The present invention relates to the predictive coding of information signals, such as, for example, audio signals, and in particular to adaptive predictive coding. A predictive coder - or transmitter - codes signals by predicting a current value of the signal to be coded by the previous or preceding values of the signal. In the case of linear prediction, this prediction or presumption is accomplished via the current value of the signal by a weighted sum of the previous values of the signal. The prediction weights or prediction coefficients are continuously adjusted or adapted to the signal so that the difference between the predicted signal and the actual signal is minimized in a predetermined manner. The prediction coefficients, for example, are optimized with regard to the square of the prediction error. The error criterion when optimizing the predictive coder or predictor, however, may also be selected to be something else. Instead of using the least square error criterion, the spectral flatness of the error signal, i.e. of the differences or residuals, may be minimized. Only the differences between the predicted values and the actual values of the signal are transmitted to the decoder or receiver. These values are referred to as residuals or prediction errors. The actual signal value can be reconstructed in the receiver by using the same predictor and by adding the predicted value obtained in the same manner as in the coder to the prediction error having been transmitted by the coder. The prediction weights for the prediction may be adapted to the signal with a predetermined speed. In the so-called least mean squares (LMS) algorithm, one parameter is used ror this. The parameter must be adjusted in a manner acting as a trade-off between adaption speed and precision of the prediction coefficients. This parameter, which is sometimes also referred to as step-size parameter, thus determines how fast the prediction coefficients adapt to an optimum set of prediction coefficients, wherein a set of prediction coefficients not adjusted optimally results in the prediction to be less precise and thus the prediction errors to be greater, which in turn results in an increased bit rate for transmitting the signal since small values or small prediction errors or differences can be transmitted by fewer bits than greater ones. A problem in predictive coding is that in the case of transmitting errors, i.e. if incorrectly transmitted prediction differences or errors occur, prediction will no longer be the same on the transmitter and receiver sides. Incorrect values will be reconstructed since, when a prediction error first occurs, it is added on the receiver side to the currently predicted value to obtain the decoded value of the signal. Subsequent values, too, are affected since the prediction on the receiver side is performed based on the signal values already decoded. In order to obtain resynchronization or adjustment between transmitter and receiver, the predictors, i.e. the prediction algorithms, are reset to a certain state on the transmitter and receiver sides at predetermined times equal for both sides, a process also referred to as reset. However, it is problematic that directly after such a reset the prediction coefficients are not adjusted to the signal at all. The adaption of these prediction coefficients, however, will always require some time starting from the reset times. This increases the mean prediction error resulting in an increased bit rate or reduced signal quality, such as, for example, due to distortions. US Patent 6,104,996 A describes an audio coding method by means of an adaptive prediction algorithm in particular, according to this document, switching takes place between higher order prediction and lower order prediction during the coding when transients occur in order to obtain maximum prediction gain possible. This document does not disclose a predictive coding scheme with a controllable adaptive speed parameter, hence changing such adaptive speed parameter is not described. The document also does not disclose changing any parameter of the predictive coding after a predetermined time duration has elapsed, hi document '996 there is only a change from a higher prediction order to a lower prediction order and vice versa and this change further takes place in dependence on the signal properties. Consequently, it is an object of the present invention to provide a scheme for predictive coding of an information signal which, on the one hand, allows more sufficient robustness to errors in the difference value or residuals of the coded information signal and, on the other hand, allows a lower accompanying increase in the bit rate or decrease in signal quality. This object is achieved by a device according to claims 8 or 22 or a method according to claims 1 or 15. The present invention is based on the finding that the, up to now, fixed setting of the speed parameter of the adaptive prediction algorithm acting as the basis of predictive coding has to be given up in favour of a variable setting of this parameter. If an adaptive prediction algorithm controllable by a speed coefficient is started from to operate with a first adaption speed and a first adaption precision and an accompanying first prediction precision in the case that the speed coefficient has a first value and to operate with a second, but compared to the first one, lower adaption speed and a second, compared to the first one, higher precision in the case that the speed parameter has a second value, the adaption durations occurring after the reset times where the prediction errors are at first increased due to the prediction coefficients having not yet been adapted can be decreased by a first setting the speed parameter to the first value and, after a while, to the second value. After setting the speed parameter again to the second value after a predetermined duration after the reset times, the prediction errors and thus the residuals to be transmitted are more optimized or smaller than would be possible with the first speed parameter value. Put differently, the present invention is based on the finding that prediction errors can be minimized after reset times by altering the speed parameters, such as, for example, the step-size parameter of an LMS algorithm, for a certain duration after the reset times such that the speed of the adaption of the weights is increased for this duration - of course entailing reduced precision. Preferred embodiments of the present invention will be detailed subsequently referring to the appended drawings, in which: Fig. 1 shows a block circuit diagram of a predictive coder according to an embodiment of the present invention; Fig. 2 shows a block circuit diagram for illustrating the mode of functioning of the coder of Fig. 1; Fig. 3 shows a block circuit diagram of a decoder corresponding to the coder of Fig. 1 according to an embodiment of the present invention; Fig. 4 shows a flowchart for illustrating the mode of functioning of the decoder of Fig. 3; Fig. 5 shows a block circuit diagram of the prediction means of Figs. 1 and 3 according to an embodiment of the present invention; Fig. 6 shows a block circuit diagram of the transversal filter of Fig. 5 according to an embodiment of the present invention; Fig. 7 shows a block circuit diagram of the adaption controller of Fig. 5 according to an embodiment of the present invention; and Fig. 8 shows a diagram for illustrating the behavior of the prediction means of Fig. 5 for two different fixedly set speed parameters. Before discussing embodiments of the present invention in greater detail referring to the figures, it is pointed out that elements occurring in different figures are provided with same reference numerals and that a repeated description of these elements is omitted. Fig. 1 shows a predictive coder 10 according ' to an embodiment of the present invention. The coder 10 includes an input 12 where it receives the information signal s to be coded and an output 14 where it outputs the coded information signal 8. The information signal may be any signal, such as, for example, an audio signal, a video signal, a measuring signal or the like. The information signal s consists of a sequence of information values s(i), iÎ|N, i.e. audio values, pixel values, measuring values or the like. The coded information signal 8 includes, as will be discussed in greater detail below, a sequence of difference values or residuals 8(i), iÎ|N, corresponding to the signal values s(i) in the manner described below. Internally, the coder 10 includes prediction means 16, a subtracter 18 and control means 20. The prediction means 16 is connected to the input 12 in order to calculate, as will be discussed in greater detail below, a predicted value s'(n) from previous signal values s(m), mn+l". If, however, there is a speed parameter alteration time in step 96, in step 100 the control means 70 will set the speed parameter A. to a second value corresponding to a lower adaption speed but higher adaption precision, as has already been discussed with regard to coding. As has been mentioned, it is ensured either by information in the coded information signal 62 or by standardization that the speed parameter changes and reset times occur at the same positions or between the same signal values or decoded signal values, namely on the transmitter side and the receiver side. After a predictive coding scheme according to an embodiment of the present invention has been described in general referring to Figs. 1-4, a special embodiment of the prediction means 16 will be described now referring to Figs. 5-7, wherein in this embodiment the prediction means 16 operates according to an LMS adaption algorithm. Fig. 5 shows the setup of the prediction means 16 according to the LMS algorithm embodiment. As has already been described referring to Figs. 1 and 3, the prediction means 16 includes an input 120 for signal values s (n), and input 122 for prediction errors or difference values 8(n), two control inputs 124 and 126 for initializing the coefficients (O± or setting the speed parameter 5 and an output 128 for outputting the predicted value s'(n). Internally, the prediction means 16 includes a transversal filter 130 and an adaption controller 132. The transversal filter 130 is connected between the input 120 and the output 128. The adaption controller 132 is connected to the two control inputs 124 and 126 and additionally to the inputs 120 and 122 and also includes an output to pass on correction values 8?i for the coefficients ?i to the transversal filter 130. The LMS algorithm implemented by the prediction means 16 - maybe in cooperation with the subtracter 18 (Fig. 1) - is a linear adaptive filter algorithm which, put generally, consists of two basic processes: 1. A filter process including (a) calculating the output signal s'(n) of a linear filter responsive to an input signal s(n) by the transversal filter 130 and (b) generating an estimation error 8(n) by comparing the output signal s' (n) to a desired response s(n) by the subtracter 18 or obtaining the estimation error 5(n) from the coded information signal 5. 2. An adaptive process performed by the adaption controller 132 and comprising automatic adjustment of the filter coefficients ?i of the transversal filter 130 according to the estimation error 5(n). The combination of these two cooperating processes results in a feedback loop, as has already been discussed referring to Figs. 1-4. Details of the transversal filter 130 are illustrated in Fig. 6. The transversal filter 130 receives at an input 140 the sequence of signal values s(n). The input 140 is followed by a series connection of m delay elements 142 so that the signal values s(n-l) ... s(n-m) preceding the current signal value s (n) are present at connective nodes between the m delay elements 142. Each of these signal values s(n-l) ... s (n-m) or each of these connective nodes is applied to one of m weighting means 144 weighting or multiplying the respective applying signal value by a respective prediction weighting or a respective one of the filter coefficients ?i, i = 1 ... m. The weighting means 144 output their results to a respective one of a plurality of adders 146 connected in series so that the estimation value or predicted value s'(m) results to output 148 of the transversal filter 130 from the sum of the last adder of the series connection. In a broader sense, the estimation value s'(n) comes close to a value predicted according to the Wiener solution in a, in a broader sense, stationary surrounding when the number of iterations n reaches infinity. The adaption controller 132 is shown in greater detail in Fig. 7. The adaption controller 132 thus includes an input 160 where the sequence of difference values 5(n) is received. They are multiplied in weighting means 162 by the speed parameter X, which is also referred to as step-size parameter. The result is fed to a plurality of m multiplication means 164 multiplying it by one of the signal values s(n-l) ... s (n-m) . The results of the multipliers 164 form correction values d?i ... d?m. Consequently, the correction values d?i ... d?m represent a scalar version of the internal product of the estimation error 8(n) and the vector from signal values s(n-l) ... s (n- m) . These correction values are added before the next filter step to the current coefficients ?i ... d?m so that the next iteration step, i.e. for the signal value s(n+l), in the transversal filter 130 is performed with the new adapted coefficients ?i —» ?i + d?i. The scaling factor X used in the adaption controller 132 and, as has already been mentioned, referred to as step- size parameter may be considered to be a positive quantity and should meet certain conditions relative to the spectral content of the information signal in order for the LMS algorithm realized by the means 16 of Figs. 5-7 to be stable. Here, stability is to mean that with increasing n, i.e. when the adaption is performed with infinite duration, the means square error generated by the filter 130 reaches a constant value. An algorithm meeting this condition is referred to as mean square stable. An alteration of the speed parameter ? causes an alteration in the adaption precision, i.e. in precision, since the coefficients ?i may be adjusted to an optimum set of coefficients. Maladjustment of the filter coefficients results in an increase in the mean square error or the energy in the difference values 8 in the steady state n—>. In particular, the feedback loop acting on the weights ?i acts like a low-pass filter, the determination duration constant of which is inversely proportional to the parameter X. Consequently, the adaptive process is slowed down by setting the parameter ? to a small value, wherein the effects of this gradient noise on the weights ?i are largely filtered out. This has the reverse effect of reducing maladjustment. Fig. 8 illustrates the influence of setting the parameter X to different values ?i and ?2 on the adaption behavior of the prediction means 16 of Figs. 5-7 using a graph where the number of iterations n or the number of predictions and adaptions n is plotted along the x axis and the mean energy of the residual values 8(n) or the mean square error is plotted along the y axis. A continuous line refers to a speed parameter ?i. As can be seen, the adaption to a stationary state where the mean energy of the residual values basically remains constant requires a number ni of iterations. The energy of the residual values in the settled or quasi-stationary state is Ei. A broken graph results for a greater speed parameter X2, wherein, as may be seen, fewer iterations, namely n2, are required until the steady state is reached, wherein the steady state, however, entails a higher energy E2 of the residual values. The settled state at Ei or E2 exhibits not only settling of the mean square error of the residual values or residuals to an asymptotic value, but also settling of the filter coefficients (o± to the optimum set of filter coefficients with a certain precision which in the case of X-i is higher and in the case of X2 is lover. If, however, as has been described referring to Figs. 1-4, the speed parameter A. is at first set to the value \2, an adaption of the coefficients (fli will at first be achieved quicker, wherein the change to A-i after a certain duration after the reset times then provides for the adaption precision for the following duration to be improved. All in all, a residual value energy graph allowing a higher compression than by one of the two parameter settings alone is achieved. With regard to the above description of the figures, it is pointed out that the present invention is not limited to LMS algorithm implementations. Although, referring to Figs. 5-8, the present invention has been described in greater detail with regard to the LMS algorithm as an adaptive prediction algorithm, the present invention may also be applied in connection with other adaptive prediction algorithms where matching between adaption speed on the one hand and adaption precision on the other hand may be performed via a speed parameter. Since the adaption precision in turn influences the energy of the residual value, the speed parameter may always at first be set such that the adaption speed is great, whereupon it is then set to a value where the adaption speed is small, but the adaption precision is greater and thus the energy of the residual values is smaller. With such prediction algorithms, for example, there need not be a connection between the input 120 and the adaption controller 132. Additionally, it is pointed out that, instead of the fixed duration described above after the reset times for triggering the speed parameter change, triggering may also be performed depending on the adaption degree, such as, for example, triggering a speed parameter change when the coefficient corrections 5co, such as, for example, a sum of the absolute values thereof, fall below a certain value, indicating an approximation Lo Lhe quasi-stationary state, as is shown in Fig. 8, to a certain approximation degree. In particular, it is pointed out that depending on the circumstances the inventive scheme may also be implemented in software. The implementation may be on a digital storage medium, in particular on a disc or a CD having control signals which may be read out electronically which can cooperate with a programmable computer system such that the corresponding method will be executed. In general, the invention thus also is in a computer program product having a program code stored on a machine-readable carrier for performing the inventive method when the computer program product runs on a computer. Put differently, the invention may thus also be realized as a computer program having a program code for performing the method when the computer program runs on a computer. WE CLAIM 1. A method for predictively coding an information signal including a sequence of information values by means of an adaptive prediction algorithm the prediction coefficients (?i) of which may be initialized and which is controllable by a speed parameter (?) to operate with a first adaption speed and a first adaption precision in the case that the speed parameter (A.) has a first value and to operate with a second, compared to the first one, lower adaption speed and a second, compared to the first one, higher adaption precision in the case that the speed parameter (?) has a second value, comprising the steps of: A) initializing (40) the prediction coefficients (?i); B) controlling (42) the adaptive prediction algorithm to set the speed parameter (?) to the first value; C) coding (44) successive information values of the information signal by means of the adaptive prediction algorithm with the speed parameter (?) set to the first value as long as a predetermined duration after step B) has not expired to code a first part of the information signal; D) after expiry of the predetermined duration after step B), controlling (50) the adaptive prediction algorithm to set the speed parameter (?) to the second value; and E) coding (44) information values of the information signal following the information values coded in step C) by means of the adaptive prediction algorithm with the speed parameter (?) set to the second value to code a second part of the information signal following the first part. 2. The method according to claim 1, wherein step C) is performed using adaption of the prediction coefficients (?i) initialized in step A) to- obtain adapted prediction coefficients (?I) and wherein step E) is performed using adaption of the adapted prediction coefficients (?i) . 3. The method according to claims 1 or 2, wherein steps A)-E) are repeated intermittently at predetermined times to code successive sections of the information signal. 4. The method according to claim 3, wherein the predetermined times cyclically return in a predetermined time interval. 5. The method according to one of the preceding claims, wherein step D) is performed after a predetermined duration has passed after step B). 6. The method according to one of the preceding claims, wherein from steps C) and E) differences between information values of the information signal and predicted values are obtained representing a coded version, of the information signal. 7. A device for predictively coding an information signal including a sequence of information values, comprising: means (16, 18) for performing an adaptive prediction algorithm the prediction coefficients (?I) of which may be initialized and which is controllable by a speed parameter (A.) to operate with a first adaption speed and a first adaption precision in the case that the speed parameter (A.) has a first value and to operate with a second, compared to the first one, lower adaption speed and a second, compared to the first one, higher adaption precision in the case that the speed parameter (A.) has a second value; and control means (20) coupled to the means for performing the adaptive prediction algorithm and effective to cause: A) initialization (40) of the prediction coefficients (?I) ; B) control (42) of the adaptive prediction algorithm to set the speed parameter (A.) to the first value; C) coding (44) of successive information values of the information signal by means of the adaptive prediction algorithm with the speed parameter (A) set to the first value as long as a predetermined duration after the control B) has not expired to code a first part of the information signal; D) after expiry of the predetermined duration after the control B) , control (50) of the adaptive prediction algorithm to set the speed parameter (?) to the second value; and E) coding (44) of information values of the information signal following the information values coded in the coding C) by means of the adaptive prediction algorithm with the speed parameter (?) set to the second value to code a second part of the information signal following the first part. 8. The device according to claim 7, wherein the control means (20) is formed to cause coding C) to be performed using adaption of the prediction coefficients (?I) initialized in A) to obtain adapted prediction coefficients (?i) and coding E) to be performed using adaption of the adapted prediction coefficients (?I) . 9. The device according to one of claims 6 to 8, wherein the control means (20) is formed to cause steps A)-E) to be repeated intermittently at predetermined times to code successive sections of the information signal. 10. The device according to claim 9, wherein the control means (20) is formed such that the predetermined times cyclically return in a predetermined time interval. 11. The device according to claims 9 or 10, wherein the control means (20) is formed such that step D) is performed after a certain duration after step B) has passed. 12. The device according to one of claims 7-11, wherein the means for performing an adaptive prediction algorithm is formed to obtain differences between information values of the information signal and predicted values representing a coded version of the information signal. 13. A method for decoding a predictively coded information signal including a sequence of difference values by means of an adaptive prediction algorithm the prediction coefficients (?i) of which may be initialized and which is controllable by a speed parameter {X) to operate with a first adaption speed and a first adaption precision in the case that the speed parameter (?) has a first value and to operate with a second, compared to the first one, lower adaption speed and a second, compared to the first one, higher adaption precision in the case that the speed parameter {?) has a second value, comprising the steps of: F) initializing (90) the prediction coefficients (?I) ; G) controlling (92) the adaptive prediction algorithm to set the speed parameter (A.) to the first value; H) decoding (94) successive difference values of the predictively coded information signal by means of the adaptive prediction algorithm with the speed parameter (?) set to the first value as long as a predetermined duration after step G) has not expired to decode a first part of the predictively coded information signal; I) after expiry of the predetermined duration after step G), controlling (100) the adaptive prediction algorithm to set the speed parameter {X)to the second value; and J) decoding (94) difference values of the predictively coded information signal following the difference values decoded in step H) by means of the adaptive prediction algorithm with the speed parameter (?) set to the second value to decode a second part of the predictively coded information signal. 14. The method according to claim 13, wherein step H) is performed using adaption of the prediction Coefficients (?i) initialized in step F) to obtain J) is performed using adaption of the adapted prediction coefficients (?i) . 15. The method according to claims 13 or 14, wherein steps F) -J) are repeated intermittently at predetermined times to decode successive sections of the predictively coded information signal. 16. The method according to claim 15, wherein the predetermined times cyclically return in a predetermined time interval. 17. The method according to one of claims 13 to 16, wherein step I) is performed after a predetermined duration has passed after step G). 18. The method according to one of claims 13-17, wherein steps H) and J) include adding differences in the predictively coded information signal and predicted values. 19. A device for decoding a predictively coded information signal including a sequence of difference values, comprising: means (16, 18) for performing an adaptive prediction algorithm the prediction coefficients (?i) of which may be initialized and which is controllable by a speed parameter (?) to operate with a first adaption speed and a first adaption precision in the case that the speed parameter (?) has a first value and to operate with a second, compared to the first one, lower adaption speed and a second, compared to the first one, higher adaption precision in the case that the speed parameter (?) has a second value; and control means (20) coupled to the means for performing the adaptive prediction algorithm and effective to cause: F) initialization (40) of the prediction coefficients (?I.) ; G) control (42) of the adaptive prediction algorithm to set the speed parameter (?) to the first value; H) decoding (44) of successive difference values of the predictively coded information signal by means of the adaptive prediction algorithm with the speed parameter (A.) set to the first value as long as a predetermined duration after the control G) has not expired to decode a first part of the predictively coded information signal; I) after expiry of the predetermined duration after the control G) , control (50) of the adaptive prediction algorithm to set the speed parameter (?) to the second value; and J) decoding (44) of difference values of the predictively coded information signal following the difference values decoded in the decoding H) by means of the adaptive prediction algorithm with the speed parameter (?) set to the second value to decode a second part of the predictively coded information signal. 20. The device according to claim 19, wherein the control means (20) is formed to cause the coding H) to be performed using adaption of the prediction coefficients (?I.) initialized in F) to obtain adapted prediction coefficients (?i), and the coding J) to be performed using adaption of the adapted prediction coefficients (?I). 21. The device according to claims 19 or 20, wherein the control means (20) is formed to cause steps (F-J) to be repeated intermittently at predetermined times to decode successive sections of the predictively coded information signal. 22. The device according to claim 21, wherein the control means (20) is formed such that the predetermined times cyclically return in a predetermined time interval. 23. The device according to one of claims 19 to 22, wherein the control means (20) is formed such that step I) is performed after a predetermined duration after step G) has passed. 24. The device according to one of claims 19-23, wherein the means for performing an adaptive prediction algorithm includes means for adding differences in the predictively coded information signal and predicted values. If an adaptive prediction algorithm controllable by a speed coefficient is started from to operate with a first adaption speed and a first adaption precision and an accompanying first prediction precision in the case that the speed coefficient has a first value and to operate with a second, compared to the first one, lower adaption speed and a second, but compared to the first one, higher precision in the case that the speed parameter has a second value, the adaption durations occurring after the reset times where the prediction errors are at first increased due to the, not yet, adapted prediction coefficients may be decreased by at first setting the speed parameter to the first value (42) and, after a while, to a second value (50). After the speed parameter has again been set to the second value after a predetermined duration after the reset times, the prediction errors and thus the residuals to be transmitted are more optimized or smaller than would be possible with the first speed parameter value.