KR100732171B1 - Method and apparatus for mixing digital data - Google Patents

Abstract

An apparatus and a method for mixing digital data are provided to improve mixing efficiency of a sub-picture and video data and reduce the capacity of a memory required for mixing. A digital data mixing apparatus includes a first decoder(100) for decoding a video stream, a second decoder(110) for decoding highlight information of a sub-picture, and a third decoder(120) for decoding a sub-picture command and pixel data in a sub-picture stream. The digital data mixing apparatus further includes a memory(130) for storing the pixel data decoded by the third decoder, and a mixer(140) having a palette composed of YCbCr values. The mixer obtains YCbCr values of the sub picture according to the video stream decoded by the first decoder, a control signal, the highlight information decoded by the second decoder, and the sub picture command and the pixel data decoded by the third decoder and overlays the YCbCr values on the video stream.

Description

Digital data mixing apparatus and method {Method and apparatus for mixing digital data}

1 is a block diagram of a DVD decoder chip according to the prior art

2 is a diagram for explaining a general subpicture unit.

3 is a block diagram illustrating a data mixing device according to the present invention.

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* Description of the symbols for the main parts of the drawings *

100: first decoder unit 110: second decoder unit

120: third decoder unit 121: subpicture command decoder

122: repeat length coded pixel decoder 130: memory section

140: mixer 141: control unit

142: decompression unit 143: mixer

The present invention relates to digital multimedia broadcasting reception, and more particularly, to a digital multimedia broadcasting receiver capable of receiving a slide show and a method of multimedia broadcasting service thereof.

Due to the development of digital imaging equipment, high quality image storage and transmission equipment has become practical and widely used. Digital satellite broadcasting was also active in the United States and Europe. In the United States, HDTV broadcasting began in late 1998, and DVD began to spread. In short, DVD stands for DIGITAL VIDEO (or VERSATILE) DISC, which uses MPEG2 compression technology to deliver over 500 horizontal resolutions and DOLBY DIGITAL 5.1Ch surround sound, which is the same size as a CD and stores movies on one disc. It has a large capacity and can be compatible with video CDs and music CDs.

A standard for DVDs called Digital Video Discs or Digital Versatile Discs was developed by a consortium of 10 companies, and analog VHS tapes have been used since DVD players were first released in Japan in November 1996. It is rapidly replacing and making a big difference in our lives.

The DVD video features an audio stream change, a subpicture stream change, a camera angle change, etc. in addition to the normal playback, and a fast forward, fast reverse slow forward, It supports trick play and random access such as slow reverse, pause on, pause off, still off. It also provides a chapter skip feature that allows you to skip to the next chapter or to the previous chapter. In addition, there are user operation functions related to various buttons, and user operation functions include a menu such as title, root, sub picture, audio, and angle. It also includes a menu call function. Also, such as parental management information, it is possible to limit the playback of scenes or discs that are not suitable for children.

The trend of recent DVD players is to play CD-R, CD-RW, CD-DA as well as general DVD titles, and some of them play DVD-Audio, SACD, VCD, SVCD, DVD-R, DVD ± RW, HDCD, MP3. Supportable players are also being released.

These DVD videos support up to 32 subtitles and up to nine camera angles and have up to eight digital audio tracks that can store up to eight channels. The video compression method of video follows MPEG-2 and MPEG-1, and the video format supports video formats compatible with NTSC (National Television System Committee) and PAL (Phase Alternating Line) methods. The frame rate is an interlaced video having a frame rate of 29.97 Hz at 720 and 480 horizontally and vertically.

In the case of the PAL method, a frame rate of 25 Hz of 720 and 576 formats may be provided. Audio supports Linear PCM, Dolby AC-3, MPEG audio modes and optionally supports Digital Theater System (DTS).

Here subpicture refers to subtitles (subtitles), menus, captions, karaoke, simple animations, etc. These are two-bit run-length encoded bitmaps for each pixel. It consists of a pattern pixel, an emphasis pixel-1, and an emphasis pixel-2 and is assigned binary data values of 00, 01, 10, and 11, respectively. The background pixel, the pattern pixel, the emphasis pixel-1, and the emphasis pixel-2 may each take one color in 16 palettes, and have 16 contrasts referring to general transparency values from transparent to opaque. One contrast value may be taken from the (contrast) value. The transmission rate of the subpicture is up to 3.36Mbps per stream and the maximum size of the subpicture unit is 53220 bytes. The subpicture is mainly displayed through the OSD and provides the user with information about the contents of the DVD in the form of characters. Thus, along with video, it is an important means of providing information to the user visually.

The fast forward function in the DVD player provides a method for a user to play the contents of a DVD at a high speed. In general, a user searches for a relatively large amount of data in a short time or moves to a desired scene. Used as a means to move.

Nowadays, as DVDs are transitioning from providing video storage to high quality re-writeable technology, it is important to integrate and integrate DVD player functions into chips from a technical point of view.

Hereinafter, a DVD decode chip according to the prior art will be described with reference to the accompanying drawings.

1 is a block diagram of a DVD decoder chip according to the prior art.

As shown in FIG. 1, the DVD decoder chip according to the related art includes a demux unit 10, an MPEG-2 decore unit 20, and a sub-picture unit (hereinafter abbreviated as SPU) decoder unit 30. And a highlight decoder 40, a memory 50, a first mixer 60, a second mixer 70, and a host input unit 80.

The memory unit 50 may include first to Nth buffers 51 to 56, and the first to Nth buffers 51 to 56 may include an OSD buffer, an image buffer, a subpicture buffer, a highlight buffer, an SPU buffer, and the like. The picture buffer and the like are constituted.

After the DVD bit stream is properly stored in a predetermined buffer of the memory unit 50 via the demux unit 10, the DVD bit stream is stored in the MPEG decore unit 20, the SPU decoder unit 30, and the highlight decoder unit 40. It is used as an input.

Here, the subpicture data is decoded by the SPU decoder 30.

The decoded SPU is stored in the fifth buffer 55 of the memory unit 50 and then mixed with the image data decoded by the MPEG decoder unit 20 in the first mixer 60.

The data mixed in the first mixer 60 is mixed with the OSD data of the first buffer 51 and output if necessary in the second mixer 70.

2 is a view for explaining the structure of a general subpicture unit.

A unit constituting one subtitle in a general DVD video subtitle is called an SPU (sub picture unit), which is composed of ES (Elementary Stream) data.

As illustrated in FIG. 2, the subpicture unit includes a 4-byte sub picture unit header, pixel data PXD, and a sub picture display control sequence table (SP_DCSQT).

The pixel data and subpicture display control sequence table may each have a maximum of 26610 bytes. The subpicture unit header is composed of two bytes indicating the subpicture unit size and two bytes indicating the start address of the display sequence table.

The pixel data is RUN-Length Coding bitmap data and 2 bits are allocated per pixel.

There are four types of pixel data, as shown in Table 1. It consists of a background pixel, a pattern pixel, an emphasis pixel-1, and an emphasis pixel-2, and has binary data values of 00, 01, 10, and 11, respectively.

Each pixel data (background pixel, pattern pixel, emphasis pixel-1, emphasis pixel-2) has a color pixel depth of 4 bpp (bits per pixel). In other words, a color value of 4 bits is assigned to one pixel, and one value can be taken from 16 color palettes.

Each pixel may also have 16 levels of contrast. Contrast here means general transparency, where 0 means full transparency and 15 means full opacity.

One SP_DCSQT consists of the start time of the SP_DCSQT, the start time of the next SP_DCSQT, and then several commands.

Each command is shown in Table 2.

That is, the subpicture display control sequence table SP_DCSQT is composed of n + 1 subpicture display control sequences SP_DCSQ # 0 to SP_DCSQ #n.

Each subpicture display control sequence contains two bytes of SP_DCSQ_STM indicating the start time of the subpicture display control sequence, two bytes of SP_NXT_DCSQ_SA indicating the start address of the next subpicture display control sequence, and n display control commands. SP_DCCMD # 1 ~ SP_DCCMD #n).

Each display control command (SP_DCCMD) is a set of commands for controlling the display of subpictures. The display control command (SP_DCCMD) has nine components. That is, 1 byte FSTA_DSP (Forcedly set display start timing of pixel data) forcibly starting the display of pixel data regardless of the on or off state of the display of the subpicture, and 1 byte which is a command for starting the display of the subpicture. STA_DSP (Sets display start timing of pixel data) of STS, 1 byte STP_DSP (Sets display stop timing of pixel data) which is a command to stop display of sub-picture, and 3-byte SET_COLOR (Sets color code which gives color code to pixel) of pixels data, 3 bytes of SET_CONTR (Sets contrast between pixel data and main picture) to adjust the contrast between the pixel data and the main picture, 7 bytes of SET_DAREA (Sets display area of pixel to set the display area of the pixel data) data), a 5-byte SET_DSPXA (Set command that sets the address of the first pixel data used for display s display start address of pixel data), CHG_COLCON (Sets change of color and contrast for pixel data) to change pixel color and contrast when video frame changes, and CMD_END (End of Display) to indicate the end of display control command. Control Command).

When a subtitle is displayed in a general DVD video, it can be obtained as follows. The sub picture decoder 140 decodes the PS (Program Stream) at the Packetized Elementary Stream (PES) level and decodes the packet header part to obtain a PTS (Presentation Time Stamp) value. The display time is obtained by adding the PTS value obtained through this process to the start time SP_DCSQ_STM # 0 of the subpicture display control sequence obtained in the subpicture display sequence SP_DCSQ # 0.

The time point at which the display of the subpicture is turned off is a value obtained by adding the value of SP_DCSQ_STM # 1 which is a value decoded in the next subpicture display sequence SP_DCSQ # 1 to the PTS value thus obtained.

In general, when the subtitle is turned on or off, PTS + SP_DCSQ_STM #m (an integer between m = 0 and n) is used. However, in general DVD movies, the SP_DCSQ_STM value at the time when the subtitle is turned on is always 0, so the PTS value Only when the subtitle is turned on can be known.

To sum it up, if we take a closer look at the Commands, 03h represents the color (4bit) for the four types of PXD. 04h represents a transparency level (contrast, color code) for four types of PXD. In other words, it is the transparency level of the background and pattern, and the emphasis 1 and 2 pixels.

Other instructions include the contrast between the pixel data and the background, the horizontal and vertical start and end information of the area displaying the PXD, and the offset of the top field and bottom field. (offset), etc.

The color code (4 bits), which is the contents of SET_COLOR of the instruction code 03h, is used as a palette select signal having 16 Y, Cb, and Cr values, so that the actual Y, Cb of the pixel Obtain Cr (8bit) value. As described above, the decoded SPU is stored in the memory and then mixed with the video data in the first mixer.

At this time, in the related art, the format of data stored in the memory is the YCbCr value of each pixel.

The SPU requires 16 bits of storage per pixel (CbY or CrY), which requires approximately 5.3 Mb (720 x 478 x 16 bit) of memory space, excluding control data such as start points and transparency levels. .

Accordingly, an object of the present invention is to provide a digital data mixing apparatus and method for improving the mixing efficiency of subpicture and video data.

The present invention provides a first decoder for decoding an image stream, a second decoder for decoding highlight information of a subpicture, a third decoder for decoding a subpicture command and pixel data in the subpicture stream. And a memory unit for storing pixel data decoded by the third decoder unit, a palette including a YCbCr value, image data and control signals decoded by the first decoder unit, and highlights in the second decoder unit. And a mixer configured to perform mixing to obtain the actual YCbCr value of the subpicture and to overlay the image data according to the information, the subpicture command decoded by the third decoder unit, and pixel data. to provide.

The third decoder includes a sub picture unit (SPU) command decoder for processing a control command related to the sub picture, and a repetition length coded pixel decoder.

The mixer determines the direction information (horizontal or vertical direction) of the image information using the control signal of the first decoder unit, receives the coordinates (x, y) of the subpicture data to be overlaid, and determines the mixing start point. A transparency table having four levels of pixel data (2 bits) is obtained by obtaining a real YCbCr value from pixel data with a control unit for determining and a palette composed of the YCbCr values. ) Transparency and color are selected using the selection signal of the color table and the color table, and then, the color (4bit) is again converted into 16 Y, Cb, and Cr values. Preferably, the decompression unit obtains an actual YCbCr value using a select signal of a palette and a mixer unit mixing the image data and the sub picture.

According to an aspect of the present invention, there is provided a method of decoding an image stream, decoding highlight information of a subpicture, decoding a subpicture command and pixel data in a subpicture stream, and storing the decoded pixel data. Step, mixing to obtain the actual YCbCr value of the sub-picture and overlay on the image data through a palette consisting of a YCbCr value according to the decoded image data and control signal, highlight information, sub-picture command and pixel data It provides a digital data mixing method comprising the step of performing.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

In addition, the same components as in the prior art are given the same names and the same reference numerals for convenience of description, and detailed description thereof will be omitted.

Hereinafter, a digital data mixing device according to the present invention will be described with reference to the accompanying drawings.

3 is a block diagram illustrating a digital data mixing device according to the present invention.

The digital data mixing apparatus according to the present invention includes a first decoder unit 100, a second decoder unit 110, a third decoder unit 120, a memory unit 130, and a mixer 140.

For example, the first decoder unit 100 may be an MPEG-2 decoder, the second decoder unit 110 may be a highlight decoder, and the third decoder unit 120 may be configured as an SPU decoder.

Accordingly, when the demux unit (refer to (10) of FIG. 1) separates the video stream, subpicture stream, and highlight from the DVD data read from the DVD, the first decoder unit 100 stores them in the respective buffers of the memory unit. Decode the video stream.

The second decoder 110 decodes the highlight in the highlight buffer.

Also, the third decoder unit 120 decodes the sub picture stream in the sub picture buffer.

The third decoder 120 may include an SPU command decoder 121 for processing a control command related to a subpicture, and a repetition length coded pixel decoder for decoding and storing the pixel data shown in Table 1 in the memory 130. 122).

The memory unit 130 stores the pixel data having 2 bits per pixel from the third decoder unit 120.

The mixer 140 has a palette composed of 16 YCbCr values, and includes image data and control signals decoded by the first decoder unit 100, highlight information in the second decoder unit 110, and a third one. In accordance with the SPU command from the decoder unit 120 of the decoder unit 120 receives the coordinates (x, y) of the subpicture data to be overlaid with the video signal, and determines the mixing start point, the memory unit The actual YCbCr value is obtained from the 2-bit pixel data stored at 130. At this time, since the type of data stored in the memory unit 130 is pixel data of 2 bits rather than YCbCr requiring 16 bits per pixel, the maximum memory necessary for storing subpicture data is YCbCr. Compared to 5.3Mb, it can be reduced to 675Kb (720 * 478 * 2bit), which is 12.5%.

In addition, the mixer 140 includes a control unit 141, a decompression unit 142, and a mixer unit 143.

Herein, the control unit 141 determines the direction information (horizontal or vertical direction) of the image information using the control signal of the first decoder unit 100. Also, the mixing start point is determined by receiving the coordinates (x, y) of the subpicture data to be overlaid with the video signal.

The decompression unit 142 obtains the actual YCbCr value from the pixel data with a palette composed of 16 YCbCr values. In this case, the type of data stored in the memory unit 130 is not YCbCr, which requires 16 bits per pixel, but 2 bits of pixel data, and the maximum memory required for storing subpicture data is YCbCr. Compared to 5.3Mb, it can be reduced to 675Kb, which is 12.5%. The decompressor 142 uses pixel data (2 bits) as a select signal for a transparency table and a color table having four levels of transparency and color. After (color) is selected, the actual YCbCr value is obtained by using color (4 bit) as a select signal of a palette having 16 Y, Cb, and Cr values.

Therefore, since the storage space required by the memory unit 130 requires storage space of 2 bit pixel data, not only the memory can be reduced but also the amount of computation can be reduced. In other words, most of the DVD menu screen or subtitle data is composed of a background pixel type. In the related art, regardless of the type of pixel data, the YCbCr value and the transparency ( In contrast to the operation with the transparency value, the mixer 140 according to the present invention omits the mixing operation when the pixel type is the background, and simply the video data ( The video data may be passed to the display stage (not shown) through the mixer unit 143.

At this time, the mixing operation in the mixer 140 is as shown in Table 3.

As described above, the present invention can reduce the size of the memory required for mixing to a size of up to 12.5%.

In addition, instead of storing Y, Cb, and Cr data, it is possible to reduce the amount of computation required for mixing by storing pixel data.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

Claims (4)

A first decoder to decode the video stream; A second decoder to decode highlight information of the subpicture; A third decoder for decoding a subpicture command and pixel data in the subpicture stream; A memory unit which stores pixel data decoded by the third decoder unit; According to a video data and control signal embedded in a palette composed of YCbCr values and decoded in the first decoder unit, highlight information in the second decoder unit, and subpicture commands and pixel data decoded in the third decoder unit. And a mixer configured to perform mixing for obtaining the actual YCbCr value of the subpicture and overlaying the image data. The method of claim 1, And the third decoder comprises a sub picture unit (SPU) command decoder for processing a control command related to the sub picture, and a repetition length coded pixel decoder. The method of claim 1, The mixer determines the direction information (horizontal or vertical direction) of the image information using the control signal of the first decoder unit, receives the coordinates (x, y) of the subpicture data to be overlaid, and determines the mixing start point. With a control unit An actual YCbCr value is obtained from pixel data with a palette composed of the YCbCr values, and a transparency table and a color table having four levels of pixel data (pixel bits (2 bits)) Transparency and color are selected using the select signal of the color table, and then the palette (color (4bit)) is selected again with 16 Y, Cb and Cr values. a decompressor for calculating the actual YCbCr value using the (select) signal, And a mixer unit for mixing the image data and the sub picture. Decoding an image stream, decoding highlight information of the subpicture, and decoding the subpicture command and pixel data in the subpicture stream; Storing the decoded pixel data; Performs mixing to obtain the actual YCbCr value of the subpicture and overlay the image data through a palette composed of YCbCr values according to the decoded image data and control signal, highlight information, subpicture command, and pixel data. Digital data mixing method comprising the steps of.

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