Data receiver and data transmitter

Details Data receiver and data transmitter Data receiver and data transmitter

2000-11-21

2004-02-24

Huynh, Kim (Department: 2182)

Electrical computers and digital data processing systems: input/

Input/output data processing

Input/output access regulation

C710S020000, C710S062000

Reexamination Certificate

active

06697886

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a data reception and transmission method that controls recording and playback devices for disks, tapes, or the like via a digital interface.
BACKGROUND ART
In recent years, the IEEE (The Institute of Electrical and Electronics Engineers, Inc.) 1394 method has been attracting attention as a serial transmission method. The IEEE 1394 method can be used not only for the transmission of computer data traditionally supported by SCSI (small computer system interface) and other systems, but also for the transmission of AV data such as audio and video data. This is because two communication methods, asynchronous and isochronous, are defined for the IEEE 1394 method. Isochronous communication is a data transmission method that can be used for the transmission of data such as AV data that has a real-time requirement. In isochronous communication, the bandwidth required for the transmission of data is secured prior to the initiation of the transmission. Then, the data transmission is performed using the thus secured bandwidth. This ensures the real time transmission of the data. Asynchronous communication, on the other hand, is a transmission method used for the control of devices and the transmission of data such as computer data that does not have a real-time requirement.
Various methods have been proposed to provide transmission protocols for IEEE 1394. One of them is a protocol called the AV protocol. The AV protocol is expected to be standardized as IEC (International Electrotechnical Commission) 61883, and defines such methods as isochronous transmission and reception of time-critical AV data and asynchronous transmission and reception of commands to be given to devices.
IEEE 1394 uses a concept called “plug” in order to handle the input and output of AV data in AV playback devices or recording/playback devices for compact discs (hereinafter CDs), minidiscs (hereinafter MDs), etc. The plugis a virtual connection terminal between AV devices, and is responsible for the transmission and reception of isochronous communication data, asynchronous communication data, etc. In a combination device incorporating a plurality of functions into one unit, the plug may be provided for each function unit. For example, a combination CD and radio cassette player/recorder is considered to be a combination of the various function units, i.e., the CD player, the tuner (radio), and the cassette tape recorder.
There are two types of plug: the receiving plug for receiving data from the outside and the transmitting plug, for transmitting data to the outside. These plugs have their own attributes and operating states. In the AV protocol, however, no methods are defined for handling information concerning these plugs. In view of this, there have been proposed a method of holding these pieces of information in a list structure and a method of externally accessing the list. One example is the AV/C DISC Subunit Proposal version 0.7 presented at the IEEE 1394 Trade Association (hereinafter TA).
The plug is a virtual and functional concept for handling AV data, and does not refer to a physical terminal itself on the IEEE 1394 bus. In some cases, the plug may directly handle the data of an analog input/output terminal or data of an optical input/output terminal that handles ICE 958 data.
The IEEE 1394 bus is capable of transmission at 100, 200, and 400 Mbps with a single terminal; for comparison, the linear PCM signal used for input and output of MD, for example, is 1.4 Mbps for two channels. This means that one IEEE 1394 terminal has a sufficient capacity to handle both input and output simultaneously. Furthermore, device control signals can also be handled at the same time. In the following description, the receiving plug, the transmitting plug, and control signals are described as if they were independent terminalis, but it will be noted that the plug is nothing but a virtual and functional concept, and that the number of IEEE 1394 terminals physically mounted on an actual device is one or two or so (for the cascading of devices).
The prior art plug information handling proposed in the above draft of standard (AV/C DISC Subunit Proposal version 0.7) will be described below with reference to drawings.
FIG. 5
is a block diagram showing a recording and playback disc subunit according to the prior art. One or a plurality of such subunits together constitute one device. In
FIG. 5
reference numeral
401
is the disc subunit (hereinafter sometimes referred to simply as the subunit),
402
is a receiving plug,
403
is a transmitting plug,
404
is a description structure called a descriptor, and
405
is a state list, included in the description structure
404
, for showing the state of the subunit.
FIG. 5
assumes the use of MD; therefore, one receiving plug and one transmitting plug are provided. Here, a stereo signal can be handled by one plug.
The description structure
404
includes attribute information and state information of the subunit
401
, attribute information and contents information of media, etc. in the form of a list structure, and is used to transmit/receive information between subunits. The details of how reading and writing is performed on each list are described in the AV/C Digital Interface Command Set General Specification published by the IEEE 1394 TA.
FIG. 6
is a diagram showing the structure of the state list
405
included in the description structure
404
for showing the state of the subunit. The state list
405
is stored in a memory within the subunit, but here it is shown like a hierarchical structure to show the contents in simplified form.
The state list
405
comprises four broad categories: (1) list length, (2) general state, (3) receiving plug state, and (4) transmitting plug state.
The list length (1) indicates the length of the state list
405
. Since the description structure
404
is made up of a plurality of lists, this list length is used to compute the starting address of the list that follows the state list
405
. The general state (2) stores general information concerning the subunit, such as information indicating whether a medium is in the subunit, and in the case of a device error, the cause and the last executed command.
The receiving plug state (3) includes the number of receiving plugs (m) and the receiving plug state [x] (x=1 to m). In the illustrated prior art example, since the number of receiving plugs is one, only one receiving plug state is shown. The receiving plug state [x], whose detailed contents are shown at
406
in
FIG. 6
, consists of five portions, (a) receiving plug state length, (b) receiving plug number, (c) operating mode, (d) current position, and (e) plug setting.
The receiving plug state length (a) indicates the length of the receiving plug state portion. The receiving plug number (b) shows the identification number of the receiving plug. The operating mode (c) will be described in detail later. The current position information (d) indicates the current record position (music track number, etc.) on the medium currently associated with the receiving plug. How this is done depends on the media recording format; in the case of MD, the position is indicated by the track number and by hours:minutes:seconds:frames from the beginning of the track. In the plug setting portion (e) are stored a list identifier in the media recording hierarchy (in the case of MD, this automatically is a route list since MD does not have a recording hierarchical structure), recording format (audio, video, MIDI, still image, etc.), and detailed information concerning the recording format (in the case of audio, sampling frequency, sampling bit length, compression scheme, number of recording channels, etc.). The plug setting comprises one that beforehand the subunit has as unique values and is not alterable from the outside (for example, MD sampling frequency, sampling bit length, compression scheme, etc.) and the other that is alterable from the outside depending on the subunit (number of recor

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