JPH05122683A - Picture storage transfer device - Google Patents

Abstract

PURPOSE:To prevent the deterioration of the picture quality by averaging the rapid generation of the information amount due to the intra-frame encoding according to the data writing speed in a storage part by controlling the cycle of the cyclic refresh in an encoding part based on the information amount generated by an encoder. CONSTITUTION:The difference between blocking picture data and the former frame is quantized in the inter-frame cycle, which is made into an inter-frame differential encoding frame by an encoder 4 to be stored in a storage medium 1. In the intra-frame cycle, a cycle refresh control part 10 varying the cycle of frame cyclic refresh according to the generated information amount from the encoder 4 sends the intra-frame for generating an intra-frame encoding frame to be inserted for each constant frame of the inter-frame difference encoding frame. Thus, the rapid generation of the information amount due to the intra-frame encoding can be averaged to some extent according to the data writing speed in a storage part by varying the cycle of the cyclic refresh.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image communication technique for highly efficient encoding, storing and transmitting an image signal.

[0002]

2. Description of the Related Art A conventional technique using an image storing and transmitting apparatus will be described below. Figure 2 is a journal of the Television Society vo14
3. The figure of No. 10 (1989) "Video encoding method for storage media using periodical intraframe encoding" is shown as an example. Here, 1 is an interframe difference calculator for obtaining an interframe difference, and 2 is a discrete cosine transformer (D
CT), 3 is a quantizer, 4 is a variable-length encoder, 5 is an inverse quantizer, 6 is an inverse DCT, 7 is a calculator for local decoding, 8 is a frame memory, 9 is an intraframe and a frame. Switch between, 10 is a cycle refresh control,
Reference numeral 11 is a storage medium, and 12 is an information generation amount detection unit.

Next, the detailed operation of the prior art will be described. First, the blocked image data is input to the inter-frame difference calculator 1 to take the difference from the previous frame.
After that, the discrete cosine transformer 2 performs DCT to transform into a frequency domain coefficient, and then the quantizer 3 quantizes it. On the other hand, the quantized data is variable-length coded by the variable-length encoder 4 and recorded in the storage medium 7. On the other hand, the quantized data is inversely quantized by the inverse quantizer 5, and further inversely DCT-transformed by the inverse discrete cosine transformer 6.

After that, for local decoding, the arithmetic unit 11 adds the result to the previous frame and inputs it to the frame memory 8. Then, the intra-frame / inter-frame switch 9 selects the intra-frame and the inter-frame. Here, it receives the control of the cycle refresh control 10.
The selected output of 9 is input to the arithmetic unit 7 and the arithmetic unit 1 to perform in-loop arithmetic. Further, the amount of generated variable-length coded data per arbitrary time is counted by the information generation amount detection unit 12, the quantization width of the quantizer 3 is controlled, and the amount of generated information is controlled.

Further, FIG. 3 shows a periodic refresh control unit 10
1 shows an example of the conventional refreshing method in 1 above, one division is one frame. In this case, the intra-coded frames are inserted at a ratio of 1 frame to 15 frames. Intra-frame coding insertion methods for storage media systems include a method of inserting at a constant cycle, a method of detecting a scene change of an input image and setting only the first frame of the scene change within the frame, or a combination thereof. There is. These methods are for performing image editing, fast-forwarding, searching, etc. on the storage medium.

[0006]

Since the conventional refresh method is carried out as described above, the following problems occur in the image storing and transmitting apparatus of FIG. Usually, in image coded transmission that is not a storage medium, transmission efficiency is improved by sending a large amount of inter-frame differential encoded data in order to reduce the amount of information to be transmitted. The regular insertion in the frame is not often performed because the amount of information increases.
However, in the case of a storage medium, since the main purpose is to edit an image on the storage medium, it is the actual situation that the frame must be inserted regularly.

However, in terms of efficiently writing data in the storage medium, there is no substitute for the conventional high-efficiency transmission. In addition, since the storage medium stores image data for a long time,
Hard disks and optical disks are often used, and when these are used, it is necessary to consider the writing speed and the seek time of the disk. For example, FIG. 4 shows the transition state of the information generation amount in the variable speed encoder. However, when the variable speed encoding device and the storage medium are combined, the encoding speed depends on the writing speed of the storage medium.

In other words, if the amount of information generated between frames is large and the inside of a frame is inserted by periodic refresh, the amount of information will temporarily become huge, and if the writing speed of the storage medium is exceeded, this information will be written. In order to suppress the amount, the quantization width is increased or the frame is dropped, so that the image quality is affected. Further, if the maximum information generation amount between frames + the maximum information generation amount within a frame is kept below the writing speed of the storage medium, the image quality in inter-frame coding will deteriorate. There is a problem that the image quality is further affected when an encoder without frame drop is used.

The present invention has been made in order to solve the above-mentioned problems, and determines a cycle of periodic refreshing according to the amount of information generated, and provides an image storing and transmitting apparatus that stores more efficiently and has less deterioration. The purpose is to get.

[0010]

An image storage / transmission apparatus according to the present invention quantizes a difference between blocked image data and a previous frame in an interframe period, and converts the difference into an interframe difference encoded frame by an encoder. By the periodic refresh control unit that stores in the storage medium and changes the period of the frame period refresh according to the amount of information generated from the encoder in the intra-frame period, It is characterized in that an inner frame for generating an intra-frame encoded frame to be inserted is transmitted.

[0011]

The synchronous refresh control section according to the present invention varies the cycle of the cycle refresh according to the amount of information generated in the encoder, so that the intra-frame coding can be performed rapidly according to the data writing speed in the storage section. The amount of information generated can be averaged to some extent.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of an image storage / transmission apparatus according to this embodiment. Reference numeral 1 is an interframe difference calculator for obtaining an interframe difference, and 2 is a discrete cosine converter (DC
T), 3 is a quantizer, 4 is a variable length encoder, 5 is an inverse quantizer, 6 is an inverse DCT, 7 is an arithmetic unit for local decoding,
8 is a frame memory, 9 is a switcher for switching between frames and 10 is a cycle refresh control, 11
Is a storage medium, and 12 is an information generation amount detection unit.

Next, the operation of one embodiment of the present invention,
The operation will be described. First, the blocked image data is input to the inter-frame difference calculator 1 to take the difference from the previous frame. After that, the discrete cosine transformer 2 performs DCT to transform into a frequency domain coefficient, and then the quantizer 3 quantizes it. On the other hand, the quantized data is variable length coded by the variable length encoder 4 and recorded in the storage medium 11. On the other hand, the quantized data is dequantized by the dequantizer 5,
Further, the inverse discrete cosine transformer 6 performs inverse DCT transformation.

After that, the arithmetic unit 7 adds the result to the previous frame for local decoding and inputs it to the frame memory 8.
Then, the intra-frame / inter-frame switching unit selects the intra-frame and the inter-frame. Here, the periodic refresh control unit 10 receives the control of the periodic refresh. The selected output of the switch 9 is input to the arithmetic unit 7 and the arithmetic unit 1 to perform in-loop arithmetic. The process up to this point is the same as that of the conventional storage and transmission apparatus, but in the present invention, the information generation amount detection unit 12 detects the information generation amount of variable-length coded data per arbitrary time, and the periodic refresh control unit 10 is notified. Give feedback and make the refresh cycle variable.

[0015]

As described above, according to the present invention, the cycle of the cycle refresh in the encoder is configured to be controlled based on the amount of information generated in the encoder. Depending on the data writing speed, it is possible to average the abrupt information generation amount due to the intra-frame coding to some extent, and it is possible to suppress the deterioration of image quality in the inter-frame coding.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an image storage / transmission device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional image storage / transmission device.

FIG. 3 is a state diagram of periodic refresh in a conventional image storage / transmission apparatus.

FIG. 4 is a transition state diagram of an information generation amount in a conventional image storage transmission device.

[Explanation of symbols]

 1 Operator for taking the difference between frames 2 Discrete cosine transform (DCT) 3 Quantizer 4 Variable length encoder 5 Inverse quantizer 6 Inverse discrete cosine transform (IDCT) 7 Local decoding operator 8 Loop frame memory 9 Intra-frame / inter-frame switching unit 10 Periodic refresh control unit 11 Storage medium 12 Information generation amount detection unit

Claims (1)

[Claims] 1. A difference between blocked image data and a previous frame is quantized in an inter-frame cycle, an inter-frame difference encoded frame is stored in a storage medium by an encoder, and the above-mentioned encoding is performed in an intra-frame cycle. An internal frame for generating an intra-coded frame that is interpolated for each constant frame of the inter-frame differential coded frame is transmitted by the cycle refresh control unit that makes the cycle of the frame cycle refresh variable according to the amount of information generated from the device. An image storage and transmission device characterized by: