JPS6365276B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a television signal encoding device that encodes and transmits television signals.

Currently, various encoding devices for converting television signals into digital signals have been developed. These devices are going to be used for transmitting images, audio, and data signals in educational facilities, teleconferencing, etc., and they can transmit not only television signals but also signals other than television signals (i.e., audio signals, facsimile, etc.). simultaneous transmission of resolution information, data information) is required. Conventionally, when transmitting signals other than television signals simultaneously with television signals, the following method has been used.
The first method is to provide a separate transmission path for signals other than the television signal, the second method is to superimpose a signal other than the television signal on the blanking section of the television signal, and the third method is to provide a transmission path for the television signal. This is a method in which a part of the blanking section is deleted and a signal other than the television signal is inserted.

However, the first method of providing a separate transmission line has the drawback of requiring a new line to be installed. Furthermore, the second and third methods that utilize the blanking section of the television signal have the disadvantage that there is a limit to the amount of data that can be superimposed or inserted. Also, the third
This method has the disadvantage that it cannot accurately transmit the input television signal because it requires operations such as deleting a part of the television signal and adding a solid waveform in the receiving section.

An object of the present invention is to provide a television signal encoding device capable of simultaneously transmitting television signals and signals other than television signals, which eliminates the above-mentioned drawbacks.

A specific object of the present invention is to provide a television signal encoding device capable of multiplexing and transmitting a television signal and a signal other than a television signal, which is capable of faithfully transmitting a television signal without deforming the television signal waveform. An object of the present invention is to provide a signal encoding device.

The present invention detects the time when a television signal is in a level range where noise is difficult to visually see, reduces the number of quantization bits in the encoder of the television signal at that time, and uses the reduced bits to generate signals other than the television signal. This is a television signal encoding device that can multiplex transmit television signals and signals other than television signals by inserting and transmitting signals without visually deteriorating the image quality of the television signal waveform. In this explanation, the number of quantization bits is controlled by the TV signal level distribution, but when a predictive encoder (DPCM) is used as an encoder, the number of quantization bits is controlled using the level distribution of the differential signal of the predictive encoder. may be controlled.

According to the present invention, there is no need to install a new line,
The transmission amount of signals other than television signals is not limited by the blanking period, and television signals can be transmitted more accurately, eliminating the drawbacks of the conventional technology.

Furthermore, according to the present invention, other data can be multiplexed onto the television code, and by controlling the level of the input television signal, the amount of data that can be multiplexed can be controlled. For this reason, faxes, data,
In educational facilities equipped with many video terminals, etc., the assignment of transmission channels to encoders can be changed by controlling the input signal level.

Next, embodiments of the present invention will be described with reference to the drawings.

Referring to FIG. 1, a television signal encoding device according to an embodiment of the present invention is a device that multiplexes and transmits a television signal and a data signal. In FIG. 1, a television signal from an input terminal 1 is converted into a PCM code by an analog-to-digital converter (A/D converter) 41 of a television encoder 4.
At step 2, the signal undergoes code conversion processing such as bit degeneracy, and is input to the multiplexing circuit 10. Input data signals A and B
enters from the input terminals 2 and 3, and the data encoder 6,
At step 7, the signal is converted into a digital signal and temporarily stored in memory devices 8 and 9. The output signals of the memories 8 and 9 are input to a multiplexing circuit 10, multiplexed with the encoded television signal, and outputted from an output terminal 11.

The controller 5 monitors the level distribution of the output signal of the A/D converter 41, and when the level distribution is within a predetermined level range, controls the code converter 42, and controls one of the television signals of the code converter 42. The number of output code bits per sample point is reduced by bit deletion, and the data in the memories 8 and 9 is read out at the deleted bit positions and is applied to the multiplexing circuit 10, where it is multiplexed.

Next, the multiplexing method will be explained using FIG. 2. FIG. 2A shows a television signal waveform in units of one horizontal scanning line, and the T _SYNC interval is a horizontal synchronization interval. Further, 101 is a synchronization signal, and 102 is a color burst. a is the dynamic range of the television encoder 4, and the controller 5 monitors the level of the input television signal to see in which range the input television signal is located.

When the input television signal is in the level range of or, temporally, during the intervals T1, T2, T3, T4, the input television signal is very bright or dark, and visually the signal-to-noise conversion (S /N) is low to some extent, it is difficult to see it as noise. The present invention utilizes this property to reduce the number of encoded bits when the level of the input television signal is in the range of or.

FIG. 2B shows the output signal of the multiplexing circuit 10. In this way, if the level of the input television signal is at or in Figure 2A, the television signal is 1.
8 bits per sample point are transmitted, while if the input television signal is in the level range of or, the least bit (LSD) is removed in transcoder 42;
A television signal is transmitted at 7 bits per gage, and at this time, a data signal is sent to the LSD (part D in Figure 2 B).
is inserted and transmitted.

As described above, the number of encoded bits in very bright and dark portions of a television signal is reduced by bit deletion, and a data signal is inserted into the deleted bit portion for transmission. In the receiving section, if the signal level of the received data is within the range of or in FIG. 2A, the LSD is separated and output as a data signal.

According to this embodiment, data signals can be multiplexed and transmitted without subjectively degrading the image quality of the television signal and without increasing the transmission data rate. Moreover, since there is no manipulation on the waveform of the television signal, faithful waveform transmission is possible. Furthermore, by controlling the level of the input signal, the information on which data can be transmitted can be made variable. In other words, by lowering the input television signal to a low level (black level), it is possible to increase the amount of data transmitted.

In this embodiment, the level of the input television signal is detected digitally (that is, based on the output signal of the A/D converter 41 in FIG. 1), but the invention is not limited to this; may be processed. The method of determining the signal level range and the number of bits to be reduced are not limited to the present embodiment.

In addition, as a method for reducing the number of bits, in this example,
Although the quantization accuracy is reduced by removing the LSD, the present invention is not limited to this, and is not limited to this. There are methods such as quantization using a device. For example, in Figure 2A
During the T _SYNC period, the input level is less than 1/2 of the dynamic range of the television encoder, so a method can be used to delete the MSD bit.

In addition, in this embodiment, PCM is used as a television encoder.
Although the explanation has been made using an encoder, the present invention is not limited to this.
A predictive encoder such as DPCM (Differential PCM) may be used, and in this case, it can be realized by controlling the number of bits of the quantizer of the predictive encoder depending on the level of the input signal, the level of the difference signal, etc.

Further, in this embodiment, a data signal is inserted into code data for a television signal, but it can also be used to insert parity bits, synchronization signals, redundant bits for error correction, etc. of code data. Moreover, it goes without saying that signals other than television signals include audio signals and image signals.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a television signal encoding apparatus according to an embodiment of the present invention, and FIG. 2 is a waveform diagram for explaining the operation of FIG. 1. 1... Input end for television signal, 2... Input end for data signal A, 3... Input end for data signal B, 4...
... TV encoder, 41 ... Analog-digital converter, 42 ... Code converter, 5 ... Controller, 6 and 7 ... Data encoder, 8 and 9 ... Memory device, 1
0... Multiplexing circuit, 11... Output end.

Claims (1)

[Claims] 1. A television signal encoding device that encodes and digitally transmits a television signal, which receives the television signal and generates a first equal-length code signal having a first code length and a first equal-length code signal with a number of encoded bits less than the first code length. a first encoder that encodes and outputs a second equal-length code signal having a second code length, and at least one second code that receives and encodes an information signal different from the television signal; a storage device that receives and stores the output signal of the second encoder, and a multiplexing circuit that receives and multiplexes the output signal of the first encoder and the output signal of the storage device; Only when the level of the television signal is within a predetermined level range, the first encoder outputs the second equal-length code, and the encoding is reduced from the first equal-length code. The output signal of the storage device is read out in the bit number part and applied to the multiplexing circuit, and if the level of the television signal is not within the predetermined level range, the output signal is read out from the first encoder to the first encoder. and a controller for outputting an equal-length code signal of and applying it to the multiplexing circuit, and a signal obtained by multiplexing the television signal and the information signal is obtained at an output end of the multiplexing circuit. TV signal encoding device.