JP3771161B2 - Image stream recording apparatus and method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus and method for recording a compressed image stream.
[0002]
[Prior art]
In image compression such as MPEG, inter-frame prediction is performed. The MPEG prediction method includes bidirectional prediction in which prediction is performed using past and future images for a compressed image, unidirectional prediction in which prediction is performed using only past images, and prediction is not used. There are two ways. An image compressed using bi-directional prediction is a bi-directional predictive encoded image (hereinafter referred to as a B picture), and an image compressed using uni-directional prediction is an inter-frame forward predictive encoded image (hereinafter referred to as a P picture). ), An image that is compressed without being predicted is called an intra-frame encoded image (hereinafter referred to as an I picture). By combining this compression method and the image input order, the image is represented as B0, I2, P5.
[0003]
When compression coding is performed on a video whose image input order is B0B1I2B3B4P5B6B7P8B9B10P11..., I2B0B1P5B3B4P8B6B7P11B9B10 ( Next I picture)... Are exchanged to create a stream. Here, a unit from an I picture (I2) to the next I picture on the encoded stream is referred to as a GOP (Group Of Pictures). The image stream can be decoded in GOP units.
[0004]
[Problems to be solved by the invention]
Since MPEG uses the above-described image compression encoding method, decoding cannot be performed from any picture in the stream. That is, in the example of the stream described above, when recording is started when the data of the image B4 is sent, the image streams I2B0B1P5B3B4P8B6B7P11B9B10... After the image B4 are recorded. When decoding the recorded image stream, it is necessary to perform motion processing using the image I2 and the image P5 in order to decode the image B4 compressed using bidirectional prediction. However, since the image I2 and the image P5 do not exist on the recorded stream, they cannot be decoded. Further, in order to decode the image P8 compressed using the unidirectional prediction, the image P5 is necessary. However, the image P5 does not exist on the similarly recorded stream and cannot be decoded. Therefore, the image from the image B4 is recorded as stream information but cannot be decoded and viewed. The image that can be decoded is an image after the GOP starting from the next I picture.
[0005]
As described above, there has been a problem in that an inter-frame compressed image stream sent cannot be recorded and decoded as it is from an arbitrary point in time.
[0006]
An object of the present invention is to provide an image stream recording apparatus and method capable of decoding an image stream at the time when recording is started.
[0007]
The image stream recording apparatus of the present invention records an image stream composed of screen data subjected to inter-frame compression by bi-directional prediction and screen data subjected to intra-frame compression, and decodes and displays this image stream on a monitor A buffer for temporarily storing a predetermined amount of the image stream supplied from the outside, and the image stream temporarily stored in the buffer being sequentially supplied and instructed to start recording. Detecting means for detecting the leading position of GOP, which is a unit for decoding the image stream, from the supplied image stream; and decoding the image stream supplied from the outside and converting it into a video signal; A decoder for displaying the image displayed on the monitor when the start of recording is instructed. A decoder for extracting a Time Code information or Temporal Reference information, and image stream after the head position of the GOP, which is detected by said detecting means, said extracted by the decoder Time Code information or the Temporal Reference information and the recording medium And a recording means for recording, and when a cueing operation is performed, the decoder decodes the image stream from the start position of the GOP recorded on the recording medium by the recording means, and the recording The Time Code information or the Temporal Reference information recorded on the medium is extracted, and the image when the recording start is instructed is determined and displayed on the monitor.
[0008]
The image stream recording method of the present invention records an image stream composed of screen data subjected to inter-frame compression by bi-directional prediction and screen data subjected to intra-frame compression, and the image stream is decoded and monitored. In the image stream recording method to be displayed, a predetermined amount of the image stream supplied from the outside is temporarily stored in a buffer, and when the start of recording is instructed, the image stream temporarily stored in the buffer The head position of GOP that is a unit of decoding of the image stream is detected, the image stream supplied from the outside is decoded and converted into a video signal, and displayed on the monitor when the start of recording is instructed extracting Time Code information or Temporal Reference information about images, And image stream after the head position of the GOP issued, and extracted the Time Code information or the Temporal Reference information recorded on the recording medium, when the operation of the indexing is performed, recorded before type recording medium The image stream is decoded from the head position of the recorded GOP, and the Time Code information or the Temporal Reference information recorded on the recording medium is extracted and the image when the recording start is instructed is extracted. It is discriminated and displayed on the monitor.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the drawings.
[0010]
FIG. 1 is a block diagram showing a configuration of an image stream recording apparatus according to an embodiment of the present invention.
[0011]
An image stream obtained by a receiving circuit, an encoding circuit, or the like (not shown) is input to the buffer 1. The buffer 1 stores input image streams in the input order. The buffer 1 has a capacity capable of storing image data of 1 GOP or more. The buffer 1 sends the image data to the GOP detection circuit 3 in order from the oldest image data when the capacity becomes full.
[0012]
A GOP detection circuit 3 is connected to the buffer 1. The GOP detection circuit 3 performs a GOP head image detection process on the image stream sent from the buffer 1. The decoder 5 decodes an image stream obtained by a reception circuit, an encoding circuit, etc. (not shown) and converts it into a video signal. A monitor 7 such as a TV is connected to the decoder 5. The video signal converted by the decoder 5 is sent to a monitor 7 such as a TV, and the user can view the decoded video on the monitor 7.
[0013]
The record button 9 is used by the user to instruct the image stream recording apparatus to record. The GOP detection circuit 3 can detect that the recording button 9 has been pressed by the user. A recording circuit 11 is connected to the GOP detection circuit 3. The recording circuit 11 receives the image stream sent from the GOP detection circuit 3 and records the received image stream on the recording medium 13. The recording medium 13 is a medium capable of recording data such as a magnetic tape, a magnetic disk, and an optical disk. The decoder 5 reads an image stream from the recording medium 13. The decoder 5 decodes the image stream read from the recording medium 13 and converts it into a video signal.
[0014]
Next, an image stream recording method according to this embodiment will be described with reference to FIGS. FIG. 2 is a flowchart for explaining the image stream recording operation in this embodiment. FIG. 3 is a diagram for explaining the state of the image stream when it is recorded.
[0015]
First, it is assumed that an image stream... B3B4P8B6B7P11B9B10I2B0B1P5B3B4P8B6B7P11B9B10I2B0... Is sent in the order shown in FIG. Here, BOP3 to B3B4P8B6B7P11B9B10 are GOP1, GOP2 is the first image I2 up to the second image B10, and GOP3 is the second image I2 and later. In this embodiment, 1 GOP is composed of 12 images.
[0016]
The buffer 1 sequentially accumulates image streams sent in the order shown in FIG. (Step S1) It is assumed that the buffer 1 has a capacity capable of storing images of 1 GOP or more, and 15 images can be stored in this embodiment. When the capacity of the buffer 1 becomes full, image data is sent to the GOP detection circuit 3 in order from the oldest image data.
[0017]
The GOP detection circuit 3 receives the image stream from the buffer 1 and determines whether or not the recording button 9 is pressed. (Step S3) In a state where the recording button 9 is not pressed, the GOP detection circuit 3 discards the image stream input from the buffer 1 as it is. (Step S <b> 5) When the GOP detection circuit 3 detects that the user presses the recording button 9, the GOP detection circuit 3 performs the process of detecting the head image of the GOP for the image stream input from the buffer 1. (Step S7)
As shown in FIG. 3B, when the user presses the record button 9 when the GOP2 image B6 is sent, the buffer 1 has an image stream B3B4P8B6B7P11B9B10I2B0B1P5B3B4P8 composed of 15 images before the image B6. Accumulated. When the GOP detection circuit 3 detects that the user presses the recording button 9, the GOP detection circuit 3 detects the first image of the GOP for the image streams B3B4P8B6B7P11B9B10I2B0B1P5B3B4P8 sent from the buffer 1. In the detection process, the GOP detection circuit 3 extracts picture coding type (hereinafter referred to as PCT) data of the picture layer in MPEG from the image stream. The GOP detection circuit 3 determines the type of encoding of each image based on the PCT data. When the GOP detection circuit 3 detects the image (I2) of the I picture by this coding type determination, the GOP detection circuit 3 determines that the detected image I2 is the head image of the GOP and sends the image stream after the detected image I2 to the recording circuit 11. .
[0018]
The recording circuit 11 records the image stream sent from the GOP detection circuit 3 on the recording medium 13, whereby the image stream I2B0B1P5B3B4P8B6B7P11B9B10I2B0... Shown in FIG. (Step S9) Thereafter, it is determined whether or not the end of the recording operation is instructed (step S11). When the end is determined, the image stream recording apparatus ends the recording operation.
[0019]
An image P5 and an image P8 necessary for decoding the image B6 when the user presses the recording button 9 are present in the image stream shown in FIG. Further, the image I2 is necessary for decoding the image P5, and the image P5 is necessary for decoding the image P8. These images are also recorded in the image stream shown in FIG. Exists. As described above, when the recording button 9 is pressed in the image B6, the image stream is recorded from the head image I2 of the GOP2 on the recording medium 13, whereby the image B6 can be decoded. In the present embodiment, the example in which the recording button 9 is pressed by the user when the image B6 is sent has been described. However, decoding can be performed by performing the same process for other images.
[0020]
Next, another embodiment of the present invention will be described with reference to FIG.
[0021]
FIG. 4 is a block diagram showing a configuration of an image stream recording apparatus according to another embodiment of the present invention. In FIG. 4, the same parts as those in FIG.
[0022]
In FIG. 4, the decoder 41 detects pressing of the recording button 9 by the user. When detecting that the user presses the recording button 9, the decoder 41 sends information related to the image currently displayed on the monitor 7 to the recording circuit 43. The recording circuit 43 records the image stream sent from the GOP detection circuit 3 on the recording medium 13 and receives information about the image at the time when the recording button 9 is pressed from the decoder 41 and records it as additional information of the image stream to be recorded. 13 is recorded.
[0023]
This additional information is recorded on the recording medium 13 in a header format or a table format that can correspond to the recorded image stream. When the decoder 41 reads data from the recording medium 13 and decodes the image stream, the decoder 41 also reads additional information recorded on the recording medium 13 together with the image stream. During normal playback, the additional information read by the decoder 41 is not used, but when an operation such as cueing is performed, the decoder 41 uses the read additional information to display an image (when the user presses the recording button 9). In FIG. 3, the image stream from the image B6) is displayed on the monitor 7.
[0024]
As additional information for discriminating an image when the recording button 9 is pressed by the user, time code (hereinafter referred to as TC) information of the GOP layer and temporal reference (hereinafter referred to as TR) information of the picture layer in MPEG. Use. The TC information is time information of an image inserted into the stream when the image stream is encoded. The TR information is information indicating the order in which the image to be decoded is displayed in the image included in the GOP. When TC information or TR information is used as additional information, when the user detects that the recording button 9 is pressed, the decoder 41 sends the TC information or TR information of the image when the recording button 9 is pressed to the recording circuit 43 for recording. The circuit 43 records the sent TC information or TR information on the recording medium 13. When the cue operation is performed, the decoder 41 performs the decoding process from the head of the image stream recorded on the recording medium 13, but when the recording button 9 is pressed using the read TC information or TR information. Are determined and displayed on the monitor 7.
[0025]
In the present embodiment, the recording medium is described as being incorporated in the image stream recording apparatus. However, the present invention is not limited to this, and the recording medium may be externally attached to the apparatus, or removable from the apparatus. It may be.
[0026]
【The invention's effect】
According to the present invention, when the start of recording is instructed, the head image of the image group to which the image at the time of the start of recording belongs is detected from the image stream accumulated in the buffer, and the detected head image is recorded on the recording medium. By recording the image stream, it is possible to obtain information necessary for decoding the image at the time when the start of recording is instructed.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an image stream recording apparatus according to an embodiment of the present invention.
FIG. 2 is a flowchart for explaining an image stream recording operation;
FIG. 3 is a diagram for explaining a state of an image stream when it is recorded.
FIG. 4 is a block diagram showing a configuration of an image stream recording apparatus according to another embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Buffer 3 GOP detection circuit 5, 41 Decoder 7 Monitor 9 Recording button 11, 43 Recording circuit 13 Recording medium

Claims (2)

In an image stream recording apparatus for recording an image stream composed of screen data subjected to inter-frame compression by bi-directional prediction and screen data subjected to intra-frame compression, decoding the image stream and displaying it on a monitor,
A buffer for temporarily storing a predetermined amount of the image stream supplied from the outside;
When the image stream temporarily stored in this buffer is sequentially supplied and recording start is instructed, the head position of GOP which is a unit of decoding of the image stream is detected from the supplied image stream. Detection means;
A decoder that decodes the image stream supplied from the outside, converts the image stream into a video signal, and displays the image signal on the monitor. When the start of recording is instructed, the time code information or Temporal Reference regarding the image displayed on the monitor A decoder for extracting information;
A recording means for recording an image stream after the head position of the GOP detected by the detection means and the Time Code information or the Temporal Reference information extracted by the decoder on a recording medium;
When a cueing operation is performed, the decoder decodes the image stream from the start position of the GOP recorded on the recording medium by the recording means, and the Time Code information recorded on the recording medium or image stream recording apparatus for causing the Temporal Reference information extracted and was judged the image when the recording start is instructed is displayed on the monitor. In an image stream recording method of recording an image stream composed of screen data subjected to inter-frame compression by bidirectional prediction and screen data subjected to intra-frame compression, and decoding the image stream and displaying it on a monitor,
The image stream supplied from the outside is temporarily stored in a buffer in a predetermined amount, and when the start of recording is instructed, the image stream is temporarily stored in the buffer from the image stream in units of decoding. Detect the start position of a GOP,
The image stream supplied from the outside is decoded and converted into a video signal, and when the start of recording is instructed, time code information or temporal reference information regarding the image displayed on the monitor is extracted,
Recording the detected image stream after the first position of the GOP and the extracted time code information or temporal reference information on a recording medium,
If the operation of the indexing is performed, along with the head position of the GOP recorded before type recording medium performs decoding of the picture stream, the Time Code information or the Temporal Reference information recorded on said recording medium An image stream recording method comprising: extracting the image and determining the image when the recording start is instructed and displaying the image on the monitor.

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