Music – Instruments – Electrical musical tone generation
Reexamination Certificate
2000-06-23
2002-08-06
Donels, Jeffrey (Department: 2837)
Music
Instruments
Electrical musical tone generation
C709S253000, C713S400000
Reexamination Certificate
active
06429364
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a data transmission and receiving apparatus and method for sending and receiving data recorded to a recording medium such as an optical disc or magnetic tape by way of a digital interface.
BACKGROUND ART
The IEEE 1394 system has attracted attention recently as a serial transmission method for digital data. Not only can the IEEE 1394 system be used in place of the conventional SCSI standard for computer data transmissions, it can also be used for transmitting AV data. This is because two communications methods are defined in the IEEE 1394 system: asynchronous communication and isochronous communication. Isochronous communication is a data transmission method that can be used for transmitting data requiring real-time performance such as AV data. In isochronous communication the bandwidth required for data transmission is obtained before transmission starts. Data is then transmitted using that bandwidth. The real-time characteristic of the data transmission is thereby assured. Asynchronous communication, on the other hand, is a transmission method used for transmitting data that does not require real-time performance, such as transmitting computer data. This can be thought of as equivalent to transmission methods such as the conventional SCSI transmission method.
Various methods have been proposed as high level transmission protocols under the IEEE 1394 system, and one of these can be referred to as the AV protocol. The AV protocol is being standardized as IEC 61883, which defines sending and receiving AV data requiring real-time performance using isochronous communication, and sending and receiving control commands asserted to devices using asynchronous communication.
The AV/C command set is one of the above-noted control command systems. Control commands for VCRs, for example, are defined in the AV/C command set. A method for expressing information stored by the device (such as the device state and recording medium descriptor) using a list structure is also defined in the AV/C command set.
As an example of the prior art, this method is described below with reference to FIG.
13
.
FIG. 13
is a schematic diagram showing an example of the list structure defined by the AV/C command set. As shown in the figure, list A
2001
consists of a list header
2002
and zero or more (N shown in the figure) objects
2003
. Information relating to list A
2001
overall is written to the list header
2002
. The objects
2003
are equivalent, for example, to a unit such as an audio track recorded to a disk; a descriptor relating to each audio track, for example, is written to an object
2003
. In addition, a structure with the same concept as the directory of a computer file system can also be used as an object, and can be used to express a list having a hierarchical structure. In
FIG. 13
object #
3
of list A
2001
is shown as an object indicating a directory, in this example having a list B
2101
as a list for a level under object #
3
in list A
2001
. This list B
2101
has a list header
2102
and objects
2103
similarly to list A
2001
.
These lists are generated inside the device, and can be accessed by an external device by way of IEEE 1394 so that the external device can obtain the information stored by the other device.
When an object contains a descriptor for AV data, for example, AV data recorded to a recording medium can be reproduced by specifying the object ID and sending a play command, for example, to the device. Moreover, if a list is specified and a play command is sent to the device, AV data is reproduced in the order written in the list.
A variety of information can be written using this list structure. For example, devices that use AV discs can write the content recorded to the disc, and the sequence for program playback. The sequence for program playback can also be specified from an external device by accessing the list describing the program playback sequence from an external device.
An example of a title or text file access sequence in a conventional data transmission and receiving apparatus is described below with reference to FIG.
14
.
FIG. 14
shows a list structure for a case in which the list shown in
FIG. 13
is applied to an optical disc to is recorded an audio track, audio title, or text, for example.
FIG. 14
shows a typical content list
1301
, audio list
1311
, and title list
1351
structure. In this example audio data for two songs, song A and song B, is recorded to the optical disc. In the audio data descriptor, the title information is represented by title list
1351
separately from the content list
1301
.
The content list
1301
is a list of the overall content recorded to the optical disc. The content list
1301
contains a first object
1303
and second object
1304
. First object
1303
and second object
1304
are objects for presenting a directory; first object
1303
has audio list
1311
, and second object
1304
has text file list
1331
, as lists one level lower.
Audio list
1311
consists of list header
1312
, first object
1313
, and second object
1314
. In this case, first object
1313
and second object
1314
correspond respectively to the descriptor for songs A and B (not the audio data itself). In addition, the list header
1312
comprises number of songs (number of objects)
1321
. In this case the number of songs is two. The first object
1313
and second object
1314
respectively comprise the playback time
1322
and
1324
of each song, and a pointer
1323
and
1325
to each song title.
The text file list
1331
comprises list header
1332
, first object
1333
, second object
1334
, and third object
1335
, and stores a text file descriptor. A descriptor relating to a text file includes, for example, the content written to that text file (an identifier indicating a lyrics file or artist information file, for example), the file size, and file creation date and time. In this example the first object
1333
corresponds to a text file representing the entire optical disc, for example, a text file descriptor (not the text file data itself) such as the artist information when the disc records only audio data from a single artist. The second object
1334
and third object
1335
correspond respectively to a text file descriptor (not the text file data itself) for songs A and B. In this case these store a file descriptor relating to a lyrics file and artist information file.
Each object of title list
1351
records the title data itself. In this case it is assumed that a disc title representing the overall audio list is written to first object
1333
, the title of song A is written to second object
1354
, and the title of song B is written to third object
1355
. Link information (an ID for second object
1354
) to the second object
1354
of title list
1351
is written in the pointer
1323
to the title in the first object
1313
, that is, the object indicating song A in the audio list
1311
. Likewise, link information (an ID for the third object
1355
) to the third object
1355
of title list
1351
is written in the pointer
1325
to the title in the second object
1314
that is the object indicating song B.
By thus using a list structure with a general format, an external device can access data stored by a data transmission and receiving apparatus by way of a digital interface without knowing the device-specific data storage structure.
For example, when an external device wants to access a disc title in a data transmission and receiving apparatus, it accesses title list
1351
and reads first object
1333
. In this case, the first object in the title list is predefined as a disc title. In addition, to access the title of song A, it reads content list
1301
, obtains the ID for the audio list, reads the audio list, obtains the pointer
1323
to the title of song A, and based on this accesses the second object
1334
of title list
1351
. In this case, if the audio list object can be accessed, the method of accessing the corresponding title information is known m
Kondo Satoshi
Muraki Kenji
Donels Jeffrey
Matsushita Electric - Industrial Co., Ltd.
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