Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1998-11-23
2002-09-03
Christensen, Andrew (Department: 2615)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000, C386S349000
Reexamination Certificate
active
06445872
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a digital broadcast recording and reproducing apparatus for receiving, recording and reproducing television broadcasts of a digital format.
BACKGROUND ART
Although television broadcasts are presently provided in the analog format, it is considered that the analog television broadcasts will be successively replaced by digital television broadcasts (hereinafter, referred to as digital TV broadcasts) in the future because of the necessities of further improvement of image quality and increasing the number of broadcast channels.
In the digital TV broadcast, by compression-coding video signals, a multiplicity of channels can be secured within a limited frequency band. In a presently-proposed digital TV broadcast, an MPEG2 format which is a video signal compression coding format standardized by a working group of the moving picture experts group (hereinafter, referred to as MPEG) is used for compression-coding of the video signals. Video signals are compression-coded into coded data according to the MPEG2 format. The coded data of a multiplicity of channels (e.g. eight channels) are brought together into a bit stream which is a data string. The bit stream is modulated and transmitted as a digital broadcast signal.
On the other hand, for recording of television broadcasts at home, presently, a video tape recorder of the VHS format which is an analog format is mainly used (hereinafter, referred to as VHS format VTR). Moreover, recently, digital video tape recorders based on the DV format standardized by “the HD digital VCR conference” which is a conference for examining home digital VTR standards have been put on the market (hereinafter, referred to as DV-format VTR), so that high-image-quality recording has been possible.
FIG. 6
shows a system configuration in the case of recording, by the DV format VTR, a program of a digital TV broadcast received by use of a digital TV broadcast receiver
120
commercially available as “Set Top Box.”
In
FIG. 6
, reception signals of radio waves from a satellite received by an antenna
110
are input to an antenna input terminal
121
of the receiver
120
for receiving digital TV broadcasts. The signals input from the antenna input terminal
121
are demodulated by a tuner section
122
, and a bit stream is output. From the bit stream, the data string of a desired channel is selected by a channel selection section
123
, and the selected data string of the channel is decompression-decoded and put back into video signals according to the MPEG2 format by an MPEG2 decoder
124
. The video signals are output to a video output terminal
125
. Then, the video signals are input to a video recording input terminal
131
for inputting recording video signals of a DV format VTR
130
. The input video signals are reproduced by way of an encoder
132
for video signal compression coding of DV-format (hereinafter, referred to as DV encoder), a recording and reproducing section
133
and a decoder
134
for decompression-decoding of DV-format video signals (hereinafter, referred to as DV decoder), and the reproduced video signals are output to a video reproduction output terminal
135
. The reproduced video signals are displayed on a monitor image receiving apparatus
140
.
The operation to record and reproduce a program of a digital TV broadcast to and from the format DV VTR in the above-described configuration will be described in detail hereafter.
Radio waves of a digital TV broadcast from a satellite are received by the antenna
110
and supplied to the receiver
120
. At the receiver
120
, the signals are received by the antenna input terminal
121
and demodulated by the tuner section
122
into a bit stream. The bit stream is input to the channel selection section
123
and the data string of a desired channel is selected. The selected data string is decompression-decoded by the MPEG2 decoder
124
and put back into video signals, and are output to the video output terminal
125
. At the DV format VTR
130
, the video signals are input from the video recording input terminal
131
, compression-coded by the DV encoder
132
, and recorded by-the recording and reproducing section
133
.
At the time of reproduction, the signals reproduced by the recording and reproducing section
133
are decompression-decoded by the DV decoder
134
, and the. resultant signals are output to the video reproduction output terminal
135
. The signals are monitored by the image receiving apparatus
140
.
The maximum recording time of DV format VTRs is 4 hours and 30 minutes when a standard cassette tape is used. Even when the thin tape for VHS VTRs is used in the three times mode, the maximum recording time is only 8 hours. Recording times of these lengths are insufficient to-record a multiplicity of programs on a multiplicity of channels of digital TV broadcasts by programming the VTR to do so by use of a timer in advance (hereinafter, referred to as timer recording).
In multi-channel digital broadcasts, since the number of programs broadcasted for a week is great, it is considered that a great number of programs are programmed to be recorded in one timer recording setting. Moreover, an occasion will be more likely to arise when programs on a plurality of channels broadcasted during the same time period are to be recorded at the same time. However, the present VHS format VTRs and DV format VTRs with short recording times cannot satisfactorily meet such a demand.
Therefore, paying attention to the fact that the compression rate of the MPEG2 format is much higher than that of the DV format, a method can be considered that uses an MPEG2-format VTR instead of the DV format VTR of
FIG. 6
in order to increase the recording time. The recording rate of the DV format is 41.85 Mbits/second including sound and sub codes (see Nikkei Electronics Books “Data ashuku gijitsu (Data compression technology)”, p144). On the contrary, when standard television signals are coded according to the MPEG2 format, the information amount is 6 to 8 Mbits/second (see Bulletin of the Institute of Image Information and Television Engineers, Vol. 50, No. 1 (1996), p40). Therefore, when an MPEG2-format VTR is used, recording can be performed for a time five to seven times longer. However, in the system configuration of
FIG. 6
, since MPEG2-format digital broadcast signals are decoded by the MPEG2 decoder
124
in the receiver
120
called Set Top Box, the signals decoded as data to be supplied to the MPEG2-format VTR are necessarily converted again to MPEG2-format signals by use of an MPEG2 encoder. Since the MPEG2 encoder requires very complicated signal processing compared with the MPEG2 decoder, the circuit scale thereof is enormous and is expensive. Therefore, at the present time, it is considerably difficult to employ this for home appliances in view of the cost.
Objects of the present invention are to solve the above-mentioned problems, to realize long-time digital recording without the use of the expensive MPEG2 encoder for recording and reproduction of the digital broadcasts, and moreover to realize a digital broadcast recording and reproducing apparatus capable of simultaneous timer-recording programs on a plurality of channels.
DISCLOSURE OF THE INVENTION
In order to meet the above-mentioned objects, a digital broadcast recording and reproducing apparatus according to the present invention comprises: a tuner section for demodulating a received compression-coded digital broadcast signal corresponding to a multiplicity of channels into a data string including coded data; recording channel selection means for selecting coded data of channels to be recorded from the above-mentioned data string, and outputting a formed data string; recording and reproducing means for recording and reproducing the data string output from the above-mentioned recording channel selection means; and a decoder for decompression-decoding the coded data of the data string reproduced by the above-mentioned recording and reproducing means, and outputting a video signal. Accordin
Iida Makoto
Sano Nobuya
Akin Gump Strauss Hauer & Feld L.L.P.
Chieu Po-Lin
Christensen Andrew
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