Method and system for object retransmission without a continuous network connection in a digital media distribution system

The present invention provides a method and system for object retransmission in an asynchronous environment without a continuous network connection in a digital media distributor (DMD) system. The method and system include receiving objects in a receiver from a central site, generating a response document in the receiver, and sending the response document asynchronously to the central site. The received response documents are then utilized in the central site to determine which object to retransmit to the receiver. In another aspect of the present invention, the central site manages the inventory of objects in the receiver by instructing the receiver to delete objects not needed.

RELATED APPLICATIONS

The present invention is related to co-pending U.S. patent application Ser. No. 09/420,802, entitled MULTIMEDIA INFORMATION COMPUTER SYSTEM AND METHOD OF OPERATION OF A PLAYLIST SCHEDULER; to U.S. patent application Ser. No. 09/524,082, entitled METHOD AND SYSTEM FOR OPTIMIZATION OF DISTRIBUTION TO REDUCE STORAGE REQUIREMENTS IN A DIGITAL MEDIA DISTRIBUTOR; and to U.S. patent application Ser. No. 09/523,827, entitled METHOD AND SYSTEM FOR ENSURING RELIABLE PLAYOUT IN A DMD SYSTEM, all of which are assigned to the assignee of the present invention.

FIELD OF THE INVENTION

The present invention relates to digital media distribution, and more particularly to object retransmission in an asynchronous environment without a continuous network connection in a digital media distributor (DMD) system.

BACKGROUND OF THE INVENTION

Although broadcasters have sophisticated systems for inserting national commercials into a program stream, including integrated traffic and billing systems, there are numerous obstacles to implementing a system to insert local commercials at small markets into a national program feed distributed by satellite. Until now, such local spot insertion advertising was the responsibility of the local broadcaster or cable operator.

Inserting local advertising poses several nontrivial technical, logistical and business challenges. First, literally hundreds of widely distributed local operators (or affiliates) would need to receive the commercials; ad agencies would have to ship analog tapes to hundreds of organizations, with different traffic and billing systems. These tapes would need to be tested for quality assurance, tracked, and stored until needed. They would then have to be distributed to video tape recorders and readied for computer controlled playout (analog) at the proper time, 24 hours a day, seven days a week. Such infrastructure generally exists at well-funded affiliates in major markets but is nonexistent and prohibitively expensive for smaller operators or affiliates in small markets.

Managing such tapes with ads for local commercials and inserting them properly into the program feed is a complex undertaking not well-suited for the smaller operators, especially for channels with smaller audiences in smaller markets. A quality broadcast involves more than excellent program material; it must provide seamless insertion of national and local advertisements, promotions, and station identifications.

Equally important is the ability to maintain the integrity of the national television programming. Centralized control of the channel's programming (playout) is required to prevent local affiliates from tampering with the programming.

Accordingly, a need exists for an efficient system for retransmission of digital media data in an asynchronous environment to receivers of a digital media distributor system. The present invention addresses such a need.

SUMMARY OF THE INVENTION

The present invention provides a method and system for object retransmission in an asynchronous environment without a continuous network connection in a digital media distributor (DMD) system. The method and system include receiving objects in a receiver from a central site, generating a response document in the receiver, and sending the response document asynchronously to the central site. The received response documents are then utilized in the central site to determine which object(s) to retransmit to the receiver. In another aspect of the present invention, the central site manages the inventory of objects in the receiver by instructing the receiver to delete objects not needed.

Through a method and system in accordance with the present invention, the central site manages object retransmission to the receiver in an asynchronous environment without a continuous network connection. Particularly through the implementation of the present invention, streamlined management of retransmission ensures efficient and accurate delivery of objects to the receivers.

DETAILED DESCRIPTION

The present invention relates to digital media distribution, and more particularly to object retransmission in an asynchronous environment without a continuous network connection in a DMD system. Objects include assets or spots, which are media files, and system supporting files, which are non-media files. The following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the preferred embodiment and the generic principles and features described herein will be readily apparent to those skilled in the art. Thus, the present invention is not intended to be limited to the embodiment shown but is to be accorded the widest scope consistent with the principles and features described herein.

In accordance with the present invention, a DMD system provides a complete end-to-end system that gives local cable or network affiliates the ability to provide local ads and announcement insertion together with the delivery of cable or network feeds. In general, the DMD integrates the entire process of sales, traffic, digital encoding and storage of spots, transmission of data, local insertion of digital ads and announcements, account reconciliation, and billing. Assets (i.e., media such as commercials, station identification, public service announcements, etc.) are digitized by the cable or network operator, and then digitally transmitted to the local cable head-ends or network affiliates from a central site. These digital assets are then stored on the receiver servers located at each head-end or affiliate.

A block diagram of a DMD in accordance with the present invention is illustrated inFIG. 1. As shown, the DMD includes three major components: a central site10, a distribution network12, and a receiver14. Generally, receivers14are grouped into zones. All receivers14within the same zone play the same material at the same time, including all network programs, national spots, local commercials, announcements, etc. The central site10is the location for the digital encoding of MPEG-2 files from source video tapes, storage and management of digital files, management of receivers14, and distribution of schedules and MPEG-2 files. Thus, the processing, analysis, distribution, and management of data occurs at the central site10. The distribution network12is the mechanism by which the receiver(s)14receive program streams and digital spots. The data distribution is accomplished via various methods, such as a satellite and/or land-based distribution. The broadcaster may choose to have the program stream sent via terrestrial links (e.g., token ring, ethernet, etc.), while the spot insertion is sent via satellites or vice versa.

Each of the receivers14house a receiver server16. By way of example, a suitable receiver server16includes a Pentium processor-based device with a hard disk for local storage and a video switch card (to switch between program and commercial insertion) running software including Windows NT, DMD programming, Lotus Notes client, Program Loader, and Symantec pcANYWHERE. These unattended, computerized systems receive the local insertion and provide As-Run file generation. The receiver server16is a video server that receives and stores digitized spots utilized for local insertion at the cable head-end. The receiver server16receives digitally encoded ads via satellite or other distribution network. These spots are decoded to an analog signal and inserted into the cable or network operator feed at scheduled times, i.e., into scheduled local availability times. The receiver server16can be customized in various configurations based on the number of output channels required, the type of output format (e.g., NTSC, PAL), the amount of local storage required (i.e., the number of spots on disk), the type of network (satellite or terrestrial), the type of trigger for spot insertion (e.g., time of day, VITC, cue-tome, VBI trigger), the audio format and connections (stereo, mini-XLR or XLR), the redundancy requirements (RAID, mirrored disks), and the preview channel.

By way of example, the following provides a sample process that illustrates an example of one process which the DMD solution can support. A zone, defined by cable or network operators in an area, sells a commercial in the local availability time. The videotaped segment for the commercial is digitally encoded. The digital material is scheduled for delivery to each receiver server16prior to broadcast. The playlist, digitized spots, and the broadcast program stream are sent, via satellite, to all of the receiver servers16within the zone. All of the receivers14within the zone air the local spots for that zone at the scheduled time. As-Run logs are retrieved by the central site10from the receiver servers16. As-Run logs are sent to the local markets, reviewed, reconciled, and customers are billed. Commercials and As-Run logs are then archived.

The central site10efficiently distributes objects and thus manages the resources of the receivers14. By managing these resources, the central site10can determine when to send information to the receivers14. A main component in producing the management of the resources is the central site server18. By way of example, a suitable central site server18includes an IBM RS/6000 F50 dual CPU system, or a Pentium II compatible PC, running the IBM UNIX operating system, AIX, DB2 server software, Lotus Notes server software, ADSM, Windows NT (for PC-based central site server), and the DMD programming. Suitable components for the control workstations19include Pentium compatible PCs running Windows NT, Lotus Notes client, DB2 client, Microsoft Internet Explorer, and DMD programming.

The central site server18includes software on a suitable computer readable medium that is architected using a layered model, in which each layer isolates the upper layers from the details of the lower layers and individual components within a layer provide a unique set of services, as is well appreciated by those skilled in the art.

FIG. 2illustrates an example of a suitable layered architecture for the central site server18. The top layer20addresses the external interfaces of the central site server18, including a graphical user interface (GUI) component20aand the interfaces to the external systems20b. The GUI component20a, e.g., using Lotus Notes, provides administrators and operators with the ability to monitor and control the DMD. The interfaces to external systems20binclude interfaces to traffic systems, which interface to the central site18by way of files exchanged on an Internet file server, for example, interfaces to receivers14which send Lotus Notes messages, and interfaces to encoder systems, which store encoded spot files in a disk pool server for retrieval by the central site server18.

Underneath the top layer is a layer24of specialized components including a stage manager component26, an uplink server component28, a transmission scheduler component30, and a response document processor component32. This layer24also includes specialized components for creating commands, managing access to all the database queues and other data stores, and providing automated agents that run based on time or events to manage the external interfaces, e.g., processing files received from traffic systems. The stage manager26manages any tape related activity, the uplink server28manages transmissions through the uplink network (12,FIG. 1), and the transmission scheduler30manages scheduling tasks. The response document processor module32analyzes and interprets responses from receivers14. Also included as a next layer is a programming layer34. The layer34includes the programming libraries and APIs (application programming interfaces) that are used to build the specialized components. The lower two layers include an operating system layer36and a hardware layer38for the fundamental operation of the central site server18, as is well appreciated by those skilled in the art.

The transmission scheduler30of layer24is responsible for managing transmissions from the central site10to the receiver servers16. The transmission scheduler30manages the transmission by executing a plurality of transforms (i.e., bodies of logic that take particular inputs and perform certain operations to produce particular outputs) and utilizing a plurality of queues, as described in co-pending U.S. patent application No. Ser. No. 09/524,082 entitled METHOD AND SYSTEM FOR OPTIMIZATION OF DISTRIBUTION TO REDUCE STORAGE REQUIREMENTS IN A DIGITAL MEDIA DISTRIBUTOR, assigned to the assignee of the present invention, and incorporated herein by reference. Receivers14, however, may not receive objects that have been transmitted from the central site due to, for example, power outages, satellite problems, or bad weather. Once communications have been reestablished, the central site10automatically begins the synchronization process and sends both additional assets and commands as needed.

In accordance with the present invention, the central site10coordinates object retransmission to the receivers14through the utilization of the response document processor (RDP) module32. The RDP module32analyzes a response document generated by each receiver14in a zone, and determines which, if any, objects to retransmit.

FIG. 3illustrates a flow diagram showing the process of generating a Response Document in the receiver in accordance with the present invention. Referring toFIGS. 1 and 3together, first the central site10transmits playout objects to the zone, where the playout objects include assets, playlists, and purge lists via step100. Next, the objects are transmitted to the receivers14via step110, and received by each receiver (1through N)14in step115. In a preferred embodiment, each receiver14utilizes the objects to manage its inventory and to ensure proper delivery of spots on time. Next, each receiver14deletes the files listed on the purge list via step120. Thereafter, each receiver14examines the assets listed on the playlist, compares them with the inventory on hand, and generates a list, the Missing Assets List via step130. The Missing Assets List provides information concerning which assets are missing and will be needed soon. The generation of the Missing Assets List is described in more detail in co-pending application Ser. No. 09/523,827 entitled, METHOD AND SYSTEM FOR ENSURING RELIABLE PLAYOUT IN A DMD SYSTEM, assigned to the assignee of the present invention, and incorporated herein by reference.

Next, each receiver14will create a log of all objects received within a predetermined time period, via step140. This log is referred to as the Delivered Files Log. The predetermined time period is referred to as the Receiver Time Window. The objects' respective received times are also recorded.

Next, each receiver14generates a Response Document, which includes the Missing Assets List and the Delivered Files Log, via step150. In a preferred embodiment, a Content List is also included. The Content List provides the receiver's14asset inventory.

Once the Response Document is complete, it is ready for delivery to the central site10. Communication between each receiver14and the central site10is asynchronous, i.e., the receiver14periodically reports back to the central site10but does not maintain a continuous network connection to the central site10. The call back times are predetermined and periodic, e.g. every thirty (30) minutes. The time period between call backs for a receiver14is referred to as the Receiver Time Window. Thus, as mentioned above, the Delivered Files Log lists the objects received by the receiver during the time between call backs to the central site10.

Next, each receiver14calls the central site10at the receiver's predetermined time, via step160. Thereafter, the receiver14delivers the Response Document to the central site10, via step170. In a preferred embodiment, the Response Document is sent to the central site10via modem. The scope of the present invention, however, is not limited to any one particular mode of transmission, as one skill in the art would appreciate that other modes of transmission, such as LAN, are available.

Object retransmission is based on the contents of the Response Documents delivered from the receivers14in a zone to the central site10. At the central site10, the Response Document Processing (RDP) module32(FIG. 2) performs a process to analyze the Response Document from each receiver14in a zone. The RDP process is a four step process to determine which objects, if any, must be retransmitted to a zone or receiver14.

The first step in the RDP process is to create a purge list for each receiver14. The second step is to perform a zone level Missing Asset Process to determine which, if any assets, to retransmit to the zone. The third step in the RDP process is to perform a zone level Delivered Files Log Process to determine which objects, if any, to retransmit to the zone. Finally, the fourth step is to perform a receiver level Delivered Files Log Process to determine which objects to retransmit to the receiver14. To understand the RDP process in more detail, refer now to the following description in conjunction with the accompanying figures.FIGS. 4 and 4Aillustrate a data flow diagram of the RDP process in accordance with the present invention.

Referring now toFIGS. 1,2, and4together, first, in step200, the central site10receives the Response Documents from the receivers14in the zone. The RDP process starts by creating a purge list for each receiver14, via step210. In this step of the process, the RDP module32analyzes the Content List (which reports the asset inventory at the receiver14) and compares that list to the asset inventory list for the zone. Assets in the receiver14, but not in the zone, are not needed and are placed on the purge list.

In the second step of the RDP process, the RDP module32performs a zone level Missing Asset process, via step230, wherein the RDP module32analyzes the Missing Assets List section of the Response Document for each receiver14and compiles the missing assets for all the receivers14in the zone. The RDP module32instructs the scheduler module30to retransmit all the missing assets to the zone, via step225. This step of the RDP process is “receiver-centric” because it is based solely on the Missing Assets Lists generated by the receivers14.

In the third step of the RDP process, the RDP module32performs zone level Delivered Files Log processing, via step230. Here, the Delivered Files Log is analyzed from the perspective of the zone. In other words, the RDP module32examines the files received by all the receivers with received times falling within a Zone Time Window. The Zone Time Window starts when the last Zone Time Window ended, and ends when the first receiver14in the zone calls back to the central site10. Therefore, because the Zone Time Window is determined by the first call back from a receiver14in the zone, the Receiver Time Window (i.e., the time period between call backs for a particular receiver) can be slightly offset from the Zone Time Window.

The RDP module32examines the Delivered Files Logs from all the receivers14, and compares that with the objects the central site10transmitted to the zone within the Zone Time Window. The RDP module32determines which objects, if any, need to be retransmitted to the zone, keeping in mind that assets in step225have already been scheduled for transmission to the zone. The RDP module32compares the objects identified in step230with the assets already in the retransmit queue from step225, via step232.

By performing step232, the RDP module32optimizes transmission efficiency to the zone because assets already in the queue in step225are not retransmitted to the zone more than once. Referring now toFIG. 4A, the scheduler30is instructed to retransmit to the zone those objects identified in step232, via step235.

The fourth and final step in the RDP process involves the RDP module32performing receiver level Delivered Files Log processing. In step240, each object in the Delivered Files Log is compared to the objects transmitted by the central site10to the zone within the Receiver Time Window. In this process step, the RDP module32determines which, if any, objects to retransmit directly to the receiver14, keeping in mind that objects identified in steps225and235are already scheduled to be retransmitted to the zone. The RDP module32compares the objects identified in step240with those already in the retransmit queue from steps225and235, via step242.

By performing step242, the RDP module32optimizes transmission efficiency to the receiver14because objects retransmitted to the zone are not retransmitted to the receiver14. In step245, the scheduler30is instructed to retransmit to the receiver14those objects identified in step242. At this point, the RDP process is complete, and the scheduler30retransmits the objects to the zone and to the receivers14, via step250.

By analyzing the objects, missing and not received, from the zone and receiver14levels, the RDP module32can ensure that all the receivers14in a zone receive the appropriate assets and command files in a timely manner. Moreover, the four step RDP process ensures that assets already slated for retransmission will not be transmitted more than once to the zone (multicast) or to an individual receiver14(uni-cast). Thus, processing time in the central site10is minimized and transmission resources are optimized. In addition, the present invention enables efficient object retransmission in an asynchronous environment without a continuous network connection, thereby offering reliable object transmission without heavier network investment.

Through the RDP module32of the present invention, Response Documents, generated by the receivers14and provided back to the central site10in an asynchronous environment, are analyzed to determine whether object retransmission is necessary. Once the RDP module32identifies objects which should have been, but were not, received by on or more receivers14in a zone, the RDP module32ensures that the objects will be retransmitted to the receivers14either through a multicast to the zone or directly. In this manner, the efficient retransmission of objects to the receivers14is achieved.