摘要:
A system and method for distributing real-time, compressed, digital video data from a video library composed of multiple mass storage devices through a digital video data server to large numbers of viewers via distribution networks is provided. The server obtains selected frames of video data for viewer-requested programs from high-speed memory using a buffering strategy, replicates the data via a multi-cast technique for each viewer listed in an assigned synchronization group and forwards the data to each viewer's site where it is decompressed, decoded, and converted for display on a television monitor or computer display. Each viewer maintains interactive control over the transmission of the digital video data.
摘要:
A method of and apparatus for efficiently providing video on demand services to a cable television subscriber. The provider system consists of two major subsystems. The first subsystem, called a video server, streams video to video on demand subscribers through the cable television network. The second subsystem, called the transaction server, performs virtually all remaining provider functions including, security, accounting, storage and spooling of video data, etc. The transaction server preferably uses a large scale mainframe computer. The video server subsystem may be a partitioned portion of same large scale mainframe computer.
摘要:
In order to implement alternative pathways and procedures for handling a separate set of software locks, an arrangement of circuits is described. These circuits allow for generating and handling specific requests for communal software locks without additional software development through pathways and procedures separate from ordinary lock handling operations. A side door communications pathway is set up to handle the communal locks separately from the ordinary data transfer pathways through which ordinary software locks get handled. Supporting and controller circuits handle the locking and unlocking process as well as communicating results of lock requests back to requesters.
摘要:
An apparatus and method of efficiently recovering from physical disk drive (or logical file) failures in transaction based digital data processing systems. As transactions are sequentially processed, compacted audit trail records are prepared to indicate modifications resulting from each transaction. The audit trail records are stored in storage areas on a disk drive in accordance with the physical data base disk drive(s) or logical file(s) to which the corresponding transaction refers. A physical disk drive or logical file is dumped to magnetic tape whenever the associated audit trail storage area is full, thus clearing the audit trail storage area for further use. When a physical disk drive or logical file fails, the most recent dump is read. Modifications to each file of the dump are made as compacted audit trail data is processed. The modified files are destaged to a spare disk drive.
摘要:
A system and method for maintaining a backup data base. An initial backup copy of a data base is made and stored separate from an active primary data base. Each time the primary data base is updated, audit information pertaining to the data base update is stored in non-volatile storage. A recovery processor continuously reads the audit information from the non-volatile storage and updates the backup data base accordingly, thereby maintaining a backup data base which is nearly up-to-date with the primary data base.
摘要:
Apparatus for measuring the rate of occurrence and duration of digital events through the technique of multiple sampling at times random to the occurrence of the digital events. The digital events to be sampled are represented as the presence or absence of binary ones or zeroes that can be sensed in a subject conductor at a given point in time. Since the probability of sensing a binary state of true or false at any particular but randomly determined time is a function of the duty cycle, sensing the binary state of or sampling a given digital event a given number of times produces a correspondingly statistically significant measure of the duty cycle of the digital event. The greater the number of samples, the greater the confidence in the measure of the duty cycle. The number of samples necessary to evoke a given confidence level is determined through the use of basic statistics. The point in time at which sampling occurs must be random to permit statistical validity. Though true randomness may be philosophically unattainable, randomness for sampling purposes is achieved through reading a random number table stored within a programmable read only memory (PROM) in response to a time standard running synchronously to the occurrence of the digital events to be sampled. Each entry from the random number table determines whether sampling will occur when it is read from the PROM. The binary state of each subject conductor is recorded at the sampling time as an increment to a counter or increment to the contents of an addressable location in a random access memory (RAM).
摘要:
A read-only memory, adapted to be addressed by the operation code portion of a computer instruction word, stores at addressable locations therein a flag indicating whether a particular combination of operation code bits is a valid combination.