EP0536784A2
Expired / Lapsed
EP
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An adaptive coding method for interlaced scan digital video sequences
Assignee: Panasonic Holdings Corp
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Filing: 1992-10-09
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Granted: —
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Expires: 2012-10-09
Abstract
Abstract The present invention relates to efficient coding of interlaced scan video sequences. Input picture (1) is partitioned into smaller blocks (2) of pixel data where the two fields in each block are examined (3) for correlation. If the difference between the two fields in the block is low (or the correlation is high), the block will be coded (6) with a frame coding method that assumes all lines in the block are progressive scanned, and therefore, with efficient inter-frame motion compensation method and chrominance data intra-frame sub-sampling method designed. On the other hand, if the difference between the two fields in the block is high (or the correlation is low), the block will be coded (5) with a field coding method where more emphasis is made on exploring correlation within each field (intra-field) and correlation of each field and its neighboring fields (inter-field); furthermore, intra-field sub-sampling of the chrominance data is better performed in such block.
Inventors
- 👤 Lucas Hui Yau Wai
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 14:10
CPC Classifications
H; H04; H04N; H04N21/00; H04N21/40; H04N21/43; H04N21/434; H04N19/00; H04N19/10; H04N19/102; H04N19/103; H04N19/105; H04N19/112; H04N19/134; H04N19/136; H04N19/137; H04N19/50; H04N19/503; H04N19/51; H04N19/577; H04N19/60; H04N19/61; H04N21/20; H04N21/23; H04N21/236
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
104 words
A method of coding an interlaced scan digital video signal comprising the steps of: partitioning (2) each frame of said interlaced scan digital video signal (1) into smaller blocks of pixel data; determining (3) a difference of pixel values of two fields within each said block; subjecting each said block according to the determined difference to a field coding process (5) where at least one of an intra-field correlation or an inter-field correlation is exploited to achieve information compaction, or to a frame coding process (6) where at least one of an intra-frame correlation or an inter-frame correlation is exploited to achieve information compaction.
Claim 2
Dependent Claim
66 words
A method according to Claim 1, wherein the step (3) of determining a difference of pixel values of two fields within each block comprises the steps of: calculating a mean square error between even and odd line pairs of said block; calculating a mean square error between consecutive odd line pairs and consecutive even line pairs of said block; comparing the two calculated mean square errors.
Claim 3
Dependent Claim
119 words
A method according to Claim 1 or 2, wherein the frame coding process (6) comprises the steps of: determining whether or not said block needs to be subjected to an inter-frame motion compensation process (20); subjecting said block according to the determined result to said inter-frame motion compensation process (20) where an inter-frame correlation is exploited to reduce the amount of information which needs to be coded in said block; subjecting said block or the result of the inter-frame motion compensation process (20) according to the determined result to a frame restructuring process (21) so as to be spatially partitioned into smaller sub-blocks; subjecting said sub-blocks to a block coding process (22) where information in each sub-block is compressed.
Claim 4
Independent Claim
123 words
A method according to any preceding claim, wherein the field coding process (5) comprises the steps of: determining whether or not said block needs to be subjected to an inter-field motion compensation process (26); subjecting said block according to the determined result to said inter-field motion compensation process (26) where an inter-field correlation is exploited to reduce the amount of information which needs to be coded in said block; subjecting said block or the result of the inter-field motion compensation process (26) according to the determined result to a field restructuring process (25) where even lines and odd lines of said block are separated into smaller sub-blocks; subjecting said sub-blocks to a block coding process (22) where information in each sub-block is compressed.
Claim 5
Dependent Claim
178 words
A method according to Claim 3 or 4, wherein the inter-frame motion compensation process (20) comprises the steps of: determining whether to subject said block to an inter-frame motion prediction process (42, 48) or to an inter-frame motion interpolation process (47); subjecting said block according to the determined result to said inter-frame motion prediction process (42, 48) where a forward motion vector is detected with reference to a previous coded frame, a motion compensation is performed using the detected forward motion vector, and the motion compensated block is compared with the original said block; subjecting said block according to the determined result to said inter-frame motion interpolation process (47) where a forward motion vector is detected with reference to a previous coded frame, a backward motion vector is detected with reference to a future coded frame, three motion compensations are performed respectively using the detected forward motion vector, the detected backward motion vector, and both the detected forward and backward motion vectors, and comparisons are made between the three motion compensation results together with the original said block.
Claim 6
Independent Claim
36 words
A method according to any of Claims 3 to 5, wherein the frame restructuring process (21) further comprises the step of subjecting said sub-blocks that contain chrominance information to an intra-frame sub-sampling process to reduce resolution.
Claim 7
Dependent Claim
50 words
A method according to Claim 3, wherein the block coding process (22) comprises the steps of: discrete cosine transforming (80) each of said sub-blocks into DCT coefficients; quantizing (81) the DCT coefficients; zig-zag scanning (82) the quantized DCT coefficients; variable length coding (83) the result of the zig-zag scanning (82).
Claim 8
Dependent Claim
127 words
A method according to Claim 7, wherein the block decoding process comprises the steps of: demultiplexing/VLC decoding (90) the encoded information to reproduce the zig-zag scanned sub-block and the included side information describing the sub-block; inverse zig-zag scanning (91) followed by inverse quantizing (92) of said sub-block to reproduce the DCT coefficients; inverse DCT (93) processing said coefficients; subjecting the result of the inverse DCT (93) processing to an inverse of the inter-frame or inter-field motion compensation process (94,95) according to the coded picture type (I, P or B-picture) and the coded result of the inter-field difference detection process to reproduce the reconstructed sub-block; inverting (97, 98) the frame/field restructuring process according to the coded result of the inter-field difference detection process to reproduce the reconstructed block.
Claim 9
Dependent Claim
50 words
A method according to Claim 5, wherein the block coding process (22) comprises the steps of: discrete cosine transforming (80) each of said sub-blocks into DCT coefficients; quantizing (81) the DCT coefficients; zig-zag scanning (82) the quantized DCT coefficients; variable length coding (83) the result of the zig-zag scanning (82).
Claim 10
Dependent Claim
127 words
A method according to Claim 9, wherein the block decoding process comprises the steps of: demultiplexing/VLC decoding (90) the encoded information to reproduce the zig-zag scanned sub-block and the included side information describing the sub-block; inverse zig-zag scanning (91) followed by inverse quantizing (92) of said sub-block to reproduce the DCT coefficients; inverse DCT (93) processing said coefficients; subjecting the result of the inverse DCT (93) processing to an inverse of the inter-frame or inter-field motion compensation process (94,95) according to the coded picture type (I, P or B-picture) and the coded result of the inter-field difference detection process to reproduce the reconstructed sub-block; inverting (97, 98) the frame/field restructuring process according to the coded result of the inter-field difference detection process to reproduce the reconstructed block.
Claim 11
Dependent Claim
234 words
A method according to Claim 4, wherein the inter-field motion compensation process (26) comprises the steps of: determining whether to subject said block to an inter-field motion prediction process (63, 65) or to an inter-field motion interpolation process (64); subjecting said block according to the determined result to said inter-field motion prediction process (63, 65) where a first forward motion vector is detected with reference to a previous coded field for even lines of said block, a second forward motion vector is detected with reference to a previous coded field for odd lines of said block, a motion compensation is performed using the detected first and second forward motion vectors, and the motion compensated block is compared with the original said block; subjecting said block according to the determined result to said inter-field motion interpolation process (64) where first and second forward motion vectors are detected with reference to previous coded fields for the even and odd lines of said block respectively, first and second backward motion vectors are detected with reference to future coded fields for the even and odd lines of said block respectively, three motion compensations are performed using respectively the detected first and second forward motion vectors, the first and second backward motion vectors, and the first and second forward and backward motion vectors, and comparisons are made between the three motion compensation results together with the original said block.
Claim 12
Dependent Claim
32 words
A method according to Claim 4, wherein the field restructuring process (25) further comprises the step of: subjecting said sub-blocks that contain chrominance information to an intra-field sub-sampling process to reduce resolution.
Claim 13
Dependent Claim
50 words
A method according to Claim 4, wherein the block coding process (22) comprises the steps of: discrete cosine transforming (80) each of said sub-blocks into DCT coefficients; quantizing (81) the DCT coefficients; zig-zag scanning (82) the quantized DCT coefficients; variable length coding (83) the result of the zig-zag scanning (82).
Claim 14
Dependent Claim
128 words
A method according to Claim 13, wherein the block decoding process comprises the steps of: demultiplexing/VLC decoding (90) the encoded information to reproduce the zig-zag scanned sub-block and the included side information describing the sub-block; inverse zig-zag scanning (91) followed by inverse quantizing (92) of the sub-block to reproduce the DCT coefficients; inverse DCT (93) processing said coefficients; subjecting the result of the inverse DCT (93) processing to an inverse of the inter-frame or inter-field motion compensation process (94,95) according to the coded picture type (I, P or B-picture) and the coded result of the inter-field difference detection process to reproduce the reconstructed sub-block; inverting (97, 98) of the frame/field restructuring process according to the coded result of the inter-field difference detection process to reproduce the reconstructed block.
Claim 15
Dependent Claim
50 words
A method according to Claim 11, wherein the block coding process (22) comprises the steps of: discrete cosine transforming (80) each of said sub-blocks into DCT coefficients; quantizing (81) the DCT coefficients; Zig-zag scanning (82) the quantized DCT coefficients; variable length coding (83) the result of the zig-zag scanning (82).
Claim 16
Dependent Claim
128 words
A method according to Claim 15, wherein the block decoding process comprises the steps of: demultiplexing/VLC decoding (90) the encoded information to reproduce the zig-zag scanned sub-block and the included side information describing the sub-block; inverse zig-zag scanning (91) followed by inverse quantizing (92) of the sub-block to reproduce the DCT coefficients; inverse DCT (93) processing said coefficients; subjecting the result of the inverse DCT (93) processing to an inverse of the inter-frame or inter-field motion compensation process (94,95) according to the coded picture type (I, P or B-picture) and the coded result of the inter-field difference detection process to reproduce the reconstructed sub-block; inverting (97, 98) of the frame/field restructuring process according to the coded result of the inter-field difference detection process to reproduce the reconstructed block.
References Cited (Backward Citations)
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