Mapping Udf and Bdfs Extents

Abstract

The present invention relates to a method of ensuring seamless playback of video files stored as a BDFS (Blu-ray Disc File System) file in a UDF (Universal Disk Format) file system using a UDF and BDFS combination format, said method of seamlessly playing back the video files comprising the step of creating a BDFS extent by mapping it to at least one UDF extent, wherein said mapping is based on rules defined by BDFS.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, preferred embodiments of the invention will be described referring to the figures, where:

FIG. 1 illustrates the Blu-ray UDF BDFS Combination format,,

FIG. 2 illustrates UDF extents mapped to several BDFS extents in two different ways,

FIG. 3 illustrates one UDF extent mapped to one BDFS,

FIG. 4 illustrates two BDFS extents mapped by fitting it to two UDF extents.

DESCRIPTION OF PREFERRED EMBODIMENTS

In FIG. 1, a UDF and BDFS combination format is illustrated. Blu-ray UDF BDFS Combination format has one or more special files distinguished through a file name extension like *.bdv. This “bdv” file serves as a container for the Blu-ray file system books as it is defined for BD RE.

The format comprises three zones: first a lead-in zone 11, next a data zone 13 and finally a lead-out zone 15. The data zone 13 comprises a block 3 with a UDF anchor and partition information, after that the UDF partition starts in 5. The UDF file system information and file data are shown as 7 and it comprises a special file 9 with BDFS content. At 17, the UDF partition ends.

According to the present invention in order to obtain seamless playback of video, the UDF and BDFS extents should be matched as good as possible. Both file systems should, when they allocate their extents, take into account the extent sizes of the other file system to preserve the BDFS allocation rules as best as possible.

One way of doing this is to create UDF extents. These UDF extents should be created such that an optimal match between the UDF extents and the BDFS extents is possible in a way that the BDFS allocation rules are maintained as much as possible.

This is illustrated in FIG. 2 and 3. The BDFS file in this example has a size of 40 Mbyte.

In FIG. 2 BDFS 121 this is achieved by using the 20 Mbyte extent and the 2×10 Mbyte free space areas from UDF 22. Seamless playback is in that case not assured because an extra jump on UDF level is needed to jump from the first 10 Mbyte extent to the second 10 Mbyte extent. The extent size of only 10 MB is a violation of the BD allocation rules where the minimal extent size should be 12.5 Mbyte for seamless playback (shown in BDFS 1)

The solution to this problem is illustrated in FIG. 2 as BDFS 223 and is to use the two largest extents of 20 Mbyte (see BDFS 2 in FIG. 2). This presents no problems because a jump occurs only after 20 Mbyte.

Another simpler example is the situation in FIG. 3. In this case the BDFS volume needed 33 is 20 Mbyte, and we have on the UDF level a 10 Mbyte and a 20 Mbyte free space area. In this example the BDFS volume 33 is mapped onto an extent in the UDF level 31 that is created in the largest free space area (20 MB) and no jumps are needed on the UDF level, guaranteeing seamless playback. This is not the case when the first 10 Mbyte extent is used and 10 Mbyte of the second 20 Mbyte extent.

In FIG. 4 the BDFS volume 41 has two extents; this could for example be two clips or files. The BDFS volume uses the 2×20 Mbyte extent of UIDF to form the volume. Seamless play is achieved by mapping the first 14 Mbyte to extent A in UDF 42 and the second 16 Mbyte to extent B in UDF. This prevents a jump after 6 MB of the second extent (of 16 MB) has been played.

Two examples of performing this mapping could be:

A) The UDF file system has an allocation API (Application interface), which gives the possibility to force on UDF the extents and sizes it has to create for the file that will be written.

Thereby the following steps are performed from the host point:

• 1. Create file
• 2. Set end-of-file (given the file size)
• 3. Use the allocation API to set the extents needed
• 4. Write the file

B) Just write the file to the media, and then rearrange the extents as is appropriate according to the techniques described above.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word ‘comprising’ does not exclude the presence of other elements or steps than those listed in a claim. The invention can be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a device claim enumerating several means, several of these means can be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

1. A method of ensuring seamless playback of video files stored as a BDFS (Blu-ray Disc File System) file in UDF (Universal Disk Format) file system using a UDF and BDFS combination format, said method of seamlessly playing back the video files comprising the step of: creating a BDFS extent by mapping it to at least one UDF extent, wherein said mapping is based on rules defined by BDFS.

2. A method according to claim 1, wherein said method comprises creating UDF extents, said creating of UDF extents being performed based on said rules defined by BDFS.

3. A method according to claim 1, wherein said method comprises mapping the BDFS extent to an existing UDF extent, said mapping being based on said rules defined by BDFS.

4. A method according to claim 1, wherein said mapping is at least based on the BDFS rule defining the minimum size of an extent in BDFS, whereby a BDFS extent is only mapped to a UDFS extent having at least said minimum size.

5. A method according to claim 1, wherein, if possible, the mapping of a BDFS extent to a UDF extent is performed when said UDF extent is at least the same size as said BDFS extent.

6. A method according to claim 1, wherein one BDFS extent is mapped to more UDFS extents.

7. A computer-readable medium comprising data enabling a storage device to perform the method according to claim 1.

8. A storage device enabling seamless playback of video files stored as a BDFS (Blu-ray Disc File System) file in UDF (Universal Disk Format) file system using a UDF and BDFS combination format, said device comprises: means for creating a BDFS extent by mapping it to a UDF extent, wherein said mapping is based on rules defined by BDFS.