JP2001186515A - Decoder for channel signals - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the possibility of occurrence of overflows in the decoding of 1st and 2nd channel signals. SOLUTION: The decoder has input buffers 44 and 46, that temporarily store left and right channel information sets respectively, decoding sections 52 and 54 that decode the information stored in the input buffers 44 and 46, and a decoding control section 50 that controls the decoding sections 52 and 54 to start decoding by the decoding sections 52 and 54 in response to that a data quantity stored in the input buffer 46 exceeds a prescribed upper limit, and the data quantity stored in the input buffer 44 exceeds a prescribed lower limit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an MPEG (Moving) used, for example, in a digital satellite broadcast receiver.
The present invention relates to a decoding apparatus for data encoded in accordance with an image compression encoding method such as a Picture Experts Group (2) method, and more particularly, to a method for correlating signals of a plurality of channels, such as a multi-view profile method defined in MPEG. The present invention relates to a decoding apparatus for a signal of a plurality of channels encoded using the same.

[0002]

2. Description of the Related Art A standard called a multi-view profile is defined in MPEG2. This standard defines a format capable of transmitting video signals of a plurality of channels, such as a stereo image composed of a left-eye image and a right-eye image. Here, the fact that the right eye image is considered to have a high correlation with the left eye image is used.

Referring to FIG. 4, a left channel which is a video signal for the left eye (this may be referred to as “Lch”).
Are transmitted in the order of L1, L2, and L3. For example, L1 represents an image encoded by intra-frame encoding, and L2 represents a difference between an image obtained from L1 using forward prediction and an actual image. During playback, a plurality of images are inserted between the image represented by L1 and the image represented by L2. Data below L3 transmitted after L2 is data for decoding those images. These represent the difference between the image obtained by bidirectional prediction using L1 and L2 and the actual image, respectively.

When reproducing the left channel image, first, L1
And decodes the corresponding image GL1. Next, the data of L2 is received, and the image G obtained from the image obtained by forward prediction from the image GL1 and the image
Decode L2. Further, L3 data is received, and the image GL3 is decoded from the image obtained by the bidirectional prediction using the image GL1 and the image GL2 and the L3 data. The same applies hereinafter.

[0005] On the other hand, the image of the right channel (this is sometimes referred to as "Rch") is decoded as follows.
R1 which is the first data transmitted is 1 of the right eye image.
Represents the first image, and is actually the first image G of the left channel
It represents the difference between L1 and the actual first right-eye image. Therefore, the images GL1 and R1 obtained by the processing of the left channel
Thus, the first right-eye image GR1 can be decoded. R2, which is the next data, is 2 predicted from the second image GL2 of the left channel and the first image GR1 of the right channel.
The difference between the right-eye image and the actual right-eye image is shown. Therefore, the second right-eye image GR2 can be decoded from the images GL2 and GR1 and the data R2. The same applies hereinafter.

In a stereo image or the like, it is considered that a left eye image and a right eye image have a high correlation. Therefore, generally, when the above-described method is used, the right channel is only a difference, and the data amount can be compressed.

Referring to FIG. 5, a decoding apparatus 100 for decoding a multi-channel signal according to such a multi-view profile standard is used, for example, in a satellite broadcast receiver, and has a satellite broadcast of a contracted channel. A descrambling unit 40 for descrambling the signal, and a transport stream (TS) in which a plurality of channels are multiplexed, which are output from the descrambling unit 40, are separated into a left channel, a right channel, and an audio channel (" Ach ”). A TS separation unit 42 for separating the signal into
The left channel output from the TS separation unit 42,
Lch input buffer 44, Rch input buffer 46 and audio input buffer 48 for temporarily storing right channel and audio channel data, and decode data stored in Lch decoding unit 52, Rch decoding unit 54 and audio decoding unit 56, respectively. The Lch decoding unit 52, the Rch decoding unit 54, and the audio decoding unit 56, and the data amount stored in the Lch input buffer 44 and the data amount stored in the audio input buffer 48 are monitored. Decoding unit 5
4 and a decoding control unit 110 for controlling the start of decoding by the audio decoding unit 56.

Lch decoding section 52 by decoding control section 110
The start of decoding is controlled by the following processing. Referring to FIG. 6, first, data output from TS separation section 42 is transferred to respective buffers 44, 46, and 48.
(112). Next, it is determined whether the data stored in the Lch input buffer 44 has exceeded a predetermined upper limit MAX (114). For example, this upper limit MAX is L
The capacity is set to half of the capacity of the channel input buffer 44.

If it is determined in step 114 that the amount of data stored in the Lch input buffer 44 has not reached the upper limit MAX, the control returns to step 112 to fetch the next data. If it is determined in step 114 that the amount of data stored in the Lch input buffer 44 has reached the upper limit MAX, step 11
At 6, the decoding process by the Lch decoding unit 52 and the Rch decoding unit 54 is started.

Thereafter, at step 118, the amount of data stored in the audio input buffer 48 reaches a predetermined lower limit MIN.
Is determined. The lower limit MIN is a predetermined constant.

As described above, conventionally, decoding of both the left and right channels is started only when the data amount of the left channel reaches a certain amount. This is because, as described with reference to FIG. 4, the left channel includes a signal serving as a reference for decoding the right channel image, and the right channel includes only difference data. Is unlikely to overflow, and it is considered sufficient to monitor only the data amount of the buffer of the left channel.

[0012]

However, in the above-described configuration of the conventional decoding apparatus 100, for example, when the amount of data transmitted via the right channel exceeds the amount of data transmitted via the left channel, However, there is a problem that the right channel buffer may overflow. This is particularly likely when the correlation between the right channel image and the left channel image is low. Further, when completely different images other than the stereo image are transmitted via the left channel and the right channel, the possibility that such a problem occurs is extremely high.

Such a problem is caused by a channel for transmitting a reference image, and other channels for transmitting data which is generally considered to have only a small amount of data, such as a difference from the image, based on the reference image. This can be generally applied to an apparatus for decoding a signal of a plurality of channels including a channel.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a plurality of channels including a first channel for transmitting a reference image and a second channel for transmitting data encoded based on the reference image. An object of the present invention is to reduce the possibility of occurrence of overflow in a decoding device that decodes a signal.

[0015]

According to a first aspect of the present invention, there is provided an apparatus for decoding a multi-channel signal, comprising: a first channel connected to receive encoded reference information serving as a reference for decoding; Information provided via a second channel connected to receive the encoded information, which is decoded with reference to the reference information, for the signals decoded from the first and second channels; A multi-channel signal decoding device for decoding while maintaining a predetermined temporal relationship between the first and second channels for temporarily storing information received on first and second channels, respectively. And a first and second decoding means connected to the first and second buffer devices, respectively, for decoding information held in the first and second buffer devices. Are connected to the first and second buffer devices, the amount of data held in the second buffer device exceeds a predetermined upper limit, and the amount of data held in the first buffer device is Decoding control means for controlling the first and second decoding means to start decoding by the first and second decoding means in response to exceeding the lower limit.

In this configuration, when the amount of data held in the second buffer device exceeds the upper limit and the amount of data held in the first buffer device exceeds the predetermined lower limit, Decoding is started. Therefore, unlike the related art, if the amount of data held in the first buffer device does not reach the upper limit but reaches the lower limit, decoding is performed when the amount of data held in the second buffer device exceeds the upper limit. Is started, and there is little possibility that the second buffer device overflows.

According to a second aspect of the present invention, in addition to the configuration of the first aspect of the present invention, the multi-channel signal decoding apparatus is further connected to first and second buffer devices, and further comprises a second buffer. Detecting that the amount of data held in the device exceeds the upper limit and that the amount of data held in the first buffer is less than or equal to the lower limit, clears the first and second buffer devices. Means for doing so.

Even if the amount of data held in the second buffer device exceeds the upper limit, if the amount of data held in the first buffer device including reference information is less than the lower limit, , Decoding is impossible or meaningless. Therefore, in this case, by clearing both the first and second buffer devices, it is possible to avoid overflow of the second buffer device. Even if the buffer device is cleared in this way, the amount of data of the reference information among the cleared data is small, so that the effect on the decoding result is negligible.

According to a third aspect of the present invention, in addition to the configuration of the first or second aspect of the present invention, the multi-channel signal decoding apparatus further comprises: Means for controlling the first decoding means so as to start decoding by the first decoding means in response to exceeding the predetermined upper limit value.

According to the third aspect of the present invention, when the information received from the first channel including the reference information exceeds a predetermined upper limit, decoding of the information of the channel is started. The risk of the first buffer device overflowing is small.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention in which the present invention is applied to a digital broadcast receiver will be described below with reference to the drawings. Referring to FIG. 1, a digital broadcast receiver 10 to which a decoding device according to the present invention is applied switches and outputs a stereo image signal of both left and right channels of a received digital broadcast to a television receiver 14 at a predetermined cycle, and ,
By controlling the switching between the left and right liquid crystal shutters of the glasses 16 with liquid crystal shutters worn by the user, the user can view different images with the left and right eyes to realize stereoscopic viewing. In this digital broadcasting, it is assumed that MPEG2 is adopted as a transmission method of an image signal and a multi-view profile is adopted.

Referring to FIG. 1, a digital broadcast receiver 10 is connected to an antenna 12, and selectively receives and demodulates a digital broadcast, performs error correction processing, and outputs a received signal. A decoding unit 22 for descrambling, decoding the left channel signal, the right channel signal and the audio signal multiplexed in the received signal, and a decoding device 2
Image switching unit 2 for switching the left and right channel signals output by the second unit 2 and providing the same to the television receiver 14
4, a control unit 26 for controlling various operations performed in the decoding device 22, a storage device 30 for storing data used by the control unit 26 for control, and data that needs to be held. And an image switching unit 24 controlled by the control unit 26 to synchronize the selection of a video signal by the image switching unit 24 and the switching of the liquid crystal shutter of the glasses 16 with a liquid crystal shutter in a predetermined cycle.

Referring to FIG. 2, decoding device 22 has substantially the same configuration as conventional decoding device 100 shown in FIG. 5, but Lch input buffer 44, Rch The Lch decoding unit 52 and the Rch decoding unit 54 monitor the amount of data coupled to the input buffer 46 and the audio input buffer 48 and stored in both the Lch input buffer 44 and the Rch input buffer 46.
Control the start of decoding of the audio input buffer 4
8 to monitor the amount of data stored in the audio decoding unit 5
Lch decoding unit 52 for controlling the start of decoding by
Is different from the decoding apparatus 100 in FIG.

Referring to FIG. 3, decoding device 22 has Lch decoding units 52 and R according to the following control structure.
The start of decoding by the channel decoding unit 54 and the audio decoding unit 56 is controlled. First, the Lch input buffer 44, the Rch
Input buffer 46 and audio input buffer 48
The data of the left channel, the data of the right channel, and the data of the audio channel output from the TS separation unit 42 are fetched (70).

Subsequently, it is determined whether the amount of data stored in the Lch input buffer 44 has exceeded a predetermined upper limit MAX (72). If it is determined that the amount of data stored in the Lch input buffer 44 has exceeded the upper limit MAX, the Lch decoding unit 52 starts decoding left channel data (74). Since the decoding by the Lch decoding unit 52 is started at this time, there is little danger that the Lch input buffer will overflow. Note that the upper limit value MAX is set to a value within a range that does not cause the Lch input buffer 44 to underflow or overflow due to decoding, for example, １ ／ of the capacity of the Lch input buffer 44.

Subsequently, it is determined whether the amount of data stored in the Rch input buffer 46 has exceeded a predetermined lower limit value MIN (76). The lower limit value MIN is a constant and is set to, for example, the data amount for one picture. If Rc
If it is determined that the amount of data stored in the h input buffer 46 does not exceed the predetermined lower limit value MIN, the next data is fetched into the buffer (78), and the determination in step 76 is performed again. Then, the Rch input buffer 46
When it is determined that the amount of data stored in the right channel exceeds the predetermined lower limit MIN, the right channel decoding process by the Rch decoding unit 54 is started (80).

In parallel with the control of the start of the decoding of the right channel, a process of decoding the audio signal by the audio decoding unit 56 is also performed. Step 74 described above
Thereafter, it is determined whether the amount of data stored in the audio input buffer 48 exceeds a predetermined lower limit value MIN. Here, the lower limit value MIN is equal to the lower limit value M in step 76.
What is necessary is just to set it to the data amount of audio data equivalent to IN, that is, equivalent to the reproduction time for one picture. If it is determined in step 92 that the amount of data stored in the audio input buffer 48 does not exceed the predetermined lower limit MIN, the data is further fetched into the buffer (90), and the determination in step 92 is performed again. Thus, as a result of the determination in step 92, the audio input buffer
Is determined to exceed the predetermined lower limit value MIN, the audio decoding unit 56 starts decoding audio data.

Returning to step 72, step 72
If it is determined that the data amount stored in the Lch input buffer 44 does not exceed the predetermined upper limit value MAX, conventionally, the processing corresponding to step 70 is immediately performed.
That is, the next data was taken into the buffer. However, in the decoding device 22 according to the present invention, the next data is not taken in immediately, but the data amount of the right channel is further checked.

That is, first, it is determined whether or not the amount of data stored in the Rch input buffer 46 exceeds the upper limit value MAX. The upper limit value MAX is also set at step 7
2 is set in the same manner as the upper limit value MAX. In principle, the two MAX's need not be set to the same value, but in practice they will often be set to the same value. Rch
The amount of data stored in the input buffer 46 is equal to the upper limit M
If it is determined that AX has not been exceeded, the control returns to step 70, and the next data is taken in as in the conventional case.

If it is determined in step 82 that the amount of data stored in the Rch input buffer 46 exceeds the upper limit MAX, the amount of data stored in the Lch input buffer 44 is further reduced to a predetermined lower limit. It is determined whether or not MIN is exceeded (84). The result of this determination Lc
If the amount of data stored in the h input buffer 44 does not exceed the predetermined lower limit value MIN, Lc
The data stored in the h input buffer 44, the Rch input buffer 46, and the audio input buffer 48 are all cleared once (86), and the process returns to step 70. Such processing is performed for the following reason.

If the data amount of the right channel is sufficient but the data amount of the left channel is not sufficient, it means that there is no data to be a reference. Since the right channel data is decoded based on the left channel image decoded by the left channel data,
If the data amount of the left channel is not sufficient, it is impossible or impossible to decode only the data of the right channel. Therefore, in this case, all the data is once discarded.

Since the data amount of the left channel, which is a reference, among the data to be discarded is small,
Even if the data is discarded in this way, it is considered that the adverse effect on the decoding result is not so large.

If it is determined in step 84 that the amount of data stored in the Lch input buffer 44 exceeds the predetermined lower limit MIN, both the Lch input buffer 44 and the Rch input buffer 46 perform decoding. Means that a sufficient amount of data is stored in the
The decoding process of the left channel and right channel data by the Lch decoding unit 52 and the Rch decoding unit 54 is started (88). At the same time, the decoding process for the audio data from step 92 on is also started. Since the decoding process for audio data has already been described, the details thereof will not be repeated here.

As described above, the decoding device 2 of this embodiment
According to 2, when the amount of data stored in the Lch input buffer 44 exceeds a predetermined amount, and when the amount of data stored in the Rch input buffer 46 exceeds a predetermined upper limit and the Lch input When it is determined that the data amount stored in the buffer 44 exceeds the predetermined lower limit, decoding of the data of both the left and right channels is started. Therefore, when the amount of data stored in the Lch input buffer 44 is small and the amount of data stored in the Rch input buffer 46 is large, decoding is started unlike the related art. Therefore, when the data amount of the right channel is large, the possibility that the Rch input buffer 46 overflows is far less than that of the related art.

Further, in this embodiment, when starting decoding, it is always confirmed that the minimum data is stored in both buffers, and decoding is not started when the upper limit is not satisfied. For this reason, the buffer is less likely to underflow.

As described above, the present invention has been described based on one embodiment. However, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims. It is. For example, in the above example, there were two channels. However, the invention can be applied to any application in which images are generally transmitted separately on multiple channels and are intended to be played back simultaneously. In the above-described embodiment, MPEG is used for image transmission.
However, the present invention is not only applicable to MPEG, and one channel for transmitting information including reference information and another channel for transmitting information decoded with reference to the reference information. The present invention can be applied to any use.

The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a digital broadcast receiver according to the present invention.

FIG. 2 is a block diagram illustrating a configuration of a conventional digital broadcast receiver.

FIG. 3 is a flowchart illustrating a decoding process of the digital broadcast receiver.

FIG. 4 is a diagram illustrating a decoding process of a stereo image.

FIG. 5 is a block diagram of a conventional multi-channel signal decoding device.

FIG. 6 is a flowchart of a process performed by a signal control unit of a conventional multi-channel signal decoding device.

[Explanation of symbols]

10 digital broadcast receiver, 20 receiver, 22,
100 decoding device, 26 control unit, 30 storage device,
42 TS separation unit, 44 Lch input buffer, 46
Rch input buffer, 48 audio input buffer,
50, 110 decoding control unit, 52 Lch decoding unit, 54
Rch decoding unit, 56 audio decoding unit.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C059 KK35 MA00 PP04 PP13 SS02 TA00 TB01 TC15 TD12 UA05 UA38 5J064 AA00 BA01 BB01 BC01 BC02 BC14 BC22 BC25 BC27 BD02 5K047 AA03 AA11 BB01 DD02 HH01 JJ00

Claims (3)

[Claims] 1. A first channel connected to receive encoded reference information serving as a reference for decoding, and a first channel connected to receive encoded information decoded with reference to the reference information. Multi-channel signal for decoding information provided via a second channel to be decoded while maintaining a predetermined temporal relationship between the signals decoded from the first channel and the second channel A first and second buffer device for temporarily holding information received on the first and second channels, respectively; and a first and a second buffer device, respectively. Connected first and second decoding means for decoding information held in the first and second buffer devices, and connected to the first and second buffer devices; In response to the amount of data held in the second buffer device exceeding a predetermined upper limit and the amount of data held in the first buffer device exceeding a predetermined lower limit, A decoding control means for controlling the first and second decoding means so as to start decoding by the first and second decoding means. 2. The method according to claim 1, further comprising the steps of: connecting the first buffer device to the first buffer device, the data amount stored in the second buffer device exceeding the upper limit, and being stored in the first buffer device; 2. The multi-channel signal decoding device according to claim 1, further comprising: a unit configured to detect that the amount of data stored is equal to or less than the lower limit value and clear the first and second buffer devices. 3. 3. The method according to claim 1, wherein the first decoding unit starts decoding in response to an amount of data held in the first buffer device exceeding a predetermined upper limit. 3. The multi-channel signal decoding device according to claim 1, further comprising a unit for controlling a decoding unit.