JP3879231B2 - Digital tuner and its channel switching method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a digital tuner for receiving program information supplied by digital broadcasting and a channel switching method thereof.
[0002]
[Prior art]
With the recent progress of compression coding technology and the like, it is possible to realize a multi-channel television program, and a service for distributing a television program by digital broadcasting is being implemented. With such multi-channel broadcasting, it is possible to provide a large number of programs specialized in various genres, and users can enjoy a wide variety of information by expanding the choices of programs.
[0003]
[Problems to be solved by the invention]
However, on the other hand, since the number of channels has become extremely large due to the increase in the number of channels (currently several tens to hundreds), it takes time for the user to find the target channel, and the burden for that is also increased.
In general, in digital broadcasting, video and audio information is supplied in a compressed form by MPEG2, MPEG1, etc., so that information received on the tuner side is decoded (ie, decoding, decompression, etc.). There is a need. Therefore, it takes an extra time for decoding the received video and audio by the time required for decoding (hereinafter referred to as decoding time) as compared with the conventional analog broadcasting until the received video and audio are reproduced on the television receiver. For this reason, when a user performs an operation of switching channels one after another (so-called channel surfing) in order to search for a target channel, a certain time (about 1 to 2 seconds at present) is required for each switching. There was a problem that it took a lot of time to reach the target channel.
[0004]
The present invention has been made under such a background, and it is an object of the present invention to provide a digital tuner and a channel switching method thereof that allow a user of digital broadcasting to quickly select a desired channel.
[0005]
[Means for Solving the Problems]
In order to solve the above-described problem, the invention according to claim 1 is configured to receive program information of a specified channel from among compression-coded program information supplied through a plurality of channels by digital broadcasting. In a digital tuner that decodes program information and sends it to a playback device, channel scan information storage means for storing channel scan information comprising a sequence of channel numbers, and channel scan information stored in the channel scan information storage means In accordance with the channel number sequence shown, the channel switching means for sequentially switching channels, the first decoder for decoding the program information of the designated channel, in parallel with the decoding process by the first decoder , By channel switching means A second decoder then decodes the channel program information should be switched Te, and a storing means for storing the decoding result of the second decoder, thereby, the second decoder decodes the program information When switching to the selected channel is designated by the channel switching means, the decoded program information stored in the storage means is sent to the playback device for at least the delay time associated with the decoding by the second decoder. It is characterized by doing.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
A: Configuration of Embodiment FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an antenna which receives a broadcast wave transmitted via a communication satellite (CS) or a broadcast satellite (BS). This broadcast wave is mainly a signal obtained by digitally compressing and encoding video and audio (hereinafter referred to as video / audio signal), but text information is also added as necessary.
[0009]
Reference numeral 2 denotes a digital tuner which decodes a video / audio signal received from the antenna 1 and supplies it to the television receiver 3. The television receiver 3 displays a video corresponding to the video signal supplied from the tuner 2 on a monitor, and sounds a sound corresponding to the audio signal supplied from the tuner 2 from a speaker.
[0010]
Here, the configuration of the digital tuner 2 will be described. First, reference numeral 20 denotes a tuner unit that captures a broadcast wave signal received by the antenna 1. The tuner unit 20 alternately switches a channel designated by the operator and a channel adjacent to the channel in the forward direction (channel switching direction) under the control of the CPU 22 described later, and is supplied from the antenna 1. The video / audio signals of both channels are received in parallel.
[0011]
Reference numerals 21a and 21b denote decoders that respectively decode the received video / audio signals (that is, decoding processes such as decoding and decompression). One of these decoders 21a and 21b decodes the video / audio signal of the channel designated by the operator, and the other decoder is adjacent to the designated channel in the forward direction in parallel with this. Decodes the video / audio signal of the channel.
[0012]
The CPU 22 controls each part of the tuner 2 connected via the bus BUS. That is, the CPU 22 implements various operations to be described later by executing a predetermined control program stored in the ROM 23. The RAM 24 is used as a work area for the CPU 22 such that a control program is loaded from the ROM 23.
[0013]
Reference numeral 25 denotes an AV (audio / visual) / I / F (interface), which further converts the decoded video / audio signal into a signal that can be reproduced by the television receiver 3. An operation I / F 26 receives an optical signal corresponding to the operation transmitted from the remote controller R, converts it into an electrical signal, and outputs it to the bus BUS.
[0014]
Here, the remote controller R includes an operation surface including an operator that performs various operations by an operator and a circuit that transmits an optical signal corresponding to the operation. FIG. 2 is a plan view showing a configuration example of the operation surface of the remote controller R. In the figure, R0 is a power button for instructing on / off of power, R1 and R2 are volume up and volume down keys for adjusting the volume, R10 is a numeric keypad for inputting a channel number, and R20 is A selection key for confirming channel selection based on the input channel number, R21 and R22 are arrow keys for switching channels forward or backward, R30 is a scan key for instructing a channel scan described later, and R31 Is a program key for instructing the start and end of a program mode, which will be described later, R40 is a cancel key for instructing to cancel the input operation or stop processing, and R50 is a message or input information for guiding the input. It is a liquid crystal panel. The remote controller R detects an operation on each of the above-described operating elements and transmits an optical signal corresponding to the operation.
[0015]
Now, returning to FIG. 1 again, the configuration of the digital tuner 2 will be described. In FIG. 1, reference numeral 28 denotes a card I / F into which an IC card CD is inserted. Data is read from and written to the IC card CD under the control of the CPU 22. The IC card CD records information related to a user's ID number (that is, an identification number unique to the user) and usage history for charging according to the usage status of the user. When the IC card CD is inserted into the card I / F 28, the user is authenticated based on the ID number, and the tuner 2 can be used.
[0016]
Reference numeral 30 denotes a modem connected to the telephone line N, which transmits a transmission signal modulated by the data signal supplied from the CPU 22 to the telephone line N, while demodulating a transmission signal transmitted via the telephone line N. The obtained data signal is supplied to the CPU 22. That is, the digital tuner 2 is connected to a host computer (not shown) installed in a digital broadcasting service center via a telephone line N, and is charged according to the usage history recorded on the IC card CD. It has become so.
[0017]
Reference numeral 32 denotes a hard disk, which stores channel scan information in a channel scan operation mode to be described later. The contents and use of this channel scan information will be described later.
[0018]
B: Operation of Embodiment Next, the operation of the embodiment having the above configuration will be described.
In this embodiment, the operator can select a channel by each of (1) direct selection by channel number, (2) channel surfing by the arrow key R21, and (3) channel scanning. Hereinafter, description will be made by paying attention to the operation at the time of channel selection by each of these methods.
[0019]
(1) Direct selection by channel number First, the case of directly selecting a channel by channel number will be described.
First, when the operator operates the numeric keypad R10 of the remote controller R to input a channel number and then presses the selection key R20, an optical signal corresponding to the channel number is transmitted, which is received by the operation I / F 26 and is received as an electrical signal. To the CPU 22. Thereby, CPU22 detects the channel number designated by the operator.
[0020]
Then, the CPU 22 supplies the tuner unit 20 with a control signal for alternately switching the channel to be tuned at a high speed so as to receive signals of both the channel designated by the operator and the channel adjacent to the channel in the forward direction. Thereby, the tuner unit 20 switches the tuning for both the channel designated by the operator and the adjacent channel on the forward direction at high speed based on the control signal supplied from the CPU 22 and receives both signals. That is, since the switching speed of the reception channel by the CPU 22 is sufficiently faster than the transmission speed of the transmission wave, the tuner unit 20 can receive the broadcast waves of two channels in parallel.
[0021]
Thus, of the received signals, the signal of the channel designated by the operator is decoded by the decoder 21a, and the signal of the adjacent channel on the forward side is decoded by the decoder 21b. The video / audio signal decoded by the decoder 21a is converted into a signal that can be reproduced by the television receiver 3 via the AV / I / F 25, and then supplied to the receiver 3. As a result, the television receiver 3 reproduces the video and audio of the channel designated by the operator.
[0022]
On the other hand, the video / audio signals decoded by the decoder 21 b are sequentially written in a ring buffer set in the RAM 24. This ring buffer is set so as to always store a signal that is traced back by a time corresponding to at least the decoding time (about 1 to 2 seconds) of the decoders 21a and 21b.
[0023]
In this way, while the program of the designated channel is played back, in the background processing of the CPU 22, the signal of the channel adjacent to the channel in the forward direction is decoded in parallel, and the result is written to the RAM 24 as needed. ing.
[0024]
(2) Channel Surf by Arrow Key R21 Next, a so-called forward channel surf in which the forward arrow key R21 is pressed one after another to switch the channel in the forward direction will be described.
When the operator depresses the forward arrow key R21 of the remote controller R during reproduction of the channel specified in (1) above, an optical signal corresponding to the operation is transmitted, and this is received by the operation I / F 26 and is received as an electrical signal. After being converted to, it is supplied to the CPU 22. Thereby, the CPU 22 detects that there is an instruction to switch to the adjacent channel on the forward direction side.
[0025]
As a result, the CPU 22 controls the tuning of the tuner unit 20 so as to receive signals supplied from both the switching destination channel and the channel further adjacent to the forward direction side, as in the case of (1) above. Thus, both signals are received in parallel, the signal of the switching destination channel is decoded by the same decoder 21b as before, and the signal of the channel further adjacent to the switching destination channel in the forward direction is decoded by the decoder 21a. .
[0026]
On the other hand, the CPU 22 reads the video / audio signal of the switching destination channel that has already been decoded by the background processing from the ring buffer of the RAM 24 at the time when the switching instruction is given, and outputs this to the AV / I / F 25. Thereby, when the forward arrow key R21 is pressed, the reproduction content of the television receiver 3 is quickly switched without waiting for the decoding time. Then, after reading all the decoded signals from the ring buffer, the CPU 22 outputs the signals sequentially decoded by the decoder 21b to the AV / I / F 25. Thereby, the reproduction of the switching destination channel is continuously performed. On the other hand, the signals of the adjacent channels on the forward direction side decoded by the decoder 21a are sequentially written in the ring buffer similar to the above described separately set in the RAM 24 in the background processing of the CPU 22. Thus, channel switching in the forward direction is performed.
[0027]
When the operator further presses the forward arrow key R21 of the remote controller R, the CPU 22 starts reproduction from the decoded signal of the switching destination channel written in the ring buffer, while reproducing the switching destination channel. In the middle, the signal of the channel adjacent to the switching destination channel in the forward direction and the recording operation thereof are performed in the background.
[0028]
In this way, even when the operator presses the forward arrow key R21 one after another, the signal of the channel adjacent to the forward direction is always decoded in the background, so there is a waiting time corresponding to the decoding time when switching the channel. Therefore, it becomes possible to smoothly perform channel surfing in the forward direction.
[0029]
(3) Channel Scan Next, program input of a channel to be scanned will be described first, and then channel scan for automatically scanning channels based on the input program will be described.
[0030]
First, when the operator presses the program key P31, the CPU 22 recognizes this and sets the operation mode to the program mode. In this program mode, the operator repeats the input of the channel number with the numeric keypad R10 and the confirmation of the input with the selection key R20, thereby sequentially specifying the channels to be scanned. The designated channel number is sequentially recognized by the CPU 22.
[0031]
When all the desired channels are input as described above, the operator instructs the end of the program input by pressing the program key P31 again. When the program key P31 is pressed in the program mode, the CPU 22 recognizes that the program input has been completed, stores information consisting of a sequence of the designated channel numbers in the hard disk 32 as channel scan information, and then the program mode End.
[0032]
Thereafter, when the power is turned off and the power is turned on again, the previously programmed channel scan information is read from the hard disk 32 and loaded into the RAM 24. Thereby, the channel scan information is updated to the latest one.
[0033]
Next, when the operator presses the scan key R30, the CPU 22 recognizes that the channel scan is instructed, and refers to the channel scan information stored in the RAM 24. The CPU 22 sequentially switches the reproduction channel in accordance with the channel number sequence indicated by the channel scan information. Also in this case, as in the case of (2), the CPU 22 decodes the signal of the channel to be switched next (in this case, the channel to be scanned next instead of the adjacent channel in the forward direction) in the background. The result is stored in the ring buffer set in the RAM 24. When the channel is switched, reproduction is started from the signal stored in the ring buffer, so that a quick channel scan can be performed without waiting for decoding.
[0034]
When the selection key R20 is pressed during this channel scan, the CPU 22 stops the channel scan. Therefore, the operator can select the channel by pressing the selection key R20 at the timing when the channel is switched to a desired channel during the channel scan.
[0035]
C: Modified Example (1) Although satellite broadcasting is used in the embodiment, the present invention is not limited to this, and can also be applied to wired broadcasting such as terrestrial broadcasting and CATV. In short, the present invention can be applied to any form in which program information that needs to be decoded on the tuner side is broadcast on multiple channels, and is not limited by the form of broadcasting.
[0036]
(2) In the embodiment, as an example, one tuner unit 20 has been described as switching two channels alternately and receiving simultaneously. However, the present invention is not limited to this, and two tuner units 20 are provided. Thus, the two channels may be received simultaneously.
[0037]
(3) In addition, in the embodiment, it is configured to be compatible only with the forward channel surf for simple configuration, but not limited to this, in order to support both forward and reverse channel surf, A configuration may be adopted in which signals of channels selected and channels adjacent to both the forward and reverse directions are decoded and stored in the background. In this case, three sets of tuner units and decoders may be provided so that three channels can be received and decoded in parallel.
[0038]
(4) In the embodiment, the decoding result of the signal received from the adjacent channel is written in the ring buffer set in the RAM 24 by the amount of data corresponding to the reproduction time of about 1 to 2 seconds. However, it is not limited to such a configuration. Since the delay time associated with decoding varies depending on the performance of the decoders 21a and 21b, if the delay time corresponds to, for example, about one frame of data, the buffer capacity is stored for that one frame. Setting it to a possible size is sufficient. Further, it is not always necessary to configure as a ring buffer. For example, it is possible to record received data corresponding to a delay time of decoding, such as a so-called ping-pong buffer that alternately writes and reads data for two buffers. The buffer may be configured in any manner.
[0039]
(5) In the embodiment, the channel scan information is recorded on the hard disk 32. However, the stored contents are not limited to the hard disk 32 as long as the stored contents are preserved even when the power is turned off. Other storage media such as a writable ROM may be adopted.
[0040]
【The invention's effect】
As described above, according to the first aspect of the present invention, since there is no waiting time corresponding to the decoding time of the program information at the time of channel switching, channel switching can be performed quickly.
[0041]
According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, the user can enjoy high-speed channel surfing.
[0042]
According to the invention described in claim 3, in addition to the effect of the invention described in claim 1, the user selects a specific channel from among many channels, and performs channel scanning only for the selected channel. Therefore, a desired channel can be selected quickly.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.
FIG. 2 is a plan view showing a configuration example of an operation surface of a remote controller R in the same embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Antenna, 2 ... Digital tuner, 3 ... Television receiver, 20 ... Tuner part, 21a, 21b ... Decoder (1st and 2nd decoder), 22 ... CPU, 23 ... ROM, 24 ... RAM (memory | storage means) 25 ... AV / IF, 26 ... operation IF, 28 ... card IF, 30 ... modem, 32 ... hard disk, BUS ... bus, CD ... IC card, R ... remote control.

Claims (1)

In a digital tuner that receives program information of a designated channel among program information that is compressed and encoded supplied by a plurality of channels by digital broadcasting, decodes the received program information, and sends it to a playback device.
Channel scan information storage means for storing channel scan information comprising a sequence of channel numbers;
Channel switching means for sequentially switching channels according to a sequence of channel numbers indicated by the channel scan information stored in the channel scan information storage means,
A first decoder for decoding program information of the designated channel;
In parallel with the decoding process by the first decoder, a second decoder for decoding program information of a channel to be switched next by the channel switching means ;
Storage means for storing a result of decoding by the second decoder,
Thus, when switching to the channel in which the second decoder is decoding the program information is designated by the channel switching means , the storage means stores at least the delay time associated with the decoding by the second decoder. A digital tuner, wherein the stored decoded program information is sent to the playback device.

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