MXPA00008819A - Method and device for recording real-time information - Google Patents

Abstract

In a method of recording real-time information on an information carrier, e.g. audio on an optical disc, the real-time information is compressed to units comprising a variable amount of compressed data, and playback parameters are determined in dependence of the compressed data. The playback parameters comprise an access list (Main_Acc_List) having entries, each subsequent entry being assigned to a subsequent interval of a fixed playback time and comprising a pointer (Entry[N]) to a unit within said interval. In a player the real-time information may be accessed at a selected point of playing time. The corresponding entry in the access list is determined by dividing the selected time by the interval. The entry provides the pointer (Entry[N]) to the unit corresponding to the selected playing time. Interpolation may be used for calculating an address at a selected playing time within an interval, and the accuracy may be improved by a margin parameter (Access_Flags[N]), which indicates the maximum distance between the unit of the selected playing time and the interpolated address.

Description

METHOD AND DEVICE FOR REGISTERING INFORMATION IN REAL TIME FIELD OF THE INVENTION The invention relates to a method for recording information in real time and reproduction parameters related to these an information carrier, a method in which the information in real time is compressed to units that comprise a variable amount of data. tablets, and the reproduction parameters are determined depending on the compressed data. The invention further relates to a recording device for recording information in real time on an information carrier, the device comprises processing means for compressing the information in real time to units comprising a variable amount of compressed data, processing means for generate reproduction parameters depending on the compressed data, recording means for recording the compressed data and the reproduction parameters. The invention further relates to an information carrier containing real-time information and reproduction parameters related thereto, the information in real time is represented by units comprising a variable amount of compressed data. The invention further relates to a reproduction device for reproducing information in real time of the information carrier, the device comprises reading means for recovering from the information carrier the units and reproduction parameters and processing means for processing the reproduction parameters.

BACKGROUND OF THE INVENTION A method for recording information in real time on an information carrier is known from PCT application WO 98/16014 (PHN 16452). Real-time information is information that has a real-time nature to be reproduced at a prescribed rate, usually audio and video information, or a combination of audio and video. In the known method the audio information is digitally encoded and compressed into units, which represent short segments of the audio signal and usually have a fixed duration of the playing time, for example 15 msec. The compression rate is variable and responds to the complexity of the information in real time, so that this results in a compressed data signal with a variable data rate. Therefore, the length of the units, ie the amount of compressed data to be stored per unit, is variable. The reproduction of the audio information requires all the compressed data of the respective units, and in this way the reading has to start at the beginning of a unit. The compressed data may be recorded on an information carrier, for example an optical disc similar to a DC (compact disc), which usually comprises several musical elements (usually called tracks), for example each comprising a song. The reproduction parameters to access and reproduce the information in real time are generated by activating the playback functions. For example, for an audio CD, a Content Index (IDC) is generated and stored in the information carrier, and it comprises indicators of the location of the elements to access the elements. Also the parameters indicative of the reproduction time of the elements are included in the IDC. Consequently, the IDC on an IDC can be used to access the recorded audio at the beginning of an element, that is to say at the reproduction time corresponding to the start of the element. However, the IDC can not be used to directly access the recorded audio at a selected point in the playback time within an item.

BRIEF DESCRIPTION OF THE INVENTION An object of the present invention is to provide recording and reproduction means for having a more flexible access to recorded information in real time. For this purpose, the method as described in the opening paragraph is characterized in that the reproduction parameters comprise an access list having entries, each subsequent entry is assigned to a subsequent interval- of a fixed reproduction time and comprises an indicator for a unit within of the interval. This has the effect that for a reproduction time arbitrarily selected the indicator of a unit at the selected point of the reproduction time can be easily determined from the access list, in particular, because the interval has a fixed size, example a second. The invention is also based on the following recognition. For audio recordings in the prior art, such as on a DC, the IDC contains item start addresses and playback time data, and allows access to the audio in an article based on the article. The intermediate points in the reproduction time within an element can be calculated from the initial direction of the element and the reproduction time within the element up to the selected point, because there is a fixed relation between the reproduction time and the amount of data of the digital audio signal stored. For a variable-compressed real-time signal there is no fixed relationship. Using linear interpolation for an element based on the start and end points of the element of an IDC would result in greater inaccuracy. For example, when you start a musical element with a part that is easy to compress, and end with a part which is difficult to compress in part, any interpolation to a point in time in the middle part of the element would be severely deviated towards the end of the element. Also explore the music at a higher speed by jumping fixed distances and then play a unit resulting in a relatively high speed in the first part, and a low speed in the second part. The inventors have recognized that the new access list according to the invention allows exact access of selected points of the reproduction time within a real-time recorded signal of a variable bit rate. An embodiment of the method according to the invention is characterized in that the reproduction parameters include a duration parameter indicative of the fixed reproduction time. Consequently the size of the step within the access list is set by the length of the interval. This has the advantage that the number of entries in the access list can be adapted to the requirements of the recorded signal with the required accuracy. A further embodiment of the method according to the invention is characterized in that the reproduction parameters include a margin parameter indicative of a correction of a calculated indicator of a unit within the range. Access to a point in time within a range may be required, and an interpolation may be used to calculate an indicator. However, since the calculated indicator may be after the actual position of the desired point in time, a margin may be added to start the reading process before the calculated indicator. By determining the margin exactly required during registration, and including the maximum value of the margin "actually required in the reproduction parameters, the reproductive device can interpolate and correct the interpolated indicator by the margin recovered from the reproduction parameters. that the reading process will always begin shortly before or at the unit of the point at the selected time In accordance with the invention, the recording device as described in the opening paragraph is characterized as claimed in the claim. as described in the opening paragraph, it is characterized as claimed in claim 5. Further, the reproducing device as described in the opening paragraph is characterized as claimed in claim 7. The effects and advantages of the information carrier and the device registration and / or reproduction have been explained above with ref Erencia to the method. Additional preferred modalities of the method, devices and information carrier according to the invention are given in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS These and other aspects of the invention will be apparent from and determined best with reference to the embodiments described by way of example in the following description and with reference to the accompanying drawings, in which Figure 1 * shows a record carrier, Figure 2 shows an access_list syntax Figure 3 shows a syntax of Main_Acc_list_cc ^ Figure 4 shows a method for determining the access margin Figure 5 shows a player device, and Figure 6 shows a device for registry. The corresponding elements in the different Figures have identical numerical references.

DETAILED DESCRIPTION OF THE INVENTION The figure shows a disc-shaped record carrier 11 having a track 19 and a central hole 10. The track 19 is arranged according to a spiral pattern of turns constituting substantially parallel tracks on a layer of information. The record carrier may be an optical disk having an information layer of a recordable type or a pre-registered type. Examples of a recordable disc are the CD-R and CD-RW, and the DVD + RW, while the 'Audio CD is an example of a pre-registered disc. The pre-registered type can be manufactured in a well-known manner by means of a first registration of a master disk and via intermediate steps of subsequent pressing of disks for the consumer. Track 19 on the recordable type of the record carrier 'is indicated by a stamped track structure provided during the manufacture of the blank record carrier. The information is represented on the information layer by optically detectable marks recorded along the track. The marks have different optical or magnetic direction properties, than their surroundings, for example depressions and reflective areas. Figure lb is a cross-section taken along the line bb of the registration carrier 11 of the recordable type, in which a transparent substrate 15 with a recording layer 16 and a protective layer 17 is provided. The structure of the track it is constituted, for example, by a pre-slot 14 which allows a read / write head to follow the track 19 during the scan. The pre-bead 14 can be implemented as an indentation or elevation, or it can consist of a material having different optical properties than the pre-bead material. The record carrier contains information in real time, for example audio information, which is subdivided into elements (also called tracks) for the convenience of the user. Such an element can have a playing time of a few minutes, for example the songs of 'an album or the movements of a symphony. Usually the reproduction information to identify the elements is provided on the record carrier, for example in the so-called Content Index (IDC) or included in a file system such as ISO 9660 for the CD-ROM or UDF for DVD. The reproduction parameters may include the playback time and start address of each element, and also additional information such as the title of the song. The reproduction information is localized according to a predefined format, for example registered over a predefined place on the record carrier, usually in or directly after the entry area. Alternatively, the reproduction information may be included in a file with a predefined name, or an indicator on a predefined location indicating the whereabouts of the reproduction information. The audio information is recorded in a digital representation after analog-to-digital (A / D) conversion. The A / D conversion examples are the 16-bit PCM per sample at 44.1 kHz as is known for the audio CD in a 1-bit Sigma Delta modulation at a high oversampling rate, for example 64 times the frequency of the sample (Fs), usually called bitstream. Bitstream conversion is a high quality encoding method, with the options of high quality decoding or low quality decoding with the additional advantage of a simpler decoding circuit. After the A / D conversion of the digital audio is compressed to compressed audio data, which has a variable bit rate and is recorded on the information layer, as described in the document mentioned in the introduction. Compression is required to achieve a convenient total playback time and high quality sound and / or multiple channels. The compression operates on digital audio units, usually with a predefined playing time, for example at 75 units / sec. The parameters of the audio signal of a unit and the additional information, for example, a residual signal, are transmitted by each unit. The compression encodes the information in real time with a variable number of bits, consequently the units have a variable amount of compressed data. The compressed data is to be read from the record carrier at such a rate that, after decompression, substantially the original time scale of the real-time information is restored when it is played. Consequently, the compressed data must be retrieved from the record carrier at a variable bit rate. According to the invention, the reproduction parameters on the information carrier comprise an access list 12, shown schematically in Figure la. The access list 12 has entries comprising access information, "each subsequent entry is assigned to a subsequent interval of a fixed playing time.The access list 12 can be stored on the information carrier in a separate file or it can be part of a data structure comprising additional reproduction parameters, for example defined in a standard An example of a syntax of an access list is described below with reference to Figures 2 and 3. The reproduction time of the interval is select a practical value, for example 1 second, or a fixed number of units, for example 100 units, to allow easy determination of the access point for any selected point in the playback time, by dividing the selected access time by the length of the interval, the corresponding entry in the access list is derived.An entry comprises an indicator of a unit within of the interval, usually the first unit. Reproduction can begin at the beginning of a unit, that is, in the direction indicated by the indicator. It should be noted, that the access list has a different function than the IDC. The IDC is organized as a list of reproducible elements that allows to start the reproduction of the signals registered at the beginning of the element, while the access list is organized according to the reproduction time in steps of size, fixed allowing direct access to any selected point in the playing time, for example to scan music at high speed or repeat a certain fragment between arbitrarily selected points. In one embodiment of the invention the indicator indicates the last unit in a range. This has the advantage that the unit before the start unit can be recovered to preset a decompressor. In a further mode, the reproduction parameters include a duration parameter indicative of the fixed reproduction time. Setting the fixed playing time of the interval allows you to select the access accuracy and the total size of the access list. In this embodiment, the length parameter can be selected substantially proportionally inverse to a total reproduction time of the real-time information to be recorded. This has the effect that the access list can be read in a memory of a fixed size, while the maximum accuracy is achieved for accessing information in real time for the given memory size. Figure 2 shows a syntax of the Access_List. The Access__List is an example of the access list * "described above, and contains a Table with Start Addresses associated with Time Codes for an area with compressed audio data on an information carrier.The indicators for a desired Time Code T is the Logical Sector Direction of the sector that contains the first byte of a multiplexed table T, which contains the respective unit of compressed audio data.The Access_List has a fixed size of 55,536 bytes (32 sectors). The format of each element in the Access_List are given (for example, 16 Units means an unsigned 16-bit integer) The Access_List is an ordered sequence of 8 bytes that identifies the first sector - of the Access_List.The value of the Sign_List_of_Access may example is "SACD_ACC." NJEntradas contains the number of Entries in the List_Acc_Principal.The relationship between N_Entries, the_Reproduction_Total_ Time and the Tam Year_Paso_Principal is defined in the following formula.

N_Entradas = 1 + Total Reproduction Time - 1 Size_Principal_Pass In this formula Time_Reproduction_Total and Size_Paso_Principal are expressed in units. The maximum allowed value of N_Entries is 6550 for a size of the Master_Account of 32768 bytes and a size of a 5-byte entry. The area with the registered data is divided into units intervals of Master_Pass_Size. For each one of the units of Master_Pass_Size, the Multiplexed Table Start Address is coded in the Master_Acc_List. The Master_Pass_Size can_ be a multiple of 10 to facilitate the calculation. The List_Acc_Principal contains the Start Addresses of the Multiplexed Tables at intervals of units of Size_Paso_Principal. The reserved section 2 may contain additional access information, for example Sub_Access information. In one embodiment, the reproduction parameters include a margin parameter indicative of a correction of a calculated indicator of a unit within the range. To access a unit at a point in the playback time within a range is not available in the access list. The indicator for such unit can be calculated by interpolation. However, there may be a difference between the interpolated indicator and the actual indicator of the desired unit. A margin parameter must be added to the calculated indicator to arrive at an indicator in (or shortly before) the desired unit. After the positioning of the reading head the reading can be started and any data read before the desired unit can be discarded. In one embodiment, the margin parameter is determined for each interval in a substantially individual manner, and included in the respective entry in the access list. Alternatively, a parameter range can be determined for a larger area on the information carrier, for example a margin parameter for every 10 intervals, or for the entire information carrier. In the previous example (described with reference to Figure 2) for each encoded Home_Address, the Main_Acc_List contains the Margin_Access parameter to estimate the intermediate Start Addresses. Alternatively, an entry may contain the margin parameter or an indicator for additional access information, for example in the Sub Access information. ~~ Figure 3 shows the syntax _ of the Main_Acc_List. The Main_Acc_List has for each interval [N] a description of Access_Guide [N] and an Input indicator [N]. The Access_Parameters [N] have an Access_Positor format, which contains for the interval [N] an indicator for additional access information (for example in an Sub_Access area), or the Access_Marge which is necessary to estimate the Start Address for a Time Code .ded within the respective interval. In an embodiment, the Access_Guide contains a bit of Sub_Access [N], which, set to one, indicates that for the Interval [N] the additional access information is encoded in Sub_Access. An indicator of Ptr_Sub_Acceso [N] is available to locate the additional access information. If Sub_Access [N] is set to zero, in Interval [N] the Start Address can be estimated by modified linear interpolation with Access_Marge [N]. For the last Interval in an Audio Area, the Sub_Access [N] must be set to zero. ~~ The Access Margin contains a correction factor for calculating the estimated Start Address between two Inputs, that is, it indicates the maximum distance between the unit of the selected playing time and the interpolated address. The estimated Start Address for a given Time Code T, can be calculated with the following formulas, in which the linear interpolated address is indicated as the IterpfT Address]: Estimated Start Address [T] = Max (Input [N] InterP Address [N] - Access Margin [NT] T N = Trunc .Tamañ o_Paso_ Principal) Direccldn_Interp [T] = Input [N] + Size_Paso_Princ ± pal _ T is the Selected Time Code expressed in units, Entry [T] contains the Home_Address of the Multiplexed Table [N * Size__Principal_Pass]. Access_Forge [N] must contain "a larger value of Inter_Address [T] Start_Address [T], • where Start_Address [T] _ is the start address of the Multiplexed Table T. For the last interval of the Track Area, a different calculation method is used for Inter_Address [T], in which total DF is the Final Address of the Registration Area: D-reoción_rnte-p [TIlnal] - Input [N] + Í? IE? Useful, '1+ ((Tien? P _Rept' d? < -i? N 'l ut al - 1) m >? 1 irr ñ rabo_p -ncipüi) Figure 4 shows a method to determine the access margin. The access margin can be determined by each interval and / or a global access margin can be determined for the total registered area. After starting at 40 (START) the recording of the audio input in a first step 41 (SET), the fixed playing time of the interval is set, for example 75 units for an interval length of one second, and the initial value of the global access margin is set to 0. In a second step 42 (COMPRESS) an audio range is compressed to units, and the initial addresses are kept - in a temporary memory. In a third step 43 (INTERPOLAR) the interpolated start addresses for all units in the interval are calculated by linear interpolation. In a fourth step 44 (COMPARE, MAINTAIN BIGGER) the interpolated addresses are compared with the actual addresses stored, and the largest negative value of the difference is the access margin for that interval N: Access_Break [N]. The value of the Access_Marge [N] can be entered in the access list for the Interval [N], and / or can be compared with the global access margin to determine the largest value to be the updated global access margin. In a test 45 (NEXT) it is decided if the registration was completed. If there is a next interval, the process is repeated from the second step 42. If the record ends, in a step 46 (STORE ACCESS) the global access margin can be entered in the access list and the access list is stored in the information carrier Figure 5 shows a reproduction device for reading the record carrier 11, record carrier which is identical to the record carrier shown in Figure 1. The device is provided with drive means 21 for rotating the record carrier 1 , and a read head 22 for scanning track 19 on the record carrier. The apparatus is provided with positioning means 25 for proximal positioning of the reading head 22 on the track in the radial direction (perpendicular to the longitudinal direction of the track). The reading head comprises an optical system of a known type for generating a beam of radiation 24 guided through optical elements and focused to a radiation spot 23 on a track of the information layer of the record carrier. The radiation beam 24 is generated by a radiation source, for example a laser diode. The read head further comprises a focusing actuator for moving the focus of the radiation beam 24 along the optical axis of the beam and a tracking actuator for positioning at the point 23 in a radial direction over the center of the track. The tracking actuator may comprise, for example, coils for radially moving an optical element or means for changing the angle of a reflective element with respect to the optical axis of the beam 24. The radiation reflected by the information layer is detected by a detector of a type usual, for example a four-quadrant diode, in the read head 22 to generate a read signal and additional detector signals including a tracking error signal and a focus error signal, which apply to the tracking and focusing actuators. The read signal is processed by recovery means 27 to recover the data, reading means which are of a usual type for example comprising a channel decoder and an error collector. The recovered data is passed to data selection means 28. The data selection means selects the compressed audio data of all the read data and passes the compressed audio data to the buffer 29. The selection is based on data indicators. type of data also recorded on the record carrier, for example headings in a multiplexed frame. The compressed audio data is passed from the buffer 29 to a decompressor 31 via the signal 30. This signal may also be available as an output signal for an external decompressor. It is decompressor 31 decodes the compressed audio data to reproduce the original audio information at output 32. It should be noted, that decompressor 31 may be separated from the reading means, for example, in an autonomous housing combined with a digital converter to high-quality analog audio (D / A converter) according to the indicated by the dotted rectangle 33 in Figure 5. It should be noted, that alternatively the buffer can be placed before the data selection means, and it may be arranged to store at least the data of a full turn 13 of the track. In such a configuration the data can be read from the disk at high speed, and as soon as the memory 29 is full, the reading is interrupted and the beam 24 moves backward. The device is further provided with a control unit 20 for receiving commands from a user or from a central computer to control the apparatus via control lines 26, for example a collective system conductor, connected to the drive means 21, the means of positioning 25, the recovery means 27 and the data selection means 28, and possibly also the buffer 29 for the control of the filling level of the buffer memory. Up to this point, the control unit 20 comprises a control circuit, for example a microprocessor, a program memory and control gates, to carry out the procedures described below. The control unit 20 can also be implemented as a state machine in logic circuits.

According to the invention, the control unit 20 and the data selection means 128 are arranged to recover the data reading reproduction parameters, in particular the access list. An order to access the recorded audio at a selected playback time is performed as follows. First, a control area of the disk and the access list retrieved from the read signal are read by the data selection means 28. The control unit 20 divides the selected playing time by the fixed playing time of the interval, and truncates value. The resulting entry is located in the access list using the truncated value as an index. The entry contains an indicator for a start address of a unit of the playing time of that interval, and the read head moves in the starting direction. The reading process starts at. the start address, and the data is analyzed by the data selection means 28 to locate the actual start of the unit with the selected time. The data read in that unit is discarded, and playback starts when the unit selected above, which can take the average of half the interval time. However, usually shorter time is needed, since the SB reading performs at a higher speed as described above. The start of a unit is recognized in the usual way by detecting a synchronization pattern, header. In one embodiment, the control unit 20 is arranged to calculate an indicator for a unit between a range by interpolating between indicator values of two adjacent inputs. Linear interpolation can be used in the first unit of the selected interval and the first unit of the next interval. In the case that the interpolated address can be beyond the specified unit, the device can be arranged only to accept the difference, ie start a little after the selected time, or jump back the predefined sequence, for example a turn of the track, and read again. In one embodiment, the control unit 20 is arranged "to correct the value interpolated by a margin parameter." The margin parameter may be a predefined value (for example, of a standard) taken into account during registration, or it must be a value global for the actual record on the information carrier Due to the subtraction of the margin of the interpolated address the reading process starts before, and the selected unit is always after the starting point, consequently, there is no need to jump In a modality, where the access margin is present in the access list for substantially every interval, the control unit is arranged to recover the respective access margin for the interval comprising the specified point in the reproduction time. , and to correct the direction estimated by the subtraction of the access margin.An example of detailed formulas for the calculation was referred above with reference to Figures 2 and 3. In one embodiment of the reproduction device, the control unit comprises a memory 51 and is arranged to store the access list of the information carrier in the memory. The access list is stored in the memory .51 once the information carrier is inserted into the playback device. This is accelerated to additional access operations. Figure 6 shows a record-keeping device for writing information about a record carrier 11 according to the invention of a type of which is (re) writable. During the write operation, marks are formed that represent the information about the record carrier. The marks may be in any optically readable form, for example in the form of areas with a different reflection coefficient than their surroundings, obtained when it is recorded in materials such as a dye, an alloy or a phase change material, or in the form of areas with a magnetization direction different from its surroundings, obtained when recording the optical magnet material. The writing and reading of information on optical discs and the usual format, correction of exhors and channel coding rules are known in the art, for example for the DC system. The marks can be formed by means of a beam 24 of electromagnetic radiation, usually of a laser diode, focused to a point 23 on the recording layer. The recording device comprises similar basic elements, such as the reproduction device described above with Figure 5, that is to say a control unit 20, and drive means 21 and positioning means 25, but has a writing head 39. The information The audio is presented on the first input of the data compression means 35, which can be placed in a separate housing. Suitable compression means are described in the document mentioned in the introduction. The variable bit rate compressed data at the output of the compression means.35 is passed to a buffer 36. From the buffer 36 the compressed data is passed to data combining means 37 to combine that data and the parameters of reproduction to a total data flow. The total data stream to be recorded is passed to the writing means 38. The writing head 39 is coupled to the writing means 38, which comprise for example a device for formatting, or an error encoder 'and a channel encoder. The data presented at the input of the writing means 38 are distributed over logical and physical sectors according to the format and coding rules and converted into a written signal for the writing head 39. The control unit 20 is arranged to control the buffer 36, the data combining means 37 and the writing means 38 via control lines 26 and to perform the positioning procedure as described above for the reading apparatus. The control unit 20 comprises a memory 61 for temporarily storing the reproduction parameters during registration. One embodiment of the recording device also comprises the characteristics of the reproduction device and a combined read / write head and is situated for reading. According to the invention, the control unit 20 of the recording device is arranged to determine an access list having inputs, each subsequent entry is assigned to a subsequent interval of a fixed "playing time. they are arranged to include the access list in the reproduction parameters, the length of the interval is set and the control unit subdivides the input signal into intervals, for each interval an indicator is determined for a unit within the interval, usually the first unit The indicator is entered in the access list, which is mounted in the access memory 61. The access list, when complete, is stored from the memory to the information carrier In one embodiment the control unit is arranged to determine an access margin parameter, as described with reference in Figure 4. In addition the recording apparatus or a recording medium The sponsor can be arranged to create modes of the information bearer as described above with reference in Figures 1A and IB. Although the invention has been explained by modalities using a variable compressed audio format, the access list may also be applied to access any compressed real-time signal, stored with a variable bit rate, such as MPEG2 video For compressed MPEG2 video, the units comprise a sequence of video frames, and they are called group images (GOP). Also for the information carrier an optical disk has been described, but other means, such as a magnetic tape disk, can be used. In addition, the invention lies with each and every novel feature or combination of features described above.

Claims (10)

CHAPTER CLAIMEDICATORÍO Having described the invention, it is considered as a novelty and, therefore, the content is claimed in the following CLAIMS:

1. - A method for recording information in real time and related reproduction parameters on an information carrier, a method in which the real-time information is compressed to units comprising a variable amount of compressed data, and the reproduction parameters are determined depending on the compressed data, characterized in that the reproduction parameters comprise an access list having inputs, each subsequent entry being assigned to a subsequent interval of a fixed playing time and comprising an indicator for a unit within the range. ,

2. The method according to the claim 1, characterized in that the reproduction parameters include a length parameter indicative of the fixed reproduction time and / or a margin parameter indicative of a correction of a calculated indicator of a unit within the range.

3. The method according to claim 2, characterized in that the length parameter is selected, substantially, inversely proportional to a total reproduction time of the information in real time to be recorded and / or where the margin parameter is determined individually for several intervals, the individual margin parameters being in the reproduction parameters.

4. A recording device for _registering information in real time on an information carrier, the device comprises means for compressing information in real time to units comprising a variable amount of compressed data, processing means for generating reproduction parameters depending on the compressed data and recording means for recording the compressed data and the reproduction parameters, characterized in that the processing means are arranged to include in the reproduction parameters in the access list having entries, each subsequent entry being assigned to 'a Subsequent interval in a fixed playing time and comprising an indicator for a unit within the range.

5. An information carrier containing real-time information and reproduction parameters related thereto, the information in real time is represented by units comprising a variable amount of compressed data, characterized in that the reproduction parameters comprise an access list that has inputs, each subsequent entry is assigned to a subsequent interval of a fixed playing time and comprises an indicator for a unit within the range. The information carrier according to claim 5, characterized in that the reproduction parameters include a duration parameter indicative of the fixed reproduction time and / or a margin parameter indicative of a correction of the calculated indicator of a unit within the interval. 7. A reproduction device for reproducing information in real time of an information carrier according to claim 5 or 6, the device comprises read-out means for recovering from the information carrier the units and parameters of reproduction, and processing means for processing reproduction parameters characterized in that the processing means are arranged to access the information in real time at a selected reproduction time by processing the access list. The reproduction device according to claim 7, characterized in that the processing means are arranged to calculate an indicator for a unit within a range by interpolating between indicator values of two adjacent inputs. The reproduction device according to claim 8, characterized in that the processing means are arranged to correct the indicator calculated by means of the margin parameter. The reproduction device according to claim 7, characterized in that the processing means are arranged to store the access list "in a memory.