JP2014090270A - Coding system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coding system in which each encoder is capable of achieving autonomous GOP synchronization.SOLUTION: An encoding unit 3 encodes an image signal in units of GOP. An elapsed time operation unit 8 determines the elapsed time from a reference time to the current time. A current position computing unit 9 determines the current position by dividing the elapsed time by a processing time required for processing one GOP. A start position computing unit 10 determines the start position by rounding-up the decimal point of the value of current position. A synchronization start time computing unit 11 determines the synchronization start time by adding the start position and the integrated processing time to the reference time. An encoder rising from the stop state starts GOP synchronization with other encoder from the synchronization start time.

Description

  The present invention relates to an encoding system in which a plurality of encoding devices encode image signals in synchronization with each other by GOP (Group Of Picture), and select or multiplex their outputs.

  In a conventional encoding system, by providing a common reference synchronization information generation device and a GOP cycle generation device outside a plurality of encoding devices, the encoding outputs of the plurality of encoding devices are GOP synchronized (for example, Patent Document 1).

JP 2001-177828 A

  However, there is a problem that if these common devices fail, the system does not operate. In addition, since it is assumed that a common reference synchronization information generation device is installed in the vicinity of a plurality of encoding devices, it is difficult to achieve GOP synchronization of a plurality of encoding devices installed at distant locations. There was also.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain an encoding system in which each encoding apparatus can autonomously establish GOP synchronization.

  An encoding system according to the present invention includes: a plurality of encoding devices that encode image signals in synchronization with each other by GOP (Group Of Picture); and a switching device that switches and selects outputs of the plurality of encoding devices. Each of the encoding devices encodes the image signal in units of GOPs, and an elapsed time from the reference time to the current time. An elapsed time calculation unit that calculates the current position, a current position calculation unit that calculates the current position by dividing the elapsed time by the processing time required to process one GOP, and rounds up the decimal point of the value of the current position A start position calculation unit that calculates a position; and a synchronization start time calculation unit that calculates a synchronization start time by adding the sum of the start position and the processing time to the reference time. , When starting from the stop state, GOP synchronization with another encoding apparatus is started from the synchronization start time.

  According to the present invention, each encoding device can autonomously establish GOP synchronization.

It is a block diagram which shows the encoding system which concerns on Embodiment 1 of this invention. It is a block diagram which shows the encoding apparatus which concerns on Embodiment 1 of this invention. It is a figure for demonstrating operation | movement of the encoding apparatus which stood up from the stop state by failure. It is a block diagram which shows the encoding system which concerns on Embodiment 2 of this invention.

  An encoding system according to an embodiment of the present invention will be described with reference to the drawings. The same or corresponding components are denoted by the same reference numerals, and repeated description may be omitted.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing an encoding system according to Embodiment 1 of the present invention. The plurality of encoding devices 1a to 1n are video encoders that encode image signals in synchronization with each other by GOP (Group Of Picture). The switching device 2 switches and selects the outputs of the plurality of encoding devices 1a to 1n, multiplexes the image signals, and sends them to the decoder side.

  FIG. 2 is a block diagram showing the coding apparatus according to Embodiment 1 of the present invention. This encoding device corresponds to each of the encoding devices 1a to 1n in the system of FIG. The encoding unit 3 encodes the image signal in GOP units.

  The memory 4 stores a reference time of GOP synchronization processing that is common to all the encoding devices 1a to 1n. As this reference time, it is desirable to designate a time of regular visits (XX minutes per hour, XX hours every day, etc.).

  The receiving unit 5 receives a signal from a GPS (Global Positioning System) satellite 6 with an antenna 7, and obtains the current time based on the signal. The elapsed time calculation unit 8 obtains an elapsed time from the reference time to the current time.

The current position calculation unit 9 obtains the current position by dividing the elapsed time by the processing time (fixed length) required for processing one GOP (see Equation 1 below). The current position represents how many frames the GOP position at the current time is shifted from the GOP position at the reference time.
(Equation 1)
Current position = (Elapsed time from reference time to current time) / (Processing time required for processing one GOP) (Equation 1)

  The start position calculation unit 10 calculates the start position by rounding up the decimal point of the current position value. This start position represents the position of the first frame of the next GOP.

The synchronization start time calculation unit 11 obtains the synchronization start time by adding the sum of the start position and the processing time required for processing one GOP to the reference time (see Equation 2 below).
(Equation 2)
Synchronization start time = start position * (processing time required for processing one GOP) + reference time (Expression 2)

  FIG. 3 is a diagram for explaining the operation of the encoding apparatus that has started up from a stopped state due to a failure. The encoding apparatus that has started up from the stopped state starts GOP synchronization with another encoding apparatus from the above-described synchronization start time. That is, it is assumed that the GOP position at the current time is shifted from the GOP position at the reference time by the number of frames on the assumption that the GOP is continuously processed regardless of the operation state such as when the encoder is operating or stopped. GOP synchronization is obtained by obtaining the synchronization start time from the result. Thereby, each encoding apparatus 1a-1n can take GOP synchronization autonomously.

  The conventional coding system has a problem that the system does not operate when a common reference synchronization information generation device or GOP cycle generation device provided outside the plurality of coding devices fails. There is also a problem that accurate GOP synchronization cannot be achieved if there is a variation in delay between the common apparatus and the plurality of encoding apparatuses. On the other hand, in this embodiment, since each encoding device can autonomously establish GOP synchronization, the common device can be deleted, and the above problem can be solved.

  Also, by obtaining the current time based on the signal received from the GPS satellite 6 by the encoding device, GOP synchronization with the encoding device at a remote location is possible, and application to multi-way relay and the like can be expected.

  Here, it has been described that the receiving unit 5 receives the GPS signal with the antenna 7, but the Internet standard time may be received via the network. That is, the receiving unit 5 may obtain the current time based on a signal received via the Internet. However, the present time may be obtained by receiving the time from any infrastructure clock.

  The encoding unit 3 of the encoding apparatus that has started up from the stop state performs encoding in GOP units having a fixed length from the synchronization start time, but the fixed-length GOP has a length from the start up until the synchronization start time. Encoding may be performed in units of different variable length GOPs. Thereby, encoding can be started immediately after starting up.

Embodiment 2. FIG.
FIG. 4 is a block diagram showing an encoding system according to Embodiment 2 of the present invention. In this system, the switching device 2 of FIG. The multiplexing device 12 multiplexes the streams output from the encoding devices 1a to 1n and outputs the result as one stream. Other configurations are the same as those of the first embodiment, and the same effects can be obtained.

1a to 1n encoder, 2 switching device, 3 encoder, 5 receiver, 8 elapsed time calculator, 9 current position calculator, 10 start position calculator, 11 synchronization start time calculator, 12 multiplexer

Claims (4)

A plurality of encoding devices that encode image signals in synchronization with each other by GOP (Group Of Picture);
A switching device that switches and selects the outputs of the plurality of encoding devices, or a multiplexing device that multiplexes the outputs of the plurality of encoding devices and outputs them as one stream,
Each encoding device
A coding unit for coding the image signal in GOP units;
An elapsed time calculation unit for obtaining an elapsed time from the reference time to the current time;
A current position calculation unit for obtaining a current position by dividing the elapsed time by a processing time required for processing one GOP;
A start position calculation unit that obtains a start position by rounding up the decimal point of the value of the current position;
A synchronization start time calculation unit for obtaining a synchronization start time by adding the start position and the processing time integrated to the reference time;
An encoding system that has started up from a stopped state starts GOP synchronization with another encoding apparatus from the synchronization start time.   The encoding system according to claim 1, wherein each encoding device further includes a reception unit that obtains the current time based on a signal received from a GPS (Global Positioning System).   The encoding system according to claim 1, wherein each encoding device further includes a receiving unit that obtains the current time based on a signal received via the Internet.   The encoding unit of the encoding device that has started up from a stop state performs encoding in GOP units of a fixed length from the synchronization start time, and is longer than the fixed length GOP from the start up to the synchronization start time. The encoding system according to any one of claims 1 to 3, wherein encoding is performed in units of GOPs having different variable lengths.

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