JPH10200891A - Data transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To switch and transmit digital compression image data by a prescribed bit stream unit matched with real time by generating a drop frame corresponding to frame synchronizing signals and drop frame signals and synchronizing a time code provided in encoding data and a prescribed frame number. SOLUTION: In a time code generator 5, second pulses SPL whose cycle is one second synchronized with reference synchronizing signals SVD are generated and the second pulses SPL are sent out to a GOP pulse generator 8. Drop frame pulses SDF are generated at the timing of the drop frame for each exact minute excluding 0, 10, 20, 30, 40 and 50 minutes and are sent out to the GOP pulse generator 8 and a drop frame ID generator 9. By thinning the frame number of 1 GOP by the timing of the drop frame for each exact minute, the deviation of the time code and the frame number of 1 GOP is dissolved and 1 GOP is outputted synchronized with the real time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmitting apparatus, and more particularly, to a data transmitting apparatus which switches and transmits a program and / or a commercial (CM) on the basis of real time in digital broadcasting.

[0002]

2. Description of the Related Art Conventionally, NTSC (National Terevisi) of analog television broadcasting broadcast in Japan, North America and the like.
on System Committee) In the case of color synchronization, the number of frames is 29.97 frames / second ([Hz]) in a 24-hour time code, so the time code increments slightly from real time . This shift is 108 frames per hour (3.6 seconds) when the time code is counted in color synchronization. Therefore, in order to correct the difference between the color synchronization and the real time, for each minute (1 minute, 2 minutes ...) that is not divisible by 10, except 0, 10, 20, 30, 40 and 50 minutes, two Skip the frame, 00 frame and 01 frame respectively. Such a code correction mode is called a drop frame.

[0003]

By the way, MPEG2 (M
In a digital broadcast in which compressed data obtained by compressing information based on the oving Picture Experts Group 2) standard is reproduced and transmitted, as shown in FIG.
Picture) is encoded as 15 frames.
When editing such compressed image data of the MPEG2 standard, for example, if the bit stream is switched at the boundary of a GOP, a maximum of 1 G
There is a 0.5 second time lag in OP. For this reason, in television broadcasting, when it is attempted to switch and transmit a program or CM by time management based on real time, a difference occurs between the timing of the actually transmitted program or CM and the real time. There was a problem.

The present invention has been made in view of the above points, and is intended to propose a data transmission apparatus capable of switching and transmitting digital compressed image data in units of a predetermined bit stream in real time. is there.

[0005]

According to the present invention, in order to solve the above-mentioned problems, a predetermined number of frames is set to one for image data.
A reference synchronization signal generating means for generating a reference synchronization signal for encoding image data in a data transmitting apparatus for generating encoded data by performing compression encoding as a unit and transmitting the encoded data in units of a predetermined number of frames. Drop frame signal generating means for generating a drop frame signal based on the time code of the encoded data, and frame synchronizing signal generating means for generating a frame synchronizing signal for recognizing a predetermined number of frames based on the reference synchronizing signal and the time code. A drop frame generating means for generating a drop frame in accordance with the frame synchronization signal and the drop frame signal, and generating a drop frame in accordance with the frame synchronization signal and the drop frame signal to thereby generate a time code of the encoded data. It can be synchronized with a predetermined number of frames and.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

(1) First Embodiment In FIG. 1, 1 indicates a data transmitting apparatus as a whole,
The synchronization signal generator 2 generates a reference synchronization signal SVD of video data synchronized with the real time of the broadcast as shown in FIG. 2A and sends it to the VTRs 3 and 4 for reproduction and the time code generator 5. Upon reproducing the video data SV1 and SV2, the reproducing VTRs 3 and 4 synchronize the video data SV1 and SV2 with the synchronization signal SVD and send them to the MPEG2 encoders 6 and 7, respectively.

At this time, the time code generator 5 generates a second pulse SPL (FIG. 2 (B)) whose cycle synchronized with the reference synchronization signal SVD is 1 second, and converts the second pulse SPL to G
The signal is sent to the OP pulse generator 8, and 0 minutes, 10 minutes,
A drop frame pulse SDF (FIG. 2 (C)) is generated at the drop frame timing of each positive minute except for 20 minutes, 30 minutes, 40 minutes, and 50 minutes, and the drop frame pulse SDF is generated by the GOP pulse generator 8 and Drop frame ID
Send to generator 9.

The GOP pulse generator 8 includes a reference synchronization signal SVD shown in FIG. 2A and a second pulse SPL shown in FIG.
GOP pulse SGP every 15 frames in synchronization with
(Shown as D1 in (D)). On the other hand, when the drop frame pulse SDF is input, the GPS pulse generator 8 generates a GOP pulse SGP (denoted as D2 in FIG. 2D) in 13 frames. The GOP pulse generator 8 sends the generated GOP pulse SGP to each of the MPEG2 encoders 6 and 7.

The drop frame ID generator 9 generates a low-level "L" output drop frame ID in accordance with the timing of the input drop frame pulse SDF (FIG. 2 (E)).
To each of the MPEG2 encoders 6 and 7, respectively.

[0011] The MPEG2 encoder 6 encodes the video data SV1 based on the GOP pulse SGP and the drop frame ID. Similarly, the MPEG2 encoder 7 encodes the video data SV2 based on the GOP pulse SGP and the drop frame ID. In this case, when the drop frame ID is at the high level "H", the encoder 6 or 7 generates a bit stream in the order of "IBBPBBPBBPBBPBB", for example, assuming that the number of frames of one GOP to be transmitted is 15 as shown in FIG. (Shown as F1 in FIG. 2). When the drop frame ID is at the low level “L”, the encoder 6 or 7 sets the number of frames of one GOP to be transmitted to 13 or less.
As a frame, for example, “IBBPBBPBBPBBB”
A bit stream is generated (shown as F2 in FIG. 2). As a result, when no drop frame occurs, 15 frames of GOPs per second are 2 GOPs.
1 when a drop frame is generated
13 frames GOP and 15 frames GOP are 2G per second
OP is transmitted.

By controlling the number of frames of one GOP according to the drop frame ID in this way, the encoded data SV10 and SV20 in which two GOPs are synchronized with one second of the real time are transmitted to the stream switch 10, respectively. I have. Stream Switch 1
0, the encoding data SV1 composed of one or a plurality of GOP units by switching while synchronizing with the time in units of seconds based on the second pulse SPL.
0 and the SV 20 are edited, and the edited data is transmitted.

In the above configuration, the reproduced video data SV1 and SV2 are reproduced by the VTRs 3 and 4, and the video data SV1 and SV2 are synchronized with the reference synchronizing signal SVD of the video data generated by the synchronizing signal generator 2. It is sent to MPEG2 encoders 6 and 7. At this time, the reference synchronization signal SVD is also sent to the time code generator 5 at the same time. The time code generator 5 generates a second pulse SPL (FIG. 2 (B)) whose cycle synchronized with the reference synchronization signal SVD is 1 second and sends it to the GOP pulse generator 8, and also generates a drop frame for each minute. A drop frame pulse SDF (FIG. 2C) is generated at the timing, and the drop frame pulse SDF is sent to the GOP pulse generator 8 and the drop frame ID generator 9.

The drop frame ID generator 9 generates a drop frame ID according to the drop frame pulse SDF.
(FIG. 2 (E)) is generated and the drop frame ID is generated.
To the GOP pulse generator 8 and each of the MPEG2 encoders 6 and 7.

Here, the GOP pulse generator 8 corresponds to FIG.
As shown in (D), a GOP pulse SGP (indicated as D1 in FIG. 2) is generated every 15 frames in synchronization with the input second pulse SPL and every 15 frames, and a drop frame pulse SDF is input. 1G in case
GOP pulse S every 13 frames with OP as 13 frames
GP (shown as D2 in FIG. 2). In this manner, by skipping the number of frames of one GOP at the timing of a drop frame for every minute, the difference between the time code and the number of frames of one GOP is eliminated, and one GOP can be output in synchronization with real time. The GOP pulse generator 8 generates the GOP pulse S
The GP is sent to each of the MPEG2 encoders 6 and 7.

As shown in FIG. 3, the MPEG2 encoder 6
And 7 are the GOP pulse SGP and the drop frame ID.
0 min, 10 without drop frame
1 minute at 1 minute for 20 minutes, 30 minutes, 40 minutes, 50 minutes
The encoded data SV10 and SV20 are output with the number of frames as 15 frames and 15 frames, respectively (FIG. 3).
(A)), at the timing of the drop frame for each minute, the number of frames of one GOP per second is 13 frames,
Encoding data SV10 and SV2 as 15 frames
0 is output (FIG. 3B). The MPEG2 encoders 6 and 7 send the encoded data SV10 and SV20 generated so that one GOP is synchronized with real time to the stream switch 10. Thus, the stream switch 10 can perform cut editing by switching the encoding data SV10 and SV20 in which one GOP is synchronized in real time in accordance with the real time.

According to the above arrangement, when reproducing the compressed data information compressed by the MPEG2 system, the second pulse SPL generated in the time code generator 5 and the drop frame pulse SDF generated every minute are used. The encoding data SV10 and SV20 are decimated by a drop frame every minute by using the GOP pulse SGP and the drop frame ID generated by the GOP pulse SGP. After the correction, the encoded data SV10 and SV20 can be transmitted in synchronization with real time. Thus, the encoded data SV1
0 and 1 GOP of the SV 20 can be switched and transmitted in synchronization with real time.

In the above-described embodiment, a case has been described in which compressed data information-compressed according to the MPEG2 standard is synchronized in real time, but the present invention is not limited to this.
It may be used for compressed data that has been information compressed according to one standard or the like, and is applied to an information compression method in which the number of frames of one GOP, which is a unit of reproducing compressed data, is not synchronized with real time. The same effect as that of the embodiment can be obtained. In the above embodiment, the number of frames forming one GOP by drop frames is 15
Although the case where the number of frames forming one GOP is thinned from 13 frames and 15 frames to 15 frames has been described, the present invention is not limited to this. For example, the number of frames forming one GOP is reduced to 14 frames and 14 frames. May be set.

[0019]

As described above, according to the present invention, by generating a drop frame in accordance with the frame synchronization signal and the drop frame signal, the time code of the image data and the predetermined number of frames are synchronized to encode data. Can be realized in synchronization with real time.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of data transmission and transmission according to the present invention.

FIG. 2 is a timing chart for explaining generation of a drop frame.

FIG. 3 is a timing chart for explaining time management of encoded data according to the embodiment;

FIG. 4 is a timing chart for explaining conventional time management of encoded data.

[Explanation of symbols]

1. Data transmission device 2. Synchronous signal generator 3, 4
... VTR, 5 ... Time code generator, 6, 7 ... M
PEG2 encoder, 8 ... GOP pulse generator, 9 ...
... Drop frame ID generator, 10 ... Stream switch.

Claims (2)

[Claims] 1. A data transmitting apparatus for generating encoded data by compressing and encoding image data with a predetermined number of frames as one unit and transmitting the encoded data in units of the predetermined number of frames. Reference synchronizing signal generating means for generating a reference synchronizing signal at the time of encoding; drop frame signal generating means for generating a drop frame signal based on the time code of the encoded data; and the predetermined signal based on the reference synchronizing signal and the time code. A data transmitting apparatus comprising: frame synchronizing signal generating means for generating a frame synchronizing signal for recognizing the number of frames; and drop frame generating means for generating a drop frame according to the frame synchronizing signal and the drop frame signal. . 2. The method according to claim 1, wherein said drop frame generating means transmits the predetermined number of frames consisting of 15 frames at a rate of two units per second, and outputs the predetermined number of frames consisting of 15 frames per second in accordance with the generation timing of the drop frames. 2. The data transmission apparatus according to claim 1, wherein the transmission is switched to the transmission of the predetermined number of frames.