KR20050093434A - Personal video recoder and the operating method by using it - Google Patents

Abstract

The present invention relates to a personal video storage device that facilitates trick play of an image stream in a personal video recorder (PVR) and an image playback method using the same.

According to the present invention, when a video stream stored in a personal video storage device (PVR) is uploaded with a trick play request, the MPEG decoder converts the P frame into an I frame so that the MPEG decoder can easily access the B frame so that the trick play is performed. There is an easy effect, and only need to decode the anchor frame required according to the requested speed, it can save time and efficiently perform trick play.

Description

Personal video storage device and video playback method using it {Personal Video Recoder and the operating method by using it}

The present invention relates to a personal video storage device that facilitates trick play of an image stream in a personal video recorder (PVR) and an image playback method using the same.

Recently, the terrestrial receiver has become more complicated and various products are released according to the trend of widespread and advanced. Recently, the most popular topic is the personal video recorder (PVR).

 PVR is a personal digital video recording device that records and plays back information on a hard disk. Unlike a VCR that stores video signals on a magnetic tape, a PVR is a new concept of digital recording device that records and plays back information on a hard disk. It is a next-generation recording device that can record a certain amount of broadcast programs depending on the capacity without a VCR through the hard disk drive built into the set-top box or television body.

When the PVR selects a channel, the signal currently broadcasted to the hard drive is digitally stored and played simultaneously. Therefore, if the stop button is pressed and the play button is pressed again, the stored broadcast signal is played again from the point where it was stopped. You can also watch the program that's currently being broadcast, play it back in slow motion, or skip the boring part, making it easy to find and edit the part you want.

That is, the personal video recording device has not only basic recording but also trick play such as fast forward play, reverse play, stop function, and various additional functions to meet the needs of other users. Providing.

Conventionally, as a method of compressing an image in such a digital broadcast, a method of compressing an image using a correlation between screens based on MPEG is difficult, and thus it is difficult to independently reproduce a frame to be played. It is not easy to support various add-ons.

That is, in the conventional PVR, when storing a stream for trick play of the video stream, index information of the stream is extracted and stored in the form of an index file.

Various information may be stored in the index file. In particular, for trick play, address information of a storage medium in which an I frame is stored is stored.

Thereafter, the stored video stream is uploaded from the storage medium, and the position of the I frame of the video stream is found using the index information stored in the trick play, and the stream is processed at the requested speed.

In this case, in the case of the trick play at low speed, the display time for each image is extended after decoding all the frames as in the case of the normal display.

However, when performing trick play at high speed, only an anchor frame such as an I frame or a P frame is usually used. This is because using up to B frames requires a lot of decoding time for high speed trick play.

As such, when the trick play is performed using only the anchor frame, the decoding time can be somewhat reduced because only the anchor frame corresponding to the appropriate position roughly needs to be decoded according to the requested double speed.

In the present invention, when uploading a video stream stored in a personal video storage device (PVR) with a trick play request, a personal video storage device for converting a P frame into an I frame to facilitate a trick play of the video stream and a video playback using the same The purpose is to provide a method.

In order to achieve the above object, a personal video storage device according to the present invention includes a broadcast receiving unit for receiving a broadcast stream; A hard disk storing the broadcast stream in I, P, and B frames which are MPEG streams; A frame processing unit which receives I and P frames during a trick play in the MPEG stream stored in the hard disk, decodes the P frames into I frames and converts the frames; And an MPEG decoder which decodes the B frame transmitted from the hard disk and the I frame processed by the frame processor.

The apparatus may further include an MPEG encoder for encoding an analog image when the broadcast stream received by the broadcast receiver is analog.

Here, the frame processing unit includes a frame decoder for decoding P frames and I frames; A frame memory in which each decoded frame is stored; And a converter for converting the P frame read from the frame memory into an I frame.

The trick play may be at least one playback mode among the normal playback, rewind, fast playback, slow playback, reverse playback, freezing of the screen, and playing only a selected portion of the broadcast stream. .

In addition, in order to achieve the above object, an image playback method of a personal video storage device according to the present invention comprises the steps of: receiving a broadcast stream; Storing the broadcast stream in I, P, and B frames, which are MPEG streams; Determining whether a trick play request is made for the broadcast stream; Decoding the MPEG stream when there is no trick play request, and transmitting the decoded MPEG stream to the frame processor if there is a trick play request; Receiving, by the frame processor, I and P frames from the MPEG stream and converting the P frames into I frames; The converted I frame and the B frame are characterized by comprising the step of playing the requested trick play.

The B frame may bypass the frame processing unit at the time of the trick play request.

Receiving the broadcast, characterized in that it further comprises the step of encoding with MPEG when the broadcast is an analog broadcast.

The frame processing unit may receive the I and P frames from the MPEG stream and convert the P frames into I frames, wherein the I and P frames are decoded and then converted.

The trick play request is a playback mode comprising at least one of normal play, rewind, fast play, slow play, reverse play, freeze screen, and play only a selected portion of the broadcast stream. It features.

Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

Digital broadcasting is compressed to a moving picture expert group (MPEG) for high definition image quality. In the MPEG, not all frames are compressed into individual images, but motion compensation is performed by using similarities between adjacent frames. Predictive and Bidirectional

In the MPEG stream, frames, which can be recovered only by the information they have, should be inserted regularly, and these frames are compressed into a clean image.

The frames compressed to the clean image are referred to as I frames, predicted frames are P frames, and interpolated frames are called B frames.

The I-code (Intra-coded frame) can come anywhere in the data stream and is used for random access of the data and is compressed in real time without reference to other images.

The P-frame (Predictive-coded frame) uses the information of the previous I frame and the information of the previous P frame when encoding and decoding.

That is, when there is a motion, most of the object itself on the front screen moves sideways without significant change. Therefore, only the difference value is encoded by using a very small difference between the previous screen and the current screen.

The B frame (Bidirectional-coded frame) uses both before and after I frames and P frames when encoding and decoding.

The B-frame has a difference value between the previous I- or P-frame and the I- or P-frame after the B-frame.

1 is a view schematically showing a trick play implementation method using a personal video storage device according to the present invention.

As shown in FIG. 1, a personal video storage device (PVR) according to the present invention includes a digital broadcast receiver 110, a hard disk (HDD) 120, an anchor frame decoder 130, a converter, 135, a frame memory 133, an MPEG decoder 140, and a display unit 150.

The digital broadcast receiver 110 receives digital broadcast.

The hard disk 120 stores the received digital broadcast as an MPEG stream.

The anchor frame decoder 130 decodes I frames and P frames.

Here, decoding of an I frame is for decoding a P frame, and decoding of each P frame is for another P frame that should be decoded with reference to this P frame.

The frame memory 133 stores each image decoded by the anchor frame decoder 130.

The converter 135 reads the decoded P frame from the frame memory 133 and newly encodes it into an I frame.

The MPEG decoder 140 satisfies the MPEG standard and decodes I, P, and B frames.

The display unit 150 displays the MPEG stream decoded by the MPEG decoder 140 to a user.

2 is a view schematically showing a trick play implementation method using a personal video storage device according to the present invention.

Here, the personal video storage device (PVR) receives the analog broadcast from the analog broadcast receiver 210, and the received analog broadcast is encoded into the MPEG stream by the MPEG encoder 215.

As described above, an MPEG stream is encoded and stored in the hard disk 220, and the description of the same elements as shown in FIG. 1 will be omitted.

Hereinafter, a process of processing a stream in a personal video storage device (PVR) having the above configuration will be described.

3 is a flowchart illustrating a method of playing a trick play in a personal video storage device according to the present invention.

First, a digital broadcast or an analog broadcast is received (S100) and an image stream is stored in the hard disk (S110).

In this case, the video stream satisfies the MPEG standard, a process of creating an index file before storing the MPEG stream on a hard disk, and the address file stores the address information of each anchor frame.

In the case of normal playback in the PVR, the stream read from the hard disk is MPEG decoded and displayed to the user.

In the case where the PVR is to be played by trick play (S120), when the upload stream read from the hard disk is a B frame, the PVR bypasses the anchor frame decoder and the converter.

When the upload stream read from the hard disk is an anchor frame such as an I frame and a P frame, the upload stream is transmitted to an anchor frame decoder, and each anchor frame is decoded and stored in a frame memory.

In this case, the converter reads the decoded anchor frame from the frame memory and converts each P frame into an I frame (S130).

As such, the stream converted for trick play becomes an IB stream including only I frames and B frames, and the stream is decoded (S140) to decode and output (display) a frame at a corresponding position according to the requested double speed. (S150).

For example, the GOP (Group Of Picture) structure of the stored stream is I1, B1, B2, P1, B3, B4, P2, B5, B6, P3, B7, B8, P4, B9, B10, P5, B11, B12. Let's say

Then, the GOP is subjected to predetermined processing by the anchor frame decoder and the converter, and the streams input to the MPEG decoder are I1, B1, B2, I2, B3, B4, I3, B5, B6, I4, B7, B8, I5. , B9, B10, I6, B11, and B12.

If the 10X speed request is requested during the trick play, the MPEG decoder decodes I1, I4, B7, and I5 to display I1 and B7 frames.

That is, the present invention uploads a stream stored in a storage medium with a trick play request, and adds a component that converts a P frame of an upload stream into an I frame in front of the MPEG decoder when a trick play request is displayed on display. For this reason, when the decoder uploads, the frame actually received consists of only I frames and B frames.

In this way, when the MPEG decoder wants to decode a specific B frame from the stream, it is possible to access the B frame randomly because it is necessary to decode the two I frames closest to the B frame.

In addition, the MPEG decoder does not have to decode all anchor frames in order to decode a particular frame, which is efficient in terms of time.

Although the present invention has been described with reference to the embodiments illustrated in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

In the present invention, when a video stream stored in a personal video storage device (PVR) is uploaded with a trick play request, the MPEG decoder converts the P frame into an I frame so that the MPEG decoder can easily access the B frame so that the trick play is easy. It works.

In addition, since the present invention only needs to decode the anchor frame required according to the requested double speed, there is an effect of saving time and efficiently performing trick play.

1 is a view schematically showing a trick play implementation method using a personal video storage device according to the present invention.

2 is a schematic view of a trick play implementation method using a personal video storage device according to the present invention;

3 is a flowchart showing a method of playing with trick play in a personal video storage device according to the present invention.

<Description of Signs of Major Parts of Drawings>

110: digital broadcast receiver 120, 220: hard disk

130, 230: anchor frame decoder 133, 233: frame memory

135, 235: Converter 140, 240: MPEG decoder

150, 250: display unit 210: analog broadcast receiving unit

Claims (9)

A broadcast receiver for receiving a broadcast stream; A hard disk storing the broadcast stream in I, P, and B frames which are MPEG streams; A frame processing unit which receives I and P frames during a trick play in the MPEG stream stored in the hard disk, decodes the P frames into I frames and converts the frames; And an MPEG decoder which decodes the B frame transmitted from the hard disk and the I frame processed by the frame processor. The method of claim 1, Personal video storage device further comprises an MPEG encoder for encoding analog video when the broadcast stream received by the broadcast receiving unit is analog. The method of claim 1, The frame processing unit includes a frame decoder for decoding P frames and I frames; A frame memory in which each decoded frame is stored; And a converter for converting the P frame read from the frame memory into an I frame. The method of claim 1, The trick play is at least one playback mode of normal playback, rewind, fast playback, slow playback, reverse playback, freezing the screen, and playing only a selected portion of the broadcast stream. Personal storage device. Receiving a broadcast stream; Storing the broadcast stream in I, P, and B frames, which are MPEG streams; Determining whether a trick play request is made for the broadcast stream; Decoding the MPEG stream when there is no trick play request, and transmitting the decoded MPEG stream to the frame processor if there is a trick play request; Receiving, by the frame processor, I and P frames from the MPEG stream and converting the P frames into I frames; And the converted I frame and the B frame are reproduced with the requested trick play. The method of claim 5, And the B frame bypasses the frame processing unit when the trick play request is made. The method of claim 5, In the step of receiving the broadcast, If the broadcast is an analog broadcast, video encoding method of the personal storage device further comprising the step of encoding by MPEG. The method of claim 5, In the frame processing unit receiving the I, P frame from the MPEG stream and converting the P frame to I frame, And the I and P frames are decoded and then converted. The method of claim 5, The trick play request is a playback mode comprising at least one of normal play, rewind, fast play, slow play, reverse play, freeze screen, and play only a selected portion of the broadcast stream. An image playback method of a personal storage device.