JP2001309255A - Receiver of digital tv broadcasting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a receiver of digital TV broadcasting capable of shortening the required time to output a video and an audio at the changing of channels. SOLUTION: The receiver of digital TV broadcasting comprises a first tuner 12 receiving channels for usual viewing, a second tuner 15 receiving channels for unusual viewing and a recording unit 18 storing received TS data at each channel, and the receiver switches automatically and periodically the channel received by the second tuner 15 not receiving the usual viewing channels, so that the receiver patrols to a predetermined storage area of the recording unit 18 and proceeds respective few minutes recording for the received TS data of each channel in a few or all channels.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a digital television broadcast receiver for receiving a digital television broadcast.

[0002]

2. Description of the Related Art Conventionally, in digital television broadcasting by satellite, a signal received from a parabolic antenna is separated and selected for each transponder by a tuner, and a PS is selected by a demodulator.
K demodulation and error correction processing are performed, and TS data is output. By the TS separation, video and audio PES data corresponding to the viewing channel is finally separated. The separated PES data is supplied to a subsequent AV decoder, where the compressed video / audio data is decoded, and a video signal and an audio signal are output.

[0003] Here, the channel selection processing operation inside the receiver when the viewer switches channels will be described. When the information of the selected channel, that is, the service ID is given, the PA
T (program association table) is received by the currently received transponder, and the service ID is received.
And if the service ID does not exist, NIT
(Network Information Table).

[0004] A service ID in the service list descriptor of the NIT is searched, and the TS of the service ID is searched. I
D and the carrier frequency of the TS data.

[0005] To change the receiving transponder, the receiving frequency is changed. At this time, it takes about 500 ms at the maximum for frequency tuning and PSK carrier reproduction.

When the PAT is received again, the PM of the service ID is
T Get PID and its PMD PMT based on PID
(Program map table). PMT
The stream type (video,
After recognizing the elementary PID for each
Separate packets with a PID that matches the mental PID
I do. Up to 10 for such video and audio stream extraction
It takes 0 ms.

For video decoding, it is necessary to analyze a sequence header normally inserted for each GOP, obtain parameters necessary for video decoding, and set a decoder. When 1 GOP is set to 15 frames, it takes about 500 ms at maximum to receive a sequence header in a video stream. Also, it takes about 500 ms at maximum from writing the video elementary stream to the vbv buffer to synchronizing and outputting the video based on the time stamp.

[0008] The required time from the switching of the channel to the output of the selected video is the sum of the above times, and is a maximum of about 1.6 seconds.

[0009]

As shown in the prior art, digital television broadcasting has a problem that it takes more time to output video and audio at the time of channel switching than current analog television broadcasting.

It is an object of the present invention to provide a digital television broadcast receiver capable of shortening the time until video and audio are output when switching channels.

[0011]

A first tuner for receiving a channel for normal viewing, a second tuner for receiving a channel not for normal viewing, and a recording unit for storing received TS data for each channel, The channel of the second tuner which does not receive the channel for normal viewing is automatically and periodically switched, and the received TS data of each channel of several channels or all channels is stored for several seconds in a predetermined recording area of the recording unit. It is characterized in that it is recorded while traveling.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic signal processing block diagram of a BS digital television broadcast receiver. The signal received from the parabolic antenna 11 is separated and selected for each transponder by the first tuner 12 or the second tuner 15, and the first demodulator 13 or the second demodulator 16
Performs 8PSK demodulation and error correction processing to output TS data.

The first TS separator 14 or the second TS
The separator 17 finally separates video and audio PES data corresponding to the viewing channel. The separated PES data is supplied to the subsequent AV decoder 19, where the compressed video / audio data is decoded, and the video signal and the audio signal are output.

FIG. 2 shows a processing flow of channel selection operation inside the receiver when the viewer switches channels.
Note that FIG. 2 omits the conditional reception processing.

When the information of the selected channel, that is, the service ID, is given, a PAT (program association table) is received by the transponder currently receiving, and the service ID is searched. (Network Information Table).

The service ID in the service list descriptor of the NIT is searched, and the TS of the service ID is searched. I
D and the carrier frequency of the TS data.

The receiving frequency is changed to change the receiving transponder. At this time, a maximum of 500 ms is required for frequency tuning and PSK carrier reproduction.

The PAT is received again, and the PMT of the service ID is received.
Get PID and its PMD PMT based on PID
(Program map table).

Elementary PID for each stream type (video, audio, etc.) corresponding to the service ID in the PMT
After that, a packet having a PID matching the elementary PID is separated. Since the PSI information of PAT and PMT is inserted into the TS data at intervals of 100 ms, it takes a maximum of 100 ms to extract the video and audio streams.

For video decoding, it is necessary to analyze a sequence header normally inserted for each GOP, obtain parameters required for video decoding, and set a decoder. Assuming that 1 GOP = 15 frames, it takes a maximum of 500 ms to receive a sequence header in a video stream.

Also, the video elementary stream is called vbv
It takes a maximum of 500 ms from writing to the buffer to synchronizing and outputting the image based on the time stamp.

The time required from the switching of the channel to the output of the selected video is about 1.6 seconds at the maximum as shown in FIG. As described above, there is a problem in that the image output time at the time of channel switching in digital television broadcasting is much longer than that in conventional analog television broadcasting.

In order to solve such a problem, the present invention significantly reduces the time until image output when switching channels and provides operability equivalent to that of a conventional analog TV broadcast channel selection operation.

FIG. 1 is a block diagram of a digital television broadcast receiver assuming satellite broadcasting such as BS digital television broadcasting. The recording unit 18 is connected to the second tuner 15, the second demodulator 16, and the second TS separator 17 in two systems including a tuner, a demodulator, and a TS separator. A first tuner 12, a first demodulator 13, a first TS separator 14, and an AV decoder 19 are used for normal BS digital television broadcast viewing.

The AV decoder 19 shown here has a first T
It is assumed that PES data for two channels from the S separator 14 and the second separator 17 can be decoded. Of course 2
One that has been separately decoded by the AV decoders may be switched.

FIG. 3 shows an example of the channel switching operation of the present invention. The received TS data of, for example, all channels of the BS digital television broadcast is automatically and periodically switched and recorded on the path of the second tuner 15, the second demodulator 16, the second TS separator 17, and the recording unit 18. The received data of each channel is circulated and recorded in a predetermined recording area for several seconds in the unit.

When switching from the viewing of channel A to the viewing of channel E at the timing shown in FIG. 3, first, the TS data of channel E for a few seconds previously recorded in the recording unit 18 is reproduced. , A
The decoded output is displayed through the V decoder 19 (video,
voice).

When the first tuner 12, the first demodulator 13, the first TS separator 14, and the decoding output display of the TS data of the system of the AV decoder 19 become possible, the reproduction of the recording unit 18 is started. The display is switched to the decoded output display (video and audio) of the TS data of the system of the first tuner 12.

In this case, the channel switching time from the recording unit 18 to the picture is 500 ms required for frequency tuning and PSK carrier reproduction in FIG.
100 required to capture PSI and PMT PSI information
Since ms is reduced, the maximum is 1.0 second.

The T selected by the second tuner 15
When writing the S data to the recording unit 18, the head of the GOP is searched, and by writing from the TS packet data including the head of the GOP, the time until the reproduction picture is reproduced from the recording unit 18 can be further reduced. Normally, the sequence header is arranged at the head of the GOP, so that it is possible to reduce the time required to receive the sequence header in the video stream of FIG. 2 by 500 ms, and further reduce the time required for rendering, which conventionally required 1.6 seconds. Things can be up to 0.5 seconds.

At the time of switching the channel of the digital television broadcast, the data of the designated channel recorded in the recording unit 18 is reproduced and decoded and displayed, and before switching to the on-air video of the designated channel, the channel is switched again by a remote controller or the like. When the operation is performed, the display is not switched to the decoding output display (video / audio) of the TS data on the first tuner 12 side, and the recording unit 1 is continued.
The reproduction of the TS data of the last designated channel recorded in No. 8 is performed and the display is switched to the decode output display.

FIG. 4 shows a timing chart of this operation. In FIG. 4, channel B is first selected by the channel switching instruction while channel A is being viewed, and the TS data of channel B previously recorded in the recording unit 18 by the system of the second tuner 15 is converted into the second TS separator. 17, decode through AV decode 19, output and display (video, audio). It is assumed that the recording unit 18 records, for example, TS data of each channel for three seconds.

In FIG. 4, channel B is first selected by the channel selection remote controller, and channel B on the first tuner 12 side is selected.
If the channel D is selected again before the TS data of the channel D is decoded and output display is possible, the TS data of the channel D recorded in advance in the recording unit 18 is reproduced and the second channel is reproduced.
(Video, audio) switching operation for outputting and displaying through the TS separator 17 and the AV decoder 19. Hereinafter, the switching operation to the channels C and E in FIG.

As described above, in order to perform so-called zapping viewing in which channels are switched one after another by a channel selection remote controller, switching between channels has conventionally taken a long time, which is not practical. Zapping viewing becomes possible with a feeling similar to that of conventional analog television broadcasting.

[0035]

According to the present invention, for example, in the case of BS digital television broadcasting, the channel switching time, which normally takes about 1.6 seconds at most after a channel is switched until a picture appears, is reduced to about 0.5 seconds in the present invention. It can be switched. In addition, zapping for switching remote controllers one after another takes too much time to switch, which is extremely inappropriate. However, the present invention enables zapping for practical use.

[Brief description of the drawings]

FIG. 1 is a schematic signal processing block diagram of a BS digital television broadcast receiver according to the present invention.

FIG. 2 is a flowchart illustrating a tuning operation process of a BS digital television broadcast receiver when a channel of the BS digital television broadcast is switched.

FIG. 3 is a timing chart illustrating an example of a channel switching operation according to the present invention.

FIG. 4 is a timing chart illustrating an operation during zapping viewing according to the present invention.

[Explanation of symbols]

11 parabolic antenna, 12 first tuner, 13 first demodulator, 14 first TS separator, 15 second tuner, 16 second demodulator, 17. second TS separator, 18 recording unit, 19 AV decoder, 20 monitor.

Claims (4)

[Claims] 1. A first tuner for receiving a normal viewing channel, a second tuner for receiving a non-normal viewing channel, and a recording unit for storing received TS data for each channel, wherein the normal viewing channel is provided. Automatically and periodically switches the channel of the second tuner that has not received the signal, and receives the T
A digital television broadcast receiver, wherein S data is circulated and recorded for several seconds in a predetermined recording area of the recording unit. 2. When the digital TV broadcast channel is switched, the received TS data of the specified channel recorded in the recording unit is reproduced until the received TS data of the specified channel is decoded and displayed on the normal viewing side. The decoding output display of the reception TS data of the designated channel is switched to the decoding output display of the reception TS data of the normal viewing side when the decoding output display of the reception TS data of the designated channel is established on the normal viewing side. Digital television broadcast receiver as described. 3. When a digital TV broadcast channel is switched, received TS data of a designated channel recorded in the recording unit is reproduced, decoded and displayed, and
If the channel switching operation is performed again before the viewing side switches to the decoding output display of the reception TS data of the specified channel, the reception TS data of the last specified channel recorded in the recording unit is reproduced. 2. A decoded output is displayed on the display.
A digital television broadcast receiver according to claim 1. 4. The digital television broadcast receiver according to claim 1, wherein the recording in the recording unit is performed from the beginning of a TS packet including a GOP.