JP2000350199A - Video encoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a video encoder that can apply high efficiency coding processing to a video signal in a shorter processing delay time without causing missing-frame of a reproduced video image at a receiver side. SOLUTION: A timing control section 104 outputs a data read start signal (RS) to a data read section 105 in timing at a point of time when a data storage section 102 stores data by a predetermined initial storage amount based on a coding start signal (SS) and data storage amount information (FD). Thus, the data storage amount in the data storage section 102 is not zero but has a finite offset in excess of zero at all times. Simultaneously since a video coding section 101 receives a feedback input of the data storage amount information (FD) and conducts coding processing at a constant average bit rate, the data storage section 102 always stores video coded data (ED) by a required minimum data storage amount. The high efficiency coding can be applied to the video signal in a shorter processing delay time without causing missing-frame of a reproduced video image at a receiver side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video coding apparatus, and more particularly to a video coding apparatus for compressing a video signal by a high-efficiency coding process (with a low delay) within a shorter processing delay time. Related to the device.

[0002]

2. Description of the Related Art In recent years, as a device for converting video information into digital data having a smaller required band, use of a video encoding device for multimedia or the like in a communication medium, a storage medium, or a fusion thereof has been actively performed. Are being considered. Hereinafter, the configuration of this conventional video encoding device will be described.

FIG. 7 is a block diagram showing a configuration of a conventional video encoding device. In FIG. 7, a conventional video encoding device includes a video encoding unit 701 and a data storage unit 702.
, A data storage amount measuring unit 703, and a data reading unit 7
05.

A video encoding unit 701 converts an input video signal (VS) based on data accumulation amount information (FD) (representing the amount of data output by itself) fed back from the data accumulation amount measurement unit 703. , And compresses the data at an average bit rate by an encoding process, and outputs it as encoded video data (ED). The data storage unit 702 is composed of a buffer memory or the like, stores video encoded data (ED) output from the video encoding unit 701, and uses the storage amount as transfer count data (CD) as a data storage amount measurement unit 703. Output to The data storage amount measurement unit 703 measures the data storage amount of the video encoded data (ED) stored in the data storage unit 702 using the transfer count data (CD), and stores the data storage amount information (FD). To the video encoding unit 70
Output to 1. On the other hand, when the measured data storage amount of the data storage unit 702 becomes zero (when the data amount read by the data reading unit 705 exceeds the data storage amount), the data storage unit A frame drop command signal (SKP) is output to 705. The data reading unit 705 is a video encoding unit 70
As soon as 1 starts storing video encoded data (ED) in the data storage unit 702, the stored video encoded data (ED) is read from the data storage unit 702 and output as a video encoded stream (ES). . In this reading process, the data reading unit 705 outputs the frame drop command signal (S
KP), the video encoding data (ED) for one or more screens is discarded, thereby reducing the accumulation time consumed in the data storage unit 702 and processing time required for video encoding. , And even if the data storage amount of the data storage unit 702 becomes zero, the frames of the video to be encoded are dropped and the video encoding process is forcibly continued.

FIG. 8 is a diagram showing an example of data transfer timing in the data storage unit 702 for explaining the operation of the conventional video encoding device of FIG. The data storage amount (BF) shown in FIG. 8 is a time series representation of the data storage amount in the data storage unit 702.

[0006]

However, as described above, in the conventional video coding apparatus, the video coding unit 701 stores the video coded data (E) in the data storage unit 702.
When the storage of D) is started, the data reading unit 705 immediately starts the data storage unit 70 in order to reduce the processing delay time.
2 to read out the video coded data (ED) and output it to the outside of the device. For this reason, in the above-described conventional video encoding device, as a response to the case where the data storage amount of the data storage unit 702 becomes zero, the data reading unit 705 outputs the frame drop command signal (output by the data storage amount measurement unit 703). S
In accordance with the signal of KP), the processing of discarding the video coded data (ED) for one or more screens is performed.
However, if the processing of discarding the video encoded data (ED) for one or more screens is performed, the reproduced video on the receiving side is not continuous, and some frames are dropped and the reproduced video is discontinuous. There was a problem of becoming.

In the conventional video coding apparatus, the data storage amount measuring unit 703 reduces the data storage amount of the video coded data (ED) in the data storage unit 702 to less than one video. Since the data accumulation amount information (FD) is calculated based on the data accumulation amount information (FD), the data accumulation amount information (FD) does not provide an appropriate clue for the average bit rate calculation in the video encoding unit 701, and is always lower. It has to be coded at the bit rate. For this reason, there is a problem that the image quality of the reproduced video on the receiving side is deteriorated.

Further, in the above-mentioned conventional video encoding device,
Since the only purpose is to reduce the processing delay time required for video encoding, the image quality mode is sequentially changed according to the content of the video program, such as a high quality mode and a low delay mode (normal quality mode) for each video program. There was also a problem that it could not be selected.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a high-efficiency encoding process for a video signal within a shorter processing delay time without dropping frames in the reproduced video on the receiving side without realizing image quality degradation. To provide a video encoding device capable of performing such operations. Further, another object of the present invention is to provide a video encoding device capable of selecting and operating an image quality mode such as a high image quality mode and a low delay mode for each video program according to the content of the video program. Is what you do.

[0010]

A first aspect of the present invention is a video encoding apparatus for compressing data of a video signal by an encoding process. Based on the data storage amount information corresponding to the code amount, the input video signal is output at a constant average bit rate, and video encoded data is output, and the video signal is encoded at the first output timing of the video encoded data. A video encoding means for outputting a start signal, a data storage means for temporarily storing video encoded data, and a storage amount of the video encoded data stored in the data storage means for measuring data storage amount information. The data storage amount measuring means and the video coding means, which output the first video coded data in the data storage means, reach a predetermined initial storage amount from That is, based on the encoding start signal and the data storage amount information, the timing control means for outputting the result of the detection as a data read start signal, and the data stored from the data storage means according to the signal of the data read start signal. Data reading means for reading and outputting encoded video data.

As described above, according to the first aspect, the process of reading data from the data storage means is started after the amount of video encoded data stored in the data storage means reaches a predetermined initial storage amount. I do. Therefore, by previously operating the initial accumulation amount, the processing delay time consumed by the data storage unit can be operated to an arbitrary length. That is, it is possible to set a shorter processing delay time while considering two conflicting parameters, that is, the relationship between the reproduction image quality and the processing delay time on the receiving side. Also, since the output data rate is controlled by the data accumulation amount information fed back to the video encoding means, even if an arbitrary initial accumulation amount is selected, the data storage means does not cause a failure such as underflow or overflow. The video signal can be highly efficiently coded within a shorter processing delay time without dropping the frame of the reproduced video.

[0012] A second invention is an invention according to the first invention, wherein the video encoding means obtains information on the initial storage amount from the timing control means, and stores a part of the data in the encoded video data. It is characterized in that information relating to the initial accumulation amount is embedded in a field and output.

As described above, according to the second aspect, the first aspect
In the video encoding process, information on a predetermined initial storage amount is embedded in the video encoded data and transmitted to the receiving side. Thereby, on the receiving side, the operating point of the same received data storage means as the transmitting side, that is,
The initial storage amount in the reception data storage unit at the start of reception can be specified, and as a result, the processing delay time in the reception data storage unit can be minimized while securing the amount of video encoded data necessary for maintaining the reproduction image quality. It is possible to keep it to the limit. Therefore, the video signal can be efficiently encoded and reproduced / decoded within a shorter processing delay time without deteriorating the reproduction image quality in the receiver.

[0014] A third invention is an invention according to the second invention, further comprising a program operating means for outputting information on an initial storage amount relating to a running video program, and wherein the timing control means comprises: It is characterized in that the initial accumulation amount can be obtained.

As described above, according to the third aspect, the second aspect
In the present invention, the information on the initial storage amount predetermined in the timing control means can be transmitted from the program operation means, so that external control of the processing delay time can be performed.

A fourth invention is an invention according to the third invention, wherein the program operating means changes and outputs an initial storage amount for each video program.

As described above, according to the fourth aspect, the third aspect
In the present invention, external control of the processing delay time can be performed for each video program. This makes it possible to select and operate an image quality mode such as a high image quality mode and a low delay mode (normal image quality mode) for each image program according to the content of the image program.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 is a block diagram showing a configuration of a video encoding device according to a first embodiment of the present invention. 1, the video encoding device according to the first embodiment includes a video encoding unit 101, a data storage unit 102, a data storage amount measurement unit 103, a timing control unit 104, and a data read unit 105. Prepare.

The video encoding unit 101 performs data compression on the input video signal (VS) by a high-efficiency encoding process, and outputs it to the data storage unit 102 as encoded video data (ED). Here, the video encoding unit 101 receives, as feedback, data accumulation amount information (FD) representing the amount of data output by the video encoding unit 101 from the data accumulation amount measuring unit 103 so that the output data rate becomes a constant average bit rate. To control. More specifically, the video encoding unit 101 uses an MPEG (Moving P
and an encoder that satisfies the video coding method as defined in the ITU-T H Recommendation such as the Picture Experts Group. Further, the video encoding unit 101 outputs an encoding start signal (SS) to the timing control unit 104 at the timing of outputting the first encoded video data (ED). The data storage unit 102 is, for example, a FIFO memory that outputs the video encoded data (ED) output from the video encoding unit 101 as write data, and outputs read video encoded data (RD) as read data. Data storage unit 10
2 counts the number of transfers of the write data and the read data, and uses the count results as transfer count data (CD) as a data accumulation amount measuring unit 10.
Output to 3.

The data storage amount measurement unit 103 receives the transfer count data (CD) output from the data storage unit 102 and calculates the difference between the data amount written in the data storage unit 102 and the read data amount. The calculated value is output to the video encoding unit 101 and the timing control unit 104 as data accumulation amount information (FD). Timing control unit 104
Is an encoding start signal (S
S) and the data storage amount information (FD) output by the data storage amount measurement unit 103, and the initial storage amount determined in advance after the first video encoded data (ED) is started to be stored in the data storage unit 102. n is detected. That is, the timing control unit 104 outputs the encoding start signal (S
The detection is started at the signal of S), and the data storage amount information (F
As soon as D) reaches the initial accumulation amount n, a data read start signal (RS) is output to the data read unit 105. The data reading unit 105 includes the timing control unit 1
The data read start signal (RS) output from the data read unit 04 is input, and the read video encoded data (RD) is read from the data storage unit 102 according to the signal of the data read start signal (RS), and a series of video encoded streams (RS) is read. ES) and output it.

FIG. 2 is a diagram showing an example of data transfer timing in the data storage unit 102 for explaining the operation of the video encoding device of FIG. Note that the data accumulation amount (BF) shown in FIG. 2A represents the data accumulation amount in the data storage unit 102 in a time series. FIG.
In the above description, an example in which the logical level “0” of each signal corresponds to a low level and the logical level “1” corresponds to a high level is described, but the logical relationship may be reversed.
That is, the video encoding device according to the first embodiment may be configured to operate with negative logic. Hereinafter, FIG.
The operation of the video encoding device according to the first embodiment will be described with reference to FIG.

The video coding unit 101 performs high-efficiency coding on an input video signal (VS), and generates video coded data (E).
The data is accumulated in the data storage unit 102 as D). Also,
The video encoding unit 101 starts the encoding start signal (SS) of the logical level “1” at the same time as the start of the high-efficiency encoding process (FIG. 2).
(B)) is output (point A in FIG. 2). At this point, since the data is not yet read from the data storage unit 102, the data accumulation amount (BF) increases linearly (period B in FIG. 2). The data storage amount measurement unit 103 always uses the transfer count data (CD) to store the data in the data storage unit 1.
The data accumulation amount (BF) in the data 02 is measured, and the measurement result is output as data accumulation amount information (FD) (FIG. 2C). On the other hand, the timing control unit 104 starts monitoring the data storage amount information (FD) when the encoding start signal (SS) becomes the logical level “1”. Then, the timing control unit 104 stores the data accumulation amount information (F
Upon detecting that D) has reached the predetermined initial storage amount n, it immediately outputs a data read start signal (RS) (FIG. 2 (d)) of logic level "1" (point C in FIG. 2). The data read unit 105 outputs a data read start signal (R
When the logic level of S) becomes "1", the data storage unit 10
2, the read video coded data (RD) is read and output as a series of video coded streams (ES), so that the data storage amount (BF) starts to decrease. Therefore, the data storage amount information (FD) also decreases, reflecting the decrease.

The video encoding unit 101 feeds back the data storage amount information (FD) as described above to control the output data rate to be a constant average bit rate. The data storage unit 102 does not cause underflow or overflow while taking into account the increase and decrease of the time-series data accumulation amount (BF).
Thereafter, the output data rate is controlled (D period in FIG. 2). For this reason, the data storage amount (BF) in the data storage unit 102
Will always have a finite offset value greater than zero. In other words, the encoded data (ED) of the minimum necessary data storage amount (BF) is always stored in the data storage unit 102.

As described above, according to the video encoding apparatus according to the first embodiment of the present invention, the data storage amount (BF) in the data storage unit 102 is set to the predetermined initial storage amount n.
, The process of reading data from the data storage unit 102 is started. Therefore, by previously operating the initial accumulation amount n, the processing delay time consumed in the data storage unit 102 can be adjusted to an arbitrary length. That is, it is possible to set a shorter processing delay time while considering two conflicting parameters, that is, the relationship between the reproduction image quality and the processing delay time on the receiving side. In addition, since the output data rate is controlled by the data accumulation amount information (FD) fed back to the video encoding unit 101, even if an arbitrary initial accumulation amount n is selected, the data storage unit 102 does not break down such as underflow or overflow. Since it does not occur, the video signal can be efficiently encoded within a shorter processing delay time without dropping the frame of the reproduced video on the receiving side.

(Second Embodiment) FIG. 3 shows a second embodiment of the present invention.
It is a block diagram showing the composition of the picture coding device concerning an embodiment. In FIG. 3, the video encoding device according to the second embodiment includes a video encoding unit 301 and a data storage unit 10.
2, a data storage amount measuring unit 103, a timing control unit 304, and a data reading unit 105.

As shown in FIG. 3, the video encoding device according to the second embodiment includes a video encoding unit 101 of the video encoding device according to the first embodiment,
This is a configuration in which the timing control unit 104 is replaced with a timing control unit 304. Since other configurations of the video encoding device according to the second embodiment are the same as those of the video encoding device according to the first embodiment, the other components are denoted by the same reference numerals. And the description is omitted.

Prior to the video encoding process, the timing control unit 304 first supplies a predetermined initial storage amount n to the video encoding unit 301 as initial storage amount information (PD). Next, similarly to the timing control unit 104, the timing control unit 304 includes an encoding start signal (SS) output from the video encoding unit 301 and data accumulation amount information (FD) output from the data accumulation amount measurement unit 103. ) Is detected, and it is detected that a predetermined initial storage amount n has been reached since the start of storing the first video coded data (ED) in the data storage unit 102. That is, the timing control unit 304 starts the above detection at the signal of the encoding start signal (SS), and immediately after the data storage amount information (FD) reaches the initial storage amount n, the data read start signal (RS) To the data reading unit 10
Output to 5

The video encoder 301 compresses the input video signal (VS) by a high-efficiency encoding process in the same manner as the video encoder 101, and encodes the video encoded data (E).
D) to the data storage unit 102. At this time, the video encoding unit 301 embeds the initial accumulation amount information (PD) provided from the timing control unit 304 in a part of the data field in the encoded video data (ED) and outputs the data. Then, similarly to the video encoding unit 101, the video encoding unit 301 feedback-inputs the data accumulation amount information (FD) indicating the amount of data output by itself from the data accumulation amount measurement unit 103, and outputs the output data rate. Is controlled to have a constant average bit rate. Further, the video encoding unit 30
1 outputs an encoding start signal (SS) to the timing control unit 304 at the timing of outputting the first encoded video data (ED).

FIG. 4 shows that the video encoding unit 301 shown in FIG.
1 shows an example of a data format of video encoded data (ED) in which is embedded. 4, the coded video data (ED) includes a header 401, initial storage amount information 402, control information 403, and a coded video data payload 404. The header 401 is provided at the head of the coded video data (ED), and is provided for the purpose of the receiver recognizing the head of the data string and acquiring the data fetch timing. The initial storage amount information 402 is stored in the video encoding unit 3
01 is a portion in which the initial accumulation amount information (PD) is embedded. The control information 403 is an information field including parameters necessary for decoding the video encoded data payload 404. Video encoded data payload 4
04 is the main body of the encoded video.

As described above, in the video encoding device according to the second embodiment (that is, on the transmission side), the initial storage amount information 40
By embedding 2 in the video coded data (ED) in advance, the receiving side can perform the following processing. The receiving side detects the header 401 of the video coded data (ED), acquires the data fetch timing, and acquires the initial storage amount information 402 following the header 401. And the receiving side, like the transmitting side described above,
The video encoded data (ED) is stored in the own received data storage unit until the initial storage amount n defined by the value of the initial storage amount information 402 is reached. The video coded data (ED) is read to start the decoding process.

As described above, according to the video encoding device according to the second embodiment of the present invention, in addition to the processing of the first embodiment, a predetermined initial The storage amount information (PD) is embedded in the encoded video data (ED) and transmitted to the receiving side. This allows the receiving side to define the same operating point of the received data storage unit as the transmitting side, that is, the initial storage amount n in the received data storage unit at the start of reception, and as a result, to maintain reproduction image quality It is possible to minimize the processing delay time in the received data storage unit while securing the required video encoded data amount. Therefore, the video signal can be efficiently encoded and reproduced / decoded within a shorter processing delay time without deteriorating the reproduction image quality in the receiver.

(Third Embodiment) FIG. 5 shows a third embodiment of the present invention.
It is a block diagram showing the composition of the picture coding device concerning an embodiment. In FIG. 5, the video encoding device according to the third embodiment includes a video encoding unit 301 and a data storage unit 10.
2, the data storage amount measuring unit 103, the timing control unit 504, the data reading unit 105, and the program operating unit 50.
6 is provided.

As shown in FIG. 5, the video encoding device according to the third embodiment includes a timing control unit 304 of the video encoding device according to the second embodiment.
In this configuration, a program operation unit 506 is further added in place of the program operation unit 504. Since other configurations of the video encoding device according to the third embodiment are the same as those of the video encoding devices according to the first and second embodiments, the same reference numerals are used for the other components. Numbers are assigned and explanations are omitted.

Prior to the video encoding process, the program operating unit 506 specifies a designated storage amount information (SD) (that is, information on the initial storage amount n) for defining a processing delay time for the running video program, and the timing control unit. 504 is output in advance. The timing control unit 504 receives the designated storage amount information (SD) output from the program operation unit 506, and initializes the video encoded data (ED) in the data storage unit 102 based on the designated storage amount information (SD). The storage amount n is defined.

As described above, according to the video encoding apparatus according to the third embodiment of the present invention, in addition to the processing in the second embodiment, the designated storage amount information ( SD), the initial accumulation amount n (initial accumulation amount information (PD)) predetermined in the timing control unit 504.
To determine. Therefore, by transmitting information about the initial storage amount n from the program operating unit 506, external control of the processing delay time for the video encoding device can be realized.

(Fourth Embodiment) FIG. 6 shows a fourth embodiment of the present invention.
It is a block diagram showing the composition of the picture coding device concerning an embodiment. In FIG. 6, a video encoding device according to the fourth embodiment includes a video encoding unit 301 and a data storage unit 10.
2, the data storage amount measurement unit 103, the timing control unit 504, the data read unit 105, and the program operation unit 60
6 and a program control database 607.

As shown in FIG. 6, the video encoding device according to the fourth embodiment is different from the video encoding device according to the third embodiment in that the program operating unit 506 is replaced with a program operating unit 606.
This is a configuration in which a program control database 607 is further added. Since other configurations of the video encoding device according to the fourth embodiment are the same as those of the video encoding devices according to the first to third embodiments, the same reference numerals are used for the other components. Numbers are assigned and explanations are omitted.

The program control database 607 stores designated storage amount information (SD) for each running video program. The program operation unit 606 sequentially acquires designated storage amount information (SD) corresponding to each video program from the program control database 607 and outputs the information to the timing control unit 504. Note that the video program of the designated storage amount information (SD) output from the program operation unit 606 to the timing control unit 504 and the video program of the video signal (VS) input to the video encoding unit 301 are set on the time axis in advance. And both are synchronized.

As described above, according to the video encoding apparatus according to the fourth embodiment of the present invention, in addition to the processing in the third embodiment, the program operating unit 606 determines in advance for each video program. The obtained designated storage amount information (SD) is acquired from the program control database 607, and is output to the timing control unit 504. Therefore, by transmitting information about the initial storage amount n for each video program from the program operating unit 606, external control of the processing delay time for each video program with respect to the video encoding device can be realized. Thus, it is possible to select and operate an image quality mode such as a high image quality mode and a low delay mode for each image program according to the content of the image program.

In the first to fourth embodiments, the count up to the initial accumulation amount n of the data storage unit 102 is
Although the case where counting is performed based on the actual number of data has been described, the counting may be performed based on the time until the initial storage amount calculated from the bit rate of the video coded data (ED) is reached. In this case, the initial storage amount of the reception data storage unit on the receiving side is defined by the same time.
In this case, the bit rate of the coded video data (ED) is embedded in the data field of the control information 403 in the data format and transmitted to the receiving side. Further, in the first to fourth embodiments, the data storage unit 102 and the data storage amount measurement unit 103 have been described as separate components. However, even if they are used in a configuration as an integrated functional block, the same applies. Can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a video encoding device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of data transfer timing in a data storage unit 102 for describing an operation of the video encoding device in FIG.

FIG. 3 is a block diagram illustrating a configuration of a video encoding device according to a second embodiment of the present invention.

4 is a diagram showing an example of a data format of video encoded data (ED) in which initial storage amount information (PD) is embedded in some data fields in the video encoding unit 301 of FIG.

FIG. 5 is a block diagram illustrating a configuration of a video encoding device according to a third embodiment of the present invention.

FIG. 6 is a block diagram illustrating a configuration of a video encoding device according to a fourth embodiment of the present invention.

FIG. 7 is a block diagram illustrating a configuration of a conventional video encoding device.

8 is a diagram illustrating an example of data transfer timing in a data storage unit 702 for describing an operation of the conventional video encoding device in FIG.

[Description of Codes] 101, 301, 701: Video encoding units 102, 702: Data storage units 103, 703: Data storage amount measurement units 104, 304, 504: Timing control units 105, 705: Data readout units 506, 606 … Program operation section 607… Program control database

Claims (4)

[Claims] 1. A video encoding apparatus for compressing data of a video signal by an encoding process, wherein the video encoding apparatus performs an input process based on data accumulation amount information corresponding to a code amount outputted from a data accumulation amount measuring unit and input back. Video encoding means for outputting video encoded data obtained by encoding a video signal to be encoded at a constant average bit rate, and outputting an encoding start signal at a timing at which the video encoded data is first output; and Data storage means for temporarily storing the encoded data, the data storage amount measurement means for measuring the storage amount of the video encoded data stored in the data storage means, and outputting the data as the data storage amount information That the video encoding means has reached a predetermined initial storage amount since the first video encoded data began to accumulate in the data storage means, Timing control means for detecting based on the coding start signal and the data storage amount information, and outputting the result of the detection as a data read start signal; and storing the data from the data storage means in accordance with a signal of the data read start signal. And a data reading means for reading and outputting the encoded video data. 2. The video encoding unit acquires information on the initial storage amount from the timing control unit, and outputs the information by embedding the information on the initial storage amount in a partial data field in the video encoded data. The video encoding device according to claim 1, wherein: 3. The system according to claim 1, further comprising program operating means for outputting information on the initial storage amount relating to a running video program, wherein the timing control means can acquire the initial storage amount from the program operating means. Item 3. The video encoding device according to Item 2. 4. The video encoding apparatus according to claim 3, wherein said program operating means changes and outputs said initial storage amount for each video program.