This application is based on Japanese Patent Applications No. 8-349939 filed on Dec. 27, 1996 and No. 9-059600 filed on Mar. 13, 1997, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to data communications technologies, and more particularly to real time data communications technologies. A xe2x80x9creal timexe2x80x9d response to an event is essentially simultaneous with the event itself. However, in communications, because of time delay for transmission time, signal synchronization, other necessary signal process or the like, xe2x80x9creal timexe2x80x9d does not mean strictly simultaneous.
2. Description of the Related Art
As a standard specification for communications between electronic musical instruments, a music instrumental digital interface (MIDI) specification is known. Electronic musical instruments equipped with interfaces of the MIDI specification can communicate with each other by transferring MIDI data via a MIDI cable.
For example, an electronic musical instrument transmits MIDI data of a musical performance by a player, and another musical instrument receives it to reproduce it. As one electronic musical instrument is played, another electronic musical instrument can be played in real time.
In a communications network interconnecting a plurality of general computers, various types of data are transferred. For example, live musical tone data or other MIDI data can be transmitted from one computer, which once stored the data in its storage device such as a hard disk, via the communications network to another computer which stores the received data in its storage device. A general communications network is, however, configured to perform only general data communications, and is not configured to properly process MIDI data.
Specifically, although the MIDI specification allows the xe2x80x9creal timexe2x80x9d communications to be performed between electronic musical instruments, it is not suitable for long distance communications and communications via a number of nodes. The general communications network is essentially configured to provide services of long distance communications and multiple-node communications, but it does not take account of xe2x80x9creal timexe2x80x9d communications between electronic musical instruments.
Real time communications of musical information uses a large amount of information per unit time, and the traffic of the communications line becomes heavy. As compared to point-to-point communications, point-to-multipoint communications of musical tone data is more likely to make the traffic of communications lines heavy. The heavy traffic of communications lines generates a transmission delay and hinders a real time musical performance.
It is an object of the present invention to provide technologies of musical tone data communications capable of a real time musical performance at multiple nodes.
It is another object of the present invention to provide technologies of data communications capable of avoiding a heavy traffic of communications lines.
According to one aspect of the present invention, there is provided a musical tone data communications system, comprising: transmitting means for transmitting inputted MIDI data in real time over a communication network.
According to another aspect of the present invention, there is provided a data communications system comprising: receiving means for receiving data; access checking means for checking the number of communications lines accessed externally; and transmitting means capable of reducing the amount of data received by the receiving means in accordance with the number of communications lines accessed externally, and transmitting the reduced data to the communications lines accessed externally.
If the number of accessed communications lines is large, the amount of received data is reduced to thereby alleviate the traffic congestion, whereas if the number of accessed communications lines is small, it is not always necessary to reduce the data amount.
According to a further aspect of the present invention, there is provided a communication system having a plurality of communications apparatuses each having receiving means and transmitting means, wherein: the receiving means of the plurality of communications apparatuses receive the same data; the transmitting means of the plurality of communications apparatuses can reduce the amount of data received by the receiving means and can transmit the reduced data; and the data reduced by one of the communications apparatuses is different from the data reduced by another of the communications apparatuses.
Since the data reduced by one and another of communications apparatuses is different, the quality of data transmitted from each communication apparatus is different. For example, the type or reduction factor of the reduced data may be made different at each communication apparatus. Therefore, a user can obtain data of a desired quality by accessing a proper communication apparatus.
According to still another aspect of the invention, there is provided a musical tone data communications method comprising the steps of: (a) transmitting MIDI data over a communications network; and (b) receiving the transmitted MIDI data and supplying the received MIDI data to a tone generator in real time.
MIDI data can be transmitted to a number of nodes by using a communications network. At each node, the MIDI data is reproduced in real time to generate musical tones.
According to still another aspect of the invention, there is provided a musical tone data communications method comprising the steps of: (a) transmitting MIDI data; and (b) transmitting recovery data after the MIDI data is transmitted, the recovery data indicating a continuation of transmission of the MIDI data.
If there is no communications error, transmitted MIDI data can be correctly received at a partner communications apparatus. If there is a communications error, transmitted MIDI data cannot be correctly received at a partner communications apparatus. Even in such a case, the communication error can be remedied by transmitting the recovery data.