KR100349649B1 - Variable length encoder in MPEG4 codec - Google Patents

Abstract

The present invention provides a variable length encoder of a video compression encoding apparatus. The present invention provides a variable length encoding for a relatively small amount of image information through a low transmission line allowed by a transmission channel in a video compression encoding apparatus. Error loss can be recovered and compatible with Reverse Variable Length Coding.

Description

Variable length encoder in video compression encoder {Variable length encoder in MPEG4 codec}

The present invention can be used in video telephony, video conferencing, personal digital assistant (PDA) for personal mobile communication (PCS), mobile phones and multimedia devices, and devices for IMT-2000 (3rd generation mobile communication system) video services. In particular, the present invention relates to a video compression encoding apparatus. In particular, the video compression encoding apparatus may perform variable length encoding on relatively small image information through a low transmission line allowed by a transmission channel, recover error loss during variable length encoding, and reverse variable length encoding. (Reverse Variable Length Coding) relates to a variable length encoder of a moving picture compression coding apparatus.

Various variable length coding methods such as MPEG1, MPEG2, H.261, and H.263 have been proposed in the variable length coding apparatus for encoding an image. In particular, the variable length encoding apparatus of MPEG2, which is a standard method of HDTV (HighDensity TeleVision), distinguishes the header information from the image data in order to process a large amount of image information in a short time, and encodes the header information as it is. It consists of four parallel structures, which process multiple image data at the same time.

1 shows an encoder block configuration of the international standard MPEG4. Unlike MPEG2, the biggest difference is that the shape information encoding is additionally performed.

A motion estimator 1 for generating a motion vector by performing motion estimation on a block basis of the input image data; A motion compensator (2) for performing motion compensation by using the generated motion vector; An image information encoder (4) for performing image information coding (Texture coding) on a portion of the motion compensator (2) where motion compensation is not performed; A video object plane (VOP) having a motion compensation compensated by the motion compensator 2 and a coding unit having an arbitrary shape in MEPG4 and internal information of an object encoded by the image information encoder 4 are added to the current image. A previous VOP reconstruction unit 6 for reconstructing the previous VOP which is the VOP of the previous image; A shape information encoder 9 for performing shape coding on shape information of the input image; The multiplexer 11 multiplexes the motion information estimated by the motion estimation unit 1, the internal image information encoded by the image information encoder 4, and the shape information encoded by the shape information encoder 9. Wow; The multiplexer 11 includes an output buffer 12 that buffers and outputs the multiplexed bitstream.

The operation of the encoder of the international standard MPEG4 as described above is as follows.

First, when an image screen is input, motion estimation is performed in units of blocks, and the motion vector generated therein is transmitted. Then, after motion compensation is performed using a motion vector, image coding is performed on a portion where motion compensation is not performed.

Shape coding is performed on shape information of an image. The output signal of the shape information encoder 9 varies depending on the field to which the VOP encoder is applied. As indicated by the dotted line, the output signal of the shape information encoder 9 may include the motion estimation unit 1, It can be input to the motion compensator 2 and the image information encoder 4 to be used for motion estimation, motion compensation, and image coding.

After the motion information estimated by the motion estimation unit 1, the internal image information encoded by the image information encoder 4, and the shape information encoded by the shape information encoder 9 are multiplexed by the multiplexer 11, It is sent to the bitstream through the output buffer 12.

The data input and transmitted to the multiplexer 11 are motion vector information from the motion estimation unit 1, macroblock header information from the video information encoding unit 4, video data information, and the like. Uses a variable length coding code.

However, it is not necessary to process a large amount of video information of HDTV in real time, but relatively small video information (CIF: 352 * 288, QCIF: 176 * 144) that can process even a low transmission line that a transmission channel allows. When variable length coding is required, an apparatus for encoding image information coded (texture coded) with variable length in encoding of the international standard MPEG4 should be implemented to process a relatively small amount of image information for a low transmission line.

Accordingly, the present invention has been proposed by the necessity of the prior art as described above, and an object of the present invention is

In the video compression encoding apparatus, variable length coding is performed on relatively small image information through a low transmission line allowed by a transmission channel, error loss can be recovered during variable length coding, and compatibility with reverse variable length coding is performed. The present invention provides a variable length encoder of a moving picture compression encoding apparatus.

In order to achieve the above object, the variable length encoder of the video compression encoding apparatus according to the present invention,

Coded Block Pattern for Luminance (CBPY) among macroblock header information from image coding is processed by VLC code according to intra_inter flag (control signal for selecting intra frame encoding and inter frame encoding) A luminance block pattern processing unit;

An MCBPC defining macroblock type (MB type) and CBPC (Coded Block Pattern for Chrominance) information in the macroblock header information as a VLC code;

A motion vector difference processor (MVD) for processing a difference value between a previous motion vector, which is one of the macroblock header information, and a current motion vector, by a VLC code;

A luminance DCT DC size processing unit for processing a VLC code for luminance DCT DC size (dct_dc_size_lum.), Which is one of macroblock header information;

A color difference DCT DC size processing unit for processing a VLC code for color difference DCT DC size (dct_dc_size_chro.) Which is one of macroblock header information;

An input buffer for receiving and buffering DCT coefficients TCEGF that have undergone a zigzag scan during image coding and outputting the RLC according to a clock rate required for VLC considering an escape mode;

An RLC which performs run length coding (RLC) on the DCT AC coefficients output from the input buffer and outputs control information necessary for VLC encoding;

Control signal (RVLC flag) for selecting reverse variable length coding (RVLC) and variable length coding (VLC), control signal for selecting H.263 TCOEF VLC (H.263 flag), intra frame coding and inter frame coding Selectively receiving a control signal (intra_inter flag) for selecting RVLC, intra TCOEF variable length coding (VLC), inter TCOEF VLC, and H.263 TCOEF VLC to perform selectively from the RLC First to fourth switches each of which switches a path of?

Intra TCOEF / MPEG4 intra ESC to perform VLC in MPEG4 intra TCOEF in intraescape mode when selected by the first to third switches. Execution unit;

Inter TCOEF / MPEG4 inter ESC, which performs VLC with MPEG4 inter TCOEF in inter escape mode when selected by the first to third switches. Execution unit;

TCOEF / H.263 ESC to perform an escape mode using H.263 TCOEF using inter frame encoding when selected by the first and second switches. Execution unit;

Intra RVLC TCOEF / ESC performing RVLC performing intra TCOEF when selected by the first, second, and fourth switches and performing fixed length coding (FLC) in escape mode. FLC execution unit;

RVLC performs inter TCOEF when selected by the first, second, and fourth switches, and performs fixed length coding (FLC) in escape mode. It consists of the FLC execution unit is characterized by its technical configuration.

In order to achieve the above object, the variable length encoder of the video compression encoding apparatus according to the present invention,

TCOEF VLC / RVLC ESC which performs normal VLC function and RVLC function according to RVLC flag and FLC in VLC escape mode. Execution unit;

TCOEF VLC / RVLC ESC. A TCOEF bit stream generator for reconstructing the variable length coded code and the fixed length coded code (FLC) code output from the execution unit into blocks (TCOEF VLC / RVLC buffers) in a unit of blocks in a block unit;

A technical feature of the present invention is that the TCOEF VLC / RVLC buffer (RAM) stores the TCOEF bit stream output from the TCOEF bit stream generator.

1 is a block diagram of an encoder of the international standard MPEG4;

2 is a block diagram of a variable length encoder of a moving picture compression encoding apparatus according to the present invention;

3 is a view showing an escape mode processing operation in MPEG4 encoding;

4 is a block diagram of an apparatus for outputting variable length encoding in a video compression encoding apparatus according to another embodiment of the present invention;

5 is a TCOEF VLC / RVLC ESC of FIG. 4; Internal block diagram of an execution unit,

6 is an intra / inter TCOEF VLC VLC ESC of FIG. 5; Internal block diagram of an execution unit,

7 is an intra / inter TCOEF RVLC RVLC ESC of FIG. 5; Internal block diagram of the execution unit.

<Explanation of symbols for the main parts of the drawings>

100: CBPY 110: MCBPC

120: MVD 130: luminance DCT DC size processing unit

140: color difference DCT DC size processing unit 201: input buffer

202: RLC 203-206: first to fourth switches

207: intra TCOEF / MPEG4 intra ESC. Execution Department

208: inter TCOEF / MPEG4 inter ESC. Execution Department

209: TCOEF / H.263 ESC. Execution Department

210: intra RVLC TCOEF / ESC. FLC Execution Unit

211: inter RVLC / TCOEF ESC. FLC Execution Unit

Hereinafter, the variable length encoder of the video compression encoding apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

The present invention is a complex structure of variable length coding (VLC) according to MPEG4 simple profile, variable length coding of H.263, and reverse variable length coding (RVLC) effective for error transmission. For example, shape information encoding is not considered in simple profile.

Table 1 shows a variable length coding table (VLC table) used for variable length coding of the MPEG4 simple profile encoder.

VLC Table Name Index number Number of bits Remarks One mcbpc for I-VOPs 9 1-9 2 mcbpc for P-VOPs 21 1-9 3 cbpy for four non-transparent blocks 16 2-6 4 MVD 65 1-13 5 dct_dc_size_luminance 9 2-7 Not N-bit 6 dct_dc_size_chrominance 9 2-7 Not N-bit 7 Intra Lum. And Chr. TCOEF 113 3-13 8 Inter Lum. And Chr. TCOEF 113 3-13 9 RVLC for intra TCOEF 169 4-16 10 RVLC for inter TCOEF 169 4-16

And the H.263 VLC table structure is shown in [Table 2].

VLC Table Name Index number Number of bits Compare with MPEG4 One mcbpc for I-VOPs 9 1-9 same 2 mcbpc for P-VOPs 21 1-9 same 3 cbpy for four blocks 16 2-6 same 4 MVD 65 1-13 Different configuration 5 Inter TCOEF 113 3-13 Same (escape different)

2 is a block diagram of an embodiment of a variable length encoder of a video compression encoding apparatus according to the present invention.

It has a complex structure of variable length coding conforming to MPEG4 simple profile, variable length coding of H.263, and reverse variable length coding (RVLC) effective for error transmission.

In other words, the macroblock header information and the image data derived from the image coding are processed separately. The luminance block pattern (CBPY) of the macroblock header information is converted into an intra_inter flag (intra frame encoding). a luminance block pattern processing unit 100 processing the VLC code according to a control signal for selecting inter frame encoding; MCBPC 110 for defining the information of the macro block type (MB type) and CBPC (Coded Block Pattern for Chrominance) of the macro block header information as a VLC code; A motion vector difference processor (MVD) 120 for processing a difference value between a previous motion vector, which is one of the macroblock header information, and a current motion vector, by a VLC code; A luminance DCT DC size processing unit 130 for processing a VLC code for luminance DCT DC size (dct_dc_size_lum.) Which is one of macroblock header information; A color difference DCT DC size processing unit 140 for processing a VLC code for color difference DCT DC size (dct_dc_size_chro.) Which is one of macroblock header information; Input buffer that receives and buffers DCT coefficients (TCOEF) that have undergone zigzag scan during image coding, and outputs them to the RLC 203 according to the clock rate necessary for VLC considering escape mode. 201; An RLC (202) for performing RLC (Run Length Coding) on the DCT AC coefficient output from the input buffer 201 and outputting control information necessary for VLC encoding; Control signal (RVLC flag) for selecting reverse variable length coding (RVLC) and variable length coding (VLC), control signal for selecting H.263 TCOEF VLC (H.263 flag), intra frame coding and inter frame coding The RLC (optionally) receives a control signal (intra_inter flag) for selecting the RLC, and performs reverse variable length coding (RVLC), intra TCOEF variable length coding (VLC), inter TCOEF VLC, and H.263 TCOEF VLC. First to fourth switches 203-206 that respectively switch paths from 202; Intra TCOEF / MPEG4 intra ESC for performing VLC in MPEG mode by intra-escape mode when the first to third switches 203-205 are selected. Execution unit 207; Inter TCOEF / MPEG4 inter ESC, which performs VLC in the MPEG4 inter TCOEF in an inter escape mode when the first to third switches 203-205 are selected. An execution unit 208; TCOEF / H.263 ESC, when selected by the first and second switches 203 and 204, performs an escape mode using H.263 TCOEF using inter frame encoding. Execution unit 209; Intra RVLC TCOEF / ESC.FLC execution unit 210 performs RVLC to perform intra TCOEF when selected by the first, second and fourth switches 203, 204 and 206 and fixed length coding (FLC) in escape mode. )Wow; RVLC inter TCOEF when selected by the first, second, and fourth switch (203, 204, 206) and fixed length coding (FLC) in escape mode. It consists of a FLC execution unit 211.

The control information required for VLC encoding output from the RLC 202 includes: LAST indicating whether the non-zero DCT coefficient to be encoded is the last non-zero DCT coefficient in the block, LEVEL indicating a non-zero coefficient value, and encoding. RUN indicating the number of consecutive zeros before the count.

The first switch 203 switches the control information (LAST, LEVEL, RUN) output from the RLC 202 to one of the second switch 204 and the fourth switch 206 according to the RVLC flag. The second switch 203 transmits the information output from the first switch 203 to the third switch 205 and the TCOEF / H.263 ESC. The third switch 205 switches the information output from the second switch 204 to the intra TCOEF / MPEG4 intra ESC. Execution unit 207 and inter TCOEF / MPEG4 inter ESC. The fourth switch 206 switches the information output from the first switch 203 to the intra RVLC TCOEF / ESC. FLC execution unit 210 and inter RVLC TCOEF / ESC. Switch to one of the FLC execution unit 211.

The operation of the variable length encoder of the video compression encoding apparatus according to the present invention as described above is as follows.

The information input to the input buffer 201 is information that has undergone a zigzag scan with coefficients derived from image encoding. In the input buffer 201, the coefficients are read into the RLC 202 according to the clock rate required for the VLC considering the escape mode, and the RLC 202 calculates the Run Length Coding to obtain RUN, LEVEL, and LAST. )

RVLC flags, H.263 flags, and Intra_Inter flags are used to select each module 207, 208, 209, 210 and 211.

The MPEG4 Inter TCOEF VLC table is identical to the H.263 TCOEF VLC table. However, escape mode is configured differently.

The macroblock header information from the image information coding (texture coding) and the image data are processed separately. Referring to the macroblock header information processing operation, the CBPY 100 VLCs the luminance block pattern, and the MCBPC 110 Defines MB type and CBPC (Coded Block Pattern for Chrominance) information as VLC code. In addition, the MVD 120 VLC the difference value between the previous motion vector and the current motion vector, the luminance DCT DC size processor 130 VLC the luminance DCT DC size, and the color difference DCT DC size processor 140 is the color difference DCT. VLC the DC magnitude.

Now, following the operation of the RLC, which is the image data processing, the operation of the RLC is performed. The RLC is performed on the AC coefficient value output from the input buffer 201 to output a series of events consisting of LAST, RUN, and LEVEL. To allow VLC coding.

In this case, when LAST is '0', it means that there are more non-zero coefficients in the block, and '1' means that non-zero coefficients no longer exist in the block.

In this way, the method of outputting LAST, RUN, and LEVEL by performing RLC in code is as follows.

count <= count + 1;

if (! AC_Coefficient) begin

run_cnt <= run_cnt + 1;

RLC_E <= 1'b0;

end

else begin

run_cnt <= 0;

LEVEL_tmp <= AC_Coefficient;

RUN_tmp <= run_cnt;

if (LEVEL_tmp! = 12'd0)

RLC_E <= 1'b1;

end

LEVEL <= LEVEL_tmp;

RUN <= RUN_tmp;

if (count == 65) begin -------- (1)

LAST <= 1'b1;

LEVEL <= LEVEL_tmp;

RUN <= RUN_tmp;

RLC_E <= 1'b1;

end

The input is AC_Coefficient, count flag (64 or 65), and the output is RUN, LEVEL, LAST, RLC_E (RLC_Enable). In intra mode, count == 65 in (1) is changed to 64 since LAST must be determined without subtracting the DC value. However, if Intra_dc_thr is used to process DC value in the same way as AC value, it is treated as 65 even in Intra mode. Actual RUN, LEVEL, and LAST information is represented by RLC_Enable.

3 shows an escape mode processing operation in MPEG4 encoding.

The conventional escape mode processing methods in MPEG1, MPEG2, H.261, and H.263 performed fixed length coding (FLC). However, as shown in FIG. 3, the MPEG4 escape mode applied to the present invention is processed in three steps to improve the image compression rate. In other words, it is divided into Intra TCOEF and Inter TCOEF and uses different tables, and different tables for changing LEVEL and RUN values in escape mode.

But the content of the signal flow is similar. First, the TCOEF VLC code is determined by referring to the TCOEF VLC table with the RUN, LEVEL, and LAST values from the RLC 202. Therefore, if a value exists in the corresponding index of the TCOEF VLC table, normal VLC is performed (ST11, ST12).

However, if no value exists in the corresponding index of the TCOEF VLC table, it is selected as escape mode. So we change the LEVEL value. The changed LEVEL value is LEVEL +, which is sign (LEVEL) * [abs (LEVEL) -LMAX] (ST13) (first step). Where LMAX is the maximum value of LEVEL for a given pair (LAST, RUN).

After changing the LEVEL value, the TCOEF VLC code is determined if there is a value in the corresponding index by referring to the same TCOEF VLC table (ST14, ST15).

However, if no value exists in the TCOEF VLC table in ST14, and the escape mode is selected again, the RUN value is changed. The changed RUN value is RUN +, which is RUN- (RMAX + 1) (ST16) (second stage). Where RMAX is the maximum value of RUN for a given pair (LAST, LEVEL).

After changing the RUN value like this, the TCOEF VLC code is determined by referring to the same TCOEF VLC table again (ST17, ST18). However, if the escape mode is selected because the VLC code does not exist in the TCOEF VLC table, FLC (Fixed Length Coding) is performed (ST19) (step 3).

The above operation is performed in the same way in Intra and Inter, and the configuration of the table is different.

4 is a block diagram of an apparatus for outputting variable length encoding in a video compression encoding apparatus according to another embodiment of the present invention.

TCOEF VLC / RVLC ESC which performs normal VLC function and RVLC function according to RVLC flag and FLC in VLC escape mode. Execution unit 300; TCOEF VLC / RVLC ESC. TCOEF bit stream generator 400 for reconstructing the variable length coding (VLC) code and the fixed length coding (FLC) code output from the execution unit 300 into the RAM 500 in a single bit string in block units )Wow; The TCOEF VLC / RVLC buffer (RAM) 500 stores the TCOEF bit string output from the TCOEF bit stream generator 400.

TCOEF VLC / RVLC ESC. As shown in FIG. 5, if the RVLC flag indicates VLC execution, the execution unit 300 performs a normal VLC function and performs FLC in VLC escape mode. Execution unit 310; Intra / inter TCOEF RVLC RVLC ESC. Performing RVLC function and performing FLC in RVLC escape mode if the RVLC flag indicates RVLC execution. Execution unit 320; According to the RVLC flag, the intra / inter TCOEF VLC VLC ESC. The intra / inter TCOEF VLC / FLC code and the intra / inter TCOEF RVLC RVLC ESC output from the execution unit 310. It consists of a TCOEF VLC / FLC multiplexer 330 for multiplexing the intra / inter TCOEF RVLC / FLC code output from the execution unit 320 to output the VLC code and FLC code to the TCOEF bit stream generator 400.

The intra / inter TCOEF VLC VLC ESC. As shown in FIG. 6, the execution unit 310 searches for a desired VLC mode in the TCOEF VLC table, determines whether the escape mode is based on the result, and transmits an escape mode signal to the timing controller 313 in the escape mode. An intra / inter TCOEF VLC performer 315 performing variable length coding according to the determined mode; An intra / inter RMAX and RUN + calculator 311 for calculating RMAX and RUN +; An intra / inter LMAX and LEVEL + calculator 312 for calculating LMAX and LEVEL +; The RMAX and RUN + calculated by the intra / inter RMAX and RUN + calculator 311 are provided, and the LMAX and LEVEL + calculated by the intra / inter LMAX and LEVEL + calculator 312 are received and the intra / inter TCOEF VLC is provided. A timing controller 313 performing a LEVEL and LEVEL + selection function, a RUN and RUN + selection function, and an operation control function of each corresponding block according to the escape mode signal received from the execution unit 315; An LEVEL absolute value calculator 314 for calculating an absolute value of LEVEL for TCOEF encoding under the control of the timing controller 313; The intra / inter TCOEF VLC is performed by the intra / inter TCOEF VLC execution unit 315 using the data output from the LEVEL absolute value calculation unit 314 at the end of variable length encoding using RUN, LEVEL, and LAST. A sign bit adder 317 for adding a sign bit to data from the section 315; An MPEG4 / H.263 TCOEF FLC performer 316 which operates according to an operation control signal of the timing controller 313 and performs FLC encoding on DCT coefficients of MPEG4 and H.263, respectively; Under the control of the timing controller 313, an intra / inter TCOEF VLC / FLC multiplexer 318 multiplexes the output of the code bit ether 317 and the output of the MPEG4 / H.263 TCOEF FLC execution unit 316. It is composed of

The intra / inter TCOEF RVLC RVLC ESC. The performing unit 320 includes, as shown in FIG. 7, an LEVEL absolute value calculating unit 321 for calculating an absolute value of the LEVEL for TCOEF encoding; An intra / inter TCOEF RVLC execution unit 322 for performing an RVLC by receiving the signal output from the LEVEL absolute value calculator 321, an RLC enable signal, an RVLC flag, and an intra_inter flag; A sign bit adder (323) for adding the LEVEL sign bit from the LEVEL absolute value calculator (321) to the RVLC coded code output from the intra / inter TCOEF RVLC performer (322); a TCOEF RVLC FLC execution unit 324 for performing FLC in the escape mode; The output of the TCOEF RVLC FLC execution unit 324 and the output of the sign bit adder 323 are multiplexed according to an escape mode signal from the intra / inter TCOEF RVLC execution unit 322 to perform the TCOEF VLC / FLC multiplexer. An intra / inter TCOEF RVLC / FLC multiplexer 325 is output to 330.

The operation of the apparatus for outputting the variable length encoding of the video compression encoding apparatus according to another embodiment of the present invention as described above is as follows.

TCOEF VLC / RVLC ESC. The execution unit 300 performs the normal VLC function and the RVLC function according to the RVLC flag, and performs the FLC in the VLC escape mode. The TCOEF bit stream generator 400 includes TCOEF VLC / RVLC ESC. The variable length coding (VLC) code and the fixed length coding (FLC) code outputted from the execution unit 300 are reconstructed to be written to the RAM 500 in one bit string in block units. The TCOEF VLC / RVLC buffer (RAM) 500 stores the TCOEF bit stream output from the TCOEF bit stream generator 400 and outputs it to a desired place.

TCOEF VLC / RVLC ESC. The operation of the execution unit 300 will be described in more detail. As shown in FIG. 5, two modules 310 and 320 are selected using the RVLC flag.

That is, if the RVLC flag indicates VLC performance, intra / inter TCOEF VLC VLC ESC. The execution unit 310 performs the normal VLC function and performs the FLC in the VLC escape mode. And if the RVLC flag indicates RVLC performance, intra / inter TCOEF RVLC RVLC ESC. The execution unit 320 performs the RVLC function and performs the FLC in the RVLC escape mode.

intra / inter TCOEF VLC VLC ESC. The performing unit 310 encodes MPEG-4 and H.263 using the same TCOEF VLC table, and performs intra / inter TCOEF RVLC RVLC ESC. The execution unit 320 encodes MPEG-4 and H.263 using different VLC tables.

The TCOEF VLC / FLC multiplexer 330 performs the intra / inter TCOEF VLC VLC ESC. The intra / inter TCOEF VLC / FLC code and the intra / inter TCOEF RVLC RVLC ESC output from the execution unit 310. The intra / inter TCOEF RVLC / FLC code output from the execution unit 320 is multiplexed to output the VLC code and the FLC code to the TCOEF bit stream generator 400.

And the intra / inter TCOEF VLC VLC ESC. Referring to the operation of the execution unit 310 in more detail as shown in Figure 6, the intra / inter TCOEF VLC execution unit 315, with RUN, LEVEL, LAST, first finds the index in the TCOEF VLC table, In the escape mode, the escape mode signal is transmitted to the timing controller 313. Then, the timing controller 313 selects the LEVEL + values already found by the intra / inter LMAX and LEVEL + calculator 312 and transmits them to the intra / inter TCOEF VLC performer 315 and searches for the TCOEFVLC table again. As a result, when escape mode is selected again, the TCOEF VLC table is referred to with the pre-selected RUN +. As a result, when the escape mode is selected again, the timing controller 313 controls the MPEG4 / H.263 TCOEF FLC execution unit 316 to perform FLC.

This method is the same for Intra TCOEF and Inter TCOEF, and the actual configuration table and the LEVEL + and RUN + reference tables are different. And Inter TCOEF VLC applies the same as H.263 VLC.

Since the FLC method is different in the escape mode, the FLC method is switched by the H.263 flag.

Meanwhile, the LEVEL absolute value calculator 314 calculates the absolute value of the LEVEL value. The signbit adder adds a sign_bit to an unsigned VLC code which is an output signal of the intra / inter TCOEF VLC execution unit 315.

The intra / inter TCOEF VLC / FLC multiplexer 318 multiplexes the output of the code bit ether 317 and the output of the MPEG4 / H.263 TCOEF FLC performer 316 under the control of the timing controller 313. Output to the TCOEF VLC / FLC multiplexer 330.

See also intra / inter TCOEF RVLC RVLC ESC. Referring to the operation of the execution unit 320 in detail, as shown in Figure 7, the RVLC table configuration of the Intra RVLC and Inter RVLC is different. When the RVLC is in the escape mode, both the Intra frame coding and the Inter frame coding are the same in the FLC method.

Process sign bits of LEVEL using mode information selected for RVLC encoding, perform FLC when in escape mode, and indicate their escape mode in the intra / inter TCOEF RVLC / FLC multiple call unit 325. The signal is multiplexed according to a signal and output to the TCOEF VLC / FLC multiplexer 330.

As described above, the variable length encoder of the video compression encoding apparatus performs variable length encoding on relatively small image information through a low transmission line allowed by a transmission channel in the video compression encoding apparatus, and loses an error in variable length encoding. Can be recovered and has compatibility with Reverse Variable Length Coding.

Claims (8)

An apparatus for performing variable length encoding on relatively little image information through a low transmission line allowed by a transmission channel in a video compression encoding apparatus, Coded Block Pattern for Luminance (CBPY) among macroblock header information from image coding is processed by VLC code according to intra_inter flag (control signal for selecting intra frame encoding and inter frame encoding) A luminance block pattern processing unit; An MCBPC defining macroblock type (MB type) and CBPC (Coded Block Pattern for Chrominance) information in the macroblock header information as a VLC code; A motion vector difference processor (MVD) for processing a difference value between a previous motion vector, which is one of the macroblock header information, and a current motion vector, by a VLC code; A luminance DCT DC size processing unit for processing a VLC code for luminance DCT DC size (dct_dc_size_lum.), Which is one of macroblock header information; A color difference DCT DC size processing unit for processing a VLC code for color difference DCT DC size (dct_dc_size_chro.) Which is one of macroblock header information; An input buffer for receiving and buffering DCT coefficients TCEGF that have undergone a zigzag scan during image coding and outputting the RLC according to a clock rate required for VLC considering an escape mode; An RLC which performs run length coding (RLC) on the DCT AC coefficients output from the input buffer and outputs control information necessary for VLC encoding; Control signal (RVLC flag) for selecting reverse variable length coding (RVLC) and variable length coding (VLC), control signal for selecting H.263 TCOEF VLC (H.263 flag), intra frame coding and inter frame coding Selectively receiving a control signal (intra_inter flag) for selecting RVLC, intra TCOEF variable length coding (VLC), inter TCOEF VLC, and H.263 TCOEF VLC to perform selectively from the RLC First to fourth switches each of which switches a path of? Intra TCOEF / MPEG4 intra ESC to perform VLC in MPEG4 intra TCOEF in intra escape mode when selected by the first to third switches. Execution unit; Inter TCOEF / MPEG4 inter ESC, which performs VLC with MPEG4 inter TCOEF in inter escape mode when selected by the first to third switches. Execution unit; TCOEF / H.263 ESC to perform an escape mode using H.263 TCOEF using inter frame encoding when selected by the first and second switches. Execution unit; Intra RVLC TCOEF / ESC performing RVLC performing intra TCOEF when selected by the first, second, and fourth switches and performing fixed length coding (FLC) in escape mode. FLC execution unit; RVLC performs inter TCOEF when selected by the first, second, and fourth switches, and performs fixed length coding (FLC) in escape mode. A variable length encoder of a moving picture compression encoding apparatus, characterized by comprising an FLC performer. The method of claim 1, wherein the control information required for VLC coding output from the RLC, LAST indicating whether the non-zero DCT coefficient to be encoded is the last non-zero DCT coefficient in the block, LEVEL indicating the value of the non-zero coefficient, and RUN indicating the number of consecutive zeros before the encoded coefficient. Variable length encoder of a compression encoder. The method of claim 1, The first switch switches the control information (LAST, LEVEL, RUN) output from the RLC to one of the second switch and the fourth switch according to the RVLC flag, and the second switch is output from the first switch. The third switch and the TCOEF / H.263 ESC. The third switch is configured to switch to one of the performing units, and the third switch transmits the information output from the second switch according to the intra_inter flag. Execution unit and the inter TCOEF / MPEG4 inter ESC. Switch to one of the performing units, and the fourth switch is configured to transmit the information output from the first switch according to the intra_inter flag. FLC execution unit and the inter RVLC TCOEF / ESC. Variable length encoder of the video compression encoding apparatus, characterized in that for switching to one of the FLC performer. In a variable length encoding apparatus for a relatively small image information through a low transmission line allowed by a transmission channel in a video compression encoding apparatus, TCOEF VLC / RVLC ESC which performs normal VLC function and RVLC function according to RVLC flag and FLC in VLC escape mode. Execution unit; TCOEF VLC / RVLC ESC. A TCOEF bit stream generator for reconstructing the variable length coded code and the fixed length coded code (FLC) code output from the execution unit into blocks (TCOEF VLC / RVLC buffers) in a unit of blocks in a block unit; And a TCOEF VLC / RVLC buffer (RAM) for storing the TCOEF bit stream output from the TCOEF bit stream generator. The method of claim 4, wherein the TCOEF VLC / RVLC ESC. Execution unit, If the RVLC flag indicates VLC performance, intra / inter TCOEF VLC VLC ESC performs normal VLC function and FLC in VLC escape mode. Execution unit; Intra / inter TCOEF RVLC RVLC ESC. Performing RVLC function and performing FLC in RVLC escape mode if the RVLC flag indicates RVLC execution. Execution unit; According to the RVLC flag, the intra / inter TCOEF VLC VLC ESC. An intra / inter TCOEF VLC / FLC code and an intra / inter TCOEF RVLC RVLC ESC. And a TCOEF VLC / FLC multiplexer for multiplexing the intra / inter TCOEF RVLC / FLC codes output from a processor to output VLC codes and FLC codes to the TCOEF bit stream generator. The method of claim 5, The intra / inter TCOEF VLC VLC ESC. The performing unit encodes using the same TCOEF VLC table for MPEG4 and H.263, and performs the intra / inter TCOEF RVLC RVLC ESC. And the execution unit encodes using MPEG V and H.263 using different VLC tables. The method of claim 5, wherein the intra / inter TCOEF VLC VLC ESC. Execution unit, Search for the desired VLC mode in the TCOEF VLC table to determine whether it is an escape mode, if it is an escape mode, send an escape mode signal to the timing controller, and perform intra / inter TCOEF VLC according to the determined mode. Execution unit; An intra / inter RMAX and RUN + calculator for calculating RMAX and RUN +; An intra / inter LMAX and LEVEL + calculator for calculating LMAX and LEVEL +; The escape received from the intra / inter RMAX, RUN + calculator, the RMAX, RUN +, LMAX, LEVEL + calculated by the intra / inter LMAX, LEVEL + calculator, and received from the intra / inter TCOEF VLC execution unit A timing controller which performs a LEVEL and LEVEL + selection function and a RUN and RUN + selection function and performs an operation control function of each corresponding block according to the mode signal; A LEVEL absolute value calculator for calculating an absolute value of the LEVEL for TCOEF encoding according to the control of the timing controller; Signing the data from the intra / inter TCOEF VLC performer using data output from the LEVEL absolute value calculator at the end of variable length encoding using RUN, LEVEL, and LAST in the intra / inter TCOEF VLC performer A sign bit adder for adding a bit; An MPEG4 / H.263 TCOEF FLC performer which operates according to an operation control signal of the timing controller and performs FLC encoding on DCT coefficients of MPEG4 and H.263, respectively; According to the control of the timing controller, the variable length of the video compression encoding apparatus comprising an intra / inter TCOEF VLC / FLC multiplexer for multiplexing the output of the code bit ether and the output of the MPEG4 / H.263 TCOEF FLC execution unit. Encoder. The method of claim 5, wherein the intra / inter TCOEF RVLC RVLC ESC. Execution unit, An absolute value calculation unit for calculating an absolute value of the level for TCOEF encoding; An intra / inter TCOEF RVLC execution unit configured to perform RVLC by receiving the signal output from the LEVEL absolute value calculator, an RLC enable signal, an RVLC flag, and an intra_inter flag; A sign bit adder for adding the LEVEL sign bit from the LEVEL absolute value calculator to the RVLC coded code output from the intra / inter TCOEF RVLC performer; a TCOEF RVLC FLC execution unit for performing FLC in the escape mode; Intra / inter TCOEF RVLC / FLC multiplexing outputting the output of the TCOEF RVLC FLC execution unit and the sign bit adder to the TCOEF VLC / FLC multiplexer by multiplexing the output of the sign bit adder from the intra / inter TCOEF RVLC execution unit. A variable length encoder of a moving picture compression encoding apparatus, comprising: