JP2885226B2 - Image signal encoding apparatus and image signal encoding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image coding technique, and more particularly to a technique for compensating for a phase jump in an input image signal.

[0002]

2. Description of the Related Art Since an image signal has a large amount of data, it is generally transmitted after performing high-efficiency encoding. A data stream that has been encoded with high efficiency is called a video stream. When a video stream is generated, processing is generally performed to prevent the phase of an input image signal from becoming discontinuous.
Conventionally, as such processing, even if the phase of the input image signal is discontinuous, the phase of the image signal input to the high-efficiency encoding unit is always continuous.

FIG. 6 is a block diagram showing a schematic configuration of a conventional image signal encoding apparatus of this kind. 6 detects the input frame phase signal q included in the input image signal p. Further, the reference phase generation unit 102 generates a reference frame phase signal r serving as a reference for determining whether or not the phase of the input image signal p is continuous. The input frame phase signal q output from the phase detection unit 101 is
It is used to initialize the write address of the FO 103, and the reference frame phase signal r output from the reference phase generator 102 is used to initialize the read address of the FIFO 103.

FIG. 7 shows a reference phase generator 102 shown in FIG.
FIG. 3 is a block diagram showing a detailed configuration of the embodiment. Counter 1 shown
Reference numeral 11 denotes a self-propelled counter that is reset to an initial value when the count value u matches the threshold value Th2. Further, the comparison unit 112 calculates the count value u of the counter 111 and the threshold value Th2.
And the reference frame phase signal r
Generate

[0005] The conventional image signal encoding apparatus shown in FIG.
By adjusting the delay time in the FIFO 103, a phase jump of the input image signal p is compensated. That is, a signal s obtained by delaying the input image signal p by a time corresponding to the phase difference in which the phase jump has occurred is output from the FIFO 103, and the encoding section 104 performs high-efficiency encoding based on the signal s. Therefore, even if a phase jump occurs in the input image signal p, the image signal s input to the encoding unit 104 always has a continuous phase.

FIG. 8 is a timing chart showing the operation timing of the image signal encoding apparatus shown in FIG. FIG. 8 shows an example in which a phase jump has occurred in the input frame # 2.
When the phase jump occurs, the signal is delayed by a predetermined time τ in the FIFO 103 to perform the phase compensation. This allows
The image signal s input to the encoding unit 104 has a continuous phase, and the output stream t output from the encoding unit 104 maintains the phase continuity.

[0007]

By the way, in order to obtain a reproduced image from a video stream obtained by encoding an image signal with high efficiency, it is necessary to perform a decoding process. Since decoding requires complicated processing such as inter-frame prediction, there is a possibility that a decoded image may be greatly disturbed even when a simple bit error occurs in a video stream. Therefore, when the phase of the input image signal is discontinuous, if encoding is performed without taking measures against the discontinuity, the video stream will also be discontinuous and normal decoding cannot be performed, and as a result, the decoding process will fail. Will be.

In order to prevent this, conventionally, as shown in FIG. 6, as a pre-process for performing high-efficiency encoding, an input image signal is input to a FIFO 103 to deal with a phase difference having caused a phase jump. The image signal was delayed by the time.

However, since the image signal has a vast amount of information, a large-capacity frame memory is required to delay the image signal. In addition, as the image signal is delayed in the FIFO 103, the time required for encoding is additionally required. As described above, the conventional phase compensation method has problems in terms of cost and processing speed.

The present invention has been made in view of such a problem, and an object of the present invention is to reduce the phase jump without delaying the image signal with a FIFO or the like even if the phase jump occurs in the input image signal. An object of the present invention is to provide an image signal encoding device capable of compensating.

[0011]

In order to solve the above-mentioned problems, the present invention is directed to an image signal encoding apparatus comprising an encoding means for generating an encoded stream obtained by encoding an input image signal with high efficiency. In the device, a phase jump detecting means for detecting whether or not the input image signal has caused a phase jump, and when the phase jump is detected by the phase jump detecting means,
Compensation stream generation means for generating a compensation stream according to the timing at which the phase jump has occurred, and stream selection means for selecting and outputting any of the encoded stream or the compensation stream, the stream selection means, When a phase jump is detected by the phase jump detecting means, the compensation stream is selected and output within a vertical blanking period immediately after the detection. Claim 2
In the image signal encoding apparatus according to claim 1, in the image signal encoding apparatus according to claim 1, the stream selection unit outputs the encoded stream after the phase jump, after the end of the vertical blanking period that outputs the compensation stream. . According to a third aspect of the present invention, in the image signal encoding apparatus according to the first or second aspect, the image signal encoding apparatus further includes a reference phase generation unit that generates a reference frame phase signal indicating a reference phase of the input image signal.
The phase jump detection means detects a phase jump of the input image signal based on the reference frame phase signal. According to a fourth aspect of the present invention, in the image signal encoding apparatus according to the third aspect, there is provided a phase detecting unit for detecting an input frame phase signal included in the input image signal, wherein the phase jump detecting unit is configured to detect the input frame phase. The phase of the input image signal is detected by comparing the phase of the signal with the reference frame phase signal. The reference phase generating means of claim 5 is:
5. The image signal encoding apparatus according to claim 4, wherein the reference frame phase is calculated based on a counter for counting the input image signal on a pixel-by-pixel basis and a comparison result between the count value of the counter and a predetermined threshold value. Comparing means for outputting a signal;
Initial value setting means for loading the counter with a predetermined initial value based on the input frame phase signal and the reference frame phase signal. According to a sixth aspect of the present invention, in the image signal encoding device according to the first to fifth aspects, the compensation stream generating unit includes a plurality of ROMs each storing a different type of stream, and according to a timing at which a phase jump occurs. An optimal stream is selected from the plurality of ROMs to generate the compensation stream. 8. The image signal encoding apparatus according to claim 6, wherein the compensation stream generation unit according to claim 7, wherein the first ROM stores a picture start stream, the second ROM stores a slice start stream, and a macro block. A third ROM for storing a start stream, a fourth ROM for storing a slice end stream, a fifth ROM for storing a picture end stream, and a sixth ROM for storing a stuffing stream. In the image signal encoding apparatus according to the present invention, when a phase jump is detected at the start of a frame, the compensation stream generating means is stored in the first to sixth ROMs. Each stream is sequentially selected to generate the compensation stream, and when a phase jump is detected at the beginning of a slice, the streams stored in the second to sixth ROMs are sequentially selected to generate the compensation stream. Generate. According to a ninth aspect of the present invention, in the image signal encoding method for generating and outputting an encoded stream obtained by encoding an input image signal with high efficiency, it is detected whether or not the input image signal has a phase jump. When detected, it generates a compensation stream according to the timing at which the phase jump occurred, outputs the generated compensation stream during the vertical blanking period immediately after the phase jump, and subsequently, the encoded stream after the phase jump. Is output.

The invention of claim 1 will be described with reference to FIG. 1, for example. "Encoding means" is assigned to the encoding section 1, "phase jump detection means" is assigned to the phase comparison section 5, and "compensation stream generation means". "Corresponds to the compensation stream generating unit 2, and" stream selection means "corresponds to the selector 6.

The invention of claim 3 will be described with reference to, for example, FIG. 1. "Reference phase generation means" corresponds to the reference phase generation unit 4.

The invention of claim 4 will be described with reference to, for example, FIG. 1. “Phase detecting means” corresponds to the phase detecting unit 3.

The invention of claim 5 will be described with reference to FIG. 2, for example. "Counter" is a counter 42, "comparing means" is a comparing section 43, "initial value setting means" is an AND circuit 41, Each corresponds.

The invention of claim 6 will be described with reference to, for example, FIG. 4. "ROM" corresponds to ROMs 21-26.

The invention of claim 7 will be described with reference to FIG. 4, for example. "First ROM" is a picture start stream ROM 21, "second ROM" is a slice start stream ROM 22, and "third ROM" is "third ROM". "ROM" is the macro block stream ROM 23, "4th ROM" is the slice end stream ROM 24, "5th ROM" is the picture end stream ROM 25, and "6th RO".
"M" corresponds to the stuffing stream ROM 26, respectively.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image signal encoding apparatus according to the present invention will be specifically described with reference to the drawings. The image signal encoding device described below has the following (1),
It has the two features of (2).

(1) The phase jump of the input image is detected by comparing the phase of the input image with the internal reference phase, and when the phase jump occurs, a compensation stream for terminating the video stream is output.

(2) By outputting the video stream after the phase jump following the compensation stream, the delay of the video stream is prevented.

FIG. 1 is a block diagram of an embodiment of an image signal encoding apparatus according to the present invention. The image signal encoding device in FIG. 1 includes an encoding unit 1, a compensation stream generation unit 2, a phase detection unit 3, a reference phase generation unit 4, a phase comparison unit 5,
And a selector 6.

The encoding section 1 performs high-efficiency encoding on an input image signal p input from an input terminal IN to generate an encoded stream a. The compensation stream generation unit 2 generates a compensation stream b for terminating the video stream, as described later in detail. The phase detection unit 3 detects the phase of the input image signal p to obtain the input frame phase signal c.
Is output. The reference phase generation unit 4 generates a reference frame phase signal d indicating a reference phase of the input image signal p, as described later in detail. The phase comparing section 5 compares the phase of the input frame phase signal c with the phase of the reference frame phase signal d and outputs a phase jump detection signal e. The selector 6 selects and outputs one of the coded stream a and the compensation stream b based on the phase jump detection result by the phase comparison unit 5. The output stream f output from the selector 6
Is input to a buffer (not shown) via an output terminal OUT, and then supplied to a transmission path or the like.

FIG. 2 is a block diagram showing a detailed configuration of the reference phase generator 4 shown in FIG. AND circuit 41 in FIG.
Is the input frame phase signal c detected by the phase detector 3.
And the output of the comparison unit 43 (reference frame phase signal) d is calculated and output. Output g of AND circuit 41
Is input to the load terminal LD of the counter 42. AN
When the output g of the D circuit 41 has a predetermined logic, the counter 4
2 loads the initial value. If the output g of the AND circuit 41 is not a predetermined logic, the counter 42 outputs 1 for each input pixel.
Count up by one. The comparison unit 43 includes a counter 42
Based on a comparison result between the input pixel count value h output from and the predetermined threshold value Th1.
Generate

FIG. 3 is a diagram showing a data structure of an encoded stream a output from the encoding unit 1. The stream corresponding to the input image signal for one frame corresponds to the illustrated “picture stream”. Each picture stream is composed of a “picture start stream”, 30 “slice streams”, and a “picture end stream”. Each slice stream is composed of an underflow “stuffing stream”, a “slice start stream”, 45 “macroblock streams”, and a “slice end stream”.

FIG. 4 is a block diagram showing a detailed configuration of the compensation stream generator 2. The compensation stream generation unit 2
It is composed of six types of ROMs 21 to 26 and a selector 27. When a phase jump of the input image signal p is detected by the phase comparing section 5 shown in FIG.
An optimal stream is selected and output from the OM.

Each of the ROMs stores one type of reference stream. For example, the picture start stream ROM 21 stores the picture start stream i
Is stored in the slice start stream ROM 22, and the macro block stream k is stored in the macro block stream ROM 23. Also, a slice end stream ROM
24, a slice end stream 1 is stored, a picture end stream ROM 25 stores a picture end stream m, and a stuffing stream ROM 26.
Stores a stuffing stream n for underflow.

When a phase jump is detected, the selector 27
Differs depending on the timing at which the phase jump occurs. For example, if a phase jump occurs at the start of a frame, all six types of ROMs 21 to 26
Are sequentially selected. On the other hand, if a phase jump occurs at the beginning of a slice, the picture start stream ROM 21
The remaining ROMs 22 to 26 except for are sequentially selected.

FIG. 5 is a timing chart showing the operation timing of the image signal encoding apparatus of FIG. FIG. 5 shows an example in which a phase jump has occurred in the input frame # 2.
When the phase jump occurs, the phase jump detection signal e, which is the output of the phase comparison unit 5, goes high at time T1 in the figure. Thereby, the selector 27 in the compensation stream generation unit 2 reads out the optimal stream from any of the ROMs 21 to 26 and generates the compensation stream c. In the vertical blanking period immediately after the phase jump is detected, the selector 6 shown in FIG. 1 is switched, and the compensation stream c output from the compensation stream generator 2 is output as the output stream g.

As described above, in the present embodiment, when a phase jump occurs in the input image signal p, the compensation stream b for compensating the phase jump is output during the vertical blanking period immediately after the phase jump has occurred, and the video stream is output. Since the termination processing of the stream is performed, it is not necessary to delay the input image signal p in order to compensate for the phase jump unlike the related art, and the time required for the encoding process can be reduced.

Various reference streams constituting the video stream are stored in the ROMs 21 to 26, and when a phase jump occurs in the input image, an optimum stream for compensating the phase jump is stored in the ROM 21 to 26. Since the end processing of the video stream is performed by reading from any of them, the phase compensation can be performed by a simple processing procedure.

In the above-described embodiment, as specific contents of the high-efficiency encoding, various encoding means such as MPEG1 and MPEG2 can be applied.
It is desirable to prepare an OM suitable for each encoding means.

[0032]

As described above in detail, according to the present invention, when a phase jump occurs in an input image signal, the phase jump is compensated for during a vertical blanking period immediately after the phase jump occurs. Since the compensation stream is output, it is not necessary to delay the input image signal in order to compensate for the phase jump unlike the related art, and the time required for the encoding process can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of an image signal encoding device according to the present invention.

FIG. 2 is a block diagram showing a detailed configuration of a reference phase generator shown in FIG.

FIG. 3 is a diagram illustrating a data configuration of a coded stream output from a coding unit.

FIG. 4 is a block diagram illustrating a detailed configuration of a compensation stream generation unit.

FIG. 5 is a timing chart showing operation timings of the image signal encoding device of FIG. 1;

FIG. 6 is a block diagram illustrating a schematic configuration of a conventional image signal encoding device.

FIG. 7 is a block diagram illustrating a detailed configuration of a reference phase generation unit illustrated in FIG. 6;

8 is a timing chart showing operation timings of the image signal encoding device of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Encoding part 2 Compensation stream generation part 3 Phase detection part 4 Reference phase generation part 5 Phase comparison part 6, 27 Selector 21-26 ROM 41 AND circuit 42 Counter 43 Comparison part

Claims (9)

(57) [Claims] 1. An image signal encoding apparatus comprising an encoding means for generating an encoded stream obtained by encoding an input image signal with high efficiency, wherein a phase jump detection for detecting whether or not a phase jump has occurred in the input image signal. Means, when a phase jump is detected by the phase jump detection means, a compensation stream generation means for generating a compensation stream corresponding to the timing at which the phase jump occurred, and any one of the encoded stream or the compensation stream. Stream selecting means for selecting and outputting, when the phase jump is detected by the phase jump detecting means, the stream selecting means selects the compensation stream within a vertical blanking period immediately after the detection. An image signal encoding device for outputting. 2. The image signal encoding device according to claim 1, wherein the stream selection unit outputs the encoded stream after the phase jump, after the end of the vertical blanking period that outputs the compensation stream. An image signal encoding apparatus characterized in that: 3. The image signal encoding apparatus according to claim 1, further comprising: a reference phase generation unit configured to generate a reference frame phase signal indicating a reference phase of the input image signal; An image signal encoding device for detecting a phase jump of an input image signal based on a reference frame phase signal. 4. The image signal encoding apparatus according to claim 3, further comprising: a phase detection unit configured to detect an input frame phase signal included in the input image signal, wherein the phase jump detection unit includes a signal that is output from the input frame phase signal. An image signal encoding apparatus, wherein a phase jump of an input image signal is detected by comparing a phase with the reference frame phase signal. 5. The image signal encoding apparatus according to claim 4, wherein said reference phase generation means includes a counter for counting the input image signal in pixel units, a count value of the counter, and a predetermined threshold value. A comparison unit that outputs the reference frame phase signal based on a comparison result of: and an initial value setting that loads a predetermined initial value to the counter based on the input frame phase signal and the reference frame phase signal. And an image signal encoding device. 6. The image signal encoding apparatus according to claim 1, wherein said compensation stream generation means includes a plurality of ROMs each storing a different type of stream, and a timing at which a phase jump occurs. And selecting the optimum stream from the plurality of ROMs to generate the compensation stream. 7. The image signal encoding apparatus according to claim 6, wherein the compensation stream generating means includes: a first ROM for storing a picture start stream; a second ROM for storing a slice start stream; Third ROM for storing block start stream
An image signal encoding device comprising: a fourth ROM for storing a slice end stream; a fifth ROM for storing a picture end stream; and a sixth ROM for storing a stuffing stream. 8. The image signal encoding apparatus according to claim 7, wherein said compensation stream generation means stores the phase skip in the first to sixth ROMs when a phase jump is detected at the start of a frame. The selected streams are sequentially selected to generate the compensation stream. If a phase jump is detected at the beginning of the slice, the second
An image signal encoding apparatus for sequentially selecting each stream stored in a sixth ROM to generate the compensation stream. 9. An image signal encoding method for generating and outputting an encoded stream obtained by encoding an input image signal with high efficiency, comprising detecting whether or not a phase jump has occurred in the input image signal, and detecting the phase jump. Then, a compensation stream corresponding to the timing at which the phase jump occurred is generated, and the generated compensation stream is output during the vertical blanking period immediately after the phase jump, and subsequently, the encoded stream after the phase jump is output. A video signal encoding method.