JP4357070B2 - Digital broadcast signal synchronization switching transmission device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a digital broadcast transmission facility, and more particularly, to a synchronous switching control technique that selectively compresses and encodes a bit stream independently of each other in two or more systems.
[0002]
[Prior art]
In recent years, practical use of digital broadcasting has been promoted. In this digital broadcasting, bitstreams compressed and encoded by an encoding method standardized by MPEG2 (Moving Picture Experts Group 2) are switched between studio devices. Broadcasts are synchronized and multiplexed.
[0003]
In addition, in such a digital broadcast transmission facility, when it is necessary to switch the bitstream system at the time of equipment failure or maintenance, the switching is performed after synchronizing the bitstream between the systems. By doing so, it is necessary to prevent the video decoded on the receiver side from being disturbed.
[0004]
By the way, in the digital broadcasting transmission facility as described above, in order to synchronize operation between studio devices of each system, STC (System Time Clock) is built in each studio device, and based on the time measured by this STC. It is considered to operate each studio device. However, since each system operates independently of each other, the STC of each studio device is synchronized in the period, but the STC value varies from device to device. When the stream is switched and transmitted, the video decoded on the receiver side is disturbed for a moment, which gives the viewer a sense of discomfort.
[0005]
[Problems to be solved by the invention]
As described above, in the digital broadcast transmission facility, the STC value of each studio device differs between systems, so that if the bit stream of each system is switched and transmitted as it is, the decoded video is not stable on the receiver side. Have a problem.
[0006]
SUMMARY OF THE INVENTION An object of the present invention is to provide a digital broadcast signal synchronous switching transmission device capable of performing system switching smoothly without causing disturbance in a transmission signal after synchronizing the bit stream of each system between the systems. It is to provide.
[0007]
[Means for Solving the Problems]
A digital broadcast signal synchronous switching transmission device according to the present invention is a digital broadcast signal synchronous switching transmission device that synchronizes and selectively derives digital broadcast signals having a frame structure that are compressed and encoded independently from each other in at least two or more systems. And a time management means capable of adjusting the time based on the given information, and a switching unit for selectively inputting one of the digital broadcast signals of each system based on the time by the time management means And a time management unit that is provided in each input system of the switching unit and that can adjust the time based on the given information, and processes the digital broadcast signal to be sent to the switching unit based on the time by the time management unit And a signal processing unit that adds time information in units of frames, and should be given to the switching unit and the signal processing unit of each system at the time of system switching The reference time information is inserted into a predetermined information area in the frame synchronization signal and given to the time management means of each of the switching unit and the signal processing unit of each system, and the outputs of the switching source and switching destination signal processing units are synchronized. And a synchronization generation control unit for switching the switching unit.
[0008]
In particular, when a digital broadcast signal is a bit stream generated in a format specified by the MPEG2 encoding method and the signal processing unit is a video encoding unit that encodes an input video signal into a bit stream, video encoding is performed. The unit encodes the input video signal into a bit stream based on the time by the time management means, and adds a measurement time value in units of frames, and the synchronization generation control unit uses a reference signal using SDI (Serial Digital Interface). The reference time value is inserted into the auxiliary signal packet in the middle and given to the time management means of the switching unit and the video encoding unit of each system in common, and the frame phase and the switching destination of the output of the video encoding unit as the switching source The switching control is performed so that the switching unit performs switching at a bitstream switching point after matching the frame phase of the output of the video encoding unit. Characterized in that it.
[0009]
According to this configuration, at the time of system switching, it is used by the synchronization generation control unit for bit stream synchronization in order to synchronize the measured time values measured by the time management means of each video encoding unit and switching unit. The reference time value is notified to the video encoding unit and the switching unit of each system using the auxiliary signal packet in the SDI signal. Then, the video encoding unit of each system that has received the SDI signal encodes the video signal into a bit stream so as to align the frame phase between the systems based on the reception result, and also generates a reference from the auxiliary signal packet of the SDI signal. The time value is extracted, the measured time value measured by the time management means is replaced with the reference time value, and the reference time value is added for each frame of the bit stream to be transmitted. On the other hand, the switching unit that receives the SDI signal extracts the reference time value from the auxiliary signal packet of the SDI signal, replaces the measurement time value measured by the time management means with the reference time value, and based on the reference time value Switch over.
[0010]
Therefore, according to the present invention, it is possible to make the time value of each output continuous while synchronizing the output of the video encoder of each system between the systems using the auxiliary signal packet of the SDI signal. Timing control at the time of system switching in the switching unit can be easily performed. For this reason, it is not necessary to newly provide a signal line for time adjustment, and the bit stream of each system can be smoothly switched with a simple configuration without causing disturbance in the transmission signal.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing an embodiment of a digital broadcast signal synchronization switching transmission device according to the present invention. Reference numeral 11 denotes a switch that inputs a bit stream according to two MPEG2 encoding schemes and selectively derives one of them.
[0012]
An encoder 12 is connected to the first input terminal of the switch 11, and an encoder 13 is connected to the second input terminal. The switch 11 and the encoders 12 and 13 are controlled by the synchronization generation controller 14 at the time of system switching.
[0013]
The encoder 12 performs variable-length compression coding based on the MPEG2 coding method on the input SDTV (Standard Definition TV) video signal, for example, and converts it into an MPEG2 bit stream (A material). The encoder 13 performs variable-length compression coding based on the MPEG2 coding system on the input SDTV video signal, and converts the video signal into an MPEG2 bit stream (B material).
[0014]
The synchronization generation controller 14 causes the switch 11 to connect an arbitrary input system and one output system in accordance with switching information by a user-specified input operation. At this time, when switching the input system connected to the output system, it is determined whether or not the encoder 12 is connected to the switching source, and when the encoder 12 is connected, the encoder 12 is switched to the switching source. A reference signal (hereinafter referred to as SDI signal) using SDI (Serial Digital Interface) as a frame synchronization signal is given to the previous encoder 13 to synchronize the output of the encoder 13 and the output of the encoder 12, and then the switcher. 11 switching control is performed.
[0015]
By the way, in this embodiment, the switch 11 and the encoders 12 and 13 each have a built-in STC (System Time Clock). That is, the switch 11 and the encoders 12 and 13 operate based on the time according to the STC. In addition, the encoders 12 and 13 convert the input video signal into a bit stream, and outputs an STC value measured by the STC in units of frames.
[0016]
Next, the operation of the above configuration will be described with reference to FIG. 2, FIG. 3 and FIG.
In this system, the encoders 12 and 13 generate the same bit stream independently of each other. Here, in order to easily switch between the output of the encoder 12 and the output of the encoder 13, it is conceivable to match the switchable frame phases of both bit streams. The state of the switching process of the switch 11 in this case is shown in FIGS.
[0017]
However, since the encoder 12 and the encoder 13 independently generate the bitstream, the STC value measured by the STC is different even when the frame phases are matched, and the output of the encoder 12 (see FIG. 2 (a)) is switched to the output of the encoder 13 (shown in FIG. 2 (b)), the STC value of the transmission signal becomes discontinuous as shown in FIG. 2 (c). As shown, the decoded video is disturbed on the receiver side, which gives the viewer a sense of discomfort.
[0018]
Therefore, in the present invention, the synchronization generation controller 14 adjusts the STC of each of the switch 11 and the encoders 12 and 13 so that the switch 11 can send out a transmission signal in which the STC value has continuity. The state of the switching process in this case is shown in FIGS.
[0019]
First, when the system switching instruction is input, the synchronization generation controller 14 inserts the reference STC value into the auxiliary signal packet in the SDI signal to be given to the switch 11 and the encoders 12 and 13, respectively, and switches the switch 11 and the encoder 12, 13 is supplied. Then, the switch 11 and the encoders 12 and 13 extract the reference STC value from the auxiliary signal packet of the input SDI signal, and adjust so that the STC value measured by the STC is replaced with the reference STC value. Also, the encoders 12 and 13 add the reference STC value to the frame of the bit stream to be output, so that the bits having the STC values synchronized between the systems as shown in FIGS. 3 (a) and 3 (b). The stream can be sent out. Thereafter, as shown in FIG. 3C, the synchronization generation controller 14 switches so that the bit stream output from the encoder 12 at the frame boundary is switched to the bit stream output from the encoder 13 with respect to the switch 11. Control timing. At this time, since the STC of the switch 11 is synchronized with the STC of the synchronization generation controller 14, the switching timing can be easily controlled.
[0020]
As a result, as shown in FIG. 3D, the video decoded on the receiver side is a beautifully connected video with no video disturbance.
[0021]
Note that the SDI signal generated from the synchronization generation controller 14 is a 525-line frame synchronization signal as shown in FIG. 4, and the shaded area in the figure is the auxiliary signal multiplexing possible area. In FIG. 4, the horizontal indicates the word number, the vertical indicates the line number, and one word is 10 bits. Further, the multiplexing positions of the auxiliary signal packets in this embodiment are lines 53, 143, 233, 316, 406, 496, and are indicated by black marks in the drawing.
[0022]
As described above, in the above-described embodiment, at the time of system switching, in order to synchronize the STC values measured by the STCs of the switch 11 and the encoders 12 and 13, the synchronization generation controller 14 uses them for bit stream synchronization. The reference STC value is notified to the switch 11 and the encoders 12 and 13 using the auxiliary signal packet in the SDI signal. Then, the encoders 12 and 13 that have received the SDI signal perform compression encoding on the video signal so as to align the frame phase between the systems based on the reception result, convert the video signal into a bit stream, and an auxiliary signal packet of the SDI signal. The reference STC value is extracted from the reference STC value, the measured STC value measured by the STC is replaced with the reference STC value, and the reference STC value is added to each frame of the bit stream to be transmitted. On the other hand, the switch 11 that has received the SDI signal extracts the reference STC value from the auxiliary signal packet of the SDI signal, replaces the measured STC value measured by the STC with the reference STC value, and changes the reference STC value to the reference STC value at the time of system switching. System switching is performed based on this.
[0023]
Therefore, it is possible to make the time values of the outputs continuous while synchronizing the outputs of the encoders 12 and 13 between the systems by using the auxiliary signal packet of the SDI signal. The timing control at the time of system switching in the device 11 can be easily performed. For this reason, it is not necessary to newly provide a signal line dedicated for STC adjustment, and can be realized with a simple configuration and inexpensive capital investment, and the bit stream of each system can be smoothly switched without causing a disturbance in the transmission signal. Can do.
[0024]
In the above embodiment, the case where SDTV bit streams having the same signal format are switched is described. However, the present invention can also be applied to switching two bit streams having different signal formats. Further, when two bit streams having the same signal format are handled, the present invention can also be applied to a case where one bit stream has a 3: 2 pull-down structure, for example.
[0025]
Moreover, although the case where the encoders 12 and 13 were connected to the input side of the switch 11 was demonstrated in the said embodiment, the bit stream processor which adds a process to a bit stream other than the encoders 12 and 13 is the input side of the switch 11 Even when connected to, the present invention is effective when it is necessary to synchronize the respective bit streams. Furthermore, the type of encoder may conform to a standard other than MPEG2.
[0026]
【The invention's effect】
As described above in detail, according to the present invention, the digital stream signal synchronization can be performed smoothly without causing disturbance in the transmission signal after synchronizing the bit stream of each system between the systems. A switching transmission device can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of a digital broadcast signal synchronization switching transmission device according to the present invention.
FIG. 2 is a timing chart for explaining a processing operation in the system configuration of the embodiment.
FIG. 3 is a timing chart for explaining the processing operation in the system configuration of the embodiment.
FIG. 4 is a diagram showing a format of an SDI signal applied in the embodiment.
[Explanation of symbols]
11 ... Switch,
12, 13 ... encoder,
14: Synchronous generation controller.

Claims (5)

In a digital broadcast signal synchronous switching transmission device for selectively deriving by synchronizing and synthesizing digital broadcast signals having a frame structure compressed and encoded independently from each other in at least two systems,
A switching unit that has time management means capable of adjusting the time based on given information, and that selectively inputs one of the digital broadcast signals of each system based on the time by the time management means; ,
Provided in each input system of the switching unit, having time management means capable of adjusting the time based on the given information, and converting the input signal into the digital broadcast signal based on the time by the time management means A signal processing unit for adding time information in units of frames;
Common reference time information for the switching unit and the signal processing unit of each system by inserting reference time information into a predetermined information area in the frame synchronization signal to be given to the switching unit and the signal processing unit of each system at the time of system switching And a synchronization generation control unit for switching the switching unit after synchronizing the outputs of the switching source and switching destination signal processing units. The digital broadcast signal is a bit stream generated in a format defined by MPEG2 (Moving Picture Experts Group 2) encoding method, and the signal processing unit converts the input signal into the bit stream and sends it to the switching unit. The digital broadcast signal synchronous switching transmission device according to claim 1. 3. The digital broadcast signal synchronous switching transmission device according to claim 2 , wherein the signal processing unit is a video encoding unit that encodes an input video signal into the bit stream. The video encoding unit encodes an input video signal into a bit stream based on the time by the time management means, and adds a measurement time value in units of frames. The synchronization generation control unit is configured to receive an SDI (Serial Digital Interface) 4. A digital time according to claim 3, wherein a reference time value is inserted into an auxiliary signal packet in a reference signal using), and is provided in common to the time management means of each of the switching unit and each system video encoding unit. Broadcast signal synchronous switching transmission device.   The synchronization generation control unit inserts a reference time value into an auxiliary signal packet in a reference signal using SDI, and provides the same to time management means of the switching unit and the video encoding unit of each system, and After the frame phase of the output of the original video encoding unit matches the frame phase of the output of the video encoding unit as the switching destination, the switching unit is switched at the bit stream switching point. 5. The digital broadcast signal synchronous switching transmission device according to claim 4, wherein switching control is performed as described above.

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