate, one second worth of timing signals401.

Timing signal401is input to IC frame rate calculator404, media frame rate calculator406, time reference calculator408, and time reference calculator490. IC frame rate calculator404produces a timing signal405based on timing signal401. Timing signal405is referred to as an “IC frame rate,” which represents the rate at which frames of IC data134are produced by IC manager104. One exemplary value of the IC frame rate is 30 frames per second. The frequency of IC frame rate405(referred to as the “presentation clock frequency”) may dynamically change, however. It will also be appreciated that the processing load within various components of Presentation System100may change based on the presentation clock frequency. IC frame rate calculator404may reduce or increase the rate of timing signal401to produce timing signal405.

Frames of IC data134generally include, for each valid application155and/or page thereof, a rendering of each interactive object125associated with the valid application and/or page in accordance with relevant user events. For exemplary purposes, a valid application is one that has an application presentation interval321within which the current title time of play duration292falls, based on presentation timeline130. It will be appreciated that an application may have more than one application presentation interval. It will also be appreciated that no specific distinctions are made herein about an application's state based on user input or resource availability.

Media frame rate calculator406also produces a timing signal—timing signal407—based on timing signal401. Timing signal407is referred to as a “media frame rate,” which represents the rate at which frames of media data132are produced by media content manager102. The media frame rate may be the same as, or different from, IC frame rate405. One exemplary value of the media frame rate is 24 frames per second. The frequency of media frame rate407may dynamically change, however, media frame rate calculator406may reduce or increase the rate of timing signal401to produce timing signal407.

A clock source470produces timing signal471, which governs the rate at which information associated with clips123is produced from media sources161. Clock source470may be the same clock as clock402, or based on the same clock as clock source402. Alternatively, clocks470and402may be altogether different, and/or have different sources. Likewise, media frame rate407may be the same as, or based on the same value as, timing signal471, or the timing signals may be different.

Clock source470adjusts the rate of timing signal471(which is referred to as the “media clock frequency”) based on a media state indicator signal481, which is produced by media state indicator block480. Media state indicator signal481represents a particular retrieval state of video, audio, or data information from a particular media source160(shown inFIG. 1). Such retrieval states may be directly or indirectly based on user input, or on the content of playlist128(also shown inFIG. 1). The media clock frequency may also vary based on media source characteristics162such as encoding or decoding rates. Thus, the media clock frequency may change from clip to clip.

Certain user input changes the play speed of played presentation127, and thus the speed of retrieval of video, audio, or data information from a particular media source160. For example, played presentation127may proceed in a forward direction at a normal speed, and may also proceed in both forward and reverse directions at speeds faster or slower than the normal speed. It will appreciated that normal speed is a relative term, and that normal speed may vary from presentation to presentation, and from clip to clip.

Retrieval states of video, audio, or data information from a particular media source may be defined based on various play speeds of played presentation127. For example, a normal play retrieval state is defined to occur when played presentation127proceeds in a forward direction at normal speed. A slow-forward retrieval state is defined to occur when played presentation127proceeds in a forward direction but slower than in real time. A fast-forward retrieval state is defined to occur when played presentation127proceeds in a forward direction but faster than in real time. A slow-reverse retrieval state is defined to occur when played presentation127proceeds in a reverse direction but slower than in real time. A fast-reverse retrieval state is defined to occur when played presentation127proceeds in a reverse direction but faster than in real time.

During fast-reverse and fast-forward retrieval states, the playing of certain media content is often skipped. Other user input may cause the playing of certain content to be skipped, such as when the user jumps from one part of the movie to another (by making selections from interactive menus such as menu280, for example). The user may also start and stop the movie at various places and at various times.

Retrieval states associated with locating and/or beginning to play video, audio, or data information associated with a particular clip123from a particular media source160may also be defined. For example, a closed state is defined to occur before video, audio, or data information associated with a particular clip123has been read from a particular media source160. A ready state is defined to occur when a first group of samples of video, audio, or data information from a particular media source160has been decoded and is ready to be rendered. A pre-rolling state is defined to occur between the closed state and the ready state, when steps are being taken to prepare the first group of samples of video, audio, or data information from a particular media source160for rendering. Such steps include, but are not limited to, reading information from a particular media source160, and demulitplexing, decoding and/or decrypting the information. It will be understood that the first group of samples of information from a particular media source is not necessarily the first group of samples occurring within a particular clip123, and that how a first group of samples is defined may vary from presentation to presentation, based on factors such as encoding or encryption formats or protocols.

Elapsed clip play times452represent the amounts of time that have elapsed within particular presentation intervals240associated with active clips123. For purposes of discussion herein, an active clip is one that has a presentation interval240(shown inFIG. 2) within which the current title time of play duration292falls, based on presentation timeline130. Time reference calculator454receives time references452and produces a media time reference455. Media time reference455represents the total amount of play duration292that has elapsed based on one or more time references452. In general, when two or more clips are playing concurrently, only one time reference452is used to produce media time reference455. The particular clip used to determine media time reference455, and how media time reference455is determined based on multiple clips, is a matter of implementation preference.

Time reference calculator408receives timing signal401, media time reference455, and media state indicator signal481, and produces a title time reference409. Title time reference409represents the total amount of time that has elapsed within play duration292based on one or more of the inputs to time reference calculator408.

Time reference calculator490receives timing signal401and title time reference409, and produces application time reference(s)492and page time reference(s)494. A single application time reference492represents an amount of elapsed time of a particular application play duration320(shown and discussed in connection withFIG. 3), with reference to continuous timing signal401. Application time reference492is determined when title time reference409indicates that the current title time falls within application presentation interval321of the particular application. Application time reference492re-sets (for example, becomes inactive or starts over) at the completion of application presentation interval321. Application time reference492may also re-set in other circumstances, such as in response to user events, or when trick play occurs.

Page time reference494represents an amount of elapsed time within a play duration for a particular page of an application, with reference to continuous timing signal401. Page time reference494for a particular page of an application is determined when title time reference409indicates that the current title time falls within an applicable page presentation interval (not shown). Page presentation intervals are sub-intervals of application presentation intervals321(shown inFIG. 3). Page time reference(s)494may re-set at the completion of the applicable page presentation interval(s) (not shown). Page time reference494may also re-set in other circumstances, such as in response to user events, or when trick play occurs. It will be appreciated that interactive object presentation intervals, which may be sub-intervals of application presentation intervals321and/or page presentation intervals, are also definable.

Table 1 illustrates exemplary occurrences during play of played presentation127by Presentation System100, and the effects of such occurrences on application time reference492, page time reference494, title time reference409, and media time reference455.

Having access to various timelines, clock sources, timing signals, and timing signal references enhances the ability of Presentation System100to achieve frame-level synchronization of IC data124and media data132within played presentation127, and to prioritize the glitch-free presentation of the clips that comprise media component122.

With continuing reference toFIGS. 1-4,FIG. 5is a flowchart of one method for enhancing the ability of a presentation system, such as Presentation System100, to present the media content of a particular presentation, such as clips123shown on presentation timeline130ofFIG. 2, in a glitch-free manner.

The method begins at block500, and continues at block502, where, at a first time, playing of a first set of media samples from a first media source commences. Next, at block504, a second set of media samples, playable at a second time from a second media source, is identified. A static characteristic of the second media source is ascertained, at block506. A dynamic characteristic of the presentation system is also ascertained, at block508. Next, at block510, a time offset value is determined based on the static and dynamic characteristics. Finally, at block512, the second set of media samples is pre-rendered at a time that is based on the time offset value.

For exemplary purposes, the method of the flowchart ofFIG. 5is discussed in the context of Presentation System100, particularly with reference to media component122and applications155presentable to a user in accordance with presentation timeline130(shown inFIG. 2).

Referring toFIG. 2, it is desirable to ensure the glitch-free play of media clip1230, media clip2250, media clip3251, media clip4253, and to maximize the play time of script clip255, in an environment where processing and decoding resources are limited. In one implementation, Presentation System100has one central processing unit, one graphics processing unit, and one decoder, although other arrangements are possible. It is therefore desirable that the ready retrieval state (represented by media state indicator signal481, shown and discussed in connection withFIG. 4) for at least a portion of each clip be reached at or before the title time at which the clip is scheduled for presentation on presentation timeline130. In this regard, it is important to leave adequate time for completing the pre-rolling retrieval state (also discussed in connection withFIG. 4), but it is also important to minimize undue negative effects on other important activities occurring within the presentation system, such as the playing of script clip255or other clips. Pre-rendering activities occurring within the pre-rolling retrieval state for a particular clip may result in another clip being stopped. One way in which undue negative effects can be minimized is by completing the pre-rolling retrieval state close to or at the title time at which the clip is scheduled for presentation.

In one instance, it is desirable to reach the ready state for at least a portion of media clip3251at or before TT3295, which is the time at which a transition occurs between the playing media clip1230via media pipeline1and the playing of media clip3251via media pipeline2. Because the transition at TT3295occurs while media clip2250is playing via media pipeline1(and thus there is an existing media processing load), waiting until at or too close to TT3295to enter the pre-rolling retrieval state for a portion of media clip3251could result in the user experiencing a glitch at TT3. For example, if video is scheduled for play at TT3, the video may pause for a few seconds, or some video may be dropped; if audio is scheduled for play at TT3, there may be silence for a few seconds, or some audio may be dropped. Glitches may occur with respect to play of media clip2250, media clip3251, or both media clip2250and media clip3251.

In another instance, it is desirable to reach the ready state for at least a portion of media clip4253, which is played via media pipeline2, at or before TT6298. Because the transition at TT6298occurs while script clip255is playing via media pipeline1, waiting until at or too close to TT6298to enter the pre-rolling retrieval state for a portion of media clip4253could result in the user experiencing a glitch at TT6. Entering the pre-rolling retrieval state for a portion of media clip4253too soon, however, could have the undesirable effect of reducing the play time of script clip255.

Accordingly, it is desirable to determine pre-rendering times220for at least portions of media clip3251and media clip4253. When play of Presentation Content120/played presentation127is occurring in a forward direction, the pre-rendering time for media clip3251occurs prior to TT3295, and the pre-rendering time220for media clip4253occurs prior to TT6298. It will be appreciated that pre-rendering times may also be provided for play that occurs in a reverse direction.

Pre-rendering times220are generally determined based on a time offset value, which is calculated one or more times during play of the preceding clip or clips. In one implementation, one or more steps associated with determining the time offset value may be performed when play of the preceding clip(s) commences, and one or more steps may be repeated at other times during play of the preceding clip(s), as the time for rendering the next clip approaches (but before the pre-rendering time is reached).

One aspect of the time offset value is determined by ascertaining one or more media source characteristics162(shown inFIG. 1) of the media source160from which the subsequently playable clip is receivable. Media source characteristics162such as the location of the media source, codec parameters or settings (such as encoding or decoding formats or protocols, GOP size settings, compression settings, or quality settings), or encryption parameters or settings (such as encryption types, formats, or protocols) affect the processing or decoding resources (and thus the time) needed to complete the pre-rolling retrieval state for a particular clip or portion thereof. The size of the portion of the clip to be decoded is also a static characteristic that may affect the time needed to complete the pre-rolling retrieval state.

In the instances of determining pre-rendering times for portions of media clip3251and media clip4253, one or more media source characteristics162of media source1and media source2, respectively, are ascertained. In one implementation, one or more media source characteristics162of media source1are stored in a data structure such as a table. One or more media source characteristics162of media source2are also stored in a data structure such as a table. The data structures storing media source characteristics of media source1and media source2may be the same data structures or different data structures. The data structure(s) are accessed or stored by media content manager102and communicated to presentation manager106. Media content manager102may communicate the data structures themselves, or time offset values having initial, or default, values based on the data structures. Alternatively, presentation manager106(or another component of Presentation System100) accesses the media source characteristic(s) and/or the data structure(s) directly, and determines initial time offset values.

A second aspect of the time offset value is determined by ascertaining one or more dynamic characteristics of Presentation System100. Dynamic characteristics represent conditions affecting processing or decoding operations that may change during operation of Presentation System100. Examples of dynamic characteristics include, but are not limited to, the media clock frequency, the presentation clock frequency, the media processing load, the general processing load, and the value(s) of media state indicator signal481.

In the instances of determining pre-rendering times for portions of media clip3251and media clip4253, one or more dynamic characteristics of Presentation System100could affect (for example, increase) the initial time offset value(s) established with reference to the static characteristic(s) of a particular media source. In general, when the processing or decoding load within Presentation System100is high, more time is required to complete the pre-rolling retrieval state, and the time offset value is increased.

The processing and/or decoding load is increased in various situations, such as when the media processing load is increased (for example, multiple clips are playing concurrently and/or the media clock frequency is high), when the graphics processing load is increased (for example, the presentation clock frequency is high), when the general processing load is increased (for example, other programs, such as anti-virus programs, are running concurrently), and when media state indicator signal481indicates a retrieval state that is other than the normal play retrieval state (for example, played presentation is proceeding in the forward or reverse direction at speeds faster or slower than the normal speed).

Receiving user input that affects the play speed of media component122(such as trick play, pausing, slow-forwarding, fast-forwarding, slow-reversing, or fast-reversing) can exacerbate the problem of presenting media component122in a glitch-free manner, because more processing and decoding resources are used to predict and prepare certain portions of active clips from media source(s)160during times when the play speed of media component122is affected than when media component122proceeds at normal speed.

FIG. 6is a schematic of an exemplary media timeline142(with reference to media frame rate407), which illustrates certain processing steps associated with playing media content122at speeds other than normal speed in the forward direction. Various frame number presentation times602are indicated on media timeline142. Frame number presentation times602represent times within play duration292(shown inFIG. 2) at which individual numbered sets of media data132are presentable. As shown, frame number presentation times602occur at a rate based on media frame rate407, which also defines the duration of periodic media time intervals604between frame number presentation times602. Note that it is not necessary for media frame rate407to be the same as the frame rate at which a particular clip123was encoded, although the media clock frequency may change based on the encoding frame rate for a particular clip. IC frame rate405(not shown) is assumed to be 30 frames per second (although the presentation clock frequency may also change dynamically).

A current elapsed play time608of play duration292is shown on media timeline142. Current elapsed play time608may be the current value of title time409, for example. A next presentable frame number presentation time614is also shown. Next presentable frame number presentation time614represents the frame number presentation time602associated with the next frame number (after the frame number associated with current elapsed play time709/title time409) that is presentable to a user. It will be appreciated that the next presentable frame number may be the next consecutive frame number based on playlist128, or may be a frame number one or more frame number presentation times602away from the frame number associated with current elapsed play time608. During normal play speed, subsequent IC presentation time712is selected by adding an amount based on IC frame rate407to current IC presentation time710.

When media state indicator signal481indicates that a play state is other than normal play speed (for example, fast-forward or fast-reverse), however, one way to ascertain next presentable frame number time614is to predict an amount of elapsed time620of play duration292(in addition to current elapsed play time608/title time409) that has passed based on the play speed and media frame rate407.

In one implementation, the predicted amount of elapsed time620is calculated by estimating how many predicted frame number presentation times602on media timeline142have passed since presentation of media content at current elapsed play time608/title time409. For example, the predicted amount of elapsed time620may be calculated by adding a multiplier value to current elapsed play time608. The multiplier value is obtained by multiplying a play speed factor (which may be a positive or a negative number, depending on the direction of the play speed change), by a frame rate factor. The play speed factor is obtained by dividing a value representing the play speed by media frame rate407. The frame rate factor is obtained by dividing media frame rate407by IC frame rate405.

Then, the predicted amount of elapsed time620is used to locate the particular frame number presentation time602that will be the next presentable frame number presentation time614. Often, at various play speeds, patterns can be observed between the predicted amount of elapsed time620(and frame number presentation times602corresponding thereto) and corresponding next presentable frame number presentation times614. Recognizing such patterns may reduce the need to perform calculations at each frame number presentation time602. The patterns can be represented in predetermined tables or other data structures, which can be used to look up next frame number presentation times614based on particular frame number presentation times602. Using predetermined data structures or tables in this manner, rendering of certain frames and other adjustments may be skipped. In addition, multiple media timelines may be processed concurrently (in an instance where more than one clip is playing, for example).

Referring again to the flowchart ofFIG. 5, it can be seen that accurately accounting for one or more dynamic characteristics of Presentation System100assists in determination of time offset values (and thus pre-rendering times220) that allow the pre-rolling and ready retrieval states for upcoming media clips to be completed at or around the times the media clips are scheduled for play. In the instances of determining pre-rendering times for portions of media clip3251and media clip4253, the time offset value could be increased in the presence of one or more dynamic characteristics, such as the presentation clock frequency, the media clock frequency, or the current retrieval state indicated by media state indicator signal481, to provide more time for completing pre-rolling retrieval states.

In one implementation, the time offset value used for determining pre-rendering time220for a particular clip is arrived at via negotiation between presentation manager106and media content manager102. Presentation manager106starts with the initial, or default, time offset value determined with reference to one or more static characteristics of the media source of the upcoming clip (which in one implementation is received or ascertainable from media content manager102via one or more data structures such as tables). Then, presentation manager106adjusts the initial time offset value (one or more times during play of the current clip(s)) based on one or more dynamic characteristics. The adjusted time offset value is communicated to media content manager102, which further adjusts the time offset value based on the current media processing load, and communicates the further adjusted time offset value to presentation manager106. Then, presentation manager106instructs media content manager102to place the upcoming clip into the pre-rolling retrieval state at a particular pre-rendering time220based on the further adjusted time offset value. Other implementations are also possible. In one alternative implementation, if media content manger102has knowledge of the upcoming clip(s), media content manager102could determine the pre-rendering time directly. In another alternative implementation, a single component of Presentation System100could determine the time offset values and/or the pre-rendering times.

The process(es) illustrated inFIG. 5may be implemented in one or more general, multi-purpose, or single-purpose processors, such as processor702discussed below in connection withFIG. 7. Unless specifically stated, the methods described herein are not constrained to a particular order or sequence. In addition, some of the described method or elements thereof can occur or be performed concurrently.

FIG. 7is a block diagram of a general-purpose computing unit700, illustrating certain functional components that may be used to implement, may be accessed by, or may be included in, various functional components of Presentation System100. One or more components of computing unit700may be used to implement, be accessible by, or be included in, IC manager104, presentation manager106, and media content manager102. For example, one or more components ofFIG. 7may be packaged together or separately to implement functions of Presentation System100(in whole or in part) in a variety of ways.

A processor702is responsive to computer-readable media704and to computer programs706. Processor702, which may be a real or a virtual processor, controls functions of an electronic device by executing computer-executable instructions. Processor702may execute instructions at the assembly, compiled, or machine-level to perform a particular process. Such instructions may be created using source code or any other known computer program design tool.

Computer-readable media704represent any number and combination of local or remote devices, in any form, now known or later developed, capable of recording, storing, or transmitting computer-readable data, such as the instructions executable by processor702. In particular, computer-readable media704may be, or may include, a semiconductor memory (such as a read only memory (“ROM”), any type of programmable ROM (“PROM”), a random access memory (“RAM”), or a flash memory, for example); a magnetic storage device (such as a floppy disk drive, a hard disk drive, a magnetic drum, a magnetic tape, or a magneto-optical disk); an optical storage device (such as any type of compact disk or digital versatile disk); a bubble memory; a cache memory; a core memory; a holographic memory; a memory stick; a paper tape; a punch card; or any combination thereof. Computer-readable media704may also include transmission media and data associated therewith. Examples of transmission media/data include, but are not limited to, data embodied in any form of wireline or wireless transmission, such as packetized or non-packetized data carried by a modulated carrier signal.

Computer programs706represent any signal processing methods or stored instructions that electronically control predetermined operations on data. In general, computer programs706are computer-executable instructions implemented as software components according to well-known practices for component-based software development, and encoded in computer-readable media (such as computer-readable media704). Computer programs may be combined or distributed in various ways.

Functions/components described in the context of Presentation System100are not limited to implementation by any specific embodiments of computer programs. Rather, functions are processes that convey or transform data, and may generally be implemented by, or executed in, hardware, software, firmware, or any combination thereof, located at, or accessed by, any combination of functional elements of Presentation System100.

With continued reference toFIG. 7,FIG. 8is a block diagram of an exemplary configuration of an operating environment800in which all or part of Presentation System100may be implemented or used. Operating environment800is generally indicative of a wide variety of general-purpose or special-purpose computing environments. Operating environment800is only one example of a suitable operating environment and is not intended to suggest any limitation as to the scope of use or functionality of the system(s) and methods described herein. For example, operating environment800may be a type of computer, such as a personal computer, a workstation, a server, a portable device, a laptop, a tablet, or any other type of electronic device, such as an optical media player or another type of media player, now known or later developed, or any aspect thereof. Operating environment800may also be a distributed computing network or a Web service, for example. A specific example of operating environment800is an environment, such as a DVD player or an operating system associated therewith, which facilitates playing high-definition DVD movies.

As shown, operating environment800includes or accesses components of computing unit700, including processor702, computer-readable media704, and computer programs706. Storage804includes additional or different computer-readable media associated specifically with operating environment800, such as an optical disc, which is handled by optical disc drive806. One or more internal buses920, which are well-known and widely available elements, may be used to carry data, addresses, control signals and other information within, to, or from computing environment800or elements thereof.

Input interface(s)808provide input to computing environment800. Input may be collected using any type of now known or later-developed interface, such as a user interface. User interfaces may be touch-input devices such as remote controls, displays, mice, pens, styluses, trackballs, keyboards, microphones, scanning devices, and all types of devices that are used input data.

Output interface(s)810provide output from operating environment800. Examples of output interface(s)810include displays, printers, speakers, drives (such as optical disc drive806and other disc drives), and the like.

External communication interface(s)812are available to enhance the ability of operating environment800to receive information from, or to transmit information to, another entity via a communication medium such as a channel signal, a data signal, or a computer-readable medium. External communication interface(s)812may be, or may include, elements such as cable modems, data terminal equipment, media players, data storage devices, personal digital assistants, or any other device or component/combination thereof, along with associated network support devices and/or software or interfaces.

FIG. 9is a simplified functional diagram of a client-server architecture900in connection with which the Presentation System100or operating environment900may be used. One or more aspects of Presentation System100and/or operating environment800may be represented on a client-side902of architecture900or on a server-side904of architecture900. As shown, communication framework903(which may be any public or private network of any type, for example, wired or wireless) facilitates communication between client-side902and server-side904.

On client-side902, one or more clients906, which may be implemented in hardware, software, firmware, or any combination thereof, are responsive to client data stores908. Client data stores908may be computer-readable media704, employed to store information local to clients906. On server-side904, one or more servers910are responsive to server data stores912. Like client data stores908, server data stores912may include one or more computer-readable media704, employed to store information local to servers910.

Various aspects of a presentation system that is used to present interactive content to a user synchronously with media content have been described. It will be understood, however, that all of the described components of the presentation system need not be used, nor must the components, when used, be present concurrently. Functions/components described in the context of Presentation System100as being computer programs are not limited to implementation by any specific embodiments of computer programs. Rather, functions are processes that convey or transform data, and may generally be implemented by, or executed in, hardware, software, firmware, or any combination thereof.

Although the subject matter herein has been described in language specific to structural features and/or methodological acts, it is also to be understood that the subject matter defined in the claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

It will further be understood that when one element is indicated as being responsive to another element, the elements may be directly or indirectly coupled. Connections depicted herein may be logical or physical in practice to achieve a coupling or communicative interface between elements. Connections may be implemented, among other ways, as inter-process communications among software processes, or inter-machine communications among networked computers.

The word “exemplary” is used herein to mean serving as an example, instance, or illustration. Any implementation or aspect thereof described herein as “exemplary” is not necessarily to be constructed as preferred or advantageous over other implementations or aspects thereof.

As it is understood that embodiments other than the specific embodiments described above may be devised without departing from the spirit and scope of the appended claims, it is intended that the scope of the subject matter herein will be governed by the following claims.