JPH07222146A - Device and method for processing image - Google Patents

Abstract

PURPOSE:To transfer data between the networks of different transfer rates by encoding the moving image data of a first frame rate by a second frame different from it. CONSTITUTION:Input moving image encoded data signals 4 transmitted from an external communication channel are separated into a video part and an audio part in an input control part 1 and encoded data signals 5 and 6 from the input control part 1 are supplied to a code conversion part 2. The respective encoded data signals 7 and 8 of the audio part and the video part are supplied from the code conversion part 2 to an output control part 3. Thereafter, obtained output moving image encoded data signals 9 are outputted to the external communication line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus and method, for example, moving picture coded data coded at a certain bit rate to moving picture coded data having a bit rate lower than the bit rate. The present invention relates to an image processing device and method for conversion.

[0002]

2. Description of the Related Art MPE is used as a moving image coding system for storage.
There is a method called H261 method as a moving image coding method for communication such as G method and TV conference.

[0003] For example, the MPEG system is a system developed for the storage of moving images. The bit rate is 1.5 Mbit / sec, the compression rate is relatively low, the algorithm is complicated, and the real-time property is not so important. Although it has not been done, this method emphasizes image quality. On the other hand, the H261 system was developed for video conferencing and video telephony. Assuming that it will be used in communication systems, the bit rate is low at px64kbit / sec (p is an integer), and real-time performance is important. The algorithm is also simplified.

When communicating coded data of a moving image coded by the H261 system, the coded data must be coded at a bit rate lower than the transfer rate allowed by the communication line used.

[0005]

However, considering the case of a communication network having two or more types of communication lines when the H261 system is used in the above conventional example, there are a plurality of types on the transmission side (encoding side). If encoding is performed according to the lowest transfer rate among communication lines, even a terminal connected to a communication line with a high transfer rate will see only moving images with the same image quality as a terminal connected to a communication line with the lowest transfer rate. It has the drawback of not being able to. On the contrary, if the encoding is performed according to the high transfer rate, the terminal connected to the communication line with the low transfer rate cannot reproduce in real time.

Further, in the case of communicating encoded data encoded by the MPEG system, it is not possible to communicate in real time through a communication line for a TV conference or a TV telephone, and the encoded data sent once on the receiving side is HD. It is necessary to buffer the data in a secondary storage device such as the above, and then decode and display it locally, which is a drawback that it cannot be displayed in real time. Further, in order to display the code data of the MPEG system in real time, there is a drawback that the communication line must be changed to a communication line having a transfer rate that can support the bit rate for MPEG. These drawbacks are problems occurring not only in the MPEG system H261 system but also in various systems.

The present invention aims to overcome these drawbacks.

Another object of the present invention is to provide an image processing apparatus and method suitable for transferring image data via a network.

Another object of the present invention is to provide an image processing apparatus and method having, for example, a conversion function, which transfers image data via a network.

[0010]

The present invention has been made in view of such drawbacks, and the first invention of the present application is to input coded moving image data of a first frame rate. Input means, converting means for converting moving image data of the first frame rate input by the input means to encoded moving image data of a second frame rate different from the first frame rate, and the converting means And output means for outputting the encoded moving image data of the second frame rate converted by.

The second invention of the present application is a first rate encoded moving image including a frame encoded by the intra-frame encoding method and a frame encoded by the inter-frame encoding method. Input means for inputting image data, and a frame encoded by the intra-frame encoding method is extracted from the moving image data of the first rate input by the input means to obtain a first rate different from the first rate. And a conversion means for converting the coded moving image data at a rate of 2.

According to the third invention of the present application, the encoded moving image data of the first frame rate is input, and the input moving image data of the first frame rate is referred to as the first frame rate. It is characterized in that it is converted into encoded moving image data of a different second frame rate, and the converted encoded moving image data of the second frame rate is output.

The fourth invention of the present application is that a first rate encoded moving image including a frame encoded by the intra-frame encoding method and a frame encoded by the inter-frame encoding method. A second rate different from the first rate by inputting image data and extracting a frame encoded by the intra-frame encoding method from the moving image data of the first rate input by the input means. It is characterized in that it is converted into encoded moving image data.

[0014]

1 is a block diagram showing the configuration of a moving picture coded data conversion apparatus according to a first embodiment of the present invention. 1 in the figure
Is an input control unit for inputting a moving image coded data signal sent from an external communication line and separating the coded data of the video data unit 5 and the audio data unit 6. Reference numeral 2 is a code conversion unit that performs code conversion of each code data separated into the Video part and the Audio part by 1.
3 transmits the video coded data to an external communication line (not shown), so that the video section converted in 2 and the Aud are converted.
It is an output control unit that transmits each code data of the io unit. Four
Is an input moving image coded data signal sent from an external communication line, and 5 and 6 are audio parts of an input code form,
Coded data signals of the video section, 7 and 8 are audio sections after moving picture code conversion, coded data signals of the video section, and 9 is an output moving picture coded data signal to be transmitted to an external communication line. . Reference numeral 10 denotes the entire moving image code conversion unit.

In the first embodiment, the MPE is adopted as the coding system of the moving picture coded data inputted from the external communication line.
The G system and the H261 system are used as the encoding system of the moving image encoded data output to the external communication line. That is, it will be explained that the code conversion unit of this embodiment converts the MPEG system to the H261 system.

FIG. 2 is a schematic diagram of a format of encoded data (hereinafter referred to as a bit stream) in the MPEG system. In this embodiment, I-Picture and P-Picture are used as conditions for encoding in the MPEG system.
The number of frames of re and B-Picture is M = 3, N
= 15, that is, Intra shown as 21 and 22 in the figure
-Picture shall appear every 15 frames and shall be encoded at 30 frames / sec. On the other hand, it will be described that the output coding condition in the H261 system is that the coding is performed at 2 frames / sec. The detailed operation of the code conversion unit 2 will be described below with reference to the drawings.

The image data that has been intra-frame coded in this embodiment is called intra-picture.

FIG. 3 shows a detailed block diagram of the code conversion unit in this embodiment. In the figure, 30 is a Video code conversion unit for converting Video coded data, and 31 is an Audio
It is an Audio code conversion unit that converts o-coded data. Reference numeral 32 denotes a detection unit that detects the code of the Intra-Picture part in the MPEG Video bitstream, and at the time of such detection, the header of the encoded image data of each frame may be detected. 33 is M
An MPEG Video decoding unit for decoding a PEG Intra-Picture bitstream, 34
Displays the image data decoded in 33 in Int of H261.
H261Vid converted to ra-Picture code
The eo encoding unit. 35 is MPEG Audio
An MPEG Audio decoder that decodes the bit stream, and 36 that is decoded by the decoder 35 are
A low-pass filter 37 that cuts high-frequency components of audio data, and 37 is an audio encoder compliant with the H261 system.

In the present embodiment, MPEG coded data encoded at 30 frames / sec is converted into H261 at 2 frames / sec.
Since it is considered to be dropped into a code, the conversion method of the Video section is Intra in the MPEG bit stream.
-Decode only Picture, H261 Int
It may be converted to ra-Picture. The audio unit applies a low-pass filter in the time axis direction of the audio signal in accordance with the rate at which the number of frames is dropped by the Video conversion unit, and performs conversion so as to be synchronized with the Video unit.

Intra of MPEG in this embodiment
H261 In from Picture bitstream
The method of converting a tra-picture to a bit stream may be such that the completely decoded image data format is once decoded and then re-encoded, or only the necessary part is decoded and encoded. Good. The same applies to the Audio section.

(Other Embodiments) In the first embodiment, M
Intra-Pictur in PEG bitstream
Although it has been described that the e part is converted to the Intra-Picture of H261, in the second embodiment, an example in which the frame thinning interval is converted to be slightly finer will be described. For example, setting 30 frames / sec to 6 frames / sec will be described. As for the input in this case, the MPEG system is considered as in the first embodiment.

The configuration of the video conversion unit in this case is as follows.
The structure is as shown in FIG. In the figure, 40 is an MPEG video decoder, 43 is an image buffer, 41
Are buffers 1 and 42 for storing the image data output from the decoder of 40, and buffers 2 and 44 which are input to a video encoder of H261 described later, and 44 are video encoders of H261. The data transfer from the buffer 41 to the buffer 42 is controlled by the control signal 45.

In the case of changing 30 frames / sec to 6 frames / sec, it is necessary to decode the entire MPEG Video bit stream and then encode it by the H261 system. Therefore, the 40 MPEG decoder decodes the input bit stream and outputs the resulting image data to the buffer 1 of 41. The control signal 45
Is a signal output from the CPU 49, which is H261
If the output speed of the image data in the method is 6 frames / sec, C is set so that the image data is transferred from the buffer 1 to the buffer 2 every 5 frames of the decoded frames.
The PU 49 gives a control signal to the buffer 43. In accordance with this control signal, the buffer 43 causes the buffers 41 to
The image data is transferred to the second buffer 2. H shown at 44
The 261 Video encoder inputs the image data from the 42 buffer and encodes the Video portion of H261.

The audio part is the same as that of the first embodiment, and therefore its explanation is omitted.

In this embodiment, the output side is described as 6 frames / second, but the present invention is not limited to this, and various frame numbers can be supported.

In the first and second embodiments, a detailed description of the bit rate of the bit stream is not given, but it is possible to specify parameters on the encoding side of MPEG, H261, and various bit rates can be specified. I omit it because it can be set to a value, but in general, the H261 method is M
Since the bit rate is lower than that of PEG, the data decoded by the MPEG decoder 40 based on the control signal is thinned out in the buffer 43.

Although it has been described that the number of frames to be encoded is reduced as a method of reducing the bit rate of the encoded moving image data, if there is a function capable of designating the bit rate of the encoded data output to the encoder on the output side, It is also possible to reduce the bit rate without reducing the frame rate.

Further, in the embodiment, the MPEG system is used as H26.
Although the conversion into one system has been described, the present invention is not limited to this, and H261 to H261, MPEG to MPEG,
It can be easily inferred from H261 that MPEG may be used.

It is also possible to prepare a plurality of types of decoding units on the input side, for example, two types of MPEG and H261, select which code form from the transmitted moving image coded data, and decode. .

Furthermore, a plurality of types of encoding units on the output side may be prepared.

In the embodiment described below, an example of communication lines and terminals having a network configuration as shown in FIG. 5 is disclosed. Reference numeral 50 in FIG. 5 denotes a moving image code conversion device, which will be described later, 52-
1 to 52-3 are communication lines, 53-1 to 53-5,
51-1 and 51-2 are display terminals.

The communication lines 52-1 and 52-3 in this embodiment are 1.5 Mbit / sec, and the communication line 52-2 is
It is assumed that the transfer rate is 128 Kbit / sec. Again 5
It is assumed that the display terminals 3-1 to 53-5 are equipped with an H261 decoder, and the display terminals 51-1 and 51-2 are equipped with an MPEG decoder. A block diagram of the moving picture code conversion apparatus 50 at this time is shown in FIG.

In FIG. 6, 60 is an input signal, 61 and 62 are output signals, and 61 outputs the input signal 60 as it is. On the other hand, the reference numeral 62 is configured to output the code converted to the designated moving image code through the moving image code conversion unit 10.

In this configuration, the display terminals 51-1 and 51-
2 is the communication line 52-3 to which this terminal is connected,
Since it has the same transfer rate as the input 52-1 of this network, the signal on the 62 side of FIG. 6 is connected to 52-3. On the other hand, 52-2 connects the signal on the 61 side.

Here, M is transmitted from an external communication means (not shown).
52-bit stream of PEG 1.5 Mbit / sec
Consider the case where the input is made from the line 1.

In this case, the display terminals 51-1 and 51-2 receive the MPEG bit stream transmitted from the communication path 52-1 as they are, are decoded by the MPEG decoder of the display terminal, and have a capacity of 1.5 Mbits. It is possible to display a moving image with an image quality of / sec. Meanwhile 53-1 to 5
In the display terminal 3-5, first, in the moving picture code converting unit 10 in the moving picture code converting apparatus 50, the MPEG code of 1.5 Mbit / sec is 128 by the method of the first or second embodiment.
It is converted into a code of H261 of K bits / second, and the code is simultaneously sent to each display terminal via the communication line 52-2. Each display terminal decodes the H261 code sent by using the H261 decoder and displays 1 on the screen of each terminal.
A moving image with a quality of 28 Kbit / s can be displayed.

The conversion of these encoding methods may be automatically performed by the moving image code conversion device 50 based on the result of detecting the transfer rate of the communication circuit.

In the present embodiment, the network configuration consisting of communication lines having two types of transfer rates has been described, but the present invention is not limited to this, and the transfer rate changes even in a network in which a plurality of transfer rates of 3 or more coexist. It can be easily inferred that this moving picture code conversion device can be attached to a place. Also, the transfer rate itself is not limited to 1.5 Mbit / sec and 128 Kbit / sec.

Further, even if the present invention is an MPEG system, H2
Even with the 61 system, another moving image coding system, for example, MP
It may be an EG-II system or a vector quantization system.

The present invention is also effective when data is converted between a plurality of coding methods having different frame rates.

Further, according to the third embodiment of the present invention, when the data transfer rates are different among a plurality of networks, the moving picture coding system is converted and transferred according to the transfer rates. Therefore, even if the data transfer rate between the networks is different, it is possible to output well-coded moving image data to the network.

In implementing the present invention, a computer and software may be used, or a hardware structure may be used.

According to the present embodiment, when there is a network having communication lines having a plurality of transfer rates, moving image data is to be transferred between the communication line having a high transfer rate and the communication line having a low transfer rate. The moving picture coded data conversion means for reducing the bit rate of the coded data according to the transfer rate of the communication line is provided, and the terminal connected to each line by one moving picture coded data is connected to the terminal. It is possible to reproduce in real time a moving image of a quality suitable for the transfer rate of the communication line.

As described above, according to this embodiment,
By installing a moving picture coding conversion device between communication lines with different transfer rates and converting moving picture coded data according to the transfer rate of the communication line, all display terminals match the transfer rate of the communication line. It is possible to display moving images with excellent image quality.

Various methods can be selected for reducing the bit rate of the moving image coded data, and the most preferable moving image data can be displayed on each communication line.

Furthermore, since the moving picture coding system can be selectively changed, it is possible to display even when different code data is transmitted by using the moving picture decoding function of the display terminal. .

[0047]

According to the present invention, the rate of moving image data can be changed according to various transfer rates.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a system configuration according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram of an MPEG bit stream.

FIG. 3 is a block diagram of the first embodiment.

FIG. 4 is a block diagram of a second embodiment.

FIG. 5 is a network configuration diagram of a third embodiment.

FIG. 6 is a block diagram of a third embodiment.

Claims (14)

[Claims] 1. Input means for inputting encoded moving image data of a first frame rate, and moving image data of a first frame rate input by the input means is different from the first frame rate. A conversion unit for converting to the encoded moving image data of the frame rate, and an output unit for outputting the encoded moving image data of the second frame rate converted by the conversion unit. Image processing device. 2. The encoded moving image data includes a frame encoded by an intra-frame encoding method and a frame encoded by an inter-frame encoding method, and the conversion means has a first frame rate. 2. The image processing apparatus according to claim 1, further comprising means for extracting data coded by the intraframe coding method from the moving picture data. 3. The image processing apparatus according to claim 1, wherein the input unit and the output unit are selected for lines having transfer rates different from each other. 4. The image processing apparatus according to claim 1, wherein the first frame rate is higher than the second frame. 5. Input means for inputting encoded moving image data of a first rate including a frame encoded by an intra-frame encoding method and a frame encoded by an inter-frame encoding method, By extracting a frame encoded by the intra-frame encoding method from the moving image data of the first rate input by the input means, an encoded moving image of a second rate different from the first rate is extracted. An image processing apparatus comprising: a conversion unit that converts the image data. 6. The second converter further converted by the converting means.
6. The image processing apparatus according to claim 5, further comprising output means for outputting the encoded moving image data at the rate of. 7. The image processing apparatus according to claim 6, wherein the input unit and the output unit are connected to lines having different transfer rates. 8. An encoded moving image data having a first frame rate is inputted, and the inputted moving image data having a first frame rate is inputted into a second frame different from the first frame rate.
An image processing method, comprising: converting the encoded moving image data of the second frame rate and outputting the converted moving image data of the second frame rate. 9. The encoded moving image data includes a frame encoded by an intraframe encoding method and a frame encoded by an interframe encoding method, and has a first frame rate at the time of the conversion. 9. The image processing method according to claim 8, wherein the data encoded by the intra-frame encoding method is extracted from the moving image data. 10. The image processing method according to claim 10, wherein the input and the output are selected for lines having different transfer rates. 11. The image processing apparatus according to claim 8, wherein the first frame rate is higher than the second frame rate. 12. A first rate encoded moving image data including a frame encoded by an intra-frame encoding method and a frame encoded by an inter-frame encoding method is input, and the input means is provided. By extracting a frame encoded by the intra-frame encoding method from the moving image data of the first rate input by, the encoded moving image data of the second rate different from the first rate is obtained. An image processing method characterized by converting. 13. The image processing method according to claim 12, wherein the converted moving image data of the second rate is output. 14. The image processing method according to claim 13, wherein the input and the output are connected to lines having different transfer rates.