Apple Files Patent Relating Audio/Video Control
On February 1, the US Patent & Trademark Office published Apple’s patent application titled Transmission of AV/C transactions over multiple transports method and apparatus which was originally filed in September 2006. Apple’s patent relates to implementing Audio/Video Control (AV/C) device communication systems, as in the AV/C Digital Interface Command Set specified by IEEE 1394. More particularly, the patent relates to techniques for implementing the AV/C data packets over multiple transports.
Apple first lays out the problem by stating that “the current AV/C transport layer, FCP, is a rather low performance transport protocol. While initially AV/C was designed as a low speed protocol for controlling AV devices such as camcorders, it is now being used as a file system protocol for AV storage devices such as AV disk drives. This new use will require a higher performance transport protocol for applications such as home AV servers. Such transports may be asynchronous connections or Serial Bus Protocol (SBP) connections.
In addition, certain standards bodies, such as the Video Electronics Standards Association (VESA), are specifying the transport of AV/C via IP over non-1394 networks such as ethernet. Current implementations of the AV/C protocol will not only need to support transports other than FCP but will need to simultaneously support multiple transports for AV/C control of devices with different transport capabilities. Thus, a method is required for separating the AV/C protocol implementation from the AV/C transport implementation and that also supports multiple transports running simultaneously.”
Apple’s Summary
To overcome these and other shortcomings of the prior art, this invention separates the implementation of the AV/C protocol from the implementation of the AV/C transport. In addition, it allows the transport of AV/C commands over more than one transport simultaneously. Thus, this invention allows the AV/C protocol implementation to communicate over higher performance transports such as asynchronous connections or SBP and non 1394 transports such as IP over ethernet or various wireless transports. This invention also allows the AV/C protocol to operate over multiple FCP transports that may exist over multiple 1394 networks connected to the same node.
This invention separates the implementation of the AV/C protocol layer and the AV/C transport layer. This invention defines an AV/C transport controller as a software plug-in that provides AV/C transport services to the AV/C protocol layer. The AV/C transport services provided by the AV/C transport controller abstract the implementation of the particular AV/C transport. The services are the same regardless of the type of transport (FCP, asynchronous connections, SBP, ethernet, etc.).
Each AV/C transport controller may control multiple transport instances (or transports). For example, a node containing two 1394 link interfaces and an AV/C FCP transport controller would have two instances of AV/C FCP transports.
For each available AV/C transport, the AV/C protocol layer maintains an AV/C transport reference. For each device with which it communicates, the AV/C protocol layer associates an AV/C transport reference indicating both the AV/C transport controller and the specific AV/C transport instance used to transport AV/C commands to the device.
Each AV/C transport controller is responsible for enumerating the available AV/C transport instances. For each available transport instance, the AV/C transport controller creates an AV/C transport reference and presents it to the AV/C protocol layer.
The set of AV/C transport services provided by an AV/C transport controller include handling of requests to transmit an AV/C command or response, indication of receipt of AV/C commands or responses, and indication of new devices able to communicate over the AV/C transport.
It is therefore an object of the present invention to provide a system for communicating AV/C data packets between devices without regard to protocols. It is another object of the present invention to provide a method for transmitting AV/C transactions over multiple transports without regard for protocols. It is yet another object of the present invention to provide a system for transmitting AV/C data across an IP or other non-FCP network.
Apple’s Vantage Points
Viewed from a first vantage point, an AV/C transaction data delivery system is disclosed, comprising in combination at least one transport controller; an AV/C transport layer in operative communication with the at least one transport controller; and an AV/C protocol layer in operative communication with the AV/C transport layer, the AV/C protocol layer including means for sending AV/C transaction data over more than one transport.
Viewed from a second vantage point, a method for establishing transport routing information in an AV/C transaction data delivery system is disclosed, comprising in combination detecting a transport; creating a transport ID associated with the transport; notifying a transport layer of the transport ID; indexing the transport ID; associating the indexed transport ID with a device.
Viewed from a third vantage point, a method for sending AV/C transaction data in an AV/C transaction data delivery system is disclosed, comprising in combination receiving AV/C transaction data for transport; associating the AV/C transaction data with a transport ID; providing the AV/C transaction data and transport ID to a transport layer; associating the transport ID with a transport controller bus ID; and providing the AV/C transaction data to a transport controller data record associated with the bus ID.
Viewed from a fourth vantage point, a method for receiving AV/C transaction data in an AV/C transaction data delivery system is disclosed, comprising in combination receiving AV/C transaction data by a transport controller and associating the data with a link ID; converting the link ID to a data record and a bus ID; providing the bus ID and the data to a transport layer; associating the bus ID with a transport ID; and providing the transport layer ID and data to a protocol layer.
Patent Illustrations
Apple’s Patent FIG. 2 illustrates a block diagram of one embodiment of the present invention. Noted below in Patent FIG. 3, is a schematic diagram of the AV/C Transaction Data Delivery System of the present invention.
Apple lists Erik P. Staats as the sole inventor of this patent.
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Written and researched by Neo.
