GB2418091A

GB2418091A - Portable display device and video format adaptation therefore

Info

Publication number: GB2418091A
Application number: GB0419926A
Authority: GB
Inventors: Nicola Leotta
Original assignee: NEC Technologies UK Ltd
Current assignee: NEC Technologies UK Ltd
Priority date: 2004-09-08
Filing date: 2004-09-08
Publication date: 2006-03-15
Anticipated expiration: 2024-09-08
Also published as: GB2418091B; GB0419926D0

Abstract

The present invention provides a method of adapting video data for display on a portable display device, and comprising the steps of: determining the possible plurality of format and characteristics that match both the original video file format and characteristics and the specificities of the display system within the portable device; selecting one video file format and a characteristics-adaptation process to be performed on the original file on the basis of selection criteria; and performing adaptation of the video data within the portable display device to conform to display characteristics of the selected format, wherein all three steps are performed prior to display of the video data on the said portable display device. The display format and characteristics can comprise, for example, aspect ratio, size, resolution, frame rate and colour parameters. The selection criteria may be based on the quality of the displayed image, the processing power or time required or the projected file size. As described, the handset 10 detects the possible formats and display characteristic adaptation processes available to adapt an original video file to the display system. One of the adaptation processes may then be selected.

Description

241 8091

PORTABLE DISPLAY DEVICE AND RELATED METHOD OF VIDEO

DATA ADAPTATION

The present invention relates to a portable display device, and a related method of video data adaptation. In particular, but not exclusively, the invention relates to a portable radio communications device arranged also for the display of video data.

Portable devices such as portable radio communications devices in the form of cellular phones have experienced continuous development as service providers have sought to improve the quality and variety of communication and entertainment services available by way of a video display output at the cellular phone handset.

Such video display output can, for example, comprise video output relating to the message being conveyed as part of a communication session, or a mere video sequence intended for entertainment purposes at the cellular phone handset.

Due to the wide range of video format characteristics currently available in mobile handsets or portable devices, a video file will often be made available for the mobile handset or portable device in a generic format with roughly adapted characteristics. It is then necessary for the mobile handset or portable device to adapt the video file to its own specific display format characteristics.

This fine adaptation is usually done in real time, while the video file is being viewed on the portable device.

Since such adaptation processes are demanding in terms of processing power, limited and potentially insufficient processing power is then available in the mobile handset or portable devices to display the file correctly. This can lead to real time defects, and an overall decrease in audio-video quality.

US 2002/004977 A1 discloses a system in which the radio network detects the display limitations of the handset and performs adaptation of the video file format characteristics prior to sending the adapted video file to the handset. However it is required that the portable display device receive its video files from a network with such functionality, and that the portable device supports such an adaptation process.

Thus, should the portable display device receive its video file from another source which would not support these characteristics and appropriate format pre-adaptation method, or should the portable display device not support the above-mentioned network pre-adaptation method, the system disclosed in this document will not achieve the advantages discussed.

The invention seeks to provide a method of adapting video data and a related portable device having advantages over known such methods and devices.

According to a first aspect of the present invention there is provided a method of adapting video data for display on a portable display device and comprising the steps of determining within the portable display device possible display formats of the device, selecting one such format for use on the basis of selection criteria, and performing adaptation of the video data within the portable display device to conform to display characteristics of the selected format prior to display of the video data in the said device.

In particular, the invention can provide for a method of adapting video data for display on a portable display device, the method comprising the steps of: determining the possible plurality of display format characteristics that match both the original video file format and the display system within the

portable device;

selecting one video file display format characteristic adaptation process to be performed on the original file on the basis of selection criteria, and performing adaptation of the video data within the portable display device to conform to display format characteristics of the selected format.

In particular, all three steps are performed prior to display of the video data on the said portable display device.

The present invention exhibits particular advantages as discussed below.

For example, the formatting of the video data is separated from the actual display function and this can serve to simplify the display function and ensure that full processing capacity remains available for the display function.

Thus, unlike known systems in which the format of the received video movie/clip is adapted to a display characteristic exhibited by the portable device while the movie/clip is actually being played by the device, such adaptation is conducted prior to any such required display of the movie/clip.

Once the adaptation has been completed the adapted file is then stored within the portable device memory so that it can be viewed repeatedly if required but with the adaptation process only having been performed once.

Further, the adaptation of the video data is wholly contained within the portable display device, thereby excluding any external dependency on network supported adaptation methods, or on the manner by which the portable display device will acquire the video file within its memory.

Thus, a video file from any source can advantageously be optimised for viewing on that particular display system of the portable device.

Also, it is not required for the portable display device featuring the present invention to be compatible with any network video file format characteristics adaptation mechanism since it can simply download any video file format and then adapt it within the portable device prior to viewing it.

As will be appreciated, within a portable display device embodying the present invention, the first step of the method can be to determine the possible plurality of display format characteristics that match both the original video file and the specificities of the display system within the portable device.

The display format and characteristics can comprise for instance, but not exclusively, parameters such as, the display aspect ratio, for example 4:3, 16:9, or other standard or special aspect ratios, the display size and resolution i.e. the number of horizontal and vertical picture elements (pixels), the number of frames per second, colour parameters i.e. monochrome/multi-chromatic, the number of colour levels (or grey scale levels) per pixel, and also details of the video codec.

Also, if audio exists within the video file, and an audio rendering medium is provided within the portable device, such as a speaker or headphone, the audio band, the sampling rate, the audio-video interleaving parameters, the audio codec and parameters, and other audio- video relevant parameters can be included within the said format characteristics.

The format characteristics of both the video file and display system of the portable device are thus compared and a plurality of adaptation process possibilities for the video file are thus determined so as to have the resulting file format and characteristics match the requirements of the display system.

For instance, but not exclusively, one such adaptation with a clear single choice for solution could be to re-encode a video file with 24 frames per second frame rate so as to only include 5 frames per second, which might be the maximum frame rate that the display system of the portable device could display. Here the adaptation of the parameter would be unique.

With regard to format adaptation, a choice would exist if the aspect ratio and the size and resolution between the video file and the display system are not a good match and which could lead to either the addition of black stripes, or the removal of stripes from the original video file, or the enlargemenVshrinkage of the video file picture, etc. The method of the invention can of course be arranged to select only one of the abovementioned plurality of adaptation process possibilities for the video file.

It should be appreciated that a first selection of the plurality of adaptation process possibilities for the video file can be performed as part of the first or second step within the method of the invention by eliminating all the adaptation processes that are beyond the technical capabilities of the video processing application used in the third step to actually perform this adaptation.

A subsequent step can then relate to the selection of the video file format characteristic adaptation process to be performed on the original file, as originated from the first step, described above, for the resulting video file to match the display system requirements of the portable device, based on the selection criteria.

As noted, the selection criteria can comprise the quality of the displayed image which can be determined on the basis of the displayed number of frames per second and/or the resolution of the displayed image, aiming for the best quality i.e. the largest resolution, and highest number of frames per second.

Alternatively, or in addition, the selection criteria can be based on the processing power required within the portable device for viewing the resulting video file on the display system, aiming for the lowest display processing power requirement, or for a specific processing power corresponding to a threshold within the portable device that should allow a "good enough" display quality, even in the event of typical concurrent program process taking place at the same time, such as for example continued file download management.

Alternatively, or in addition, the selection criteria can be based on the processing time required to effect the adaptation of the initial video file into the final resulting video file within the portable device, thereby limiting the adaptation process to a reasonable amount of time, that could be based on the duration of the video file and/or on the remaining battery life of the portable device. This can advantageously serve to prevent battery power running- out before the end of the adaptation process. Further, the criteria could be based on an absolute psychological time amount, to prevent the adaptation process from giving the user the impression that it "takes too long".

Alternatively, or in addition, the selection criteria can be based on the level of quality discrepancy between the original video file and the resulting video file, so as to both limit the decrease in video quality, such as shrink of picture or decrease of number of frame per second, and also to limit the increase of picture quality, which intrinsically is impossible and would only mean creating video-processing artefacts.

Alternatively, or in addition, the selection criteria can be based on the projected size of the resulting video file, aiming to obtain a resulting file size that would be below a specific threshold that would be determined on the basis of the available memory size in the portable device, and/or the size of the original video file, and/or an absolute maximum size.

Additionally, if not performed within the first step noted above, the selection criteria has to be based on the technical capabilities of the video processing application so as only to allow for video adaptation process within these said technical capabilities.

The user of the portable device may or may not have access to the parameters of the selection criteria, so as either only to be able to consult them, or to be able to modify them.

As noted, a final step can comprise performing the audio-video adaptation process selected in the second step onto the original video file so as to obtain the resulting video file, which will be optimised for display on the portable device according to the selection criteria.

This can be performed by a video-audio processing program that can be either a generic application available for the portable device, or a dedicated application only suited for this purpose.

According to another aspect of the present invention, there is provided a portable display device arranged for the display of video data, the device including means for determining possible display formats thereof, and selecting one of the said possible formats on the basis of selection criteria, and means for adapting the said video data to conform to display characteristics of the selected format prior to display of the video data on the device.

It should be appreciated that the device can be arranged so as to employ the advantageous features of the method defined above.

According to still another aspect of the present invention there is provided a computer program element for use in a portable display device, the computer program element comprising computer program code means to make the portable display execute procedure to determine possible display formats of the device, select one of the said formats for use on the basis of selection criteria, and to adapt the video data to conform to the display characteristics of the selected format prior to display of the video data on the said device.

A possible but non-restrictive split of functionality could be achieved by providing both the first and second steps within a first computer program, and the third step within a second program. In this manner, the specifics of the first and second steps could be customised for this specific use inside each different portable device that would be produced, whereas the third step could be but a particular usage of a more generic video processing application program, meant for a wider range of usages.

Of course, the computer program element can be embodied on a computer readable medium.

As will be appreciated from the discussions further below, the invention is particularly suited for processing video data which is not required to be handled on a real-time basis and where, for example, the whole of the video movie/clip can be adapted to the required format of the display of the portable device without any time constraints in place.

The invention is further advantageous since the video file can be readily adapted such that the file parameters and format thereof can be optimised having regard to the device display characteristics.

The invention is described further hereinafter, by way of example only, with reference to the accompanying drawing which is a schematic diagram illustrating the operation of a portable radio communications device with a display function according to one embodiment of the present invention.

With regard to the accompanying drawing, there is provided a schematic illustration of a portable radio communications device such as a cellular phone handset 10 which is arranged to communicate with a network infrastructure 12.

The handset 10 includes a display system 14 upon which video data received at the handset is to be displayed.

As will be appreciated, the display 14 of the handset 10 exhibits particular display format characteristics and before video data received at the hardset 10 can be viewed on the display 14 of the device 10, the format of the video data needs to be adapted to match the particular format and operating characteristics of the display 14.

The display 14 of the handset 10 may have the ability to accept a plurality of possible display formats and display characteristics and the illustrated embodiment of the present invention is provided with a control function in the form of a format detection and selection control program 16 which serves first to detect the possible formats and display characteristic adaptation processes available to adapt a particular original video file 22 to the display system 14, and then to select one of the said formats adaptation processes on the basis of particular selection criteria.

Once the available format and display characteristic adaptation process has been identified and selected by the format detection and selection control program 16, it is delivered to a video adapter 18 generally in the form of a second computer program which is arranged to adapt an original video file 22, which could originate in a transmitted video file 20 received from the network infrastructure 12. Alternatively the file could also originate in various storage devices employed to load it onto the handset 10. Such adaptation serves to achieve display in accordance with the selected format of the display 14.

The transmitted video file 20 is received by the handset 10 as original video file 22, and delivered as indicated by arrow 24 to the video adapter 18.

The resulting adapted video file 28 can then be delivered as indicated by broken arrow 30 to the display system 14.

As will be appreciated, the adaptation within the handset 10 does not lend itself to a real-time application and so is particularly advantageous when real-time operating constraints are not experienced.

The complete original video file 22 is formatted as required within the video adapter 18 prior to display on the display system 14 of the handset 10.

In slightly more detail, the format detection and selection control program 16 is advantageously arranged to auto-detect the list of possible formats and display characteristics adaptation processes available to adapt a particular original video file 22 to the display system 14 and then to select one of the said format adaptation processes according to one or more of several different criteria such as the best quality of displayed data without requiring a further adaptation. Such criteria can comprise the highest resolution and biggest number of frames per second, or/and as based on a low enough display processing requirements, low enough video adaptation processing time, low enough discrepancy in quality level between the original video file 22 and the resulting adapted video file 28, suitable size for the adapted video file 28, and of course can be based on the technical capabilities of the video adapter program 18. All of these criteria are related to the handset's display system 14, the original video file 22, and the video adapter program 18.

A user employing the handset 10 can therefore control the loading of an unaltered video file and then initiate the adaptation the original video file 22 to the video display format characteristics of the device 10 by way of the two control functions 16,18 described above.

The present invention can therefore advantageously allow the user to adapt video files which have been downloaded to the handset in advance of actually playing them such that the handset 10 then avoids expending any processing power in relation to the process while actually playing the video file.

Optimal video rendering can therefore advantageously be achieved within the handset 10 since the above-mentioned formatting serves to customise the video files to the specific format characteristics of the device 10.

Claims

Claims 1. A method of adapting video data for display on a portable

display device and comprising the steps of determining within the portable display device possible display formats of the device, selecting one such format for use on the basis of selection criteria, and performing adaptation of the video data within the portable display device to conform to display characteristics of the selected format prior to display of the video data in the said device.
2. A method as claimed in Claim 1, wherein the said step of determining comprises determining a possible plurality of format characteristics that match both the original video file and the display system within the portable device, and selecting a video file display format characteristic adaptation process to be performed on the original file on the basis of the selection criteria.
3. A method as claimed in Claim 1 or 2, wherein the said format includes the display aspect ratio.
4. A method as claimed in Claim 1, 2 or 3, wherein the said format includes display size and resolution.
5. A method as claimed in Claim 1, 2, 3 or 4, wherein the said format includes the number of frames per second.
6. A method as claimed in Claim 1, 2, 3, 4 or 5 wherein the said format includes colour parameters.
A method as claimed in Claim 1, 2, 3, 4, 5 or 6, wherein the said format is derived from the video codec.
8. A method as claimed in any one or more of Claims 1 to 7, wherein the said format includes audio characteristics within the video file.
9. A method as claimed in any one or more of Claims 1 to 8, wherein the said selection criteria relates to the quality of the image to be displayed.
10. A method as claimed in any one or more of the preceding claims wherein the said selection criteria relates to the processing power required within the portable device for viewing the video file.
11. A method as claimed any one or more of the preceding claims wherein the said selection criteria relates to the processing time required for adaptation of the video file within the portable device.
12. A method as claimed in Claim 11, wherein the limiting of the adaptation process to a reasonable amount of time is responsive to remaining battery life of the portable device.
13. A method as claimed in any one or more of the preceding claims, wherein the said selection criteria is based on the quality discrepancy between the original video file and the adapted video file.
14. A method as claimed in any one or more of the preceding claims wherein the said selection criteria relates to the projected size of the adapted video file.
15. A method as claimed in Claim 14, wherein the said specific projected adapted video file size threshold is determined on the basis of the size of the original video file.
16. A method as claimed in Claim 14, wherein the said specific projected adapted video file size threshold is determined on the basis of an absolute maximum size.
17. A portable display device arranged for the display of video data, the device including means for determining possible display formats thereof, and selecting one of the said possible formats on the basis of selection criteria, and means for adapting the said video data to conform to display format characteristics of the selected format prior to display of the video data on the device.
18. A device as claimed in Claim 17 and arranged with means for performing a method as claimed in any one or more of Claims 1 to 16.
19. A computer program element for use in a portable display device, the computer program element comprising computer program code means to make the portable device execute procedure to determine possible display formats of the device, select one of the said formats for use on the basis of selection criteria, and to adapt the video data to conform to the display format characteristics of the selected format prior to display of the video data on the said device.
20. A computer program element as claimed in Claim 19 and arranged to be provided within two or more computer programs.
21. A computer program element as claimed in Claim 19 or 20 and having computer program code means for executing procedure according to a method of any one or more of Claims 1 to 16.
22. A computer readable medium including a computer program element as defined in Claim 21.
23. A method of adapting video data substantially as hereinbefore described with reference to the accompanying drawing.
24. A portable display device substantially as hereinbefore described with reference to, and as illustrated in the accompanying drawing.