Patent Application
20180091812
The present disclosure is directed to video decoding techniques and, in particular, to selection of deblocking filter parameters.
A deblocking filter is a video filter applied to decoded compressed video to improve visual quality and prediction performance by smoothing the sharp edges that can arise from block-based coding artifacts. Filtering aims to improve the appearance of decoded pictures by reducing these artifacts.
Deblocking filtering techniques are defined in the ITU H.264 and H.265 (also “HEVC”) coding protocols. Deblocking filtering must be performed “in loop;” they are applied to reference frames that are stored for use in prediction of other image data to be coded after the reference frames are coded. When a stream is encoded, the filter strength can be selected, or the filter can be switched off entirely. Otherwise, the filter strength is determined by coding parameters (including coding modes, motion vectors, reference frames and coded residue) of adjacent blocks, quantization step size, and the steepness of the luminance gradient between blocks.
The filter operates on the edges of each 4×4 or 8×8 block in the luma and chroma planes of each picture. Only the edges that are either prediction block edges or transform block edges are subject to deblocking. Each small block's edge is assigned a boundary strength based on the coding modes (intra/inter) of the blocks, whether references (in motion prediction and reference frame choice) differ, whether any of the blocks have coded residue, and whether it is a luma or chroma edge. Stronger levels of filtering are assigned by this scheme where there is likely to be more distortion. The filter can modify as many as three samples on either side of a given block edge (in the case where an edge is a luma edge that has “Strong Filtering Mode”). In most cases it can modify one or two samples on either side of the edge (depending on the quantization step size, the tuning of the filter strength by the encoder, the result of an edge detection test, and other factors).
The inventors have determined that presently-available deblocking techniques do not provide optimal performance. Accordingly, they have identified a need in the art for deblocking techniques that improve quality of image data recovered by video decoders.
Embodiments of the present invention provide techniques for selecting deblocking filter parameters in a video decoding system. According to these techniques, a boundary strength parameter may be determined based, at least in part, on a bit depth of decoded video data. Activity of a pair of decoded pixel blocks may be classified based, at least in part, on a bit depth of decoded video data, and when a level of activity indicates that deblocking filtering is to be applied to the pair of pixel blocks, pixel block content at a boundary between the pair of pixel blocks may be filtered using filtering parameters derived at least in part based on the bit depth of the decoded video data. The filtering parameters may decrease strength with increasing bit depth of the decoded video data, which improves quality of the decoded video data.
A video coding system 100 may be used in a variety of applications. In a first application, the terminals 110, 150 may support real time bidirectional exchange of coded video to establish a video conferencing session between them. In another application, a terminal 110 may code pre-produced video (for example, television or movie programming) and store the coded video for delivery to one or, often, many downloading clients (e.g., terminal 150). Thus, the video being coded may be live or pre-produced, and the terminal 110 may act as a media server, delivering the coded video according to a one-to-one or a one-to-many distribution model. For the purposes of the present discussion, the type of video and the video distribution schemes are immaterial unless otherwise noted.
In
The network represents any number of networks that convey coded video data between the terminals 110, 150, including for example wireline and/or wireless communication networks. The communication network may exchange data in circuit-switched or packet-switched channels. Representative networks include telecommunications networks, local area networks, wide area networks, and/or the Internet. For the purposes of the present discussion, the architecture and topology of the network are immaterial to the operation of the present disclosure unless otherwise noted.
The coding system 140 may perform coding operations on the video to reduce its bandwidth. Typically, the coding system 140 exploits temporal and/or spatial redundancies within the source video. For example, the coding system 140 may perform motion compensated predictive coding in which video frame or field pictures are parsed into sub-units (called “pixel blocks,” for convenience), and individual pixel blocks are coded differentially with respect to predicted pixel blocks, which are derived from previously-coded video data. A given pixel block may be coded according to any one of a variety of predictive coding modes, such as:
The coding system 140 may include a coder 142, a decoder 143, an in-loop filter 144, a picture buffer 145, and a predictor 146. The coder 142 may apply the differential coding techniques to the input pixel block using predicted pixel block data supplied by the predictor 146. The decoder 143 may invert the differential coding techniques applied by the coder 142 to a subset of coded frames designated as reference frames. The in-loop filter 144 may apply filtering techniques, including deblocking filtering, to the reconstructed reference frames generated by the decoder 143. The picture buffer 145 may store the reconstructed reference frames for use in prediction operations. The predictor 146 may predict data for input pixel blocks from within the reference frames stored in the picture buffer.
The transmitter 150 may transmit coded video data to a decoding terminal via a channel CH.
The receiver 160 may receive a data stream from the network and may route components of the data stream to appropriate units within the terminal 200. Although
The video decoder 170 may perform decoding operations that invert coding operations performed by the coding system 140. The video decoder may include a decoder 172, an in-loop filter 173, a picture buffer 174, and a predictor 175. The decoder 172 may invert the differential coding techniques applied by the coder 142 to the coded frames. The in-loop filter 144 may apply filtering techniques, including deblocking filtering, to reconstructed frame data generated by the decoder 172. For example, the in-loop filter 144 may perform various filtering operations (e.g., de-blocking, de-ringing filtering, sample adaptive offset processing, and the like). The filtered frame data may be output from the decoding system. The picture buffer 174 may store reconstructed reference frames for use in prediction operations. The predictor 175 may predict data for input pixel blocks from within the reference frames stored by the picture buffer according to prediction reference data provided in the coded video data.
The post-processor 180 may perform operations to condition the reconstructed video data for display. For example, the post-processor 180 may perform various filtering operations (e.g., de-blocking, de-ringing filtering, and the like), which may obscure visual artifacts in output video that are generated by the coding/decoding process. The post-processor 180 also may alter resolution, frame rate, color space, etc. of the reconstructed video to conform it to requirements of the video sink 190.
The video sink 190 represents various hardware and/or software components in a decoding terminal that may consume the reconstructed video. The video sink 190 typically may include one or more display devices on which reconstructed video may be rendered. Alternatively, the video sink 190 may be represented by a memory system that stores the reconstructed video for later use. The video sink 190 also may include one or more application programs that process the reconstructed video data according to controls provided in the application program. In some embodiments, the video sink may represent a transmission system that transmits the reconstructed video to a display on another device, separate from the decoding terminal; for example, reconstructed video generated by a notebook computer may be transmitted to a large flat panel display for viewing.
The foregoing discussion of the encoding terminal and the decoding terminal (
The pixel block coder 210 may include a subtractor 212, a transform unit 214, a quantizer 216, and an entropy coder 218. The pixel block coder 210 may accept pixel blocks of input data at the subtractor 212. The subtractor 212 may receive predicted pixel blocks from the predictor 250 and generate an array of pixel residuals therefrom representing a difference between the input pixel block and the predicted pixel block. The transform unit 214 may apply a transform to the pixel residual s output from the subtractor 212 to convert the residual data from the pixel domain to a domain of transform coefficients. The quantizer 216 may perform quantization of transform coefficients output by the transform unit 214. The quantizer 216 may be a uniform or a non-uniform quantizer. The entropy coder 218 may reduce bandwidth of the output of the quantizer by coding the output, for example, by variable length code words.
During operation, the quantizer 216 may operate according to coding parameters that govern each unit's operation. The quantizer 216 may operate according to a quantization parameter (QP) that determines a level of quantization to apply to the transform coefficients input to the quantizer 216. The quantization parameter may be selected by a controller 260 based on an estimate of a target bitrate that each coded frame should match and also based on analyses of each frame's image content. The quantization parameters QP may be signaled in coded video data output by the coding system 200, either expressly or impliedly.
The transform unit 214 may operate in a variety of transform modes as events warrant. For example, the transform unit 214 may be selected to apply a DCT, a DST, a Walsh-Hadamard transform, a Haar transform, a Daubechies wavelet transform, or the like. In an embodiment, a controller 260 may select a coding mode M to be applied by the transform unit 214 and may configure the transform unit 214 accordingly. The coding mode M also may be signaled in the coded video data, either expressly or impliedly.
The pixel block decoder 220 may invert coding operations of the pixel block coder 210. For example, the pixel block decoder 220 may include a dequantizer 222, an inverse transform unit 224, and an adder 226. The pixel block decoder 220 may take its input data from an output of the quantizer 216. Although permissible, the pixel block decoder 220 need not perform entropy decoding of entropy-coded data since entropy coding is a lossless event. The dequantizer 222 may invert operations of the quantizer 216 of the pixel block coder 210. The dequantizer 222 may perform uniform or non-uniform de-quantization as specified by the decoded signal QP. Similarly, the inverse transform unit 224 may invert operations of the transform unit 214 and it may use the same transform mode M as its counterpart in the pixel block coder 210.
The adder 226 may invert operations performed by the subtractor 212. It may receive the same prediction pixel block from the predictor 250 that the subtractor 212 used in generating residual signals. The adder 226 may add the prediction pixel block to reconstructed residual values output by the inverse transform unit 224 and may output reconstructed pixel block data. Coding and decoding operations of the pixel block coder 210 and the pixel block decoder 220 are lossy processes and, therefore, decoded video data output by the pixel block decoder likely will exhibit some loss of content as compared to the input data that is supplied to the pixel block coder 210.
Where the pixel block coder 210 and pixel block decoder 220 operates on pixel block-sized increments of an image, the in loop filter 230 may operate on reassembled frames made up of decoded pixel blocks. The in-loop filter 230 may perform various filtering operations on the reassembled frames. For example, the in-loop filter 230 may include a deblocking filter 232 and a sample adaptive offset (“SAO”) filter 233. The deblocking filter 232 may filter data at seams between reconstructed pixel blocks to reduce discontinuities between the pixel blocks that arise due to coding losses. The deblocking filter may operate according to filtering parameters that are selected based on a bit depth of the decoded image data. SAO filters may add offsets to pixel values according to an SAO “type,” for example, based on edge direction/shape and/or pixel/color component level. The in-loop filter 230 may operate according to parameters that are selected by the controller 260.
The prediction buffer 240 may store filtered frame data for use in later prediction of other pixel blocks. Different types of prediction data are made available to the predictor 250 for different prediction modes. For example, for an input pixel block, intra prediction takes a prediction reference from decoded data of the same frame in which the input pixel block is located. Thus, the prediction buffer 240 may store decoded pixel block data of each frame as it is coded. For the same input pixel block, inter prediction may take a prediction reference from previously coded and decoded frame(s) that are designated as “reference frames.” Thus, the prediction buffer 240 may store these decoded reference frames.
As discussed, the predictor 250 may supply prediction data to the pixel block coder 210 for use in generating residuals. The predictor 250 may include an inter predictor 252, an intra predictor 253 and a mode decision unit 254. The inter predictor 252 may receive pixel block data representing a new pixel block to be coded and may search the prediction buffer 240 for pixel block data from reference frame(s) for use in coding the input pixel block. The inter predictor 252 may support a plurality of prediction modes, such as P mode coding and B mode coding. The inter predictor 252 may select an inter prediction mode and supply prediction data that provides a closest match to the input pixel block being coded. The inter predictor 252 may generate prediction reference indicators, such as motion vectors, to identify which portion(s) of which reference frames were selected as source(s) of prediction for the input pixel block.
The intra predictor 253 may support Intra (I) mode coding. The intra predictor 253 may search from among coded pixel block data from the same frame as the pixel block being coded that provides a closest match to the input pixel block. The intra predictor 253 also may generate prediction reference indicators to identify which portion of the frame was selected as a source of prediction for the input pixel block.
The mode decision unit 254 may select a final coding mode to be applied to the input pixel block. Typically, the mode decision unit 254 selects the prediction mode that will achieve the lowest distortion when video is decoded given a target bitrate. Exceptions may arise when coding modes are selected to satisfy other policies to which the coding system 200 adheres, such as satisfying a particular channel behavior, or supporting random access or data refresh policies. The mode decision unit 254 may output the prediction data to the pixel block coder and decoder 210, 220 and may supply to the controller 260 an identification of the selected prediction mode along with the prediction reference indicators corresponding to the selected mode.
The controller 260 may control overall operation of the coding system 200. The controller 260 may select operational parameters for the pixel block coder 210 and the predictor 250 based on analyses of input pixel blocks and also external constraints, such as coding bitrate targets and other operational parameters. As is relevant to the present discussion, when it selects quantization parameters QP, the use of uniform or non-uniform quantizers, and/or the transform mode M, it may provide those parameters to the syntax unit 270, which may include data representing those parameters in the data stream of coded video data output by the system 200. During operation, the controller 260 may revise operational parameters of the quantizer 216 and the transform unit 214 at different granularities of image data, either on a per pixel block basis or on a larger granularity (for example, per frame, per slice, per largest coding unit (“LCU”) or another region).
Additionally, as discussed, the controller 260 may control operation of the in-loop filter 230 and the prediction unit 250. Such control may include, for the prediction unit 250, mode selection (lambda, modes to be tested, search windows, distortion strategies, etc.), and, for the in-loop filter 230, selection of filter parameters, reordering parameters, weighted prediction, etc.
The pixel block decoder 320 may include an entropy decoder 322, a dequantizer 324, an inverse transform unit 326, and an adder 328. The entropy decoder 322 may perform entropy decoding to invert processes performed by the entropy coder 218 (
The in-loop filter 330 may perform various filtering operations on reconstructed pixel block data. As illustrated, the in-loop filter 330 may include a deblocking filter 332 and an SAO filter 333. The deblocking filter 332 may filter data at seams between reconstructed pixel blocks to reduce discontinuities between the pixel blocks that arise due to coding. The deblocking filter may operate according to filtering parameters that are selected based on a bit depth of the decoded image data. SAO filters may add offset to pixel values according to an SAO type, for example, based on edge direction/shape and/or pixel level. Other types of in-loop filters may also be used in a similar manner. Operation of the deblocking filter 332 and the SAO filter 333 ideally would mimic operation of their counterparts in the coding system 200 (
The prediction buffer 340 may store filtered pixel data for use in later prediction of other pixel blocks. The prediction buffer 340 may store decoded pixel block data of each frame as it is coded for use in intra prediction. The prediction buffer 340 also may store decoded reference frames.
As discussed, the predictor 350 may supply prediction data to the pixel block decoder 320. The predictor 350 may supply predicted pixel block data as determined by the prediction reference indicators supplied in the coded video data stream.
The controller 360 may control overall operation of the coding system 300. The controller 360 may set operational parameters for the pixel block decoder 320 and the predictor 350 based on parameters received in the coded video data stream. As is relevant to the present discussion, these operational parameters quantization parameters QP and transform modes M for the inverse transform unit 326. As discussed, the received parameters may be set at various granularities of image data, for example, on a per pixel block basis, a per frame basis, a per slice basis, a per LCU basis, or based on other types of regions defined for the input image.
Embodiments of the present provide techniques for selecting parameters for deblocking filtering.
If the boundary strength is non-zero, the method 400 may classify activity of the pixel blocks (box 440). Several classifications are possible, including high activity, medium activity and low activity. If a high activity classification is applied, no filtering is needed. If medium activity classification is applied, the method 400 may determine a number of pixels to modify (box 450). Then the method 400 may filter the determined number of pixels using either a normal filtering strength when medium activity classifications are applied (box 460) or a strong filtering strength when a low activity classification is applied (box 470).
As indicated, boundary strength values may be determined for pixel blocks based on a bit depth for luma components or chroma components of image data and based on coding parameters of the pixel blocks. As the luma/chroma bit depth gets larger, boundary strength values (BS) may get smaller, with the same conditions of prediction mode, motion vectors, reference frames, and residues. Two examples are illustrated in Table 1 and Table 2.
In the first example, as shown in Table 1, BS may be equal to 1 when one of two neighboring blocks is intra coded or when any other condition specified in the table is met. When none of the conditions are met, the boundary strength may be set to 0.
In another example, as shown in Table 2, when bit depth is larger than 8, the boundary strength may be set to 1 if and only if one of two neighboring blocks is intra coded. The boundary strength may be set to 0 in all other cases:
Parameters β and tC may be derived based on a bit depth for luma components of image data and quantization parameters of the pixel block and two predefined parameters slice_beta_offset_div2 and slice_tC_offset_div2. In practice, a pair of tables, called a “β-table” and a “tC-table” may be populated with values for use by the method 400. The β-table and the tC-table may store threshold values for use in activity determinations. In an embodiment, parameters β and tC may be retrieved from the β-table and tC-table using indices B and T, which may be developed as:
B=Clip(0,51,qp+(slice_beta_offset_div2<<1)), where (Eq. 1.)
qp is derived from the quantization parameters of two neighboring blocks, and slice_beta_offset_div2 represents deblocking parameter offsets for β (divided by 2) provided in a coded data stream for a slice to which the current pixel blocks belong.
The index of tC-table T may be determined based on both quantization parameter and BS as below.
T=Clip(0,53,qp+*2(BS−1)+(slice_tC_offset_div2<<1)), where (Eq. 2.)
slice_tC_offset_div2 is the value of slice syntax element slice_tC_offset_div2 and, again, may be provided in a coded data stream for a slice to which the current pixel blocks belong.
For a specific luma bit depth BD_Y, the variables β and tC may be derived as in Equations (3) and (4):
β=β′*(1<<(BD_Y−8)), and (Eq. 3.)
t
C
=t
C*(1<<(BD_Y−8)), (Eq. 4)
where the “<<” relation represents a shift operation by a predetermined number of bits. Thus, the variables β′ and tC′ for bit depth 8, which are derived from the tables, may be left-shifted according to the real bit depth BD_Y.
If BS is larger than 0 then the method may classify activity of the pixel blocks. Pixel samples across each edge of a pair of pixel blocks may be analyzed to determine local activity.
For example, pixel values may be compared against the threshold β to determine if the following relation is met:
|p2,0−2*p1,0+p0,0|+|p2,3−2*p1,3+p03,|+|q2,0−2*q1,0+q0,0|+|q2,3−2*q1,3+q0,3|<β (Eq. 5.)
If not, then high activity is present within the pixel blocks P and Q, and no filtering is required.
When BS is non-zero and the inequality in Equation (5) is met, deblocking may be applied. Deblocking may select between a normal filtering strength and a strong filtering strength based on local signal characteristics. For example, pixel values may be compared against the β and tC thresholds to determine if the following relations are met:
2*|p2,2,i−2*p1,i+p0,i|+2*|q2,i−2*q1,i+q0,i|<(β>>2), (Eq. 6.)
|p3,i−p0,i|+|g0,i−q3,i|<(β>>3), (Eq. 7.)
|p0,i−q0,i|<((5*tC+1)>>1), (Eq. 8.)
where the >> relation represents a right shift by a number of bit positions.
In this embodiment, if the Equations (6) (7) and (8) all hold for both i=0 and i=3, then low activity is present and a strong filter may be utilized. Otherwise, medium activity is present and a normal filter may be used.
When normal filtering strength is selected, the method 400 may decide how many pixels are modified. For example, the method 400 may determine if the inequality in Equation (9) is met, and, if so, two nearest pixels in block P could be changed in the filter operations (for example, in
|p2,0−2*p1,0+p0,0|+|p2,3−2*p1,3+p0,3|<(β+(β>>1))>>3 (Eq. 9.)
The method may select a number of pixels to be changed in block Q in a similar way, determining whether the following inequality is met:
|q2,0−2*q1,0+q0,0|+|q2,3−2*q1,3+q0,3|<(β+(β>>1))>>3 (Eq. 10.)
In strong filtering mode (box 470), the pixels may be changed as Equation (11).
p′=Clip((p−2*tC),(p+2*tC),pf), (Eq. 11.)
where pf is the impulse response of the filter corresponding to the pixel p.
In normal filtering (box 460), the modifications of pixels may occur as p′=p+d′. Before the offset d is added to the pixel, it may be clipped to d′ as:
d′=Clip(−c,c,d), (Eq. 12.)
where, for pixels p0, i and q0,i, c=tC and, for pixels p1,i and q1,i, c=tC>>1.
The foregoing embodiment is expected to improve operation of deblocking filters by factoring bit depth of image information in selection of deblocking parameters and, particularly boundary strength. At larger bit depths, decoded image information may be less susceptible to blocking artifacts, which lowers the need for strong deblocking. The present embodiment is expected to improve image quality, by factoring bit depth of the image information into processes that derive deblocking parameters, which may prevent deblocking filters 232 (
In another embodiment, the index of β-table B and the index of tC-table T may derived with the internal bit depth, together with BS, qp, slice_beta_offset_div2 and slice_tC_offset_div2, as:
B=Clip(0,51,qp+QpBdOffsetY+(slice_beta_offset_div2<<1)) (Eq. 13.)
T=Clip(0,53,qp+QpBdOffsetY+2*(Bs−1)+(slice_tc_offset_div2<<1)) (Eq. 14.)
where QpBdOffsetY represents a value of the luma quantization parameter range offset and is calculated as:
QpBdOffsetY=6*bit_depth_luma_minus8, and (Eq. 15.)
bit_depth_luma_minus8 specifies the bit depth of the luma samples minus 8.
Then the derived β′ and tC′ may be directly set to β and tC. There is no need to derive β and tC with β′, tC′, and bit depth as in Equations (3) and (4).
In a further embodiment, after β′ and tC′ are derived (box 420), the parameters β and tC may be modified further as:
β=β′*(1<<(BD_Y−8))*fβ (Eq. 16.)
t
C
=t
C′*(1<<(BD_Y−8))*ft
In one embodiment, fβ and ftC may be fixed coefficient values that are set smaller than or equal to 1. Alternatively, they could also be functions of luma bit depth, in which case fβ and ftC may be decreased as bit depth gets larger.
In another embodiment, bit depth may be used to generate the thresholds for filter decisions (as in Equations 5-10 above), and the clipping range values for filter operations (as in Equation 11-12). β and tC values may be derived initially without bit depth involved.
In this embodiment, a threshold X′ for filtering decisions, e.g., β in Equation (5), β>>2 in Equation (6), β>>3 in Equation (7), (5*tC+1)>>1 in Equation (8) and (β+(β>>1))>>3 in Equation (9), may be calculated first independent of bit depth. Then the threshold X for a specific bit depth may derived as:
X=X′*(1<<(BD_Y−8)) (Eq. 18.)
The clipping range value P′ for filtering operations, e.g., 2*tC in Equation 11, and c in Equation 12, also may be calculated first independent of bit depth. Then the clipping range value P for a specific bit depth may be derived as:
P=P′*(1<<(BD_Y−8)) (Eq. 19.)
In an embodiment, the threshold X and clipping value P for a specific bit depth could be further reduced as the bit depth gets larger, for example, as:
X=X′*(1<<(BDY−8))*hX (Eq. 20.)
P=P′*(1<<(BDY−8))*hP (Eq. 21.)
where hx and hp are coefficient values that smaller than or equal to 1. In one embodiment, they could be set as fixed values. Alternatively, they could vary as functions of bit depth in which hx and hp decrease as bit depth gets larger.
In a further embodiment, different filter sets may be selected for different bit depths. Consider a case where N sets of filters are used for 8 bit data, i.e., {L0, L1, L2 . . . LN−1} with decreasing strengths from L0 to LN−1. In such an implementation, N-d sets of filters may be candidates for use for 10 bit data (e.g., filters {Ld, Ld+1, . . . LN−1}) and N-e sets of filters a may be candidates for use for image data with larger bit depth (e.g., filters {Le, Le+1, . . . LN−1}). In this implementation, the filters {Le, Le+1, . . . LN−1} would be candidates for use both with the 10 bit data and the larger bit depth data but filters {Ld, Ld+1, . . . Le−1} would be candidates for use with the 10 bit data but not the larger bit depth data.
For example, at the time of this writing, the HEVC standard (ITU H.265) defines three sets of filters for use with 8 bit data. L0 is considered a strong filter, L1 is defined as the normal filter which modifies two pixel lines nearest to a block boundary, and L2 is defined as the normal filter which modifies one pixel line nearest to a block boundary. As proposed, no strong filter is used for 10 bit coding, so only L1 and L2 are used and there is no decision between strong mode and normal mode. The present embodiment would expand the set of filters that could be used for 10 bit data and would accommodate other filter definitions for image data at larger bit depths (e.g., 12-, 14- or 16-bit data).
The foregoing discussion has described the various embodiments of the present disclosure in the context of coding systems, decoding systems and functional units that may embody them. In practice, these systems may be applied in a variety of devices, such as mobile devices provided with integrated video cameras (e.g., camera-enabled phones, entertainment systems and computers) and/or wired communication systems such as videoconferencing equipment and camera-enabled desktop computers. In some applications, the functional blocks described hereinabove may be provided as elements of an integrated software system, in which the blocks may be provided as elements of a computer program, which are stored as program instructions in memory and executed by a general processing system. In other applications, the functional blocks may be provided as discrete circuit components of a hardware processing system, such as functional units within a digital signal processor or application-specific integrated circuit. Still other applications of the present invention may be embodied as a hybrid system of dedicated hardware and software components. Moreover, the functional blocks described herein need not be provided as separate elements. For example, although
Further, the figures illustrated herein have provided only so much detail as necessary to present the subject matter of the present invention. In practice, video coders and decoders typically will include functional units in addition to those described herein, including buffers to store data throughout the coding pipelines illustrated and communication transceivers to manage communication with the communication network and the counterpart coder/decoder device. Such elements have been omitted from the foregoing discussion for clarity.
Several embodiments of the invention are specifically illustrated and/or described herein. However, it will be appreciated that modifications and variations of the invention are covered by the above teachings and within the purview of the appended claims without departing from the spirit and intended scope of the invention.
