Method of and device for encoding a data stream
AssigneeKoninklijke Philips Electronics N.V.
InventorsEmmanuel David Frimout, Lincoln Lobo
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Abstract
A method of and devices for encoding an information stream (20) into a variable bit rate (VBR) encoded information stream (24) have been proposed. The application discloses an improved constraint variable bit rate (CVBR) encoding, which guarantees that in a particular recording mode on a record carrier, any contiguous selection from the recording on this record carrier can be copied to another record carrier having a storage capacity corresponding to said recording mode, without the necessity to employ a lower average bit rate an while still using the maximum variable bit rate freedom within the window to be archived.
Claims18
A method of encoding an input information stream in real-time, which input information stream comprises a stream of information units [RIN], comprising:
- an encoding step of converting the input information stream into an output information stream, said output information stream comprising a variable stream of information units [RENC], the variable stream of information units being between a minimum value RENC,MIN and a maximum value RENC,MAX, while the effect of the encoding step can be influenced by means of at least one control signal [R];
- a measuring step in which, at any instant T, a reduced quantity of information units [ENCOUT(T)−RENC,AVER·T] is calculated by subtracting a predefined average value of the variable stream of information units in the output information stream [RENC,AVER] multiplied by the instant T, from a quantity of information units [ENCOUT(T)] generated in the encoding step, in accordance with the formula ENCOUT(T)−RENC,AVER·T;
- a modification step in which a modified quantity of information units [ENCOUT(T)−RENC,AVER·T+ENCOFF(T,ΔT)] is calculated by adding an offset value [ENCOFF(T,ΔT)] to the reduced quantity of information units [ENCOUT(T)−RENC,AVER·T] in accordance with the formula ENCOUT(T)−RENC,AVER·T+ENCOFF(T, ΔT), where the offset value [ENCOFF(T, ΔT)] is chosen in dependence on values of reduced quantity of information units [ENCOUT(TX)−RENC,AVER·TX] for specific instants TX within a time interval [T−ΔT,T] where ΔT represents a predefined time period, and in dependence of at least one signalizing signal [S] generated in at least one comparison step executed for at least one value of modified quantity of information units [ENCOUT(TX)−RENC,AVER·TX+ENCOFF(T, ΔT)];
- a comparison step in which the modified quantity of information units [ENCOUT(T)−RENC,AVER·T+ENCOFF(T, ΔT)] is compared with at least one criterion, and in which at least one signalizing signal [S] is generated;
- and
- a control step in which at least one control signal [R] is generated, in which the state of the control signal depends on the state of at least one of the signalizing signals [S] generated in the comparison step, and which control signal influences the effect of the encoding step.
An encoding device for encoding an input information stream comprising a stream of information units [RIN] into an output information stream, said output information stream comprising a variable stream of information units [RENC], which variable stream of information units is between a minimum value [RENC,MIN] and a maximum value [RENC,MAX], the device comprising:
- compression means for converting the input information stream into the output information stream;
- measuring means for measuring a quantity of information units [ENCOUT(T)] generated by the encoding device;
- calculating means for calculating, at any instant T, a reduced quantity of information units [ENCOUT(T)−RENC,AVER−T] by subtracting a predefined average value of the variable stream of information units in the output information stream [RENC,AVER] multiplied by the instant T, from the quantity of information units [ENCOUT(T)], in accordance with the formula ENCOUT(T)−RENC,AVER·T, and for calculating a modified quantity of information units [ENCOUT(T)−RENC,AVER·T+ENCOFF(T,ΔT)] by adding an offset value [ENCOFF(T,ΔT)] to the reduced quantity of information units [ENCOUT(T)−RENC,AVER·T] in accordance with the formula ENCOUT(T)−RENC,AVER·T+ENCOFF(T,ΔT), where the offset value [ENCOFF(T,ΔT)] is chosen in dependence on values of reduced quantity of information units [ENCOUT(TX)−RENC,AVER·TX] for specific instants TX within a time interval [T−ΔT,T] where ΔT represents a predefined time period, and in dependence of at least one signalizing signal [S] generated by comparing means for at least one value of modified quantity of information units [ENCOUT(TX)−RENC,AVER·TX+ENCOFF(T,ΔT)];
- comparing means for comparing the modified quantity of information units [ENCOUT(T)−RENC,AVER·T+ENCOFF(T,ΔT)] with at least one criterion and for generating at least one signalizing signal [S];
- and
- control means for generating at least one control signal for controlling the compression means in dependence on the state of at least one of the signalizing signals.
Dependencies are inferred from the claim text.