Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
1998-12-30
2003-04-22
Diep, Nhon (Department: 2613)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
Reexamination Certificate
active
06553073
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a technique for transmitting compressed moving picture data of a plurality of channels by using a serial transmission path of a single channel including a light, a radio wave and so on. The present invention is suitable for use in, for example, a video server system.
BACKGROUND ART
Conventionally, the waveform of an analog composite signal was examined by using an oscilloscope, and its rising time and frequency characteristics, for example, were measured. Then, it was determined whether desired characteristics were achieved. When this analog signal was subjected to transmission or the like, its waveform itself was thus handled so as to be able to reproduce a waveform close to the original one with as little degradation as possible.
By sampling and quantizing such an analog signal to convert it into a digital form, the signal could be handled simply as digits no matter whether the signal was recorded or transmitted. Therefore, occurrence of degradation was prevented by preventing mistakes in digits.
When in this case an electric signal was converted into a digital form and handled as digits (data), for example, sampled data of bits were often connected between two devices via a cable so as to make bits parallel and data were transmitted. Such a scheme was called a parallel interface or a parallel transmission. In an 8 bit system, eight different signals were sent simultaneously from a device on a sending side to a device on a receiving side at this time. For signals sent in parallel, a parallel clock to be used for shaping when transmitting data was sent on a ninth signal path together with the data. There was thus used such a configuration that the timing of reproducing data in the device on the receiving side was always kept correct and sent data could be reproduced without errors.
In such a parallel interface, data were grouped into a block (packet) form beforehand in order to send the data efficiently and a signal corresponding to block synchronizing was added to each block prior and then transmitted. In the scheme using the block synchronizing, a part of data required to be actually sent is first defined, and a reference signal specifying its position was inserted.
In the parallel interface, a parallel clock was transmitted between devices apart from the data as described above. On the other hand, in a serial interface, only data are transmitted successively by using one cable. In the serial interface, however, mutual conversion can be facilitated by utilizing conventions of the parallel interface to the utmost. As one satisfying such a condition, an SMPTE (Society of Motion Picture and Television Engineers) 259M was standardized. Such a serial interface prescribes a procedure for making data serial and sending the serial data and a procedure for making the data parallel again. In this way, it has become possible to conduct a long distance transmission over one cable which was impossible in the conventional parallel interface.
As against an SDI (Serial Digital Interface) scheme standardized in the SMPTE 259M, there was an SDDI (Serial Digital Data Interface) scheme individually developed by the applicant of the present invention. Though the SDDI scheme is suitable for multimedia and multichannel application, it has a high compatibility with the SDI scheme.
In a system hereafter described, picture data formatted in accordance with the SDI scheme is compressed and then converted into the format of the SDDI scheme, and compressed moving picture data of a single channel is transmitted over a transmission path of the SDDI scheme. First of all, the configuration of a transmitting device will now be described. In
FIG. 1
, the transmitting apparatus includes an SDI decoder
100
for restoring original digital data from moving picture data V formatted in the SDI scheme, a video bit rate reduction encoder
101
for compressing the digital data to approximately ⅛, and an SDDI payload memory
102
for conducting preprocessing to convert the compressed moving picture data, audio data A formatted in the AES/EBU scheme and control data C to a format of the SDDI scheme at the time of writing.
Furthermore, the sending device includes an SDDI encoder
103
for adding a header portion and the like containing a synchronizing signal to payload data on the basis of a predetermined reference signal RF and generating data of the format of the SDDI scheme, and a serial interface transmitter
104
for serially transmitting the data of the format of the SDDI scheme as output data OD.
Here, the control data C is control data concerning the control of the moving picture data V and the audio data A. In the format of the SDDI scheme, the payload is a portion storing user data.
The transmitting apparatus having such a configuration conducts operation as hereafter described. When the moving picture data V formatted according to the SDI scheme is supplied to the SDI decoder
100
, the moving picture data V is processed in the SDI decoder
100
so as to restore the original digital data represented by video data
113
in FIG.
3
C. The restored original digital data is supplied to the video bit rate reduction encoder
101
. In the video bit rate reduction encoder
101
, the digital data is compressed in such a manner that four fields shown by the reference frame signal RF in
FIG. 3A
are compressed to approximately ⅛. A resultant compressed state is shown in FIG.
3
B. This compressed moving picture data, the audio data A denoted by
114
in
FIG. 3C
, and the control data C denoted by
112
in
FIG. 3C
are supplied to the SDDI payload memory
102
. At the time of writing into the SDDI payload memory
102
, the compressed moving picture data, the audio data A, and the control data C are stored for the payload in the state as shown in FIG.
3
B.
The data stored for the payload is supplied to the SDDI encoder
103
. In the SDDI encoder
103
, the header portion and the like containing the synchronizing signal which is not illustrated are added to the payload data at every four fields on the basis of the reference frame signal RF shown in
FIG. 3A
, so that data
110
having the format of the SDDI scheme is generated as shown in FIG.
3
B. The data
110
of the format of the SDDI scheme is supplied to the serial interface transmitter
104
. In the serial interface transmitter
104
, the output data OD having the format of the SDDI scheme as shown in
FIG. 3B
is serially transmitted as the data
110
at every four fields represented by the reference frame signal RF in FIG.
3
A. In the same way, data is generated in the next four fields.
The configuration of a receiving apparatus will now be described. As shown in
FIG. 2
, the receiving device includes a serial interface receiver
105
for receiving the output data OD having the format of the SDDI scheme as shown in
FIG. 3B
, an SDDI decoder
106
for restoring the original digital data from the output data OD having the format of the SDDI scheme, and an SDDI payload memory
107
for storing the restored original digital data and dividing the restored original digital data into the compressed moving picture data, the audio data A, and the control data C at the time of reading.
Furthermore, the receiving apparatus includes a video bit rate reduction decoder
108
for conducting expansion processing on the compressed moving picture data, and an SDI encoder
109
for converting the moving picture data subjected to the expansion processing to the format of the SDI scheme and outputting the original moving picture data V.
The receiving apparatus having such a configuration conducts operation heretofore described. The output data OD of the format of the SDDI scheme is supplied to the serial interface receiver
105
. In the serial interface receiver
105
, the output data OD of the format of the SDDI scheme is received. The received output data OD of the format of the SDDI scheme is supplied to the SDDI decoder
106
. In the SDDI decoder
106
, the original digital data is restored from the output d
Diep Nhon
Frommer William S.
Frommer & Lawrence & Haug LLP
Polito Bruno
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