KR20160026201A - Splicing Apparatus for Multi Channel Digital Broadcasting and Method thereof - Google Patents

Abstract

The present invention relates to a splicing device for multi-channel digital broadcasting and to a method thereof. The splicing device for multi-channel digital broadcasting comprises: a splicer for, if a switching signal is received in a first stream and a delay signal is reached in the first stream during the output of the first stream in the form of an MPEG transport stream, converting the output to a second stream after a switching time is reached in the second stream in the form of an MPEG transport stream. According to the splicing device for multi-channel digital broadcasting and the method thereof according to the present invention, a broadcasting service can be provided without interruption in a screen even if another program is inserted and transmitted without an encoding process after decoding at an MPEG2-TS level for converting two different kinds of streams during the transmission of a specific program in a digital broadcast transmitting system as the output is converted to the second stream if the switching time is reached in the second stream input after the switching signal during the output of the input first stream, and likewise the output is converted to the first stream if the switching time is reached in the first stream after the switching signal during the output of the second stream.

Description

TECHNICAL FIELD [0001] The present invention relates to a splicing apparatus for multi-channel digital broadcasting,

The present invention relates to a splicing apparatus and method for multi-channel digital broadcasting, and more particularly, to a splicing apparatus and method for multi-channel digital broadcasting, To a splicing apparatus for multichannel digital broadcasting and a method thereof.

In a current digital broadcasting environment, a broadcast switching system is required to broadcast multi-channel broadcasting and general (HD) broadcasting through the same channel.

When a broadcast is switched to a general (HD) broadcast, a multi-channel broadcast, and a general (HD) broadcast, a special method of switching the broadcast without interruption is required.

A general broadcast is an MPEG-2 TS stream having one main video and one channel containing multiple audio.

In the case of multi-channel broadcasting, it is an MPEG-2 TS stream having a plurality of channels, including a plurality of video and audio, based on main video and audio of a general broadcast.

In order to switch between general broadcasts, there is a method in which two streams compressed and transmitted are decoded and then switched at a source signal level and re-encoded.

However, in order to switch between the general broadcast and the multi-channel broadcast, it can not be solved by the switching method between general broadcasts.

When switching from general (HD) broadcasting to multi-channel broadcasting, the original video of the main video is the same, but different types of encoders must be used. Therefore, when considering switching only the sync signal of MPEG2 TS, There is a problem in that it occurs.

In order to solve this problem, when the two streams are switched at an arbitrary point in the MPEG2 TS level, the continuity of the video and the audio is damaged, and the clocks of the encoders that produce the two kinds of streams may be different. Therefore, There is a problem in that the error of the signal becomes large.

Korean Registered Patent Publication No. 10-1087666

SUMMARY OF THE INVENTION The present invention has been conceived to solve the above-described problems, and it is an object of the present invention to provide an apparatus and method for switching an output to a second stream when an input first stream is output, Likewise, when the second stream arrives at the switching time from the first stream to the first stream after the outputting and the switching signal, the output is switched to the first stream so that MPEG2 Channel digital broadcasting capable of providing a broadcasting service without interrupting the screen even when another program is inserted and transmitted after decoding at the TS level without encoding process, and a method thereof.

According to another aspect of the present invention, there is provided a splicing apparatus for multi-channel digital broadcasting, the splicing apparatus comprising: And a splitter unit for switching the output from the second stream, which is an MPEG transport stream, to a second stream after the switching point is reached when the grace signal is received in the first stream after the switching signal is received .

The grace signal may be when a P frame or an I frame begins in the first stream and the switching time may be when an I frame begins in the second stream.

The frame existing between the grace signal and the switching point may be replaced with an internal P frame and output.

A B frame that is switched from the first stream to the second stream and succeeds the first I frame of the output may be replaced with an internal P frame and output.

The number of frames of the first stream is smaller than the number of frames of the second stream when a transition signal is transmitted from the first stream to the second stream and a transition signal is received from the second stream during the output, The output frame is switched to the first stream and the frame up to the switching time point of the first stream is replaced with the inner P frame to output And a splice wedge for allowing the wedge to be formed.

The number of frames of the first stream is smaller than the number of frames of the second stream when a transition signal is transmitted from the first stream to the second stream and a transition signal is received from the second stream during the output, In many cases, the output frame of the second stream is replaced with the inner P frame by the difference of the number of frames, and the output is switched to the first stream so that the frame up to the switching time of the first stream is replaced with the inner P frame And a spiral wedge to which the spiral wing is attached.

A B frame transitioned from the second stream to the first stream and subsequent to the first I frame in the output may be replaced with an internal P frame.

In accordance with another aspect of the present invention, there is provided a splicing method for a multi-channel digital broadcast, the method comprising the steps of: (a) outputting a first stream as an MPEG transport stream; A first switch signal receiving step of receiving a switch signal from the first stream; (b) a first delayed signal waiting step to wait until the delayed signal is reached in the first stream after receiving the first switched signal; And (c) a first switching step of switching the output to a second stream in the form of MPEG transport stream when the switching time of the second stream is reached after the first delayed signal waiting step.

The grace signal in the first grace signal waiting step may be when the P frame or the I frame starts in the first stream and the switching time in the first switching step may be when the I frame starts in the second stream.

And a frame existing between the grace signal and the switching point is replaced with an internal P frame and output.

In the first transfer step, the B frame, which is switched from the first stream to the second stream and succeeding the first I frame in the output, may be replaced with an internal P frame and output.

(D1) a second switch signal receiving step of switching from a first stream to a second stream and receiving a switch signal to the second stream during outputting after the first switching step; (e1) a second grace signal waiting step of waiting after the second switch signal reception step until a grace signal is reached in the second stream; (f1) replacing an output frame of the second stream with a null packet by a difference of the number of frames when the number of frames of the first stream is less than or equal to the number of frames of the second stream after the second wait signal waiting step ; And (g1) a second transfer step in which the output after the replacement step is switched to the first stream, and the frame up to the transfer time point of the first stream is replaced with an internal P frame and output.

(D2) a second switch signal reception step of switching from a first stream to a second stream and receiving a switch signal to the second stream during an output, after the first switching step; (e2) a second grace signal waiting step waiting until the grace signal is reached in the second stream after receiving the second switch signal; (f2) replacing an output frame of the second stream with an inner P frame by a difference of the number of frames when the number of frames of the first stream is larger than the number of frames of the second stream after the second wait signal waiting step; And (g2) a second transfer step in which the output after the replacement step is switched to the first stream, and a frame up to the transfer time point of the first stream is replaced with an internal P frame and output.

And the B frame transition from the second stream to the first stream and subsequent to the first I frame of the output may be replaced by an internal P frame.

According to the splicing apparatus and method for multichannel digital broadcasting of the present invention as described above, when the input first stream is being output, the switching time is reached from the second input stream after the switching signal And switching the output to the first stream when the second stream arrives at the switching time from the first stream after the switching signal in the output stage, the specific program is transmitted in the digital broadcasting transmission system It is possible to provide a broadcast service without interrupting the screen even when another program is inserted and transmitted without decoding after decoding at the MPEG2-TS level for switching between two heterogeneous streams.

FIG. 1 is a block diagram illustrating a splicing apparatus for multi-channel digital broadcasting according to an embodiment of the present invention.
2 and 3 are flow charts illustrating a splicing method for multi-channel digital broadcasting according to an embodiment of the present invention,
4 to 14 are diagrams illustrating an example of video splicing in a splicing method for multi-channel digital broadcasting according to an embodiment of the present invention,
15 to 18 are diagrams illustrating an example of audio splicing in the splicing method for multi-channel digital broadcasting according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to facilitate a person skilled in the art to easily carry out the present invention.

A splicing device for multi-channel digital broadcasting according to an exemplary embodiment of the present invention switches between two different encoders without blocking and error of scene and sound, 1, an Asynchronous Serial Interface (ASI) input unit 100, a clock synchronization unit 200, a TS analysis unit 300, (400) and an ASI output unit (500).

As shown in FIG. 4, the ASI input unit 100 inputs a first stream, which is a main stream, and a second stream, which is a sub stream.

The first stream and the second stream should be streams having the same property even if the encoders are different.

Intervals of I frames in the first stream and the second stream should not exceed 30 frames, and B frames (Bidirectionally predictive frames) should not exceed 2 frames in succession.

For example, the first stream may be digital broadcast data generated by a program provider, and the second stream may be advertisement data.

The first stream and the second stream input to the ASI input unit 100 are data compressed in a transport stream (TS) format.

In order to merge the transport stream, the compressed data must be decompressed or decoded.

Accordingly, the first stream and the second stream data are decoded and demultiplexed into a video stream and an audio stream by a demux (not shown) by a separate decoder (not shown).

The clock of the ASI output from the ASI input unit 100 is 270 Mbps, and is parallelized to 8 bits except Start / End, which is processed at a rate of 27 MByte / S.

At this time, the signal transmitted through the ASI input unit 100 is converted into three signals of a Byte Clock signal, an SC signal, and a Data Byte, and is input to the FPGA. The clock signal of the corresponding signal is generated by a clock oscillator of the encoder.

If the output of the same encoder is the same, this clock signal will be the same for all other ports, but the output of the different encoders will use the respective oscillator, which will cause an error (generally the encoder does not synchronize to the external clock).

In addition, if the bit rate is set differently, the valid data byte input speeds will be different, making it difficult to process packets (188 TS packets) in the splice.

Accordingly, logic is required to allow the splicing unit to output the outputs of two different encoders in units of synchronized packets.

The clock synchronization unit 200 calculates the number of data generated in two input lines per unit time and arbitrarily inserts a NULL packet in a line of which the speed of the instantaneous data having a difference of more than 188 bytes is small, So that the splicing unit can receive the input on a packet basis.

If a synchronized Transport Stream (TS) 188 byte packet has been processed, the packet is analyzed first.

The analysis is performed in the order of the PAT (Program Association Table), the PMT (Program Map Table), and the data packet in the TS analysis unit 300, and this analysis is intended to obtain a property for splicing (Analysis itself does not change packets.)

Accordingly, the following analysis is performed.

First, the type of PID (Packet Indentifier) such as MPEG2 Video, AVC Video, Audio1, Audio2, PMT and PAT. Secondly, The presentation time stamp (PTS), the DTS (Decoding Timestamp) value, the PTS, the DTS, the PCR packet position, and the AC3 header in the case of the fifth audio packet The number of channels and the sampling rate of the audio, the bit rate information, the frame type (I, B, P frame) of the MPEG-2 video and the start point of the scene are analyzed.

TS analysis conforms to ISO 13818-1 MPEG2 System standard, scene analysis and audio analysis are processed according to ATSC standard.

The splicing unit 400 actually performs splicing in units of one packet based on the TS information analyzed above.

The splitter unit 400 uses an In Memory P frame block, an AC3 Silence ROM block, and a LONG Integer operation block.

The In Memory P frame block consists of 7 188-byte TS packets and the total size is 905 bytes.

The AC3 Silence ROM block is a block that pre-encodes all AC3 Bit Rate mutes specified in ROM.

In the LONG Integer operation block, the PCR, PTS, DTS, etc. have a size exceeding 32 bits, which exceeds the range that can be processed syntactically in VHDL.

Accordingly, the 33 bit Adder, the multiplyer, the 44 bit Adder, and the multiplyer are separately configured and used.

All the processing units in the splitting unit 400 are packets, and are configured to perform processing on a packet-by-packet basis without performing buffering except AC3.

The ASI output unit 500 receives the spliced data from the splitter unit 400 and converts the received data into a regenerating unit and transmits the converted data to a broadcasting receiver such as a user terminal through a normal broadcasting system .

In the splicing unit constructed as described above, splicing is performed in the following manner.

First, as shown in FIG. 2, the process of transferring the first stream to the second stream during output will be described.

As shown in FIG. 5, when a transfer signal, which is an external transfer command, is received (S101), the state of the first stream at this time is determined, and when the current frame is an I frame or a P frame In other words, until the grace signal is reached (S102).

A transfer delay as much as the waiting time may occur.

Subsequently, when the I frame or the P frame of the first frame arrives (S103), the second stream is monitored from this time, and as shown in Fig. 6, until the start of the I frame of the second stream, (S104).

After outputting the grace signal of the first stream, the first stream is replaced with the inner P frame by replacing all frames of the first stream with the first stream, and the remaining portion is filled with null packets (S105) .

For reference, the internal P frame is very small, all Residual is 0, and the motion vector is 0, and the previous frame of the frame is maintained as it is.

7, the output is switched to the second stream and output. The PTS and DTS of the I frame at this time are compensated with reference to the first stream (S107).

Here, when the second stream is switched and the B frame arrives after the first I frame in the output (S108), the B frame is replaced with the internal P frame as shown in Fig. 8 (S109).

The reason for doing this is that the corresponding B frame refers to the preceding I frame and the preceding P frame. Since the reference frame exists in both the first stream and the second stream, seamlessness at the ES level is not maintained Do not.

Subsequently, the second stream is outputted thereafter, and Time is continuously corrected and outputted.

Next, a process of transferring the second stream to the first stream during the output as shown in FIG. 3 will be described.

First, when the second stream is output, the number of frames in which the frames of the first stream and the second stream have passed is continuously counted (S201).

As shown in FIG. 9, when a transfer signal, which is an external transfer command, is received (S202), the state of the second stream is determined, and the current frame is transferred until the I frame or the P frame starts , I.e., waits until the grace signal reaches (S203).

A transfer delay as much as the waiting time may occur.

Then, when the I frame or the P frame of the second frame arrives (S204), the number of output frames of the first stream calculated beforehand is compared with the number of frames output of the second stream, (S205), the frame of the second stream is replaced with a null packet by the difference of the number of frames corresponding thereto as shown in FIG. 10, and the current output is maintained (S260).

Alternatively, the number of frames output from the first stream is compared with the number of frames output from the second stream. If the number of frames in the first stream is greater than the number of frames in the second stream, , The frame of the second stream is replaced with the internal P frame, and the current output is maintained (S207).

The reason for comparing the number of frames output by the first stream with the number of frames output by the second stream and replacing the frame of the second stream with a null packet or an inner P frame is that the number of frames of the first stream and the number of frames of the second stream Since the frame continues to flow even during replacement, the frame values of the first stream and the second stream are continuously updated while calculating the number of frames of the stream.

 As described above, when processing is performed according to the correlation between the number of frames in the first stream and the number of frames in the second stream, the output is switched to the first stream as shown in FIG. 12, All frames of the first stream are replaced with internal P frames until the I frame arrives (S208).

Then, when reaching the I frame of the first frame (S209), the first stream is outputted from this time as shown in Fig. 13 (S210).

At this time, since the number of frames of the first stream and the second stream is set as described above, it is not necessary to modify the time information when the stream is switched to the first stream.

In addition, if the second stream is switched to the first stream and the B frame comes after the first I frame in the output, since the reference frame is both the first stream and the second stream, in order to prevent this, Similarly, we replace it with an internal P frame.

Then, the first stream is continuously output.

Hereinafter, audio splicing will be described.

In the case of audio, as shown in FIG. 15, the TS packets are encapsulated and transmitted, and a plurality of TS packets form an Audio PES (Packetized Elementary Stream) block.

When the above-described encapsulated Audio PES is separated, it is coded AC3 and transmitted as shown in Fig.

Subsequently, after extracting the Audio PES from the MPEG-2 TS, each Audio PES is loaded into the AC3 ring buffer as shown in Fig.

At this time, the TimeStamp information is only once for each Audio PES, so the time of the internal AC3 Frame is estimated from this and stored as AC3 Frame.

Subsequently, as shown in Fig. 18, the switching is performed at the AC3 ring buffer level in accordance with the switching timing of the first stream or the second stream.

Thus, the seamless AC3 frame is converted into the Audio PES in the reverse order and converted to the MPEG-2 TS level.

In addition, the splicing apparatus according to the present invention may include an exchange selection switch on the outside to perform automatic switching between the first stream and the second stream, or a manual operation.

Also, RS-232 port is provided to monitor or control status information remotely, and the following commands can be processed through external interfacing.

1) Change Output

- Current output can be changed via splicing logic.

2) Set Property

- H.264 AVC PTS, DTS change, PSI information change based on 1st stream, VIDEO and AUDIO PID change to 1st stream reference, and auto change upon error recovery in case of error. You can customize it.

3) Request Line Status

- The current output line status, input line status, etc. can be obtained for monitoring.

4) Request Property

The value of the property described in 2) can be read.

5) Request Error Status

- You can get the current error status (Mini PIC function).

In addition, the splicing apparatus according to the present invention has the following functions.

1) Seamless switching function without transcoding in MPEG2 Video Stream

- MEPG2 Since video is not decoded and no transcoding is used, there is no change in image quality and the delay is minimized within several milliseconds.

2) Error-free switching function of ES level of connection at AC3 Audio

- AC3 It detects the type of audio and switches it on a frame-by-frame basis.

3) PCR Regeneration

- Because the output of the PCR of two encoders is different, the PCR is efficiently switched at the time of transfer and the PCR is corrected so that it can be recognized as one device in the decoder position. (It does not correct the position of PCR, PCR can be inserted considering the interval.)

4) PTS, DTS Regeneration

- Even if the seamless transfer of video and audio frames is completed at the ES level, the decoder may malfunction during the transfer if PTS and DTS are not corrected. Therefore, the time information of PTS and DTS is maintained at equal intervals .

5) Compensation of two encoder clocks with different ASI clocks as reference clock

- Generally, the encoder uses the internal clock.

Although the bit rate is compensated according to the signal of the external HD-SDI, the TS clock signals in the physical time are different from each other.

Therefore, a logical transfer can not guarantee complete transfer between two streams, so it is corrected with a reference clock to compensate the clock just like the output of a single encoder.

6) NULL packet correction by estimating streams of different bitrates

- Depending on the purpose of stream switching, the bitrate setting of the encoder may need to be different.

At this time, if the condition of the target bitrate can be adjusted between the streams by controlling the null packet, the bit rate can be switched using Null Packet Deletion and Insertion.

7) Support ES level splicing of multi-channel audio

- In the domestic broadcasting environment, there are generally sub audio, or there may be multiple channel audio in the audio multiplex broadcasting. This equipment enables seamless switching of up to two voices.

8) Time correction function of AVC stream in 2D stream 3D stream

- In case of 3D broadcasting designated as domestic standard, AVC stream is added as the right image.

Accordingly, the synchronization (PTS) of the left / right image must be accurate. When the apparatus is switched from 2D to 3D, it can be corrected to the time of the AVC image in accordance with the 2D base image on the left side.

9) PID remapping function

- Two different streams can have different PID configurations.

The present apparatus has a function of changing the PID of the sub stream to the PID of the main stream to maintain the same configuration.

10) Function to automatically switch to normal input in case of error on one input part

- This unit has the function of Mini PIC (Programmable Input Changer), so it can switch other signals immediately if the input signal has an error.

11) Silent insertion function for Audio ES switching

- In the case of audio switching of AC3, there may occur a problem of inserting a certain amount of data due to the problem of the interval between TS and Audio ES and delay problem. At this time, insertion of silence (ES without sound) can do.

12) Insertion of InMemory P Frame (All Residual = 0) when Video ES is switched

- In case of MEPG2 video switching, it performs switching by using a virtual P frame provided for interchanging seamless video, and has the function of forcibly inserting arbitrary P frame in special specification.

13) Depending on the mode, there are two modes, Errorless mode and Time Accuracy mode

- When switching two different streams, there is no error in the ES level of the video / audio (error information of time information may occur in this case), PCR, PTS, (In this case, audio may be damaged at some ES level and there is no error at the ES level of the video, but loss of continuity of the video time stamp may occur). Mode can be selected and used.

Meanwhile, the splicing method for multi-channel digital broadcasting according to the present invention in steps S101 to S109 and steps S201 to S210 is programmed and recorded on a recording medium such as a CD-ROM, a memory, a ROM, and an EEPROM May be stored.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of illustration, It will be readily apparent that various substitutions, modifications, and alterations can be made herein.

100: ASI input unit 200: Clock synchronization unit
300: TS analysis unit 400; West of Split
500: ASI output section

Claims (15)

1. A splicing apparatus for multi-channel digital broadcasting,
When a transfer signal is received in the first stream during the output of the first stream, which is in the form of an MPEG transport stream, and then reaches the grace signal in the first stream,
And the output is switched to the second stream after the switching point is reached in the second stream, which is an MPEG transport stream,
And a splicing device for multi-channel digital broadcasting. The apparatus of claim 1, wherein the grace signal is generated when a P frame or an I frame starts in a first stream and when an I frame starts in the second stream. . The splicing apparatus according to claim 2, wherein a frame existing between the grace signal and the switching point is replaced with an internal P frame and output. The splicing apparatus as claimed in claim 1, wherein the B frame, which is switched from the first stream to the second stream and subsequent to the first I frame, is replaced with an internal P frame and output. The method of claim 1, further comprising: when a transition is made from a first stream to a second stream and a switch signal is received from the second stream during the output,
If the number of frames of the first stream is less than or equal to the number of frames of the second stream, the output frame of the second stream is replaced with a null packet by the difference of the number of frames, A frame up to the switching point of one stream is replaced with an internal P frame and output,
And a splicing device for multi-channel digital broadcasting. The method of claim 1, further comprising: when a transition is made from a first stream to a second stream and a switch signal is received from the second stream during the output,
If the number of frames of the first stream is larger than the number of frames of the second stream, the output frame of the second stream is replaced with the inner P frame by the difference of the number of frames, A frame up to the switching point of the stream is replaced with an internal P frame and output,
And a splicing device for multi-channel digital broadcasting. The splicing apparatus according to claim 5 or 6, wherein the B frame, which is switched from the second stream to the first stream and is followed by the first I frame, is replaced with an internal P frame. 1. A splicing method for multi-channel digital broadcasting,
(a) a first switch signal reception step in which a switch signal is received in the first stream during output of a first stream in the form of an MPEG transport stream;
(b) a first delayed signal waiting step to wait until the delayed signal is reached in the first stream after receiving the first switched signal; And
(c) a first switching step of switching the output to a second stream in the form of MPEG transport stream when the switching time of the second stream is reached after the first delayed signal waiting step
And a splicing method for multi-channel digital broadcasting. The method of claim 8, wherein the grace signal in the first grace period signal waiting time is when a P frame or an I frame starts in the first stream, and the switching time in the first switching step is when an I frame starts in the second stream. A splicing method for multi-channel digital broadcasting. The method of claim 9, wherein the frame existing between the grace signal and the switching point is replaced with an internal P frame and output. The method as claimed in claim 8, wherein in the first switching step, the B frame, which is switched from the first stream to the second stream and subsequent to the first I frame of the output, is replaced with an internal P frame, A splicing method for digital broadcasting. 9. The method of claim 8, wherein after the first transfer step,
(d1) a second switch signal receiving step of switching from a first stream to a second stream and receiving a switch signal to the second stream during output;
(e1) a second grace signal waiting step of waiting after the second switch signal reception step until a grace signal is reached in the second stream;
(f1) replacing an output frame of the second stream with a null packet by a difference of the number of frames when the number of frames of the first stream is less than or equal to the number of frames of the second stream after the second wait signal waiting step ; And
(g1) the output after the replacing step is switched to the first stream, the frame up to the switching point of the first stream is replaced with the inner P frame,
And a splicing method for multi-channel digital broadcasting. 9. The method of claim 8, wherein after the first transfer step,
(d2) a second switch signal receiving step of switching from a first stream to a second stream and receiving a switch signal to the second stream during output;
(e2) a second grace signal waiting step waiting until the grace signal is reached in the second stream after receiving the second switch signal;
(f2) replacing an output frame of the second stream with an inner P frame by a difference of the number of frames when the number of frames of the first stream is larger than the number of frames of the second stream after the second wait signal waiting step; And
(g2) a second transfer step in which the output after the replacing step is switched to the first stream, the frame up to the transfer time point of the first stream is replaced with an internal P frame,
And a splicing method for multi-channel digital broadcasting. The method as claimed in claim 12 or 13, wherein the B frame, which is switched from the second stream to the first stream and subsequent to the first I frame in output, is replaced with an internal P frame. Plying method. A computer-readable recording medium having recorded thereon a program for executing a splicing method for a multi-channel digital broadcast according to any one of claims 8 to 14.

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