HK1025836B - Replay appliance for recording media containing information blocks - Google Patents
Replay appliance for recording media containing information blocks Download PDFInfo
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- HK1025836B HK1025836B HK00104952.8A HK00104952A HK1025836B HK 1025836 B HK1025836 B HK 1025836B HK 00104952 A HK00104952 A HK 00104952A HK 1025836 B HK1025836 B HK 1025836B
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- recording medium
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- information
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Description
Technical Field
The invention relates to a playback device for recording media containing information blocks, having means for accessing video information on a digital versatile disc, also called DVD, at a defined playing time, without the need to set a time map table using DVD video subtitles.
Background
According to the DVD specification version 1.0, part 3, for read-only discs containing Video specifications, a DVD-Video subtitle Set time map Table (Video Title Set time map Table) is provided on the DVD disc, with which Table it is possible to access according to the playing time for playback of a Video sequence of a movie starting from a desired playing start time. The table contains all necessary information and entry points to allow a playback device to directly access a video sequence corresponding to a defined playback time or running time period or to play back a movie already recorded on a DVD starting from a time corresponding to a predetermined playing time of the movie. For example, if the first ten minutes of a movie were missed, the video subtitle setting time mapping table could be used to jump directly to the movie at the point corresponding to this playback time while viewing continues. The scanning means of the playback device are driven directly to the scanning spot on the disc containing data corresponding to the predetermined playback time using the data contained in this video subtitle setting time map table on the disc.
The video data recording point in each program chain in the video caption during each playback of the video data is contained in the video caption setting time map table. However, such a table is not necessarily provided on the optical disc, and therefore, the playback apparatus often cannot find a recording point on the optical disc corresponding to a playback time that can be predetermined.
Disclosure of Invention
It is an object of the present invention to provide a playback apparatus for a recording medium containing information blocks, which can access video information on a DVD at a prescribed playing time even if a DVD video subtitle setting time map table is not recorded on the optical disc.
This object is achieved by the device according to the invention described below. A playback apparatus for accessing information stored on a recording medium containing information blocks at a specified playing time, characterized in that the apparatus comprises:
a scanning device for scanning data on the recording medium, the scanning device being controlled by an iterative approximation method to reach a point on the recording medium corresponding to a specified playing time;
a search means for performing a binary search of the recording medium based on the playback time, for comparing the information read from the recording medium with a binary word and estimating a playback time of the recording medium contained in a file associated with the binary word to perform the iterative approximation method; and
a comparator for comparing the playback time scanned from the recording medium with a desired playback time and driving the scanning means to a point corresponding to the comparison result of the comparator to access the information at a prescribed play time.
In one aspect, the present invention provides access to video information on a DVD at a specified playback time even if the DVD video subtitle setting time map table is not available or the DVD video subtitle setting time map table is damaged.
According to the invention, means are provided in the playback device for searching for characteristic features of the recording medium. It has been found that recording media with information blocks have so-called identifiers which can be used in an efficient way to find navigation sectors on the disc. The segments of the recording medium are searched by means provided in the playback device, and the data stream read from the recording medium is analyzed by means of such means to find a navigation sector identifier therefrom. If this flag is found, a list (state) of current playback HMes contained in the navigation sector information is calculated and compared with a predetermined play time for playing back the information stored on the recording medium. It is determined whether a point corresponding to a desired play period is located at a point before or after the playback time included in the navigation sector identifier and the navigation sector information found on the recording medium based on the result of the comparison. The recording medium is then scanned at a point corresponding to the determined direction and the procedure is repeated until the desired start position or a predetermined start area is found.
Therefore, with a playback apparatus for a recording medium containing information blocks, it is also possible to access video information on a DVD at a prescribed playing time using an efficient method of binary search if the DVD has no DVD-video subtitle setting time map table or cannot calculate the DVD-video subtitle setting time map table. The binary search performed in this case comprises comparing the information read from the recording medium that corresponds to the binary word having the characteristic of the identifier with the calculated value of the binary information contained in a file identified by the identifier.
Drawings
The present invention will be explained in detail below with reference to the accompanying drawings.
An exemplary embodiment is shown in fig. 1, which enables access to video information on a DVD at a specified playback time even if a DVD video subtitle setting time map table is not recorded on the optical disc.
Detailed Description
Due to the corruption and interleaving of the information stored in the information blocks, no time code available corresponding to audio cd (cdaudio) can be used to access the video information at the specified playing time, and if there is no DVD video subtitle setting time map or the DVD video subtitle setting time map is corrupted, it is naturally initially assumed that playback of the recording medium with the information blocks at the specified playing time is not possible.
According to the invention, the playback device comprises a search means for finding an identifier, in this case a navigation sector identifier called NV _ PCK ID. The search means preferably forms a mask of binary words corresponding to the navigation sector identifier and is arranged to find the navigation sector identifier from the data stream read from the recording medium. The method of finding the navigation sector designator using the mask of binary words corresponding to the navigation sector designator may be an iterative approximation method as shown in fig. 1, or other search methods such as a continuous search in the forward and reverse directions, or starting from an estimate. In order to play back a recording medium with information blocks according to a defined playing time, the recording medium is first scanned in a first step S1 using an iterative approximation from a position approximately corresponding to the center of the recording medium. However, the actual spot on the recording medium does not usually correspond to half the playback time of an item of video information (video object VO) on the disc, since the playback time is not proportional to the actual spot on the disc due to the data and recording structure. In addition, the amount of data required in the playback is determined by the nature of the video object VO, since usually only information about the change from one frame to the next is recorded. Therefore, the first point on the recording medium to be reached by the drive of the scanning means in the playback device should be allowed a large tolerance.
The recorded information is read from this point on the recording medium that the scanning means of the playback device jumps to and compared with the mask of binary words corresponding to the navigation sector identifiers. Once a navigation sector identifier is detected, the information contained in the navigation sector information, called navigation pack NV-PCK, can be calculated with respect to the playback time, which corresponds to the playing time from the beginning if the video information is continuously played back. Such a means for calculating the playback time, also referred to as playback time PGC, is already installed in playback devices for continuous playback of video information, and therefore no further explanation is necessary. The relation between the recording point and the playback time is then generated by the binary search thus performed and used to approximate a point that must be found on the recording medium, and a playback scan is performed at a prescribed playback time without having to set a time map table using DVD video subtitles. The point at which the recording medium must be scanned in the second step S2 is determined by comparing the playback time determined at the scanning point with the time at which playback is to be started in accordance with the specified play time, unless a matching point has been found. In the example shown in fig. 1, this facilitates playback from a play time that is before the determined position according to the specified play time, so that, in a second step S2, the recording medium is scanned by the scanning means at a point that is actually before the actual position of the point on the recording medium scanned in the first step S1. This second point may also be any point in the area before the point scanned in the first step S1. However, it is also possible to determine the time difference between the playback time determined in the first step S1 and the desired play time and to define a jump distance corresponding to this result.
A binary search is then performed again at the second point, which makes it possible to determine whether the point to be searched for playback at the specified playing time is in front of or behind the current scanning position. If the playback time determined in the second step S2 is not so far from the desired playing time, a third point on the recording medium is scanned in a third step S3 in dependence on the result of the comparison. As shown in the figure, the playback time determined in step S2 is before the desired play time, and therefore the scanning means of the playback device are driven in a third step S3 to a point on the recording medium which is after the point scanned in the second step S2 and before the point scanned in the first step S1. By using the iterative approximation method, a point corresponding to a desired play time is found on the recording medium without the DVD-video subtitle setting time map table, and the playback process is started at the prescribed play time in the fourth step S4.
In order to reduce the number of steps that need to be performed to determine a scanning spot on the recording medium that corresponds to a playback at a given playing time, it is also possible to use a tolerance window to start the playback at a distance from the predetermined playing time.
The invention is applicable to a playback device for recording media containing information blocks, which device has access means for accessing video information on a digital versatile disc called DVD at a defined playback time, without the need for a DVD video subtitle setting time mapping table, and can be universally used for accessing information on a recording medium at a defined playback time, which recording medium has a recording point which is not proportional to the playback time, and which has no index table which can be used to define the relationship between playback time and recording point.
Claims (7)
1. A playback apparatus for accessing information stored on a recording medium containing information blocks at a specified playing time, characterized in that the apparatus comprises:
a scanning device for scanning data on the recording medium, the scanning device being controlled by an iterative approximation method to reach a point on the recording medium corresponding to a specified playing time;
a search means for performing a binary search of the recording medium based on the playback time, for comparing the information read from the recording medium with a binary word and estimating a playback time of the recording medium contained in a file associated with the binary word to perform the iterative approximation method; and
a comparator for comparing the playback time scanned from the recording medium with a desired playback time and driving the scanning means to a point corresponding to the comparison result of the comparator to access the information at a prescribed play time.
2. A playback apparatus as claimed in claim 1, wherein said comparator is a mask for comparing information read from the recording medium with a binary word.
3. A playback apparatus according to claim 1, wherein said binary word is an identifier recorded on the recording medium.
4. A playback apparatus according to claim 3, wherein said identifier is a navigation sector identifier.
5. A playback apparatus as claimed in claim 1, wherein the desired playback time is a playback time within a tolerance window for accessing the recording medium at a specified play time.
6. A playback apparatus according to claim 2, wherein said binary word is an identifier recorded on the recording medium.
7. The playback device of claim 6, wherein said identifier is a navigation sector identifier.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19859845.9 | 1998-12-23 | ||
| DE19859845A DE19859845A1 (en) | 1998-12-23 | 1998-12-23 | Playback device for record carriers containing information blocks |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| HK1025836A1 HK1025836A1 (en) | 2000-11-24 |
| HK1025836B true HK1025836B (en) | 2004-01-30 |
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