JP2000324488A - Still picture transmitting method and reproducing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a still picture transmitting method and reproducing method, by which a still picture reproducing time required in an early stage is shortened in addition to the suppression of deterioration in transmission efficiency. SOLUTION: Still picture encoding circuits 2 and 3 encode same input still picture data by different encoding characteristics, obtain still picture encoding data D1 and D2 and stores them in encoding data memories 4-1 and 5-1. Encoding data read from the memories 4-1 and 5-1 are multiplexed with various kinds of identifying information and another kind of encoding data by a prescribed repetition frequency by multiplexing circuit 6 and, then, outputted to a transmission line by way of a transmission line circuit 8. Still picture encoding data D1 with a small encoding amount is repeatedly transmitted by the frequency being higher than that of still picture encoding data D2 with the larger encoding amount. Then the deterioration of transmission efficiency is suppressed and also the still picture reproducing time required in the early stage is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a still image transmitting method and a reproducing method, and more particularly to a still image transmitting and reproducing method for transmitting encoded still image data.

[0002]

2. Description of the Related Art A method of transmitting and reproducing encoded data of a still image compressed and encoded in digital broadcasting or the like has been conventionally known. This is a method of sequentially and intermittently transmitting a plurality of encoded still image data to be transmitted, and the reproducing side sequentially reproduces and outputs the transmitted encoded still image data. However, in the above transmission method, the still image encoded data once transmitted is not transmitted again. Therefore, when a still image program is received from the middle of a digital broadcast or the like, the still image encoded data is transmitted until the next still image encoded data is transmitted. A problem that cannot be displayed occurs. For example, in a still picture program transmitting a different still picture every 10 minutes, in the worst case, 10 minutes from the start of reception.
Still images cannot be displayed for minutes.

As a method for solving this problem, there is a repetitive transmission of encoded still image data. This still image transmission method is a method of repeatedly transmitting the same still image encoded data until the start of transmission of the encoded data of the next still image in the transmission of encoded data of a certain still image. For example, in the above example, the same still image coded data is
If it is repeated 0 times, that is, transmitted every minute, at worst, a still image can be displayed within one minute from the start of reception.

[0004] Thus, it can be seen that the display waiting time from the start of reception can be shortened by repeated transmission. Also,
By increasing the frequency of repeated transmission, the display waiting time from the start of reception can be further reduced.

[0005]

However, in the above-mentioned conventional still image transmission method for repeatedly transmitting encoded still image data, there is a problem that if the frequency of repeated transmission is simply increased, the transmission efficiency is reduced. This is caused by repeatedly transmitting the same encoded data to a certain still image, that is, still image encoded data having the same code amount.

[0006] The present invention has been made in view of the above points,
By repeatedly transmitting still image encoded data, a plurality of encoded data having different code amounts are transmitted for one still image, and the encoded data having a small code amount is repeatedly transmitted at a higher frequency, thereby improving transmission efficiency. It is an object of the present invention to provide a still image transmission method and a reproduction method capable of reducing the initial required time for reproducing a still image while suppressing deterioration.

[0007]

In order to achieve the above object, a still picture transmission method according to the present invention is directed to a method for transmitting a plurality of still picture data obtained by separately encoding the same still picture data using a plurality of different encoding characteristics. Is transmitted a plurality of times per unit time and at a different number of repetitions from each other.

[0008] Here, in the still picture transmission method of the present invention, the plurality of still picture coded data are hierarchically coded data or coding of a still picture in each divided area obtained by dividing the same still picture data into a plurality of areas. It may be data.

Further, in the still picture transmission method according to the present invention, the number of repetitions per unit time of the plurality of still picture encoded data is set to a larger value as the still picture encoded data having a smaller code amount. It is characterized by. Further, a plurality of encoded data obtained by separately encoding the still image data in each divided region obtained by dividing the same still image data into a plurality of regions is obtained a plurality of times per unit time and different from each other. It is characterized in that transmission is performed with the number of repetitions.

In order to achieve the above object, the still picture reproducing method according to the present invention separately encodes one or more data related to the same still picture by a plurality of different encoding characteristics. A plurality of still picture coded data obtained in this manner are transmitted a plurality of times per unit time, and a data string transmitted at a different number of repetitions is input through a transmission path, and an input data string from the transmission path is input. Immediately after or when the still image in the input data string is switched,
Among the plurality of still image encoded data, the first received still image encoded data is decoded and stored in the memory. Thereafter, the received still image encoded data has different encoding characteristics and has a larger code amount. Still image encoded data is sequentially decoded and stored in a memory, and the decoded data stored in the memory is output as a reproduction signal.

In the present invention, attention has been paid to the fact that the conventional disadvantage is caused by repeatedly transmitting the same coded data to a certain still image, that is, still image coded data having the same code amount. In contrast, by repeatedly transmitting a plurality of coded data separately coded with different coding characteristics from each other, and by weighting the number of times of repetitive transmission of each coded data, it is possible to suppress a decrease in transmission efficiency and to reproduce still images. Reduce initial turnaround time.

According to another aspect of the present invention, there is provided a reproduction method for decoding first still picture encoded data obtained by encoding input still picture data with first encoding characteristics. A second still image encoding obtained by encoding the difference data between the decoded still image data and the input still image data with a second encoding characteristic whose quantization characteristic is finer than the first encoding characteristic. Immediately after the data string transmitted multiple times per unit time together with the first still image data and at different repetition times is input via the transmission path and the input data string from the transmission path is input Alternatively, immediately after the still image in the input data sequence is switched, decoding with size conversion is performed so that the first encoded still image data has the same size as the second encoded still image data. Only once and in memory After that, the second still image encoded data is decoded only once to obtain difference data, and the difference data is added to the size-converted decoded data from the memory, and then stored in the memory. The stored data is output as a reproduction signal.

According to the present invention, it is possible to prevent redundant decoding of already decoded encoded data and decoding and decoding of erroneous hierarchically encoded data, thereby reducing the decoding processing amount and deteriorating the reproduction display quality. Can be prevented.

Further, in order to achieve the above object, the reproducing method of the present invention provides a plurality of still picture data obtained by separately encoding the same still picture data in each divided area into a plurality of divided areas. Is transmitted a plurality of times per unit time, and a data string transmitted at a different repetition number is input via the transmission path, and immediately after the input data string is input from the transmission path or the input data string. Immediately after the middle still image is switched, the first received coded data of the plurality of coded data is decoded and stored in the memory, and then decoded every time coded data of an undecoded area is received. And sequentially store the decoded data in the memory, and output the decoded data stored in the memory as a reproduced signal. According to the present invention, it is possible to prevent redundant decoding processing of encoded data that has already been decoded, thereby reducing the amount of decoding processing.

[0015]

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

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
FIG. 3 is a block diagram for explaining a transmission side according to the embodiment. The still image data to be transmitted has, for example, an image size of 704 pixels in the screen horizontal direction and 48 pixels in the screen vertical direction with respect to the luminance signal.
0 pixels (that is, 704 × 480), and the color system is a so-called YCbCr 4: 2: 0 component format.
Are supplied to the still picture coding circuit 2 and the still picture coding circuit 3 via the.

Still picture coding circuit 2 and still picture coding circuit 3
Encodes the same input still image data with different encoding characteristics. That is, the still image encoding circuit 2 sub-samples the input still image data to convert the size to 352 × 240, and encodes the image with coarse quantization characteristics by MPEG-1 intra-frame encoding. Decoding the encoded data having the encoding characteristics is sufficient to display the outline of the still image. On the other hand, the still image encoding circuit 3 encodes the input still image data with a small quantization characteristic by the intra-frame encoding of the MPEG-2 system while keeping the size of the input still image data at 704 × 480.

The encoded data D1 extracted from the still image encoding circuit 2 is written to the encoded data memory 4-1 via the terminal a of the switch SW1-1. Similarly,
Encoded data D2 extracted from the still image encoding circuit 3
Is written to the encoded data memory 5-1 via the terminal a of the switch SW2-1. At the same time, based on the control signal from the control circuit 7, the encoded data memory 4-
2 and the coded data previously output from the still picture coding circuit 2 and the still picture coding circuit 3 stored in the coded data memory 5-2 are read out, and the terminals b and SW2 of SW1-2 are read out. The signal is input to the multiplexing circuit 6 via the terminal b of -2.

Here, the encoded data memory (4-1, 4)
-2) and (5-1, 5-2) are provided in each set of two, so that the encoded data D1,
D2 is stored alternately for each set.

In the multiplexing circuit 6, the encoded data memory 4
-2 and the above-described encoded data read from the encoded data memory 5-2, to which information for identifying a still image and information for identifying the encoding characteristic type are added, and FIG.
Alternatively, as shown in FIG. 7C, the still image encoded data D1, D2
Are packetized and multiplexed at a predetermined repetition frequency, and the other coded data input via the terminal 9 is multiplexed and output to the transmission circuit 8. The transmission circuit 8
The input multiplexed signal is subjected to, for example, a transmission line encoding process and a modulation process according to the transmission line to be output, and output to the transmission line.

On the other hand, when a predetermined transmission start time for the input still image comes, the control circuit 7 switches the switches SW1-1 and SW1-1.
SW2-1, SW1-2, and SW2-2 are switched to a connection state opposite to the current connection state illustrated. As a result, the encoded data stored in the encoded data memory 4-1 and the encoded data memory 5-1 are read,
The signal is input to the multiplexing circuit 6 via the terminal a of SW1-2 and the terminal a of SW2-2, where it is multiplexed with the various kinds of identification information and other encoded data at a predetermined repetition frequency described later. After that, the data is output to the transmission line via the transmission line circuit 8.

Next, the reproduction side of the first embodiment will be described. FIG. 4 is a block diagram on the reproducing side according to the first embodiment of the present invention. In the figure, encoded data (multiplexed data) from the transmission circuit 8 of FIG. 1 via a transmission path is input to a reception circuit 22 via an input terminal 21. Further, based on the transmission path selection information input via the input terminal 23, the control circuit 24 instructs the reception circuit 22 on the transmission path to be received. For example, the reception frequency of the tuner is controlled in response to the tuning information in the broadcast reception. Receiving circuit 2
2 performs demodulation processing and transmission path decoding processing corresponding to the transmission path on the input transmission data, and supplies the data to the separation circuit 25.

The separating circuit 25 separates still picture data from the multiplexed coded data and supplies it to a still picture decoding circuit 26. The other encoded data is similarly separated and output to the outside via the output terminal 28. At this time, based on the information for identifying the still image added to the still image encoded data and the information for identifying the type of the encoding characteristic, the separation circuit 25 determines the encoded data as It is supplied to the decoding circuit 26.

1. Immediately after the start of reception or immediately after the still image to be decoded is switched based on the identification information of the still image, the still image encoded data received first regardless of the encoded data D1 and D2 is transmitted to the still image decoding circuit 26. Supply. 2. In the case where the encoded data supplied in the above 1 is D1, if the encoded data D2 is separated, the still image decoding circuit 26
To supply. Also, the coded data D1 after the above 1 is not supplied. 3. If the coded data D2 is supplied to the still picture decoding circuit 26 in 1 or 2, the coded data of the same still picture will not be supplied regardless of D1 and D2 based on the identification information of the still picture.

In the still picture decoding circuit 26, the separating circuit 25
When the input still image encoded data is D1, the MPEG-1 format intra-frame decoding process is performed, and up-sampling is performed to 704 ×
When the input still image encoded data is D2, the decoding process is performed in the MPEG-2 system.

The still picture coded data decoded by the still picture decoding circuit 26 in response to the above determination is sequentially written to the still picture memory 27. The still image memory 27 reads out the stored still image data based on a control signal from the control circuit 24 and outputs the data to the outside via the output terminal 29.

Next, repetitive transmission according to the first embodiment of the present invention will be described with reference to FIG. here,
As a result of encoding certain still image data by the still image encoding circuit 2, 10-kbyte still image encoded data D1 is output,
It is assumed that encoded still image data D2 of 60 kbytes is output as a result of encoding by the still image encoding circuit 3.

FIG. 7A shows a case where only the still picture coded data D2 is repeatedly transmitted three times in a unit time from time T0 to time T1. For example, from time T0 to time T1
If the time of is set to 10 minutes, “Data” is shown in FIG.
As shown by, still image encoded data is transmitted every 3 minutes and 20 seconds. That is, when a channel is switched in digital broadcasting or the like, a worst case is that a still image cannot be displayed for 3 minutes and 20 seconds on the reproduction side. Further, 180 kbytes are transmitted in 10 minutes for transmitting the encoded still image data D2 three times repeatedly.

FIG. 7B shows that, according to this embodiment, the 60-kbyte still picture coded data D2 is twice transmitted in the unit time from time T0 to the time T1, and the 10-kbyte still picture coded data D5 is converted into five. This is an example of repeated transmission. In this case, the still image encoded data is repeatedly transmitted seven times in 10 minutes. In other words, when still image encoded data is transmitted every about 1 minute and 25 seconds on average, a still image can be displayed in about 1 minute and 25 seconds at worst on the reproduction side. The amount of encoded data required for this is 170 k in 10 minutes.
Bytes. The data amount is 5 compared to the case of FIG.
%, The maximum value of the initial still image playback time is reduced by 57% or more.

FIG. 7C shows a case where the still picture coded data D2 is repeatedly transmitted three times and the still picture coded data D1 is transmitted five times in a unit time from time T0 to time T1 according to this embodiment. is there. In this case, the still image encoded data is repeatedly transmitted eight times in 10 minutes. In other words, by transmitting the still image encoded data every 1 minute and 15 seconds on average, a still image can be displayed in the worst case for 1 minute and 15 seconds on the reproduction side. Further, the repetition frequency of the encoded still image data D2 is the same as that in FIG. The amount of encoded data required for this is 230 kbytes in 10 minutes. In this example, the encoded still image data D2 has the same frequency as that of FIG. 7A and the amount of encoded data increases by 28% in 10 minutes, but the maximum value of the initial still image reproduction time is set to the value shown in FIG. ) Is reduced by 62% or more compared to the case of).

As described above, in the present embodiment, the still picture encoded data D1 having a small code amount is repeatedly transmitted at a higher frequency than the still picture encoded data D2 having a large code amount, thereby suppressing a decrease in transmission efficiency. In addition, the initial time required for still image reproduction can be reduced.

(Second Embodiment) FIG. 2 shows a second embodiment of the present invention.
FIG. 3 is a block diagram for explaining a transmission side according to the embodiment. In the figure, the same components as those in FIG. 1 are denoted by the same reference numerals. In FIG. 2, still image data to be transmitted (for example, the image size is 704 × 480, the same as in the first embodiment,
A color format of Y, Cb, Cr and a component format of 4: 2: 0) is supplied to the still picture encoding circuit 2 and the subtracter 11 via the still picture input terminal 1.

The still picture encoding circuit 2 sub-samples the input still picture data to convert the size to 352 × 240, and encodes it by MPEG-1 intra-frame encoding with coarse quantization characteristics. Decoding the encoded data having the encoding characteristics is sufficient to display the outline of the still image. The encoded data D1 extracted from the still image encoding circuit 2 is supplied to the common terminal of the switch SW1-1 and is also supplied to the still image decoding circuit 10, where the encoded data D1 is decoded. After being upsampled and converted into a size of 704 × 480, it is supplied to the subtractor 11.

The subtractor 11 subtracts the output decoded data of the still picture decoding circuit 10 from the still picture data input via the input terminal 1 and outputs difference data. This difference data is supplied to the still image coding circuit 3, where the size is kept at 704 × 480, which is the size of the input difference data, and is encoded by the MPEG-2 method intra-frame coding with fine quantization characteristics. I do. The above still picture encoding circuit 2,
The still image decoding circuit 10, the subtractor 11, and the still image encoding circuit 3 perform hierarchical encoding of the input still image data.
The output still image encoded data D1 of the still image encoding circuit 2 is low-layer encoded data, and the output still image encoded data D3 of the still image encoding circuit 3 is a high layer encoded output.

The encoded data D1 extracted from the still picture encoding circuit 2 is written to the encoded data memory 4-1 via the terminal a of the switch SW1-1. Similarly,
Encoded data D3 extracted from the still image encoding circuit 3
Is written to the encoded data memory 5-1 via the terminal a of the switch SW2-1. At the same time, based on the control signal from the control circuit 12, the encoded data memory 4
-2 and the encoded data previously output from the still image encoding circuit 2 and the still image encoding circuit 3 stored in the encoded data memory 5-2 are read out, and the terminal b of SW1-2 is read out.
Is input to the multiplexing circuit 6 via the terminal b of SW2-2.

In the multiplexing circuit 6, the encoded data memory 4
-2 and the above-described respective encoded data read from the encoded data memory 5-2, to which information for identifying a still image and information for identifying an encoding characteristic type are added, and FIG.
Alternatively, as shown in FIG. 8C, the still image encoded data D1, D3
Is multiplexed at a predetermined repetition frequency, and the other coded data input via the terminal 9 is multiplexed and output to the transmission circuit 8. The transmission circuit 8 subjects the input multiplexed signal to, for example, a transmission line encoding process and a modulation process according to a transmission line to be output, and outputs the multiplexed signal to the transmission line.

On the other hand, at a predetermined transmission start time for the input still image, the control circuit 12 switches the switch SW1-
1, SW2-1, SW1-2, and SW2-2 are switched to a connection state opposite to the current connection state illustrated. As a result, the encoded data stored in the encoded data memory 4-1 and the encoded data memory 5-1 are read and multiplexed via the terminal a of SW1-2 and the terminal a of SW2-2. The signal is input to the multiplexing circuit 6, where it is multiplexed with the various kinds of identification information and other coded data at a predetermined repetition frequency described later, and then output to the transmission line via the transmission line circuit 8.

Next, the reproduction side of the second embodiment will be described. FIG. 5 is a block diagram on the reproducing side according to the second embodiment of the present invention. In the figure, the same components as those in FIG. 4 are denoted by the same reference numerals. In FIG. 5, the transmission circuit 8 of FIG.
Coded data (multiplexed data). Further, based on the transmission path selection information input via the input terminal 23, the control circuit 30 instructs the reception circuit 22 on the transmission path to be received. For example, the reception frequency of the tuner is controlled in response to the tuning information in the broadcast reception. Receiving circuit 2
2 performs demodulation processing and transmission path decoding processing corresponding to the transmission path on the input transmission data, and supplies the data to the separation circuit 25.

The separation circuit 25 outputs the still picture coded data D1 based on information for identifying which still picture coding circuit has been coded on the transmission side from the multiplexed coded data.
And D3, the encoded data D1 is supplied to the still image decoding circuit 31, and the encoded data D3 is supplied to the still image decoding circuit 32. The other encoded data is similarly separated and output to the outside via the output terminal 28. At this time, based on the information for identifying the still image added to the still image encoded data and the information for identifying the type of the encoding characteristic, the separation circuit 25 determines the encoded data as It is supplied to decoding circuits 31 and 32.

1. Immediately after the start of reception or immediately after the still image to be decoded is switched based on the identification information of the still image, the first received still image encoded data D1 is supplied to the still image decoding circuit 31. This is because it is possible to reproduce only the still image encoded data D1. 2. After the above 1, after the encoded data D3 is separated, it is supplied to the still image decoding circuit 32. Further, the encoded data D1 after the above 1 is not supplied to the still image decoding circuit 31. This is because the still image encoded data D1 has already been supplied to the still image decoding circuit 31 and decoded. 3. After D3 is supplied in the above 2, the encoded data of the same still image is not supplied to the still image decoding circuits 31 and 32 regardless of D1 and D3 based on the identification information of the still image. This is because the encoded still image data D1 and D3 have already been decoded, and there is no need to decode the same still image again.

The still picture decoding circuit 31 receives the supply of the coded data from the separation circuit 25 and decodes the coded still picture data D1. This is because the intra-frame decoding process of the MPEG-1 system is performed, and 70
After the size is converted to 4 × 480, it is supplied to the still image memory 34 via the switch SW5 and stored. On the other hand, the still image decoding circuit 32 converts the still image
G-2 method intra-frame decoding processing to obtain difference data,
The difference data is supplied to the adder 33, where it is added to the D1 decoded data read from the still image memory 34, and the obtained addition result is supplied to the still image memory 34 via the switch SW5. And memorize it. Still image memory 3
4 outputs the stored still image data to the outside via the output terminal 29.

As described above, by controlling the execution of the decoding process in accordance with the hierarchical comparison with the coded data decoded in the past, the overlap decoding process of the coded data already decoded can be performed.
In addition, it is possible to prevent decoding processing and reproduction of erroneously encoded hierarchical data. As a result, it is possible to reduce the amount of decoding processing and prevent deterioration in reproduction display quality.

Next, repetitive transmission according to the second embodiment of the present invention will be described with reference to FIG. here,
As a result of encoding certain still image data by the still image encoding circuit 2, 10-kbyte still image encoded data D1 is output,
It is assumed that encoded still image data D3 of 55 kbytes is output as a result of encoding by the still image encoding circuit 3.

FIG. 8A shows a case where only the still picture coded data D2 is repeatedly transmitted three times in the unit time from the time T0 to the time T1, which is the same as that described in FIG. 7A. For example, if the time from time T0 to time T1 is 10 minutes, still image encoded data is transmitted every 3 minutes and 20 seconds. That is, when a channel is switched in digital broadcasting or the like, a worst case is that a still image cannot be displayed for 3 minutes and 20 seconds on the reproduction side. Further, the still image encoded data D2
By repeating the above three times, 180 kbytes are transmitted in 10 minutes.

FIG. 8B shows an example in which the still picture coded data D3 is transmitted twice and the still picture coded data D1 is transmitted five times in a unit time from time T0 to time T1 according to this embodiment. is there. In this case, the still image coded data D1 is transmitted five times in 10 minutes. That is,
By transmitting the encoded still image data D1 every two minutes on average, a still image can be displayed on the reproduction side in at least two minutes. The amount of encoded data required for this is 160 kbytes in 10 minutes. Although the data amount is reduced by 12% as compared with the example of FIG. 8A, the maximum value of the initial still image reproduction time is reduced by 40%.

FIG. 8C shows a case where the still picture coded data D3 is transmitted three times and the still picture coded data D1 is transmitted five times in a unit time from time T0 to time T1 according to this embodiment. is there. In this case, the still image coded data D1 is transmitted five times in 10 minutes. In other words, by transmitting the still image encoded data D1 every two minutes on average, a still image can be displayed on the reproduction side in the worst case for two minutes. Further, the repetition frequency of the encoded still image data D3 is the same as that in FIG. The amount of encoded data required for this is 215 kbytes in 10 minutes. The still image encoded data D3 has the same frequency and the encoded data amount is increased by 19% in 10 minutes as compared with FIG. 9A, but the maximum value of the initial still image reproduction time is reduced by 40% or more. .

As described above, in this embodiment, the lower layer still image coded data D1 is repeatedly transmitted at a higher frequency than the higher layer still image coded data D3, so that a reduction in transmission efficiency is suppressed, and In addition, the initial time required for reproducing a still image can be reduced, the encoding efficiency can be improved, and the entire region of the still image can be reproduced and displayed.

(Third Embodiment) FIG. 3 shows a third embodiment of the present invention.
FIG. 3 is a block diagram for explaining a transmission side according to the embodiment. In the figure, the same components as those in FIG. 1 are denoted by the same reference numerals. In FIG. 3, the still image data to be transmitted has an image size of 1920 × 1080 and a color system of so-called YC.
bCr 4: 2: 0 component format, and this still image data is transmitted via the still image input terminal 1
It is supplied to the still image area dividing circuit 13.

The still image area dividing circuit 13 determines the size of the input still image data as shown in FIG.
A first area I having a size of 80 × 1080 and a second area I having a size of 420 × 1080 at the left end and the right end of the screen, respectively.
I and the third area III are divided into a total of three areas, and the image data of the first area I is supplied to the still image encoding circuit 14 by the second area I.
I image data to the still image encoding circuit 15 in the third region I
II image data is supplied to the still image encoding circuit 16. Generally, as still image information, the central portion of the image has a higher importance than the peripheral portion, and is sufficient for displaying an outline of a still image.

The still picture coding circuit 14, the still picture coding circuit 15, and the still picture coding circuit 16 encode the input still picture image data of each divided area by MPEG-2 intra-frame coding. . The encoded data Da obtained by the still image encoding circuit 14 is supplied to the terminal a of the switch SW1-1.
Is written to the coded data memory 17-1 via. Similarly, the coded data Db obtained by the still picture coding circuit 15 is written to the coded data memory 18-1 via the terminal a of the switch SW2-1, and obtained by the still picture coding circuit 16. The encoded data Dc is written to the encoded data memory 19-1 via the terminal a of the switch SW3-1.

The multiplexing circuit 6 includes an encoded data memory 17
-2, each of the encoded data from the encoded data memory 18-2 and the encoded data memory 19-2 is added with information for identifying a still image and information for identifying an area, and is added to FIG.
(B) or as shown in FIG.
a, Db, and Dc are each packetized and multiplexed at a predetermined repetition frequency, and other encoded data from the input terminal 9 is multiplexed. The data multiplexed by the multiplexing circuit 6 is output to the transmission path after the transmission path encoding processing and modulation processing corresponding to the output transmission path are protected by the transmission circuit.

On the other hand, when a predetermined transmission start time for the input still image comes, the control circuit 20 switches SW1-1 and SW2.
-1, SW3-1, SW1-2, SW2-2, SW3-
2 from the current connection state shown to the opposite connection state. Thereby, the encoded data memory 17-
1. The encoded data stored in the encoded data memory 18-1 and the encoded data memory 19-1 as described above are read out, and the terminal a of the switch SW1-2 and the terminal a of the switch SW2-2 are respectively read. Is supplied to the multiplexing circuit 6 via the terminal a of the switch SW3-2, where various kinds of identification information are added and multiplexed with other encoded data at a predetermined repetition frequency described later. The signal is output to the transmission line through the transmission line circuit 8.

Next, the reproduction side of the third embodiment will be described. FIG. 6 is a block diagram on the reproducing side according to the third embodiment of the present invention. In the figure, the same components as those in FIG. 4 are denoted by the same reference numerals. In FIG. 6, the transmission circuit 8 of FIG.
Coded data (multiplexed data). Further, based on the transmission path selection information input via the input terminal 23, the control circuit 36 instructs the reception circuit 22 on the transmission path to be received. For example, the reception frequency of the tuner is controlled in response to the tuning information in the broadcast reception. Receiving circuit 2
2 performs demodulation processing and transmission path decoding processing according to the transmission path on the input transmission data, and supplies the data to the separation circuit 37.

The separating circuit 37 separates the still picture coded data Da, Db, Dc based on the information for identifying which area the multiplexed coded data is coded data.
It is supplied to the still picture decoding circuit 38. The other encoded data is similarly separated and output to the outside via the output terminal 28. At this time, the separation circuit 37 supplies the encoded data based on the information for identifying the still image added to the encoded still image data and the information for identifying the area as described below.

1. Immediately after the start of reception or immediately after one still image to be decoded is switched based on the identification information of the still image, the still image encoded data Da, Db, D
supply c. 2. After the above-described step 1, the data is supplied when the encoded data of the area not yet supplied to the still image decoding circuit 38 is separated. The coded data of the area once supplied is not supplied. 3. Until you supply all areas for the same still image
Repeat step 2 above.

The still picture decoding circuit 38 receives the supply of the coded data from the separation circuit 37 and decodes the coded still picture data Da, Db, Dc. This is MPEG
-2 scheme intra-frame decoding processing. Then, the data is supplied to the still image memory 39 together with information on which area of the decoded data. The still image memory 39 stores the supplied decoded data from the still image decoding circuit 38 in the memory based on the information of which area the decoded data is. The still image memory 39 outputs the stored still image data to the outside.

As described above, by controlling the execution of the decoding process in accordance with the area comparison with the encoded data decoded in the past, it is possible to prevent the overlapping decoding process of the already decoded encoded data. As a result, the amount of decoding processing can be reduced.

Next, repetitive transmission according to the third embodiment of the present invention will be described with reference to FIG. here,
Still image coding circuit 14 shown in FIG.
As a result, the still image coded data Da of 170 kbytes is output, and the still image coded data Db of 65 kbytes is output as a result of encoding by the still image coding circuit 15.
Assume that still image encoded data Dc of 65 kbytes is output as a result of encoding by the still image encoding circuit 16.

FIG. 9A shows a still picture encoded data D of 300 kbytes as a result of encoding the input still picture without dividing the area.
Is obtained, and this still image coded data D is repeatedly transmitted four times in a unit time from time T0 to time T1. For example, if the time from time T0 to time T1 is 10 minutes, still image encoded data is transmitted every 2 minutes and 30 seconds. That is, when a channel is switched in digital broadcasting or the like, in the worst case on the reproduction side, a still image cannot be displayed for 2 minutes and 30 seconds. Still picture encoded data D
Is transmitted four times, 1200 kbytes are transmitted in 10 minutes.

FIG. 9B shows that the still picture coded data Da and the still picture coded data Db and Dc are transmitted five times in a unit time from time T0 to time T1 according to this embodiment. This is the case where each transmission is repeated twice. In this case, the still image encoded data Da, which is the most important area, that is, the center portion of the still image, is repeatedly transmitted five times in 10 minutes. That is, in this example, when the still image encoded data Da is transmitted every two minutes on average, the still image center part can be displayed in the worst case for two minutes on the reproduction side. The amount of encoded data required for this is 1 in 10 minutes.
It is 110 kbytes, which is smaller than the case of FIG. In this example, the maximum value of the initial still image playback time is reduced by 20%, although the data amount is reduced by 7% or more compared to the case of FIG. 9A.

FIG. 9 (c) shows that the still picture coded data Da and the still picture coded data Db and Dc are transmitted five times in a unit time from time T0 to time T1 according to this embodiment. This is a case where the data is repeatedly transmitted four times. In this case, the still image coded data Da, which is the central portion of the still image, is transmitted five times in 10 minutes. That is, in this example, the still image coded data Da is transmitted on average every two minutes, so that the worst case is 2 on the reproduction side.
The center part of the still image can be displayed in minutes. Further, in this example, the still image encoded data Db and the still image encoded data Dc
Is the same as that in FIG. The amount of encoded data required for this is 1370 kbytes in 10 minutes. Still picture encoded data Db and still picture encoded data Dc
Is the same frequency and the amount of encoded data is
Although it increases by 14% as compared with the case of (a), the maximum value of the initial still image reproduction time is reduced by 28% or more.

As described above, in this embodiment, the still image coded data Da in the central portion of the screen, which is a still image important area, is set at a higher frequency than the still image coded data Db and Dc in other areas. By repeating transmission, it is possible to suppress a decrease in transmission efficiency and to shorten the initial required time of still image reproduction. In addition, by using a plurality of pieces of encoded data as different pieces of encoded data in which a single still image is subjected to area division encoding, decoding processing can be performed in the order of reception and the same as displaying a still image in the entire area. Display can be started with quality.

The present invention is not limited to the above-described embodiment. For example, the number of divisions of still image data may be a plurality of values other than three. It is also possible to transmit data separately encoded by still picture encoding circuits having different decoding characteristics from each other. The input still image data may of course be in another component format.

[0064]

As described above, according to the present invention,
A plurality of still image encoded data obtained by separately encoding the same still image data with a plurality of encoding characteristics different from each other is transmitted a plurality of times per unit time, and transmitted at a different number of repetitions. Thus, the initial required time for reproducing a still image can be reduced, the decoding process can be performed in the order of reception, and the entire region of the still image can be reproduced and displayed.

Further, according to the present invention, coded data having a small code amount is repeatedly transmitted at a higher frequency, so that a reduction in transmission efficiency can be suppressed and the initial required time for still image reproduction can be reduced.

Further, according to the present invention, the received still picture coded data having the smallest code amount is first decoded and stored in the memory, and thereafter, the received still picture coded data is decoded in ascending order of code amount. In this case, all the still image encoded data are decoded only once, so that a reduction in transmission efficiency can be suppressed and the initial time required for still image reproduction can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining a transmission side according to a first embodiment of the present invention.

FIG. 2 is a block diagram for explaining a transmission side according to a second embodiment of the present invention.

FIG. 3 is a block diagram for explaining a transmission side according to a third embodiment of the present invention.

FIG. 4 is a block diagram on the reproduction side according to the first embodiment of the present invention.

FIG. 5 is a block diagram on a reproducing side according to a second embodiment of the present invention.

FIG. 6 is a block diagram on a reproducing side according to a third embodiment of the present invention.

FIG. 7 is an explanatory diagram of repetitive transmission according to the first embodiment of the present invention.

FIG. 8 is an explanatory diagram of repeated transmission according to the second embodiment of the present invention.

FIG. 9 is an explanatory diagram of repetitive transmission according to a third embodiment of the present invention.

FIG. 10 is a diagram in which still image data is divided into three regions by a still image region dividing circuit.

[Explanation of symbols]

1 Still picture data input terminal 2, 3, 14, 15, 16 Still picture coding circuit 4-1, 4-2, 5-1, 5-2, 17-1, 17-
2, 18-1, 18-2, 19-1, 19-2 Encoded data memory 6 Multiplex circuit 7, 12, 20, 24, 30, 36 Control circuit 8 Transmission circuit 9 Other encoded data input terminal 10 Stationary Picture decoding circuit 11 Subtractor 13 Still picture area dividing circuit 21 Transmission data input terminal 22 Receiving circuit 23 Transmission path selection information input terminal 25, 37 Separation circuit 26, 31, 32, 38 Still picture decoding circuit 27, 34, 39 Still image memory 29 Reproduction still image data output terminal SW1-1, SW1-2, SW2-1, SW2-2, S
W3-1, SW3-2, SW5 switch

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 7/081 9A001 F term (Reference) 5C059 KK13 MA00 MA04 MA33 RB01 RB17 RC12 RD03 SS02 TA06 TA14 TA17 TB04 TC24 TD13 UA02 UA05 UA35 5C063 AA01 AB03 AB07 AB11 AC02 CA36 DA07 5C078 AA09 BA12 BA21 CA02 CA14 CA31 DA01 DB07 EA00 5K014 AA01 DA05 FA15 HA00 HA05 HA10 5K028 AA11 EE04 KK03 MM08 9A001 BB04 CC02 EE04 HH27

Claims (8)

[Claims] 1. A plurality of still image encoded data obtained by separately encoding the same still image data with a plurality of mutually different encoding characteristics are repeated a plurality of times per unit time and different from each other. A still image transmission method characterized in that the image is transmitted by the number of times. 2. Decoding first still image encoded data obtained by encoding input still image data according to a first encoding characteristic, and decoding the decoded still image data and the input still image data. A second data obtained by encoding the difference data with a second encoding characteristic whose quantization characteristic is finer than the first encoding characteristic.
And transmitting the encoded still image data together with the first still image data a plurality of times per unit time and at different repetition times. 3. The still image encoded data, wherein the number of repetitions per unit time of the plurality of still image encoded data is set to a larger value as the still image encoded data having a smaller code amount. Or the still image transmission method according to 2. 4. A plurality of encoded data obtained by separately encoding still image data in each divided region obtained by dividing the same still image data into a plurality of regions, respectively, a plurality of times per unit time, and A still image transmission method, wherein the transmission is performed with a different number of repetitions. 5. A plurality of encoded data for a still image in the plurality of divided areas, wherein the number of repetitions per unit time is set such that the most encoded data in the most important divided area in the still image is set. The still image transmission method according to claim 4, wherein: 6. A plurality of still image encoded data obtained by separately encoding one or more data related to the same still image by a plurality of encoding characteristics different from each other, each having a plurality of encoded data per unit time. Times, and a data string transmitted at a different number of repetitions is input via a transmission path, and immediately after an input data string is input from the transmission path or immediately after a still image in the input data string is switched. Of the plurality of still image encoded data, the first received still image encoded data is decoded and stored in the memory, and thereafter, the received still image encoded data has different encoding characteristics, and
A still image reproducing method, characterized in that encoded still image data having a larger code amount is sequentially decoded and stored in the memory, and the decoded data stored in the memory is output as a reproduced signal. 7. Decoding first still image encoded data obtained by encoding input still image data according to a first encoding characteristic, and combining the decoded still image data with the input still image data. A second data obtained by encoding the difference data with a second encoding characteristic whose quantization characteristic is finer than the first encoding characteristic.
Are transmitted a plurality of times per unit time together with the first still image data, and a data sequence transmitted at a different repetition number is input via a transmission path, and the input from the transmission path Immediately after the data sequence is input or immediately after the still image in the input data sequence is switched, the first still image encoded data is first set to the same size as the second still image encoded data. Decoding with size conversion is performed only once and stored in memory so that
Thereafter, the second still image encoded data is decoded only once to obtain the difference data, and the difference data is added to the size-converted decoded data from the memory, and then stored in the memory. And outputting the data stored in the memory as a reproduction signal. 8. A plurality of encoded data obtained by separately encoding still image data in each divided region obtained by dividing the same still image data into a plurality of regions, each of which is a plurality of times per unit time, and Data streams transmitted at different repetition times are input via a transmission path, and immediately after an input data row is input from the transmission path or immediately after a still image in the input data row is switched, the plurality of data streams are transmitted. Decoding the first received coded data of the coded data and storing it in the memory, thereafter decoding and storing the coded data of the undecoded area sequentially in the memory each time the received coded data is received. A still image reproducing method comprising outputting decoded data as a reproduction signal.