The present invention relates to an apparatus for processing information stored in a data carrier in which information can be stored in places defined by a first position indication and by at least a second position indication, comprising:
This apparatus finds many applications, notably for data carriers constituted by optical discs having a plurality of layers, which are scanned by a head comprising a laser. In this case, the first indication is provided by a location on the disc where the carrier head must be placed and the second position by the layer on which the laser of the carrier head must be focused.
In such discs, a file may be linked to other sub-files, and it is necessary to combine files and sub-files for a correct management of the information contained in them. This is the case, especially for the purpose of displaying movies with enhancement on a display device enables this possibility.
A known device of this type is disclosed in the patent document US 2002/0054550. This document discloses no measures for the processing of files and related sub-files.
The invention proposes an above-mentioned apparatus, which enables the processing of files and related sub-files with a relative short access time.
For this purpose, such an apparatus for processing information stored in a data carrier in which information can be stored in places defined by a first position indication and by at least a second position indication comprises:
The invention also proposes a data carrier comprising data organized in files and related sub-files such that at least a part of a file and its related sub-file are close together.
Moreover, the invention proposes a method of storing a file with a plurality of related sub-files comprising the steps of:
These and other aspects of the invention are apparent from and will be elucidated, by way of non-limitative example, with reference to the embodiment(s) described hereinafter.
In certain cases, the coding uses a base layer file and one or more enhancement layer files called related sub-files. In this technique, a base layer file is used to encode the video stream, for example, with a certain quality level, for example a good quality for usage on a small portable screen. If a user wants to display this stream on a (large) screen, the enhancement layer files can be used, which provide additional quality to the base-layer stream.
If the enhancement layer files are used, the decoder needs access to corresponding parts of both the base layer files and one or more enhancement layer files. Typically, the base layer content is stored in a separate files on each layer L0 or L1. This means that the decoder needs corresponding data from two or more separate files more or less at the same time.
If these separate files are stored on an optical medium, the access times to these separate files may become a problem as optical drives have relative large access times compared with e.g. Hard Disc Drives. The use of relatively large buffers can solve this, as can fast optical drives with respect to data-rates. The present invention, however, proposes a solution by allocating the separate files smartly on a multi-layer disc
The relatively long access times of optical drives are a result of disc spinning in the case of CLV (constant linear velocity) media and of the optical head 13 movements. Focusing on another layer in the case of multi-layer discs, however, is a very fast process in itself (i.e. when both access points are on the same radius Ri and no optical head movement or disc spinning is required).
The measures provided by the invention involve an allocation of the various files of the multiple layers (base and enhancement) such that the total overhead time (mainly caused by jumping over the disc) is minimized. The basic idea is shown below for a dual-layer disc with a base layer and two enhancement layers.
In the example, see
The sizes of and the number of regions chosen have been given only by way of example. This also means that the number of regions of the file containing the base layer and the number of regions of the files containing the enhancement layers do not have to be equal (as they are in the example). Also, the location of the base layer file on L0 and the enhancement layers sub-files on L1 as shown in
Normally the base layer files and the enhancement layers files do not strongly differ in size, thereby allowing to use the allocation structure as given in
In this example shown in
In both examples there is some space or gap left between the regions (on each of the disc layers). This is done mainly to make the drawings clearer. In usual cases, no space is left between the extents (however, it is of course allowed to leave this space). For clarification purposes, the example shown in
The advantages of this manner of allocating the various corresponding files on disc can be found in the field of total performance of the drive system, as less time spent on jumping leaves more time to read data. Next to that, there are also advantages in the total power consumption (less time spent on jumping leaves time to switch parts or the entire drive off for some periods of time, thereby saving power), noise reduction by jumping less, less wear of the drive due to the jumping, etc.
An advantage relating to a totally different issue is formed in defect management. Suppose a scratch on the disc surface ruins some data. Such a scratch typically causes data to be lost on both the first and the second layer. Allocating the data as described above will lead to the loss of a (more or less related) part of the video in both the base layer and the enhancement layers. This is an advantage because, if the base layer file is lost, the information in the enhancement layer is of no value anymore. Therefore it is better to lose the corresponding information of the enhancement layer than to lose some other information at another point in the video stream.
Although in practice with small errors the data lost in the two files on both disc layers will not correspond entirely from a timing point of view, this will be the case with large error regions.
The invention also relates to the management of the defects on an optical disc from the above considerations.
Number | Date | Country | Kind |
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03300033.2 | Jun 2003 | EP | regional |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/IB04/01911 | 6/3/2004 | WO | 12/14/2005 |