EP0348186A2
Expired / Lapsed
EP
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Bandwidth reduction system for television
Assignee: British Broadcasting Corp
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Filing: 1989-06-22
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Granted: —
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Expires: 2009-06-22
Abstract
Abstract An HDTV picture is transmitted in a 625/50 MAC channel using bandwidth reduction techniques. In an 80ms coding branch motion compensation is provided by generating motion vectors for each block of the picture. The motion estimation is performed on a downfiltered and subsampled signal, and peaks in the phase correlation surface are estimated by an inverted-V interpolator function. Vectors are assigned to the blocks by determining the assignment error over both a field period and a frame period and summing the two. A "menu" of eight vectors is available for each block. To assist compatibility, samples are repositioned before transmission by calculating the average motion per field for each block, rounding the resultant to the nearest even number of pixels and picture lines per field period, and displacing the samples in dependence upon the resultant displacement value and upon the field number from which the sample is derived. Furthermore, a filter is selectively included to provide an attenuating dip centred on 12.5 Hz.
Inventors
- 👤 Graham A. Thomas
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 19:47
CPC Classifications
H; H04; H04N; H04N7/00; H04N7/015; H04N7/0152; H04N7/0155; H04N7/0157; H04N11/00; H04N11/02; H04N7/12; H04N7/122; H04N7/125
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
154 words
A method of transmitting a video picture at high definition over a lower definition channel, comprising at least for some portions of the picture determining a motion vector indicative of the motion of the picture portion over the period of the high definition fields, and in such picture portions transmitting samples from a plurality of high definition fields in a format compatible with the lower definition format, the samples being repositioned prior to transmission so as to minimise judder in the compatible picture, the repositioning comprising calculating the average motion per field for each picture portion over the period of one picture at the lower definition format, rounding the resultant substantially to the nearest even number of pixels and picture lines per field period, and displacing the samples in dependence upon the resultant displacements and upon the distances from a datum of the timing of the high definition fields to which the samples relate.
Claim 2
Independent Claim
154 words
A method of transmitting a video picture at high definition over a lower definition channel, comprising at least for some portions of the picture determining a motion vector indicative of the motion of the picture portion over the period of the high definition fields, and in such picture portions transmitting samples from a plurality of high definition fields in a format compatible with the lower definition format, the samples being repositioned prior to transmission so as to minimise judder in the compatible picture, the repositioning comprising calculating the average motion per field for each picture portion over the period of one picture at the lower definition format, rounding the resultant substantially to the nearest even number of pixels and picture lines per field period, and displacing the samples in dependence upon the resultant displacements and upon the distances from a datum of the timing of the high definition fields to which the samples relate.
Claim 3
Dependent Claim
58 words
A method according to claim 1, in which samples from four fields 1,2,3 and 4 at the high definition format are repositioned, the samples from field 3 remaining unmoved, the samples from fields 2 and 4 being moved by plus and minus the resultant displacement, and the samples from field 1 being moved by twice the resultant displacement.
Claim 4
Independent Claim
120 words
A method of receiving a video picture representing a high definition picture over a lower definition channel, the picture being transmitted together with motion vectors indicative of the motion of at least some picture portions in the period between high definition fields, received samples being repositioned prior to decoding, the repositioning comprising calculating the average motion per field for each picture portion over the period of one picture at the lower definition format, rounding the resultant substantially to the nearest even number of pixels and picture lines per field period, and displacing the sample in dependence upon the resultant displacements and upon the distance from a datum of the timing of the high definition fields to which the samples relate.
Claim 5
Independent Claim
120 words
A method of receiving a video picture representing a high definition picture over a lower definition channel, the picture being transmitted together with motion vectors indicative of the motion of at least some picture portions in the period between high definition fields, received samples being repositioned prior to decoding, the repositioning comprising calculating the average motion per field for each picture portion over the period of one picture at the lower definition format, rounding the resultant substantially to the nearest even number of pixels and picture lines per field period, and displacing the sample in dependence upon the resultant displacements and upon the distance from a datum of the timing of the high definition fields to which the samples relate.
Claim 6
Independent Claim
71 words
A method of transmitting a video picture comprising receiving a source picture, and generating a transmitted picture by selecting specified pixels only from the source picture from different fields thereof, determining apparent motion of the picture between successive source fields, and before transmission repositioning at least some of the pixel values to different pixel positions in dependence upon the apparent motion and the source field from which the pixel is derived.
Claim 7
Independent Claim
71 words
A method of transmitting a video picture comprising receiving a source picture, and generating a transmitted picture by selecting specified pixels only from the source picture from different fields thereof, determining apparent motion of the picture between successive source fields, and before transmission repositioning at least some of the pixel values to different pixel positions in dependence upon the apparent motion and the source field from which the pixel is derived.
Claim 8
Independent Claim
74 words
A method of receiving a video picture comprising receiving a transmitted picture, and generating an output picture by up-converting the transmitted picture to a higher field rate, the picture being transmitted together with information on the apparent motion of the picture between successive output fields, and repositioning at least some of the received pixel values to different pixel positions in dependence upon the apparent motion and the output field to which the pixel relates.
Claim 9
Independent Claim
74 words
A method of receiving a video picture comprising receiving a transmitted picture, and generating an output picture by up-converting the transmitted picture to a higher field rate, the picture being transmitted together with information on the apparent motion of the picture between successive output fields, and repositioning at least some of the received pixel values to different pixel positions in dependence upon the apparent motion and the output field to which the pixel relates.
Claim 10
Independent Claim
86 words
A method of transmitting a video picture at high definition over a low definition channel, in which picture portions are subjected to bandwidth compression selectively by two or more different methods in a first of which each transmitted field comprises information from one high definition field and in a second of which each transmitted field comprises information from a plurality n of high definition fields, and selectively attenuating the transmitted signal with a notch filter to attenuate frequencies centered on 1/n times the transmitted field frequency.
Claim 11
Independent Claim
86 words
A method of transmitting a video picture at high definition over a low definition channel, in which picture portions are subjected to bandwidth compression selectively by two or more different methods in a first of which each transmitted field comprises information from one high definition field and in a second of which each transmitted field comprises information from a plurality n of high definition fields, and selectively attenuating the transmitted signal with a notch filter to attenuate frequencies centered on 1/n times the transmitted field frequency.
Claim 12
Dependent Claim
11 words
A method according to claim 6, in which n is four.
Claim 13
Dependent Claim
54 words
A method according to claim 6 or 7, in which at least for some portions of the picture a motion vector is transmitted indicative of the motion of the picture portion in the period between high definition fields, and in which the attenuation is applied only when the motion is below a predetermined value.
Claim 14
Dependent Claim
58 words
A machine method of video picture motion measurement, comprising correlating two pictures to determine correlation as a function of selective displacement, thereby to determine a plurality of peak correlation values corresponding to respective motion vectors, in which prior to correlation the pictures are prefiltered horizontally and/or vertically and subsampled substantially to reduce the complexity of the correlation step.
Claim 15
Dependent Claim
58 words
A machine method of video picture motion measurement, comprising correlating two pictures to determine correlation as a function of selective displacement, thereby to determine a plurality of peak correlation values corresponding to respective motion vectors, in which prior to correlation the pictures are prefiltered horizontally and/or vertically and subsampled substantially to reduce the complexity of the correlation step.
Claim 16
Dependent Claim
61 words
A machine method of video picture motion measurement comprising correlating two pictures to determine correlation as a function of selective displacement, thereby to determine a plurality of peak correlation values corresponding to respective motion vectors, in which the location of a peak is determined by fitting an inverted V over a high value and the adjacent values on either side thereof.
Claim 17
Dependent Claim
61 words
A machine method of video picture motion measurement comprising correlating two pictures to determine correlation as a function of selective displacement, thereby to determine a plurality of peak correlation values corresponding to respective motion vectors, in which the location of a peak is determined by fitting an inverted V over a high value and the adjacent values on either side thereof.
Claim 18
Dependent Claim
67 words
A method according to claim 10, in which the location of a peak is determined by fitting a first line through the high value and the lowest adjacent value, and then fitting a second line through the opposite adjacent point of equal but opposite gradient to the first line, whereby the point of intersection of the first and second lines indicates the location of the desired peak.
Claim 19
Dependent Claim
112 words
A machine method of video picture motion measurement, comprising correlating two pictures to determine correlation as a function of selective displacement, thereby to determine a plurality of peak correlation values corresponding to respective motion vectors, and assigning to each of a plurality of small areas of the pictures the one of the motion vectors that gives the best fit in deriving one of the pictures from the other, in which the assignment step comprises calculating for each motion vector an assignment error over both a one-field and a two-field period, summing the two assignment errors to give a total assignment error, and selecting the vector that gives the minimum total assignment error.
Claim 20
Dependent Claim
112 words
A machine method of video picture motion measurement, comprising correlating two pictures to determine correlation as a function of selective displacement, thereby to determine a plurality of peak correlation values corresponding to respective motion vectors, and assigning to each of a plurality of small areas of the pictures the one of the motion vectors that gives the best fit in deriving one of the pictures from the other, in which the assignment step comprises calculating for each motion vector an assignment error over both a one-field and a two-field period, summing the two assignment errors to give a total assignment error, and selecting the vector that gives the minimum total assignment error.
Claim 21
Dependent Claim
15 words
A method according to claim 12, in which the summing step comprises a weighted addition.
Claim 22
Dependent Claim
31 words
A method according to claim 13, in which the weighting factor is: 1 + 0.5 * mod(V) where mod(V) is the magnitude of the motion vector in pixels per picture period.
Claim 23
Independent Claim
54 words
A method of transmitting a video picture, comprising receiving a video picture from a source, bandwidth compressing the video signal generated by the source selectively by two or more different methods, controlling the selection of the bandwidth compression in response to picture content and transmitting a control signal along with the transmitted video picture.
Claim 24
Independent Claim
54 words
A method of transmitting a video picture, comprising receiving a video picture from a source, bandwidth compressing the video signal generated by the source selectively by two or more different methods, controlling the selection of the bandwidth compression in response to picture content and transmitting a control signal along with the transmitted video picture.
References Cited (Backward Citations)
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