CA1261069A - Two-channel coding of digital signals - Google Patents
Two-channel coding of digital signalsInfo
- Publication number
- CA1261069A CA1261069A CA000524786A CA524786A CA1261069A CA 1261069 A CA1261069 A CA 1261069A CA 000524786 A CA000524786 A CA 000524786A CA 524786 A CA524786 A CA 524786A CA 1261069 A CA1261069 A CA 1261069A
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- Canada
- Prior art keywords
- signal
- subsampling
- signal processing
- digitally encoded
- processing apparatus
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N11/00—Colour television systems
- H04N11/04—Colour television systems using pulse code modulation
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
- H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
- H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
- H04N19/124—Quantisation
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
- H04N19/30—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using hierarchical techniques, e.g. scalability
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
- H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
Abstract
TWO-CHANNEL CODING OF DIGITAL SIGNALS
Abstract of Disclosure A video codec is used to reduce the bandwidth of a video signal for storage and/or transmission. To transmit an uncoded quality colour NTSC television signal in digitized form requires channel bandwidth typically 90-120 Mb/s for the signal in the composite format and 216 Mb/s for the signal in the component format.
The proposed video codec achieves a reduction of the required transmission bandwidth by a factor of 2-3 by splitting the input signal into two channels, a main and a complementary channel, and by applying different coding techniques in each. In the main channel the input signal is subsampled and DPCM encoded using a fixed-rate companded quantization, whereas VWL and block coding is used to encode the complementary channel carrying the interpolation error signal.
This arrangement seeks to ensure high picture quality while being easily adaptable to different transmission rates and signal formats.
In bandwidth-on-demand applications the main channel can be used alone to provide a lesser quality signal, for example CATV quality at 35 Mb/s, with an attendant reduction in system complexity.
- i -
Abstract of Disclosure A video codec is used to reduce the bandwidth of a video signal for storage and/or transmission. To transmit an uncoded quality colour NTSC television signal in digitized form requires channel bandwidth typically 90-120 Mb/s for the signal in the composite format and 216 Mb/s for the signal in the component format.
The proposed video codec achieves a reduction of the required transmission bandwidth by a factor of 2-3 by splitting the input signal into two channels, a main and a complementary channel, and by applying different coding techniques in each. In the main channel the input signal is subsampled and DPCM encoded using a fixed-rate companded quantization, whereas VWL and block coding is used to encode the complementary channel carrying the interpolation error signal.
This arrangement seeks to ensure high picture quality while being easily adaptable to different transmission rates and signal formats.
In bandwidth-on-demand applications the main channel can be used alone to provide a lesser quality signal, for example CATV quality at 35 Mb/s, with an attendant reduction in system complexity.
- i -
Description
TWO-CHANNEL CODING OF DIGITAL SIGNALS
Field of the In~ention ... .... . . . . ~ _ The invention relates to digi-tal signal coding, and is applicable to coding of digitized colour video signals for storage and/or transmission~ The invention is applicable especially, but not exclusively, to broadcast television signals in composite or component formatO
Background of the Inventlon To transmit an uncoded broadcast quality colour NTSC
television signal in digitized form requires a channel bandwidth of, typically, 90-120 Mb/s for the signal in the composite format and 220 Mb/s for the signal in the component format. These raw bit rates are based on the practice of quantizing the broadcast video signal with 8/9 bits, and sampling the composite NTSC signal at 4fsc = 14.3 MHz (four times the subcarrier frequency) and the component signal at 13.5 MHz in agreement with the CCIR recommendation 601. It is economically advantageous to reduce the signal's bandwidth substantially, especially to fit existing or proposed transmission standards in various countries. For example, reduced bit rates of 45, 90, and 135 Mb/s may be preferred, representing multiples of the DS-3 bit rate within the North American hierarchy of digital transmission channels. In Europe, standard channel bit rates of 34 and 140 Mb/s, for example, are used.
An object of the present invention is to provide a coding arrangement which gives high picture quality while being adaptable to different sampling rates and signal formats.
Brief Summa_y oF the Invention According -to the present inven-tion, a coding arrangement provides from a digitized video signal two discrete digital signals, i.e. a main signal and a complementary signal, at the transmitter, with a different coding technique applied to each. The two signals may be multiplexed at the transmitter output for transmission, demultiplexed at the receiver input and recombined at the receiver output.
An advantage of this coding arrangement is that the first or main signal can deliver a basic picture quality while its deficiencies can be compensated for at the receiver with the information contained in the second or complementary signal. The latter may, for example, be the interpolation error between the original values of pels (picture elements) dropped prior to transmission and their reconstructed values at the receiver.
In a preferred embodiment, the first or main signal is subsampled and subjected to differential pulse code modulation (DPCM) coupled with fixed-rate companded quantization. The second or complementary signal is subjected to uniform quantization, variable word length (VWL) encoding and block encoding.
If the optimum picture quality is needed, the two signals may be combined at the receiver. It is possible, however, to use only the first or main signal, with consequent bandwidth reduction, if some reduction o~ picture quality can be tolerated. For example, both signals might giYe a 45 Mb/s broadcast quality television signal, whereas the first or main signal alone might be sufficient for CATV
quality at 3~ Mb/s. The bandwidth relinquished by omitting the .
.
second or complementary signal could be used for o-ther purposes. Such an arrangemen-t is of particular advantage for "bandwidth-on-demand"
applications and also for transmission at bit rates complying with different hierarchical s-tandards, enabling, for example, one coding scheme -to satisfy North American, European and Japanese requirements.
Brief Descriptlon of the Drawings An embodiment of the invention will now be described by way of example only and with reference to the accompanying drawings, in which:
Figure 1 is a block diagram of a two-channel encoder;
Figure 2 is a block diagram of a matching decoder;
Figure 3 shows a multi-dimensional filter and subsampler, which are part of the encoder;
Figure 4 is a block diagram of the components involved in single channel operation of the encoder;
Figure 5 is a corresponding block diagram of the matching decoder For single channel operation;
Figure 6 is a block diagram of a modified two-channel encoder;
Figure 7 shows the modified multi-dimensional filter and subsampler; and Figures 8, 9, 10 and 11 are the sampling pattern and subsampling patterns for signal processing the transmitter and receiver~
~
Referring to Figure 1~ apparatus for two-channel encoding of colour video signals, referred to herein as a transmitter~ comprises i~
an input terminal to which is applied a signal V to be encoded. The signal is digitized by an A/D converter 10 wherein it is sampled ~l th sampling frequency fs and amplitude accuracy BA. The sampling frequency may be line-locked or subcarrier-locked, in either case resulting in a signal S that has been sampled on an orthogonal aligned three-dimensional (3D) sampling structure as illustrated in Figure 8.
The two signals E and P leave by different paths. The main (first), signal P, comprises input pels obtained in the 2:1 subsampling means 56. Samples, hereafter referred to as subsampled pels, are selected from the initial orthogonal structure in a systematic three-dimensional arrangement. The subsampled pels, collectively referred to as the subsampling structure SpAT, are shown encircled in Figure 8 (by ~ay of example). They are subsequently processed in the main channel (the associated signal path) by a DPCM encoder (to be described later).
Referring to Figure 3, the complementary signal E, which emerges on a different path, is derived by forming a difference between the input pels omitted in the subsampling means 56 (and not encircled in Figure 8) and their interpolated values. The interpolated values are obtained as a response of a multi-dimensional filter 50 to the input signal. For general principles of operation of such a multi-dimensional filter, the reader is directed to the text by D.E. Dudgeon and R.M. Mersereau entitled "Multidimensional Digital Signal Processing", 1984, published by Prentice Hall Inc. Details of operation will be apparent from the examples provided.
Referring again to Figure 3, multi-dimensional filter 50 is of the interpolative kind, i.e. it operates on the subsampled pels only when producing a response for the omitted pels while leaving the .~.
, "~.,. '~"
. . , :
.
subsampled pels intact, i.e. the filter response at the locations of subsampled pels is identical to the original values of those pels.
Sub-tractor 52 pr~vides the difference between the interpolated values at the output of the filter 50 and the input signal S applied to the input of filter 50. The difference signal furnished by subtractor 52 contains zeros in the subsampled-pel locations and non-zero interpolation error values in the remaining locations. The zeros are removed from signal E by the complementary subsampling means 54.
Identical results are obtained if subsampling precedes interpolation and differencing as shown in the equivalent structure of Figure 7. It is an implementational concern that the multi-dimensional filter operates now on the subsampled pels only.
Referring again to Figure 1, signal E, which constitutes interpolation error, passes through a quantizer 14, isolated pel suppressor 15, and variable word length (VWL) and block encoder 16 to emerge as signal EI coded at BI bits per s~cond for application to multiplexer 180 The code for the variable word length encoder is shown in Table 19 which is appended hereto. For details of the construction and operation of such a VWL encoder the reader is referred to Canadian patent application serial number 440,742, filed November 8, 1983~ now patent number 1,207~911, naming 0. Bahgat as inventor.
Quantizer 14 is a uniform or mildly companded quantizer. It maps input decision ranges into output indices. For details of quantizer 14 see Table 4, which is appended hereto. The isolated pel suppressor 15 uses a sliding window to determine whether to set the current output of quantizer 14 to zero based on it being below a threshold and neighbouring indices on both sides of the current position being zero. The block encoder in means 16 segments the quantized interpolation error into two-dimensional blocks of Nh x Nv samples each. A constant overhead of 1 bit per block is assigned to indicate whether the block contains significant pels or insignificant pels. Only blocks containing at least one significant error are fed to the VWL coder. Construction and operation of a suitable block encoder are well-known and are disclosed, for example, by D.J. Connor, R.F.W. Peace and ~.G. Scholes, in "Television Coding Using Two-Dimensional Spatial Prediction", Bell System Technical Journal, Vol.
50, No. 3, pp 10~9-1061, March 1971 to which the reader is directed for reference.
As mentioned previously~ signal P passes through the differential pulse code modulation (DPCM) encoder in reaching multiplexer 18. As shown in Figure 4, the DPCM encoder comprises subtractor 209 quantizer 22, inverse quantizer 24, adder 26, predictor 28 and a feedback loop 30 from the output of predictor 28 to the adder 26. For details of the quantizer Q1' see Tables 2, 3 and 5, appended hereto. The operation of the DPCM coder is known e~
and so will not be described in detail here. Typical construction and operation of such coders are described in U.S. patent number 2,605,361 issued July 1952 naming C.C. Cutler as inventor, the article by D.J. Connor et al mentioned above, and an article by H.G. Musmann, entitled "Predictive Image Coding", in Advances in Electronics and Electron Physics~ Academic Press, Vol. Suppl. 12, pp. 73-112, 1979.
The reader is directed to these documents -For reference.
The output Ep of the DPCM coder, taken from quantizer 22, ~2~
is applied to the multiplexer l3 at the ra-te of Bp bits per second.
The ou-tpu-t oF the mul-tiplexer is therefore a multiplexed signal with BI + Bp bandwidth.
Referring to Figure 2, which is the block diagram of the receiver or decoder, the multiplexed signal, presumably having passed through a transmission channel, is applied to a demultiplexer 34 separating it into two signals, EI and Ep, corresponding to signals EI and Ep, respectively, in the transmitter prior to multiplexing. In the case of error-free transmission, EI and Ep will be the same in both the transmitter and the receiver.
Accordingly, and for simplicity, the same reference letters EI and Ep have been used in both. The interpolation error signal EI is applied to VWL and block decoder means 36 and thence to inverse quantizer 38, which is the inverse of quantizer 1~ in Figure 1. The output of the inverse quantizer 38 is the reconstituted interpolation error signal RE which is applied to an adder 40. For details of the construction and operation of a suitable VWL decoder the reader is directed to Canadian patent application serial number 440,741, ~iled November 8, 1983, now Canadian patent number 1,213,984, naming 0. Bahgat as inventor. For details of the construction and operation of a suitable block decoder, the reader is directed to the aforementioned disclosure by D.J. Connor et al.
The second, predictive, signal Ep is passed through a DPCM
decoder comprising inverse quantizer 42, identical to the inverse quantizer 24 in Figure 1, adder 44, and predictor 46. The reconstituted signal Rp, indicated likewise in the transmitter in Figure 1, undergoes upconversion by zero insertion~ then is applied to : J ~
three-dimensional filtering and upconversion means 48~ Upconversion is a reverse process to the subsampling process in that additional samples are inserted into the signal at the complemen-tary pel locations. In filtering and upconversion means 48, the upconverted 5 signal is applied to a multi-dimensional filter identical to the multi-dimensional filter in the transmitter except for a gain factor of 2 in order to recover DC. The receiver filter leaves the subsampled pels unchanged while interpolating the inserted zero-valued samples. The output of the filter is supplied to adder 40 which adds the interpolation error RE to the interpolated samples only. The output of the adder 40 represents the reconstructed video signal for application to D/A converter 50.
Embodiments of the invention can readily be configured for difFerent bit rates of the input signal, types of signal and sampling 15 rates. Examples of typical configurations follow:-Example No. 1 predictive path bit rate Bp: 34-36 Mb/s interpolative path bit rate BI: 6 Mb/s output bit rate Bp -~ BI + BoVpHD
input: composite colour NTSC signal sampling frequency fs: 4fsc (14.3 MHz, sub-carrier locked) amplitude accuracy BA: 8/9 bits predictive path quantizer Q1 6-bit companded quantizer (see Table 2) interpolative path quantizer Q2: uniform quantizer with step 3 N.B. Discrepancies between Bp + BI and total bit rates are ` ~3b.
accounted for by overhead BoVpHD such as forward error correction, markers, framing, etc.
Sub-example no. 1 sampling pattern SpAT: Field quincunx QT (Figure 9) multi-dimensional filter: 3-D filter requiring one or two field stores, equivalent to a 2-D filter operating in the 45-plane with respect to the vertical-temporal plane:
hl(n) = ~ -8 0 16 0 -8 ~
0 15 1 15 0 ~ -~2(n) =1 0 15 32 15 0 1¦
Sub-example no. 2 sampling pattern SpAT: double checkerboard DCB (see Figure 9) multi-dimensional filter: 2-D spatial filter:
h(n) = 1 0 -5 0 8 0 59 128 59 0 8 0 -5 0 1 _ _ , ..
~xa~ple No~ ~
predic-tive path bit rate Bp: 31-33 Mb/s interpolative path bit rate Bp: 9-12 Mb/s output bit ra~e Bp + BI + BOVRHD 44-47 Mb/s S input: composite colour NTS0 signal sampling frequency fs: 13.5 MHz (line locked) amplitude accuracy BA: 8/9 bits predictive path quantizer Q1 6-bit companded quantizer (see Table 2) 10 interpolative path quantizer Q2: uniform quantizer with step 3 sampling pattern SpAT: field quincunx QT (see Figure 7) multi-dimensional filter: 3-D filter requiring one field store, equivalent to a 2-D
filter operating in the 45-plane with impulse response:
~ _3 0 6 0 -3 0 h2(n) = 1 0 15 32 15 0 1 _ _ Exa~ple No. 3 predictive path bit rate Bp- 63-70 Mb/s 20 interpolative path bit rate BI: 60 65 Mb/s output bit rate Bp + BI + BOVRH~
input: component 4:2:2 studio standard (Y,R-Y,B-Y) signal sampling frequency fs: 13.5 MHz (line locked) 25 sampling pattern SpAT: checkerboard (line quincunx) QL
(see Figure 10) amplitude accuracy BA 8 bits predictive pa-th quantizer Ql: 6-bi-t companded quant;zer (see Table 3) interpolative path quantizer Q2: mildly companded quantizer with thresholding (see lable 4) 5 multi-dimensional filter: 2-D spatial filter:
h(n) = 1 0 15 32 15 0 1 Example ~o. 4 predictive path bit rate Bp: 50-60 Mb/s 10 interpolative path bit rate BI: 24-30 Mb/s output bit rate Bp -~ BI + BOVRHD 9 input: component 4:2:2 studio standard (Y,R-Y,B-Y) signal sampling frequency fs: 13.5 MHz (line locked) 15 sampling pattern SpAT: checkerboard (line quincunx) (see Figure 10) amplitude accuracy eA: 8/9 bits predictive path quantizer Ql: 5-bit companded quantizer (see Table 5) interpolative path quantizer n2: mildly companded quantizer ~ith thresholding (see Table 4) multi-dimensional filter: 2-D spatial filter:
h(n) = 1 0 15 32 15 0 1 25In the embodiment of the invention depicted in Figure 1 the complementary path for coding signal E is based on the response of the multi-dimensional filter 50 operating on the input signal. The ~L~
present invention encompasses another embodiment, to be considered a variation on that of Fiyure 1, which is shown in Figure 6. The previous arrangement is reconfigured such that the interpolative or complementary signal E is obtained by differenciny the reconstructed S Rp signal with the output of filter 50, followed by complementary subsampling in means 54, which is part of the filSering and subsampling means 12~ 2:l subsampling means 56 is shown, in Figure 6, separate from means 12. The input signal S is applied directly to its input and its output provides the main signal P. Otherwise, the remaining processing is identical.
A significant advantage of embodiments of the present invention is that the two channels can be used together to give a high quality signal using the total bandwidth. The coding deficiencies in the main or predictive path can be compensated for by the information supplied by the complementary path.
More particularly, the deficiencies of image quality in the main path arise from the information loss due to a 2:1 subsamplirlg process. This process generally results in a loss of high spatio-temporal frequency content as well as an injection, known as aliasing, of high frequencies into low frequency areas. Aliasing generally appears as an interference pattern objectionable to the viewer. The complementary path preserves, to a large extent; the information lost during subsampling in the main path. Hence it carries a signal consisting mostly of the input signal's high spatio-temporal frequencies as well as an anti-alias signal, i.e~, one which removes the alias signal embedded in the main paSh. It stands to reason that recombining the complementary channel with the main channel at the receiver has the effect of improving picture quality relative -to that provided by the main channel alone.
Advantageously, one channel may be used alone to give a signal of lesser quality using only a part of the total bandwidth.
Moreover, the remaining bandwidth, released by the other signal 9 can be used for other purposes. It is particularly envisayed that one channel be capable o-f supplying CATV quality signals at 35 Mb/s, while the two together ~ould be capable of broadcast quality at 45-~7 Mb/s.
The main channel carries inFormation from which the input picture, albeit somewhat distorted, can be reconstructed. From the information carried in the complementary channel only the interpolation error can be reconstructed, which cannot reconstitute a picture.
Figures 4 and 5 illustrate single-channel mode of operation, the unused components being shown with broken lines~ Referring to Figure 4, which corresponds to the predictor channel of Figure 1, every sample of signal S~ digitized in a similar manner as in Figure 1, is applied to optional multi-dimensional filter 525 and subsequently subsampled by means 54 according to a 2:1 sampling pattern SpAT
producing signal P. Leaving filter 52 out effects a gain in apparatus simplicity at the expense of some picture quality loss due to signal alias introduced in the subsampling process. The ensuing processing is identical to that in the predictive path in Figure 1~ therefore its description will be omitted. The main simplification of the single-channel mode is that the interpolative path, and the associated apparatus, is not used. Hence prediction error signal Ep is fed dlrectly to a channel interface~ Another difference is that the subsampled pels are subject to the bandlimiting effect of the .,~
., ' -f~
multi-dimensional fil-ter 52.
In the single-channel decoder, shown in Figure 5, the simplification consists in the non-use of the interpolative channel and demultiplexer. The predictive signal Ep is reconstituted as signal Rp in the same manner as in the predictive channel of the two-channel decoder (Figure 2). Thence it is upconverted to a full resolution in a 2:1 zero insertion processor 47. The full resolution digitized image SR is reconstructed when the zero-valued inserted samples are interpolated by the digital filter 49, identical to 52 except for scaling factor of 2. This signal is applied to D/A
processor 50 to obtain the analog video signal V at the output.
Although the specific embodiments refer to a three-dimensional filter, the invention relates generally to video codecs employing multi-dimensional filters.
In this specification, the term "sampling" may cover one stage or more stages.
Two-stage sampling and subsampling using means 10 and means 12 is preferred but a single stage of sampling could be done instead.
Then A/D conversion would be employed in both cases - generation of the main signal and oF the complementary signal.
Field of the In~ention ... .... . . . . ~ _ The invention relates to digi-tal signal coding, and is applicable to coding of digitized colour video signals for storage and/or transmission~ The invention is applicable especially, but not exclusively, to broadcast television signals in composite or component formatO
Background of the Inventlon To transmit an uncoded broadcast quality colour NTSC
television signal in digitized form requires a channel bandwidth of, typically, 90-120 Mb/s for the signal in the composite format and 220 Mb/s for the signal in the component format. These raw bit rates are based on the practice of quantizing the broadcast video signal with 8/9 bits, and sampling the composite NTSC signal at 4fsc = 14.3 MHz (four times the subcarrier frequency) and the component signal at 13.5 MHz in agreement with the CCIR recommendation 601. It is economically advantageous to reduce the signal's bandwidth substantially, especially to fit existing or proposed transmission standards in various countries. For example, reduced bit rates of 45, 90, and 135 Mb/s may be preferred, representing multiples of the DS-3 bit rate within the North American hierarchy of digital transmission channels. In Europe, standard channel bit rates of 34 and 140 Mb/s, for example, are used.
An object of the present invention is to provide a coding arrangement which gives high picture quality while being adaptable to different sampling rates and signal formats.
Brief Summa_y oF the Invention According -to the present inven-tion, a coding arrangement provides from a digitized video signal two discrete digital signals, i.e. a main signal and a complementary signal, at the transmitter, with a different coding technique applied to each. The two signals may be multiplexed at the transmitter output for transmission, demultiplexed at the receiver input and recombined at the receiver output.
An advantage of this coding arrangement is that the first or main signal can deliver a basic picture quality while its deficiencies can be compensated for at the receiver with the information contained in the second or complementary signal. The latter may, for example, be the interpolation error between the original values of pels (picture elements) dropped prior to transmission and their reconstructed values at the receiver.
In a preferred embodiment, the first or main signal is subsampled and subjected to differential pulse code modulation (DPCM) coupled with fixed-rate companded quantization. The second or complementary signal is subjected to uniform quantization, variable word length (VWL) encoding and block encoding.
If the optimum picture quality is needed, the two signals may be combined at the receiver. It is possible, however, to use only the first or main signal, with consequent bandwidth reduction, if some reduction o~ picture quality can be tolerated. For example, both signals might giYe a 45 Mb/s broadcast quality television signal, whereas the first or main signal alone might be sufficient for CATV
quality at 3~ Mb/s. The bandwidth relinquished by omitting the .
.
second or complementary signal could be used for o-ther purposes. Such an arrangemen-t is of particular advantage for "bandwidth-on-demand"
applications and also for transmission at bit rates complying with different hierarchical s-tandards, enabling, for example, one coding scheme -to satisfy North American, European and Japanese requirements.
Brief Descriptlon of the Drawings An embodiment of the invention will now be described by way of example only and with reference to the accompanying drawings, in which:
Figure 1 is a block diagram of a two-channel encoder;
Figure 2 is a block diagram of a matching decoder;
Figure 3 shows a multi-dimensional filter and subsampler, which are part of the encoder;
Figure 4 is a block diagram of the components involved in single channel operation of the encoder;
Figure 5 is a corresponding block diagram of the matching decoder For single channel operation;
Figure 6 is a block diagram of a modified two-channel encoder;
Figure 7 shows the modified multi-dimensional filter and subsampler; and Figures 8, 9, 10 and 11 are the sampling pattern and subsampling patterns for signal processing the transmitter and receiver~
~
Referring to Figure 1~ apparatus for two-channel encoding of colour video signals, referred to herein as a transmitter~ comprises i~
an input terminal to which is applied a signal V to be encoded. The signal is digitized by an A/D converter 10 wherein it is sampled ~l th sampling frequency fs and amplitude accuracy BA. The sampling frequency may be line-locked or subcarrier-locked, in either case resulting in a signal S that has been sampled on an orthogonal aligned three-dimensional (3D) sampling structure as illustrated in Figure 8.
The two signals E and P leave by different paths. The main (first), signal P, comprises input pels obtained in the 2:1 subsampling means 56. Samples, hereafter referred to as subsampled pels, are selected from the initial orthogonal structure in a systematic three-dimensional arrangement. The subsampled pels, collectively referred to as the subsampling structure SpAT, are shown encircled in Figure 8 (by ~ay of example). They are subsequently processed in the main channel (the associated signal path) by a DPCM encoder (to be described later).
Referring to Figure 3, the complementary signal E, which emerges on a different path, is derived by forming a difference between the input pels omitted in the subsampling means 56 (and not encircled in Figure 8) and their interpolated values. The interpolated values are obtained as a response of a multi-dimensional filter 50 to the input signal. For general principles of operation of such a multi-dimensional filter, the reader is directed to the text by D.E. Dudgeon and R.M. Mersereau entitled "Multidimensional Digital Signal Processing", 1984, published by Prentice Hall Inc. Details of operation will be apparent from the examples provided.
Referring again to Figure 3, multi-dimensional filter 50 is of the interpolative kind, i.e. it operates on the subsampled pels only when producing a response for the omitted pels while leaving the .~.
, "~.,. '~"
. . , :
.
subsampled pels intact, i.e. the filter response at the locations of subsampled pels is identical to the original values of those pels.
Sub-tractor 52 pr~vides the difference between the interpolated values at the output of the filter 50 and the input signal S applied to the input of filter 50. The difference signal furnished by subtractor 52 contains zeros in the subsampled-pel locations and non-zero interpolation error values in the remaining locations. The zeros are removed from signal E by the complementary subsampling means 54.
Identical results are obtained if subsampling precedes interpolation and differencing as shown in the equivalent structure of Figure 7. It is an implementational concern that the multi-dimensional filter operates now on the subsampled pels only.
Referring again to Figure 1, signal E, which constitutes interpolation error, passes through a quantizer 14, isolated pel suppressor 15, and variable word length (VWL) and block encoder 16 to emerge as signal EI coded at BI bits per s~cond for application to multiplexer 180 The code for the variable word length encoder is shown in Table 19 which is appended hereto. For details of the construction and operation of such a VWL encoder the reader is referred to Canadian patent application serial number 440,742, filed November 8, 1983~ now patent number 1,207~911, naming 0. Bahgat as inventor.
Quantizer 14 is a uniform or mildly companded quantizer. It maps input decision ranges into output indices. For details of quantizer 14 see Table 4, which is appended hereto. The isolated pel suppressor 15 uses a sliding window to determine whether to set the current output of quantizer 14 to zero based on it being below a threshold and neighbouring indices on both sides of the current position being zero. The block encoder in means 16 segments the quantized interpolation error into two-dimensional blocks of Nh x Nv samples each. A constant overhead of 1 bit per block is assigned to indicate whether the block contains significant pels or insignificant pels. Only blocks containing at least one significant error are fed to the VWL coder. Construction and operation of a suitable block encoder are well-known and are disclosed, for example, by D.J. Connor, R.F.W. Peace and ~.G. Scholes, in "Television Coding Using Two-Dimensional Spatial Prediction", Bell System Technical Journal, Vol.
50, No. 3, pp 10~9-1061, March 1971 to which the reader is directed for reference.
As mentioned previously~ signal P passes through the differential pulse code modulation (DPCM) encoder in reaching multiplexer 18. As shown in Figure 4, the DPCM encoder comprises subtractor 209 quantizer 22, inverse quantizer 24, adder 26, predictor 28 and a feedback loop 30 from the output of predictor 28 to the adder 26. For details of the quantizer Q1' see Tables 2, 3 and 5, appended hereto. The operation of the DPCM coder is known e~
and so will not be described in detail here. Typical construction and operation of such coders are described in U.S. patent number 2,605,361 issued July 1952 naming C.C. Cutler as inventor, the article by D.J. Connor et al mentioned above, and an article by H.G. Musmann, entitled "Predictive Image Coding", in Advances in Electronics and Electron Physics~ Academic Press, Vol. Suppl. 12, pp. 73-112, 1979.
The reader is directed to these documents -For reference.
The output Ep of the DPCM coder, taken from quantizer 22, ~2~
is applied to the multiplexer l3 at the ra-te of Bp bits per second.
The ou-tpu-t oF the mul-tiplexer is therefore a multiplexed signal with BI + Bp bandwidth.
Referring to Figure 2, which is the block diagram of the receiver or decoder, the multiplexed signal, presumably having passed through a transmission channel, is applied to a demultiplexer 34 separating it into two signals, EI and Ep, corresponding to signals EI and Ep, respectively, in the transmitter prior to multiplexing. In the case of error-free transmission, EI and Ep will be the same in both the transmitter and the receiver.
Accordingly, and for simplicity, the same reference letters EI and Ep have been used in both. The interpolation error signal EI is applied to VWL and block decoder means 36 and thence to inverse quantizer 38, which is the inverse of quantizer 1~ in Figure 1. The output of the inverse quantizer 38 is the reconstituted interpolation error signal RE which is applied to an adder 40. For details of the construction and operation of a suitable VWL decoder the reader is directed to Canadian patent application serial number 440,741, ~iled November 8, 1983, now Canadian patent number 1,213,984, naming 0. Bahgat as inventor. For details of the construction and operation of a suitable block decoder, the reader is directed to the aforementioned disclosure by D.J. Connor et al.
The second, predictive, signal Ep is passed through a DPCM
decoder comprising inverse quantizer 42, identical to the inverse quantizer 24 in Figure 1, adder 44, and predictor 46. The reconstituted signal Rp, indicated likewise in the transmitter in Figure 1, undergoes upconversion by zero insertion~ then is applied to : J ~
three-dimensional filtering and upconversion means 48~ Upconversion is a reverse process to the subsampling process in that additional samples are inserted into the signal at the complemen-tary pel locations. In filtering and upconversion means 48, the upconverted 5 signal is applied to a multi-dimensional filter identical to the multi-dimensional filter in the transmitter except for a gain factor of 2 in order to recover DC. The receiver filter leaves the subsampled pels unchanged while interpolating the inserted zero-valued samples. The output of the filter is supplied to adder 40 which adds the interpolation error RE to the interpolated samples only. The output of the adder 40 represents the reconstructed video signal for application to D/A converter 50.
Embodiments of the invention can readily be configured for difFerent bit rates of the input signal, types of signal and sampling 15 rates. Examples of typical configurations follow:-Example No. 1 predictive path bit rate Bp: 34-36 Mb/s interpolative path bit rate BI: 6 Mb/s output bit rate Bp -~ BI + BoVpHD
input: composite colour NTSC signal sampling frequency fs: 4fsc (14.3 MHz, sub-carrier locked) amplitude accuracy BA: 8/9 bits predictive path quantizer Q1 6-bit companded quantizer (see Table 2) interpolative path quantizer Q2: uniform quantizer with step 3 N.B. Discrepancies between Bp + BI and total bit rates are ` ~3b.
accounted for by overhead BoVpHD such as forward error correction, markers, framing, etc.
Sub-example no. 1 sampling pattern SpAT: Field quincunx QT (Figure 9) multi-dimensional filter: 3-D filter requiring one or two field stores, equivalent to a 2-D filter operating in the 45-plane with respect to the vertical-temporal plane:
hl(n) = ~ -8 0 16 0 -8 ~
0 15 1 15 0 ~ -~2(n) =1 0 15 32 15 0 1¦
Sub-example no. 2 sampling pattern SpAT: double checkerboard DCB (see Figure 9) multi-dimensional filter: 2-D spatial filter:
h(n) = 1 0 -5 0 8 0 59 128 59 0 8 0 -5 0 1 _ _ , ..
~xa~ple No~ ~
predic-tive path bit rate Bp: 31-33 Mb/s interpolative path bit rate Bp: 9-12 Mb/s output bit ra~e Bp + BI + BOVRHD 44-47 Mb/s S input: composite colour NTS0 signal sampling frequency fs: 13.5 MHz (line locked) amplitude accuracy BA: 8/9 bits predictive path quantizer Q1 6-bit companded quantizer (see Table 2) 10 interpolative path quantizer Q2: uniform quantizer with step 3 sampling pattern SpAT: field quincunx QT (see Figure 7) multi-dimensional filter: 3-D filter requiring one field store, equivalent to a 2-D
filter operating in the 45-plane with impulse response:
~ _3 0 6 0 -3 0 h2(n) = 1 0 15 32 15 0 1 _ _ Exa~ple No. 3 predictive path bit rate Bp- 63-70 Mb/s 20 interpolative path bit rate BI: 60 65 Mb/s output bit rate Bp + BI + BOVRH~
input: component 4:2:2 studio standard (Y,R-Y,B-Y) signal sampling frequency fs: 13.5 MHz (line locked) 25 sampling pattern SpAT: checkerboard (line quincunx) QL
(see Figure 10) amplitude accuracy BA 8 bits predictive pa-th quantizer Ql: 6-bi-t companded quant;zer (see Table 3) interpolative path quantizer Q2: mildly companded quantizer with thresholding (see lable 4) 5 multi-dimensional filter: 2-D spatial filter:
h(n) = 1 0 15 32 15 0 1 Example ~o. 4 predictive path bit rate Bp: 50-60 Mb/s 10 interpolative path bit rate BI: 24-30 Mb/s output bit rate Bp -~ BI + BOVRHD 9 input: component 4:2:2 studio standard (Y,R-Y,B-Y) signal sampling frequency fs: 13.5 MHz (line locked) 15 sampling pattern SpAT: checkerboard (line quincunx) (see Figure 10) amplitude accuracy eA: 8/9 bits predictive path quantizer Ql: 5-bit companded quantizer (see Table 5) interpolative path quantizer n2: mildly companded quantizer ~ith thresholding (see Table 4) multi-dimensional filter: 2-D spatial filter:
h(n) = 1 0 15 32 15 0 1 25In the embodiment of the invention depicted in Figure 1 the complementary path for coding signal E is based on the response of the multi-dimensional filter 50 operating on the input signal. The ~L~
present invention encompasses another embodiment, to be considered a variation on that of Fiyure 1, which is shown in Figure 6. The previous arrangement is reconfigured such that the interpolative or complementary signal E is obtained by differenciny the reconstructed S Rp signal with the output of filter 50, followed by complementary subsampling in means 54, which is part of the filSering and subsampling means 12~ 2:l subsampling means 56 is shown, in Figure 6, separate from means 12. The input signal S is applied directly to its input and its output provides the main signal P. Otherwise, the remaining processing is identical.
A significant advantage of embodiments of the present invention is that the two channels can be used together to give a high quality signal using the total bandwidth. The coding deficiencies in the main or predictive path can be compensated for by the information supplied by the complementary path.
More particularly, the deficiencies of image quality in the main path arise from the information loss due to a 2:1 subsamplirlg process. This process generally results in a loss of high spatio-temporal frequency content as well as an injection, known as aliasing, of high frequencies into low frequency areas. Aliasing generally appears as an interference pattern objectionable to the viewer. The complementary path preserves, to a large extent; the information lost during subsampling in the main path. Hence it carries a signal consisting mostly of the input signal's high spatio-temporal frequencies as well as an anti-alias signal, i.e~, one which removes the alias signal embedded in the main paSh. It stands to reason that recombining the complementary channel with the main channel at the receiver has the effect of improving picture quality relative -to that provided by the main channel alone.
Advantageously, one channel may be used alone to give a signal of lesser quality using only a part of the total bandwidth.
Moreover, the remaining bandwidth, released by the other signal 9 can be used for other purposes. It is particularly envisayed that one channel be capable o-f supplying CATV quality signals at 35 Mb/s, while the two together ~ould be capable of broadcast quality at 45-~7 Mb/s.
The main channel carries inFormation from which the input picture, albeit somewhat distorted, can be reconstructed. From the information carried in the complementary channel only the interpolation error can be reconstructed, which cannot reconstitute a picture.
Figures 4 and 5 illustrate single-channel mode of operation, the unused components being shown with broken lines~ Referring to Figure 4, which corresponds to the predictor channel of Figure 1, every sample of signal S~ digitized in a similar manner as in Figure 1, is applied to optional multi-dimensional filter 525 and subsequently subsampled by means 54 according to a 2:1 sampling pattern SpAT
producing signal P. Leaving filter 52 out effects a gain in apparatus simplicity at the expense of some picture quality loss due to signal alias introduced in the subsampling process. The ensuing processing is identical to that in the predictive path in Figure 1~ therefore its description will be omitted. The main simplification of the single-channel mode is that the interpolative path, and the associated apparatus, is not used. Hence prediction error signal Ep is fed dlrectly to a channel interface~ Another difference is that the subsampled pels are subject to the bandlimiting effect of the .,~
., ' -f~
multi-dimensional fil-ter 52.
In the single-channel decoder, shown in Figure 5, the simplification consists in the non-use of the interpolative channel and demultiplexer. The predictive signal Ep is reconstituted as signal Rp in the same manner as in the predictive channel of the two-channel decoder (Figure 2). Thence it is upconverted to a full resolution in a 2:1 zero insertion processor 47. The full resolution digitized image SR is reconstructed when the zero-valued inserted samples are interpolated by the digital filter 49, identical to 52 except for scaling factor of 2. This signal is applied to D/A
processor 50 to obtain the analog video signal V at the output.
Although the specific embodiments refer to a three-dimensional filter, the invention relates generally to video codecs employing multi-dimensional filters.
In this specification, the term "sampling" may cover one stage or more stages.
Two-stage sampling and subsampling using means 10 and means 12 is preferred but a single stage of sampling could be done instead.
Then A/D conversion would be employed in both cases - generation of the main signal and oF the complementary signal.
Claims (44)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Signal processing apparatus comprising an encoder for encoding an analog signal (V) to produce a coded signal, said encoder comprising:-analog to digital encoder means (10) for sampling the analog signal (V) to provide a digitally encoded signal (S);
coding means (12) responsive to the output of said encoder means (10) for providing two distinct subsampled digital signals (E,P);
said coding means (12) including subsampling means (56) for subsampling said digitally encoded signal (S) to provide a subsampled digital signal (P) corresponding to the input signal, and also including filtering and subsampling means (50,52,54) for filtering and subsampling said digitally encoded signal (S) to provide a complementary subsampled signal (E) corresponding to the difference between the digitally encoded signal (S) and a filtered signal derived by filtering the signal (S); and first and second coding means (14,15,16; 20,22,24,26,28, 30) for encoding said two distinct signals (E,P) to provide two coded distinct signals (EI, Ep), respectively, each of said first and second coding means being operative to encode in a different way to that in which the other encodes.
coding means (12) responsive to the output of said encoder means (10) for providing two distinct subsampled digital signals (E,P);
said coding means (12) including subsampling means (56) for subsampling said digitally encoded signal (S) to provide a subsampled digital signal (P) corresponding to the input signal, and also including filtering and subsampling means (50,52,54) for filtering and subsampling said digitally encoded signal (S) to provide a complementary subsampled signal (E) corresponding to the difference between the digitally encoded signal (S) and a filtered signal derived by filtering the signal (S); and first and second coding means (14,15,16; 20,22,24,26,28, 30) for encoding said two distinct signals (E,P) to provide two coded distinct signals (EI, Ep), respectively, each of said first and second coding means being operative to encode in a different way to that in which the other encodes.
2. Signal processing apparatus as defined in claim 1, wherein said filtering and subsampling means (50,52,54) for filtering and subsampling said signal comprises:-multi-dimensional filter means (50) responsive to said digitally encoded signal (S) for producing the filtered signal, subtractor means (52) for differencing said digitally encoded signal and the filtered signal to provide an interpolation error signal, and complementary sampling means (54) responsive to the output of the subtractor means (52) to provide said complementary subsampled signal.
3. Signal processing apparatus as defined in claim 1, wherein said means (12) serves to sample said digitally encoded signal in a line quincunx pattern to provide said complementary subsampled signal.
4. Signal processing apparatus as defined in claim 1, wherein said means (12) serves to sample said digitally encoded signal in a field quincunx pattern.
5. Signal processing apparatus as defined in claim 1, wherein said means (12) serves to sample said digitally encoded signal in a double checkerboard pattern.
6. Signal processing apparatus as defined in claim 1, wherein said means (10) for sampling said input signal (V) serves to provide an orthogonal aligned sampling structure.
7. Signal processing apparatus as defined in claim 5, wherein said subsampling means (56) serves to subsample said digitally encoded signal in a line quincunx pattern.
8. Signal processing apparatus as defined in claim 6, wherein said subsampling means (56) serves to sample said digitally encoded signal in a field quincunx pattern.
9. Signal processing apparatus as defined in claim 1, wherein said means (12) serves to sample said digitally encoded signal in a double checkerboard pattern.
10. Signal processing apparatus as defined in claim 1, wherein said coding means serves to encode said complementary subsampled signal using variable word length coding and to encode said subsampled digital signal using differential pulse code modulation.
11. Signal processing apparatus as defined in claim 10, wherein said coding means includes a multi-dimensional filter having the response:-
12. Signal processing apparatus as defined claim 1, wherein said encoded means is adapted to encode a composite colour NTSC signal and comprises means for sampling such signal at a sampling frequency that is sub-carrier locked.
13. Signal processing apparatus as defined in claim 12, wherein said coding means includes means for subsampling the digitally encoded signal using a double checkerboard pattern.
14. Signal processing apparatus as defined in claim 12, wherein said coding means includes means for subsampling the digitally encoded signal using a field quincunx subsampling pattern (SPAT).
15. Signal processing apparatus as defined in claim 14, wherein said coding means includes a multi-dimensional filter having one of the responses:
16. Signal processing apparatus as defined in claim 13, wherein said encoder is adapted to encode a composite colour NTSC
signal and includes means for sampling such signal at a frequency that is line locked.
signal and includes means for sampling such signal at a frequency that is line locked.
17. Signal processing apparatus as defined in claim 16, wherein said coding means serves to subsample the signal using a field quincunx pattern.
18. Signal processing apparatus as defined in claim 16, wherein said coding means includes a multi-dimensional filter having the response:-
19. Signal processing apparatus as defined in claim 16, wherein said coding means serves to subsample the signal using a checkerboard pattern.
20. Signal processing apparatus as defined in claim 1, wherein said coding means is adapted to encode a component colour NTSC
signal and includes means for sampling such signal at a frequency that is line locked.
signal and includes means for sampling such signal at a frequency that is line locked.
21. Signal processing apparatus as defined in claim 20, wherein said coding means includes means for subsampling the digitally encoded signal using a field quincunx subsampling pattern (SPAT).
22. Signal processing apparatus as defined in claim 21, wherein said coding means includes a multi-dimensional filter having one of the responses:
23. Signal processing apparatus as defined in claim 20, wherein said coding means includes means for subsampling the digitally encoded signal using a double checkerboard pattern.
24. Signal processing apparatus as defined in claim 23, wherein said coding means includes a multi-dimensional filter having the response:
25. Signal processing apparatus as defined in claim 20, wherein said coding means serves to subsample the signal using a line quincunx pattern.
26. Signal processing apparatus as defined in claim 25, wherein said coding means includes a multi-dimensional filter having the response:
27. A signal processing method for encoding an analog signal (V) to produce a coded signal, comprising the steps of:-sampling the analog signal (V) to provide a digitally encoded signal (S);
providing two distinct subsampled digital signals (E,P) from the digitally encoded signal (S) including:
subsampling said digitally encoded signal (S) to provide a subsampled digital signal (P) corresponding to the input signal, and filtering and subsampling said digitally encoded signal (S) to provide a complementary subsampled signal (E) corresponding to the difference between the digitally encoded signal (S) and a filtered signal derived by filtering the signal (S); and encoding said two distinct signals (E,P) differently from each other to provide two coded distinct signals (EI, Ep), respectively.
providing two distinct subsampled digital signals (E,P) from the digitally encoded signal (S) including:
subsampling said digitally encoded signal (S) to provide a subsampled digital signal (P) corresponding to the input signal, and filtering and subsampling said digitally encoded signal (S) to provide a complementary subsampled signal (E) corresponding to the difference between the digitally encoded signal (S) and a filtered signal derived by filtering the signal (S); and encoding said two distinct signals (E,P) differently from each other to provide two coded distinct signals (EI, Ep), respectively.
28. The signal processing method as defined in claim 27, wherein said filtering and subsampling of said digitally encoded signal comprises:-employing multi-dimensional filter means to produce from said signal (S) a filtered signal, differencing said digitally encoded signal and the filtered signal to provide an interpolated signal, and subsampling the interpolated signal obtained by such differencing step to provide the complementary subsampled signal.
29. The signal processing method as defined in claim 27, wherein said step of providing said two distinct signals, includes subsampling said signal (S) to provide said subsampled digital signal (P) of said two distinct signals, using multi-dimensional filter means to provide a filtered signal, complementarily subsampling said signal (S) to provide the complementary subsampled signal (E), such complementary subsampling using a subsampling pattern that is complementary to said subsampling used for said signal (S) and differencing said complementary subsampled signal and said filtered signal to provide said subsampled signal P.
30. A signal processing method as defined in claim 27, including the step of subsampling said digitally encoded signal in a line quincunx pattern to provide said complementary subsampled signal.
31. A signal processing method as defined in claim 27 wherein said subsampling comprises the step of subsampling said digitally encoded signal in a field quincunx pattern.
32. A signal processing method as defined in claim 27, wherein said subsampling comprises the step of subsampling said digitally encoded signal in a double checkerboard pattern.
33. A signal processing method as defined in claim 27, wherein encoding of said complementary subsampled signal uses variable word length coding and encoding of said subsampled digital signal uses differential pulse code modulation.
34. A signal processing method as defined in claim 27, including the step of sampling said input signal (V) using an orthogonal aligned sampling structure.
35. A signal processing method as defined in claim 34, wherein said subsampling comprises the step of subsampling said digitally encoded signal in a line quincunx pattern.
36. A signal processing method as defined in claim 34, wherein said subsampling comprises the step of subsampling said digitally encoded signal in a field quincunx pattern.
37. A signal processing method as defined in claim 34, wherein said subsampling comprises the step of sampling said digitally encoded signal in a double checkerboard pattern.
38. A signal processing method as defined in claim 28, comprising encoding a composite colour NTSC signal and sampling such signal at a sampling frequency that is line locked.
39. A signal processing method as defined in claim 38, wherein subsampling of the digitally encoded signal uses a field quincunx subsampling pattern (SPAT).
40. A signal processing method as defined in claim 39, wherein said filtering employs a multi-dimensional filter having one of the responses:-
41. A signal processing method as defined in claim 38, wherein said subsampling of the digitally encoded signal uses a double checkerboard pattern.
42. A signal processing method as defined in claim 41, wherein said filtering uses a multi-dimensional filter having the response:-
43. A signal processing method as defined in claim 38, including subsampling the signal using a line quincunx pattern.
44. A signal processing method as defined in claim 43, wherein said filtering uses a multi-dimensional filter having the response:- Variable-word-length code for coding of interpolation error 6-bit symetrical companded quantizer Q1 (positive cycle) for case no.1 6-bit symetrical companded quantizer Q1 (positive cycle) for case no.3 Mildly companded quantizer Q2 (positive cycle) used for quantizing interpolation error prior to VWL encoding for case no.3 and no.4 5-bit symetrical companded quantizer Q1 (positive cycle) for case no.4
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| US06/939,983 US4782387A (en) | 1986-12-08 | 1986-12-09 | Two-channel coding of digital signals |
| JP62304665A JPS63152237A (en) | 1986-12-08 | 1987-12-03 | Method and apparatus for processing signal |
| AT87310736T ATE95365T1 (en) | 1986-12-08 | 1987-12-07 | DIGITAL SIGNAL CODING IN TWO CODING CHANNELS. |
| KR870013904A KR880008676A (en) | 1986-12-08 | 1987-12-07 | Apparatus and method for two-channel coding of digital signals |
| DE87310736T DE3787637T2 (en) | 1986-12-08 | 1987-12-07 | Digital signal coding in two coding channels. |
| EP87310736A EP0274861B1 (en) | 1986-12-08 | 1987-12-07 | Two-channel coding of digital signals |
| AU82185/87A AU596717B2 (en) | 1986-12-08 | 1987-12-07 | Two-channel coding of digital signals |
| CN87107425A CN1011467B (en) | 1986-12-08 | 1987-12-08 | Two-channel coding of digital signals |
| JP62308847A JPH0656982B2 (en) | 1986-12-08 | 1987-12-08 | Signal processing system |
| BR8706607A BR8706607A (en) | 1986-12-08 | 1987-12-08 | APPLIANCE AND PROCESS FOR PROCESSING SIGNALING DECODER FOR ENCODER AND PROCESSING FOR DECODING SIGNALED ENCODES |
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| CA000524786A CA1261069A (en) | 1986-12-08 | 1986-12-08 | Two-channel coding of digital signals |
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| US7831204B1 (en) * | 1981-11-03 | 2010-11-09 | Personalized Media Communications, Llc | Signal processing apparatus and methods |
| FR2613165B1 (en) * | 1987-03-24 | 1989-06-23 | Labo Electronique Physique | HIGH DEFINITION TELEVISION IMAGE TRANSMISSION SYSTEM THROUGH A NARROW BANDPASS CHANNEL |
| FR2613166B1 (en) * | 1987-03-24 | 1989-06-23 | Labo Electronique Physique | DEVICE FOR TRANSMITTING HIGH DEFINITION IMAGES THROUGH A RELATIVELY NARROW BANDPASS CHANNEL |
| JP2829954B2 (en) * | 1987-08-22 | 1998-12-02 | ソニー株式会社 | Apparatus and method for highly efficient encoding of image signal |
| JPS6477391A (en) * | 1987-09-18 | 1989-03-23 | Victor Company Of Japan | System and device for predictive coding |
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| US5016100A (en) * | 1988-04-04 | 1991-05-14 | Zenith Electronics Corporation | Transmission of a video signal using adaptive delta modulation |
| JPH02224488A (en) * | 1989-02-27 | 1990-09-06 | Canon Inc | Picture transmission system |
| JP2925157B2 (en) * | 1989-02-28 | 1999-07-28 | キヤノン株式会社 | Data storage device |
| US5128758A (en) * | 1989-06-02 | 1992-07-07 | North American Philips Corporation | Method and apparatus for digitally processing a high definition television augmentation signal |
| US5179442A (en) * | 1989-06-02 | 1993-01-12 | North American Philips Corporation | Method and apparatus for digitally processing a high definition television augmentation signal |
| US4958226A (en) * | 1989-09-27 | 1990-09-18 | At&T Bell Laboratories | Conditional motion compensated interpolation of digital motion video |
| JPH03267880A (en) * | 1989-12-04 | 1991-11-28 | Ricoh Co Ltd | Color picture compression |
| EP0436251B1 (en) * | 1989-12-29 | 1995-09-27 | Laboratoires D'electronique Philips | Coder/decoder for digital signals to be transmitted and/or stored |
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| FR2660139B1 (en) * | 1990-03-23 | 1995-08-25 | France Etat | ENCODING AND TRANSMISSION METHOD FOR AT LEAST TWO QUALITY LEVELS OF DIGITAL IMAGES BELONGING TO A SEQUENCE OF IMAGES, AND CORRESPONDING DEVICES. |
| JP2722353B2 (en) * | 1990-04-26 | 1998-03-04 | キヤノン株式会社 | Image signal encoding device |
| US5010402A (en) * | 1990-05-17 | 1991-04-23 | Matsushita Electric Industrial Co., Ltd. | Video signal compression apparatus |
| US5057917A (en) * | 1990-06-20 | 1991-10-15 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Real-time data compression of broadcast video signals |
| GB2245805A (en) * | 1990-06-29 | 1992-01-08 | Philips Electronic Associated | Generating an anti-aliased image |
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| JP2606508B2 (en) * | 1991-10-29 | 1997-05-07 | 日本ビクター株式会社 | Video prediction encoding apparatus and decoding apparatus therefor |
| JP2830883B2 (en) * | 1991-10-31 | 1998-12-02 | 日本ビクター株式会社 | Video encoding device and decoding device therefor |
| US5280343A (en) * | 1992-01-21 | 1994-01-18 | Eastman Kodak Company | Separable subsampling of digital image data with general periodic symmetry |
| US5337085A (en) * | 1992-04-10 | 1994-08-09 | Comsat Corporation | Coding technique for high definition television signals |
| US5387940A (en) * | 1993-07-07 | 1995-02-07 | Rca Thomson Licensing Corporation | Method and apparatus for providing scaleable compressed video signal |
| US6307597B1 (en) * | 1996-03-07 | 2001-10-23 | Thomson Licensing S.A. | Apparatus for sampling and displaying an auxiliary image with a main image |
| EP1133166A3 (en) * | 2000-01-06 | 2003-08-06 | Hewlett-Packard Company, A Delaware Corporation | Using hardware to double the X-dimension in a video frame |
| US8331445B2 (en) * | 2004-06-01 | 2012-12-11 | Qualcomm Incorporated | Method, apparatus, and system for enhancing robustness of predictive video codecs using a side-channel based on distributed source coding techniques |
| US20080167881A1 (en) * | 2005-02-03 | 2008-07-10 | Bertrand Haas | Method for Two-Channel Coding of a Message |
| US9717440B2 (en) * | 2013-05-03 | 2017-08-01 | The Florida International University Board Of Trustees | Systems and methods for decoding intended motor commands from recorded neural signals for the control of external devices or to interact in virtual environments |
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1987
- 1987-12-03 JP JP62304665A patent/JPS63152237A/en active Pending
- 1987-12-07 AU AU82185/87A patent/AU596717B2/en not_active Ceased
- 1987-12-07 AT AT87310736T patent/ATE95365T1/en not_active IP Right Cessation
- 1987-12-07 DE DE87310736T patent/DE3787637T2/en not_active Expired - Fee Related
- 1987-12-07 EP EP87310736A patent/EP0274861B1/en not_active Expired - Lifetime
- 1987-12-07 KR KR870013904A patent/KR880008676A/en not_active Application Discontinuation
- 1987-12-08 JP JP62308847A patent/JPH0656982B2/en not_active Expired - Fee Related
- 1987-12-08 BR BR8706607A patent/BR8706607A/en unknown
- 1987-12-08 CN CN87107425A patent/CN1011467B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE3787637T2 (en) | 1994-01-27 |
| EP0274861A2 (en) | 1988-07-20 |
| EP0274861A3 (en) | 1990-12-27 |
| EP0274861B1 (en) | 1993-09-29 |
| CN1011467B (en) | 1991-01-30 |
| JPS63191429A (en) | 1988-08-08 |
| ATE95365T1 (en) | 1993-10-15 |
| KR880008676A (en) | 1988-08-31 |
| US4782387A (en) | 1988-11-01 |
| JPS63152237A (en) | 1988-06-24 |
| BR8706607A (en) | 1988-07-19 |
| DE3787637D1 (en) | 1993-11-04 |
| CN87107425A (en) | 1988-11-23 |
| JPH0656982B2 (en) | 1994-07-27 |
| AU8218587A (en) | 1988-06-16 |
| AU596717B2 (en) | 1990-05-10 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |