Receiver and transmitter-receiver

Details Receiver and transmitter-receiver Receiver and transmitter-receiver

2000-05-23

2003-01-28

Britton, Howard (Department: 2613)

Pulse or digital communications

Bandwidth reduction or expansion

Television or motion video signal

C375S240280

Reexamination Certificate

active

06512794

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a receiver and a transmitter/receiver for digital data including video data and audio data, and more particularly to a receiver and a transmitter/receiver suitable for a recording/reproducing apparatus for recording/reproducing uncompressed video data and compressed video data.
BACKGROUND ART
At present, as a transmission method for digital video signals, the SMPTE-259M Standard, namely, the Serial Digital Interface (hereinafter referred to as “SDI”) Standard is used generally. As is known, this SDI Standard was established by SMPTE: Society of Motion Picture and Television Engineers, and stipulates methods of converting digital data including video data and audio data into serial data and transmitting the data.
Hereinafter, the digital data transmission method in accordance with the SDI Standard will be described specifically with reference to FIG.
4
. In the following description, the transmission method in accordance with the television signal of the NTSC System at 270 Mbps will be described.
FIG. 4
is an explanatory view showing the configuration of one frame in accordance with the SDI Standard. The straight line H in
FIG. 4
indicates the horizontal pixels of the television signal, and the numerical values above the straight line H indicate pixel numbers. The straight line V in the same figure indicates the vertical line of the television signal, and the numerical values above the straight line V indicate line numbers.
As shown in
FIG. 4
, in the SDI Standard, one frame period is divided into a horizontal blanking period, and a vertical blanking period, an optional blanking period and an active video period in each field of a first field and a second field constituting one frame.
The horizontal blanking period is stipulated by the range of the horizontal pixels from pixel number 1440 to 1715. In the horizontal blanking period, its head and end portions are provided with EAV (End of Active Video) and SAV (Start of Active Video), respectively. In the horizontal blanking period between these EAV and SAV, it is possible to transmit ancillary data, such as audio data and user data.
In the active video period, video data for 1440 pixels is multiplexed in every line, and transmitted as serial data at a predetermined clock frequency. One pixel is formed of 8-bit or 10-bit video data.
In the optional blanking period, a period included in the vertical blanking period, video data can be placed and transmitted, just as in the case of the active video period.
By using this SDI Standard, the 4:2:2 component television signal for one channel can be transmitted without using any analog transmission systems, whereby signal deterioration can be prevented.
On the other hand, when video data obtained by digitizing a video signal is processed directly, the data amount of the video data becomes large, thereby requiring a very high data rate (transmission speed). Therefore, when the above-mentioned video data is recorded on a recording medium, such as magnetic tape, for example, sufficient recording time cannot be obtained.
In contrast, a method, wherein video data is compressed by bit rate reduction to the extent that visual deterioration in image quality is not recognized, and then treated, is known as an effective method. More specifically, the DV format established by the High Definition Digital Video Cassette Recorder Committee and described in “Specifications of Consumer-Use Digital VCRs using 6.3 mm magnetic tape” is available as a format obtained by applying the bit rate reduction of a video signal to consumer-use digital VTRs.
In this DV format, data is compressed in two modes depending on the television signal by carrying out bit rate reduction on the basis of DCT (Discrete Cosine Transform).
More specifically, in the DV format, the standard television signal is compressed to 25 Mbps data, and the high definition television signal is compressed to 50 Mbps data. The compressed video data is recorded on magnetic tape together with interleaved audio data, VAUX data used as data attached to the video data, sub-code data and the like. When the data compressed in the 25 Mbps mode is recorded on the magnetic tape, the data for one frame is divided into 10 tracks of the magnetic tape and recorded. In addition, when the data compressed in the 50 Mbps mode is recorded on the magnetic tape, the data for one frame is divided into 20 tracks of the magnetic tape and recorded.
When the video data compressed by bit rate reduction, such as the DV format, is transmitted by using the above-mentioned SDI Standard, it was conventionally necessary to release the compression of the video data once and to return to a base band signal. This is because the SDI Standard stipulates only the transmission method for non-compressed video data, namely, uncompressed video data, instead of compressed video data. Furthermore, the SDI Standard is aimed at video data for one channel, and does not stipulate any transmission methods for transmitting video data for multiple channels.
Therefore, a transmission method capable of multiplexing and transmitting compressed video data by using the SDI Standard without returning the compressed video signal to the base band signal was requested earnestly. To meet this kind of request, the above-mentioned Society of Motion Picture and Television Engineers established the SMPTE-305 Standard, namely, the Serial Data Transport Interface, hereinafter referred to as “SDTI”). By using this SDTI Standard, video signals for multiple channels, compressed in accordance with the DV format and MPEG (Moving Picture Experts Group) for example, can be transmitted in accordance with the SDI Standard.
Hereinafter, the digital data transmission method in accordance with the SDTI Standard will be elucidated specifically with reference to FIG.
5
. In the following, just as in the case of the SDI Standard shown in
FIG. 4
, the transmission method in accordance with the television signal of the NTSC System at 270 Mbps will be described.
FIG. 5
is an explanatory view showing a concrete example of the configuration of one frame in accordance with the SDTI Standard.
As shown in
FIG. 5
, in the SDTI Standard, a one-frame period is provided with EAV, SAV, a horizontal blanking period therebetween, vertical blanking periods and optional blanking periods, just as in the case of the SDI Standard shown in FIG.
4
. Furthermore, in the SDTI Standard, areas referred to as payloads corresponding to the active video period in the SDI Standard are provided so that digital data including compressed video data is placed and transmitted. Moreover, the above-mentioned horizontal blanking period in accordance with the SDI Standard is used as a physical layer wherein ancillary data can be placed. However, the type of the ancillary data to be transmitted in accordance with the SDI Standard differs from that in accordance with the SDTI Standard. More specifically, in the SDI Standard, the ancillary data was audio data, user data or the like as described in the above. On the other hand, in the SDTI Standard, audio data is stipulated so as to be placed in the above-mentioned payloads together with compressed video data, and transmitted. Therefore, the SDTI Standard stipulates that data referred to as an SDTI header is generated in every line in accordance with digital data to be placed in the subsequent payload, and placed and transmitted as ancillary data.
Hereinafter, the SDTI header stipulated in the above-mentioned SDTI Standard will be elucidated specifically with reference to FIG.
6
. In the following description, data to be transmitted on the basis of the SDI Standard and data to be transmitted on the basis of the SDTI Standard are simply referred to as SDI data and SDTI data, respectively.
FIG. 6
is an explanatory view showing a specific configuration of the SDTI header.
As shown in
FIG. 6
, in the SDTI header, the data of ADF (Ancillary Data Flag) is placed subsequent to the data of EAV indicating the end of the active video period. The values of ADF an

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