JPS6333024A - Information signal transmitting method and device - Google Patents

Abstract

PURPOSE:To execute the good restoring without being influenced by the characteristic of a transmission line by providing the first and second transmitting modes to obtain a sampling information signal with the frequency of four times of a transmitting band and transmit respectively a part of the signal and the remaining signal to an information signal divided into a prescribed quantity, transmitting the abovementioned signal with the first mode for a prescribed quantity and transmitting further a part of the signal of the prescribed quantity with the second mode so that the compressing ratio can be 1/2. CONSTITUTION:One picture is divided into a group for an (m) X (n) (in this example, 4 X4) number of the sampling point, all points are sampled at the group with a close image and at a coarse group, a part only is sampled. The former is an E mode and the latter is a C mode. In order to make the compressing ratio of a transmitting band into 1/2 wholly, the rate of the C mode into the 2/3 of the whole and the rate of the E mode into 1/3. Since an image information signal is divided and transmitted into the information signal of a basic picture element and the information signal of the additional picture element of the group set to the E mode concerning all divided groups, the signal can be decoded by at least the information signal of a basic picture element even when a mode information signal is erroneous in a transmission line. Since sampling is executed by the frequency of four times of the transmitting band, it is not influenced by the transmission line even when only a part of a sampling point is communicated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an information signal transmission method and apparatus for transmitting information signals using a transmission path having an fc transmission band.

[Conventional technology]

Conventionally, for example, a time axis transform band compression method is used in an information compression transmission method.
(hereinafter referred to as TAT) has been announced. This TAT method is a method for compressing and transmitting information signals by utilizing the fact that the density of information signals differs depending on the location when performing band compression of information signals. It is.

FIG. 2 shows the principle of using the TAT method in one-dimensional signal processing.

In FIG. 2, the original signal is first divided into predetermined amounts of information as shown by dotted lines, and it is determined whether the information is coarse or dense for each divided group.

Then, in the group judged to be dense, all the data obtained by sampling the original signal is transmitted as transmission data, and in the group judged to be coarse, only a part of all the data is used as transmission data. , and other data shall not be transmitted as thinned data. Note that in the figure, data indicated by an O mark is data to be transmitted (transmission data), and data indicated by an x mark is data not transmitted (thinned data).

By transmitting the data indicated by the O symbol at regular intervals, the number of data transmitted per unit time is reduced, and the band of the transmitted information signal is compressed.

The data transmitted in the above manner uses the thinned-out data that was not transmitted during decoding and the transmitted data,
Approximate restoration is performed to obtain interpolated data (marked with 0 in the figure). Note that this interpolated data corresponds to areas where the information is coarse, and is restored as data that closely approximates the thinned data, so the actual amount of information does not change compared to when all data is transmitted. This means that the transmission band of the information signal has been significantly compressed.

At this time, the decision whether to transmit all data or a part of the data in each group is determined by examining the details of the original signal, and this decision information is simultaneously transmitted as a transmission mode information signal. .

Furthermore, in the case of image information signals, the transmission band of image information can be compressed by changing not only the sampling intervals in the horizontal direction but also the sampling intervals in the vertical direction and performing two-dimensional processing.

When processing a two-dimensional signal such as an image information signal, one screen is divided into groups of mXn sampling points, and the density of the image is determined for each group. Then, in the group judged to be dense, the data obtained by sampling all of the sampling points is transmitted as transmission data, and in the group judged to be sparse, the data obtained by sampling only a part of the sampling points is transmitted. The data that has been removed will be transmitted as transmission data, and the other data will not be transmitted as thinned-out data.

Here, if we call the case where all of the sampling points are sampled the E mode, and the case where only a part of the sampling points are sampled is called the C mode, the sampling points that are transmitted and the samplings that are not transmitted in each sampling mode. The relationship with the points is as shown in Figure 3.

FIG. 3 shows sampling patterns of E mode and C mode at 4×4 sampling points, where (L) shows E mode and (b) shows C mode.

One screen of image information to be transmitted is divided into groups of 4 x 4 sampling points in order from the upper left to the lower right of the screen, and each group is divided into two groups of sampling points as described above depending on the density of the image.
Select a species sampling mode and perform sampling according to the selected sampling mode.

Figure 4 shows that one field of an NTSC television screen is divided into groups of 4 x 4 sampling points using the method described above, and each group has the E
FIG. 4 is a diagram in which sampling modes of mode and C mode are assigned. Note that O marks are sampling points that are transmitted, and x marks are sampling points that are not transmitted.

By transmitting the data of each sampling point sampled in this manner at regular intervals, the transmission band is compressed and transmitted.

Note that sampling points that are not transmitted are approximately reconstructed during decoding using data from nearby transmitted sampling points, so the amount of information does not change compared to when all data is transmitted. , the transmission band of information signals has been significantly compressed.

[Problem that the invention seeks to solve]

However, when information is transmitted using the information compression transmission method as described above, if an error or omission occurs in the mode information signal on the transmission path, the original signal cannot be restored.

In particular, in magnetic recording using the information compression transmission method, errors or omissions of the mode information signal are likely to occur frequently due to dropouts, etc., and there is a fear that the recorded information may become meaningless.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to restore information as best as possible without being affected by the characteristics of the transmission path with a simple configuration even when an unstable transmission path is used. It is an object of the present invention to provide an information signal transmission method and apparatus that can perform transmission in a manner that enables transmission.

[Means to solve the problem]

In the information signal transmission method of the present invention, when transmitting an information signal using a transmission path having a transmission band of fc, the information signal is sampled at a sampling frequency of 4fc to obtain a sampling information signal, and a predetermined amount of For the sampling information signal, a first transmission mode in which only a part of the sampling information signal is transmitted, and a second transmission mode in which only the remaining sampling information signal not transmitted in the first transmission mode is transmitted, The sampling information signal is transmitted in at least the first transmission mode for each sampling information signal of the predetermined amount, and the sampling information signal of the predetermined amount is transmitted in such a manner that the compression ratio of the transmitted sampling information signal becomes 1/2. A part of the data is further transmitted in the second transmission mode.

Further, the information signal transmission device of the present invention is a device that transmits an information signal using a transmission line having a transmission band of fc, and samples the information signal at a sampling frequency of 4fc and outputs a sampled information signal. a sampling means, a dividing means for dividing the sampling information signal into predetermined amounts, and further separating and outputting only a part of the sampling information signal from all of the predetermined amount of the sampling information signal divided by the dividing means. a first separating means; a second separating means for further separating and outputting only the sampling information signal that is not separated by the first separating means from a part of the predetermined amount of sampling information signal divided by the dividing means; The output of the first separation means and the second
and transmission signal forming means for forming a transmission signal using the output of the separation means.

[Effect]

With the above-described method and configuration, it is possible to adapt the information signal to the transmission band of the transmission path, and also to minimize the deterioration of the information signal even when the transmission path becomes unstable.

〔Example〕

Hereinafter, the present invention will be explained based on examples.

Here, as an embodiment of the present invention, a case will be described in which the present invention is applied to a VTR. In addition, the information signal handled here is a time-division multiplexed signal obtained by digitally demodulating an NTSC television signal, and when one field of television screen is divided into multiple groups, the group is
It shall consist of sampling points of ×4 bonds.

Further, the transmission band of the VTR in this embodiment is expressed as fc.

FIG. 1 is a diagram showing a schematic configuration when the present invention is applied to a recording system of a VTR.

In FIG. 1, an analog conference video signal for one field is sent to an analog/digital (A/D) converter 1, which is output from a synchronization signal generation circuit 7 in the transmission band fc.
The signal is converted into a digital φ video signal in synchronization with a sampling clock 4fc having a frequency four times as high as that of 4fc, and is supplied to the switch 2, the filter 3, and the mode determination circuit 4 as an E-mode digital video signal.

The filter 3 is a two-dimensional low-pass filter that removes high frequency components of the input E-mode digital video signal, and averages the digital video signal. Then, the E-mode digital fist video signal as shown in FIG. 3(a) averaged by the Buri filter 3 is converted to a C-mode digital video signal corresponding to % pixels by the thinning circuit 5 as shown in FIG. 3(b). - Thinning processing is performed on the video signal. The C-mode digital fist video signal processed by the thinning circuit 5 is stored in the fourth memory 6 and is also supplied to the mode determination circuit 4.

When the switch is connected to the F side in the figure, the input E-mode digital video signal is supplied to the first memory and stored, and when it is connected to the G side, the input signal is sent to the switch. 9.

When the switch 9 is connected to the H side in the figure, the input signal is supplied to the second memory 10, and when it is connected to the 1 side in the figure, the input signal is supplied to the third memory 11.

Note that the switch operation of the switch 2.9 is controlled by various synchronization signals generated by the synchronization signal generation circuit 7. From the synchronization signal generation circuit 7, a water rate synchronization signal synchronized with the input timing of the input signal for one life is inputted to the switch 2, and a pixel synchronization signal synchronized with the input timing of the input signal for one pixel is inputted to the switch 9. Ru.

By operating switches 2 and 9, the E mode digital video signal as shown in FIG.
, Δ, the pixels are divided into 4×4 pixels as shown by the marks, and the first memory 8 stores the signals corresponding to the pixels marked with Δ, and the second memory 10 stores the signals corresponding to the pixels marked Δ. is stored, and the third memory 11 stores a signal corresponding to the pixel marked with ■.

E-mode and C-mode digital video signals are input to the mode determination circuit 4, and after performing interpolation processing on the C-mode digital video signal, the E-mode digital video signal is output for each group. The image signal generated by the signal is compared with the image signal generated by the interpolated C mode digital video signal, the error information is temporarily stored, and if the error is larger than the set threshold, the image signal is converted to the E mode. , a mode information signal is generated to assign C mode to the group. That is, this mode information signal is generated so that the E mode corresponds to a group of dense parts on the screen of one field, and the C mode mode information signal corresponds to a group of coarse parts.

Furthermore, in order to equalize the transmission time of video signals for one field, it is necessary to keep the ratio to the number of pixel blocks transmitted in C mode constant.

In the above case, if the compression rate of the transmission band is to be expressed as a whole, if the proportion of C mode is % of the whole and the proportion of E mode is station, the overall band compression rate is ('4x% + lX1A) =
It becomes a repair.

Then, when allocating mode information signals to each group, the error information of all the groups stored is arranged in descending order of error, and a threshold value is set so that E mode is assigned to the upper station, and this threshold value and Compare with the error information,
If the E mode is assigned when the error information signal is larger than the threshold value, the E mode and C mode are set to be transmitted at the above ratio.

In addition, since the station with sampling frequency fs becomes the transmission band, when compressing the transmission band elegantly, HfS is the transmission band f
c. Therefore, sampling frequency f5=4f
c, and as mentioned above, in A/D converter 1, 4fc
A/D conversion is performed at a sampling frequency of . For example, in the case of E mode, the band of information signals sampled at a sampling frequency of 4fC is 2fC.
Since the transmission band is further compressed, the maximum frequency that can be generated in an actual information signal is fc, and since the VTR of this embodiment has a transmission band of fc, it is possible to reliably transmit information. Can be recorded and played back.

The mode information signal generated in mode setting circuit 4 in this manner is stored in mode memory 12.

FIG. 6 shows an example of the arrangement of mode information signals set as described above on the screen, and the arrangement of pixels on the screen to be transmitted according to the mode information signals arranged in this way is The result will be as shown in Figure 7.

However, as mentioned above, what is actually transmitted is all the basic pixels of each block of the screen as shown in FIG. 8 and information on additional pixels of the block set to E mode as shown in FIG. Basic pixel information is stored in the third memory 11 and fourth memory 6, and additional pixel information is stored in the first memory 8. Since the information is divided and stored in the second memory 10, the information stored in these memories is outputted in the form shown in FIG. 9 according to the mode information.

Hereinafter, the first memory 8. Second memory 10. Third memory 11
．． The read operation of the fourth memory 6 will be explained.

Since the mode information signal generated by the mode determination circuit 4 is stored in the mode memory 12, the memory control circuit 13 reads out the stored mode information signal from the mode memory 12.

The read mode information signal is sent to the memory control circuit 13, address calculation circuit 14. The signal is supplied to the switch 15.

The memory control circuit 13 receives a basic pixel information signal in E mode from the third memory 11 according to the input mode information signal,
The basic pixel information signal for the C mode is supplied from the fourth memory 6 to the switch 15, which also performs a switching operation in accordance with the mode information signal, and supplies the basic pixel information signal as shown in FIG. 8 to the switch 17.

Further, in the address calculation circuit 14, the first memory 8. It calculates the read address of the second memory 10 and controls the output of data from the two memories. In particular, in the mode information signal, E
When the mode is specified, the address of the pixel data to be output is calculated and output, and when in C mode, a predetermined amount of pixel data is skipped and the address is changed in a pattern. The pixel data read out by the arithmetic circuit 14 is supplied to the switch 16.

The switch 16 is a switch that is switched for each line in synchronization with the horizontal synchronization signal generated from the synchronization signal generation circuit 7. Due to this switch operation, the output of the switch 16 becomes an additional pixel information signal as shown in FIG. , are supplied to the switch 17.

The switch 17 is a switch that is switched every 0.5 field in synchronization with the synchronization signal generated by the synchronization signal generation circuit 17, and the signal outputted by this switch operation is the first signal.
As shown in Figure 0, the basic pixel date and additional pixel data are separated, output in time series, and digital/analog (D/A
) is supplied to the converter 18, converted again into an analog signal, band-limited via a low-pass filter (LPF) 19, and then recorded in the recording section 20 together with the mode information signal.

As described above, the image information signal is transmitted after being divided into the basic pixel information signal for all divided groups and the additional pixel information signal of the group set to E mode. Even if the mode information signal is incorrect, it is possible to decode it using at least the information signal of the basic pixel.

Furthermore, when recording as described above, if pixel data is not formed using a sampling clock having an appropriate frequency depending on the compression ratio of the transmission band, the transmitted pixel data will deteriorate.

Therefore, in this embodiment, since the transmission band is compressed to each station,
When forming pixel data, the A/D converter l generates a sampling clock 4 having a frequency four times as high as the transmission band fc.
By performing this in synchronization with fc, it becomes possible to record pixel data in accordance with the transmission characteristics of the VTR.

FIG. 11 is a diagram showing a schematic configuration when the present invention is applied to a reproduction system of a VTR. The operation during reproduction will be explained below using FIG. 11.

In FIG. 11, the pixel information signal and mode information signal reproduced by the reproduction section 21 are input to an A/D converter 22 and a mode error detection circuit 23, respectively.

The pixel information signal is converted from an analog signal to a digital signal by the A/D converter 22 and input to the switch 24 . A synchronization signal synchronized with the exhibition field period reproduced by the reproduction section 21 is input to the switch 24,
This switch 24 separates the digital pixel information signal recorded as shown in FIG. The switching operation of the switch 24 is switched from the E side to the M side in the figure every field period q in synchronization with the synchronization signal.

On the other hand, the reproduced mode information signal is stored in the mode memory 27 via the mode error detection circuit 23. In the mode error detection circuit 23, E of the reproduced mode information signal is detected.
Detect modes and count their number. Since the number of groups in the l field to which the E mode is assigned is predetermined, the number of E modes is counted during playback as described above, and when it matches the predetermined number, it is determined that there is no error. If they do not match, it is determined that there is an error.

When the mode error detection circuit 23 determines that there is an error in the mode information signal, the error detection signal is input from the mode error detection circuit 23 to the mode conversion circuit 28, and the error detection signal is stored in the mode memory 27 in the mode conversion circuit 28. The mode information signals are read out and all of the signals are converted into C mode signals. Further, when the mode error detection circuit 23 determines that there is no error in the mode information signal, the signal read from the mode memory 27 is output as is through the mode conversion circuit 28.

The mode information signal output from the mode conversion circuit 23 as described above is input to the readout control circuit 29, and the readout control circuit 29 selects the basic pixel memory 25 and the additional pixel memory 26 according to the input mode information signal. Each stored pixel information signal is read out.

Note that the basic pixel information stored in the basic pixel memory 25 includes E mode information and C mode information. Therefore, the basic pixel information of the C mode is set by the switch 30.
The mode interpolation circuit 31 interpolates the pixel information that was not transmitted using the transmitted pixel information, and then the E mode basic pixel information is stored in the field memory 32 as it is.

In other words, the reproduced mode information signal that has been subjected to error detection processing is input to the switch 30, and depending on the mode information, in the case of the C mode, the signal goes to the C side in the figure, and in the case of the E mode, the signal goes to the C side in the figure. It is controlled so that it is connected to the E side in the figure.

After the pixel information signals for one field are stored in the field memory 32 as described above, the pixel information signals stored in the field memory 32 are read out as image information signals by a control signal from the readout control circuit 29. D/A
The signal is converted into an analog video signal by a converter 33 and then output.

The present invention has been described above as an embodiment of the present invention.
Although the present invention has been described using an example of application to a video disc device, the present invention can also be applied to other recording/reproducing devices, communication devices, etc., such as a video disk device.

Further, in the embodiment, one screen is divided into one group with 4×4 sampling points, but the present invention can also be applied to other group configurations.

As described above, according to the present invention, sampling is performed at an appropriate sampling frequency during VTR recording and playback, so even when only a part of the sampling point is transmitted, it is not affected by the transmission path and the best possible quality during restoration is achieved. Information can be restored, and even if an error occurs in the mode information signal during the transmission path, at least part of the image sampling signal is transmitted, so it is possible to minimize the deterioration of the transmitted information. Become.

〔Effect of the invention〕

As explained above, even when an unstable transmission line is used, the present invention can restore information in the best possible manner without being affected by the characteristics of the transmission line with a simple configuration. It is possible to provide an information signal transmission method and apparatus for transmitting information.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of an embodiment of the present invention in which the present invention is applied to a recording system of a VTR. FIG. 2 is a diagram showing the principle of using the TAT method in one-dimensional signal processing. FIG. 3(a) is a diagram showing 4×4 sampling points. Figure 4 shows that one field of television screen, which is a time-division multiplexed signal obtained by component demodulating an NTSC television signal, is divided into groups of 4x4 sampling points, and E-mode and C-mode sampling is performed for each group. FIG. 6 is a diagram showing a case where modes are assigned. FIG. 5 is a diagram showing the correspondence between each of the 4×4 sampling points in FIG. 1 and each memory that stores information about each sampling point. FIG. 6 is a diagram showing an example of the arrangement of mode information signals on the screen. FIG. 7 is a diagram showing the arrangement on the screen of sampling points to be transmitted in accordance with the mode information signals arranged as shown in FIG. FIG. 8 is a diagram showing the arrangement of sampling points of basic pixels among sampling points on the screen. FIG. 9 is a diagram showing the arrangement of sampling points of additional pixels among the sampling points on the screen. FIG. 10 is a diagram showing a transmission form of information signals at sampling points of basic pixels and additional pixels. FIG. 11 is a diagram showing a schematic configuration of the reproduction system shown in FIG. 1. 2.9,15,16°17.24.30...Switch, 5...
・・・・・・・・・・・・・・・・・・% pixel thinning circuit, 6.8, 10.11... memory, 4...・・・・・・・・・・・・・・・
...Mode determination circuit. 12.27・・・・・・・・・・・・・・・Mode memory, 13・・・・・・・・・・・・・・・・・・・・・
...Memory control circuit, 20...
・・・・・・・・・Recording Department, 21・・・・・・・
・・・・・・・・・・・・・・・・・・Reproduction Department, 23...
・・・・・・・・・・・・・・・・・・・・・Mode error detection circuit, 25・・・・・・・・・・・・・・・・・・
...... Basic pixel memory, 26...
・・・・・・・・・・・・・・・・・・Additional pixel memory,
28・・・・・・・・・・・・・・・・・・・・・・・・
・Mode conversion circuit, 29...
...... Readout control circuit, 31...
・・・・・・・・・・・・・・・・・・・・・Interpolation circuit,
32・・・・・・・・・・・・・・・・・・・・・・
・Field memory.

Claims (2)

[Claims] (1) When transmitting an information signal using a transmission line having a transmission band of fc, the information signal is sampled at a sampling frequency of 4fc to obtain a sampling information signal, and a predetermined amount of the sampling information signal is ,
A first transmission mode in which only a part of the sampling information signals are transmitted and a second transmission mode in which only the remaining sampling information signals not transmitted in the first transmission mode are transmitted are provided, and the sampling information signals are transmitted in the predetermined amount. is transmitted in at least the first transmission mode for each sampling information signal, and the compression rate of the transmitted sampling information signal is 1.
2. An information signal transmission method characterized in that a part of the predetermined amount of the sampling information signal is further transmitted in the second transmission mode so that the predetermined amount of the sampling information signal is equal to /2. (2) A device for transmitting an information signal using a transmission path having an fc transmission band, the device comprising: sampling means for sampling the information signal at a sampling frequency of 4fc and outputting a sampling information signal; a dividing means for dividing each predetermined amount of the sampling information signal; a first separating means for further separating and outputting only a part of the sampling information signal from all of the predetermined amount of the sampling information signal divided by the dividing means; and the dividing means a second separation means for further separating and outputting only the sampling information signal that is not separated by the first separation means from a part of the predetermined amount of the sampling information signal divided by the first separation means; 1. An information signal transmission apparatus comprising transmission signal forming means for forming a transmission signal using the output of the first separation means and the output of the second separation means so that the information signal transmission apparatus has the following characteristics: