Apparatus and method for providing high speed download service of multimedia contents

BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION

0001The present invention relates to a VOD (Video on Demand) service, and more particularly to an apparatus and method for providing a high speed download service of multimedia contents capable of converting a format of a multimedia contents file used for a download service.

BACKGROUND OF THE RELATED ART

0002A multimedia contents file for a VOD service may be created in an MP4 file format, for example, and constructed to effectively implement a streaming service. For example, Figure 1 illustrates a structure of a general MP4 file format. As shown, the MP4 file is roughly divided into a 'moov' part corresponding to a header part and a 'mdat' part containing actual media information.

0003The 'moov' part includes a plurality of 'trak()' boxes holding meta information on each media according to a type of the media included in the multimedia contents file. That is, the trak boxes include a 'trak(video)' including meta information on video information, a 'trak(audio)' including meta information on audio information, and a 'trak(hint)' provided for a real time streaming service.

0004The multimedia contents file constructed with such a file format as shown in Figure 1 is suitable for a streaming service. The VOD service provides the streaming service and a download service together based on the above-structured multimedia contents file.

0005In general, when creating a file suitable for the streaming service, functions making an internal structure of the file complicated are included to handle problems that may arise when the stream service is provided on a real time basis. A typical function is the construction of a multiple video trak by applying a temporal scalability. In more detail, Figure 2 illustrates an example of a streaming service using a temporal scalability-based file format, in which the transmission of a base layer video and an enhancement layer video are controlled according to an available bandwidth of a network.

0006In other words, if an available bandwidth of the network is low, an RTP (Real Time Protocol) streaming server carries only the base layer video on an RTP packet, whereas if the available bandwidth of the network is higher than a prescribed value, the RTP streaming server transmits the enhancement layer video having a B (bi-directional)-frame as well as the base layer video so that a user can be provided with a video service with a high frame rate. In this instance, however, although the B-frame is advantageous in the aspect of the transmission error and scalability, it increases a transmission quantity.

0007Further, if the available bandwidth of the network is too low to transmit the base layer video, the RTP streaming server transmits only an I (intrinsic)-frame for service. However, in such a streaming service method, significant data is added to additionally store the enhancement layer video or the like, so that when the multimedia contents file is provided as a download service, the amount of data to be transmitted is significantly increased.

0008Further, because the number of packets required for transmission of the entire multimedia contents file is increased, the user's service fee is increased and a lot of time is required for the user to download the file for service.

0009Turning now to Figure 3, which illustrates a format of the multimedia contents file including a multi bit-rate media. One multimedia contents file includes multi bit-rate coded video and audio data. The multimedia contents file as shown in Figure 3 has a structure that can be serviced by selecting video and audio data suitable for the available bandwidth of the network such as the temporal scalability.

0010If the available bandwidth of the network is not less than 256 Kbps, a video V3 and an audio A3 are streaming-serviced, while if the available bandwidth is not more than 64 Kbps, quite low, a video V1 and an audio A1 are streaming-serviced.

0011However, even though the multimedia contents file having the structure including the multi bit-rate coded media is used for the download service, the number of packets required for transmission of the entire file is increased, which results in a higher service fee and increases a user's standby time for using the service.

SUMMARY OF THE INVENTION

0012Accordingly, one object of the invention is to address at least the above problems and/or disadvantages and to provide at least the advantages described hereinafter.

0013Another object of the present invention is to provide a download service that converts a file format suitable for a real time streaming service into a file format suitable for a download service.

0014To achieve at least the above objects in whole or in parts, the present invention provides a novel apparatus for downloading a multimedia file including a file converter configured to convert a larger multimedia file into a smaller multimedia file by deleting prescribed media information based on a media format contained in the larger file. Further, the file converter converts the larger file into the smaller file by deleting multi bit-rate media not corresponding to a selected bit rate or by deleting enhancement layer video.

0015Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

0016The invention will be described in detail with reference to the following drawings in which like reference numerals refer to like elements wherein: <ul id="ul0001" list-style="none" compact="compact"><li>Figure 1 is an overview illustrating a general MP4 file format;</li><li>Figure 2 is an overview illustrating a streaming service using a temporal scalability-based file format;</li><li>Figure 3 is an overview illustrating a format of a multimedia contents file containing a multi bit-rate media;</li><li>Figure 4 is a block diagram illustrating a construction of an apparatus for providing a high speed download service of multimedia contents according to the present invention;</li><li>Figure 5 is an overview illustrating the conversion of a large capacity multimedia contents file containing an enhancement layer video into a smaller capacity multimedia contents file;</li><li>Figure 6 is another overview illustrating the conversion of a large capacity multimedia contents file containing multi bit-rate media into a smaller capacity multimedia contents file; and</li><li>Figure 7 is a flow chart illustrating a high speed download service of multimedia contents according to the present invention.</li></ul>

BEST MODE OF THE INVENTION

0017An apparatus and method for providing a high speed download service of multimedia contents according to the present invention will now be described with reference to the accompanying drawings.

0018In more detail, Figure 4 is a block diagram illustrating a construction of an apparatus for providing a high speed download service of multimedia contents according to the present invention. As shown in Figure 4, the apparatus includes a file converter 100 for selectively deleting media information according to an internal attribute of a multimedia contents file for a streaming service, and for converting it into a multimedia contents file for a download service; and a file transmitting unit 200 for transmitting the multimedia contents file for the download service outputted from the file converter 100 to a terminal using Hyper Text Transfer Protocol (HTTP), for example.

0019The file converter 100 deletes certain types of media information to convert a large capacity multimedia contents file into a smaller file suitable for downloading. In this instance, the multimedia contents file for the download service maintains a same basic format of the multimedia contents file for streaming.

0020The apparatus for providing a high speed download service of multimedia contents for streaming operates as follows.

0021First, when a download service of an arbitrary large capacity multimedia contents is requested by a terminal, the file converter 100 determines an internal attribute of the corresponding multimedia contents. That is, the file converter 100 determines whether or not the multimedia contents contains an enhancement layer video or a multi bit-rate media.

0022If the multimedia contents contains enhancement layer video, the file converter deletes media information related to the enhancement layer video, while if the multimedia contents contains multi bit-rate media, the file converter deletes media information except for a bit rate selected by a user. Through this process, the file converter 100 converts a large file into a smaller file. The transmitting unit 200 then transmits the smaller file to a corresponding terminal.

0023Turning next to Figure 5, which illustrates conversion of a large capacity multimedia contents file containing an enhancement layer video into a smaller file. As shown, the large capacity multimedia contents file includes a 'moov' part (a header part), and a 'mdat' part (a media data part). The 'mdat' part includes base layer and enhancement layer video.

0024When the large capacity multimedia contents file is inputted, the tracks of the 'moov' part and the media data of 'mdat' part related to the enhancement layer video are deleted to convert the large file into a smaller capacity multimedia file. In this instance, because the base layer video and the enhancement layer video are mutually independent content, the deletion can be performed without affecting the base layer video. Further, in the multimedia contents file, a spatial position value (chunk_offset) of the remaining non-deleted media data is adjusted, and if there is a hint track in the 'moov' part, the hint track is also deleted.

0025Next, Figure 6 illustrates conversion of a large capacity multimedia contents file containing multi bit-rate media into a smaller file supporting only a single bit rate of 64 Kbps, for example. As shown, when the large file is inputted, the track of the 'moov' part and the media data of 'mdat' part except for a bit rate selected by a user (e.g., 64 Kbps) are deleted to convert the large file into a smaller file.

0026In addition, a hint track of the 'moov' part is deleted because it includes information that is not required for the download service. Further the tracks V2, V3, A2 and A3 as well as the meta information of the media data are deleted from the 'moov' part because they include information independent from the tracks V1 and A1 for the 64 Kbps bit rate. Further, data in media data part other than 'V1' and 'A1' related to 64 Kbps are also deleted.

0027In addition, an alternate_group field value among fields of the track header box and header information of the tracks V1 and A1 is also converted. The alternate_group field is a value existing in every track, and is used to determine the media data contents.

0028For example, if the alternate_group values of two or more tracks are the same natural number, the two or more tracks are determined to be video tracks, which have the same content even though the tracks have different bit rates. If the alternate_group value is '0', each video track is determined to be a video track with a different content.

0029As shown in Figure 6, because the multimedia contents file containing multi bit rates includes the same content of media data having three different types of bit rates of 64 Kbps, 128 Kbps and 256 Kbps, the alternate_group value is the natural number of the same value, not '0'.

0030However, when a large capacity multimedia file is converted into a small capacity multimedia contents having a single bit rate, because each media data has a different content, the alternate_group value should be '0'. Thus, the alternate_group value recorded in the header of the 'trak (V1)' and the alternate_group value recorded in the header of 'trak (A1)' are converted to '0'. Further, in the large capacity multimedia contents file, the chunk_offset value indicating the spatial position of the remaining media data which has not been deleted is adjusted.

0031As shown in Figures 5 and 6, the file converter 100 reduces the size of the file by converting the structure of the large capacity multimedia contents file suitable for the streaming service, thereby shortening the time required for downloading the file.

0032Turning now to Figure 7, which is a flow chart illustrating a method for providing a high speed download service of multimedia contents according to the present invention. As shown, when the user requests a download service of an arbitrary multimedia contents file (step S11), the file converter 100 determines whether there is a multi bit-rate media in the file (step S12). Note, the original multimedia file is a large file having a complicated internal structure suitable for the streaming.

0033If there is multi bit-rate media in the file (yes in step S12), the tracks of 'moov' part and the media data of 'mdat' part, which have no relation to the bit rate selected by the user are deleted (step S13). Further, the alternate_group value of the track header box of the 'moov' part is set to '0' (step S14). That is, if there is a multi bit-rate media in the file, the alternate_group value of the track header box is the same natural number, not '0', but when the file is reduced to a file of a single bit rate, the alternate_group value is set to '0' so that each media data signifies a different content.

0034If there is no multi bit-rate media in the file (no in step S12), a determination is made as to whether or not there is enhancement layer video in the multimedia file (step S15). If there is enhancement layer video (yes in step S15), the tracks of the 'moov' part and the media data of the 'mdat' part related to the enhancement layer video are deleted (step S16). Note, the multimedia contents file includes the base layer video and the enhancement layer video, each having a different content.

0035After the file is reduced to the single bit rate or after the media information related to the enhancement layer video is deleted, a chunk_offset value indicating a spatial position of the remaining non-deleted media data is adjusted (step S17). Next, any hint tracks related to the streaming service are deleted (step S18), thereby creating a small capacity contents file suitable for downloading (step S19). The small capacity multimedia contents file is then transmitted to the terminal which has requested for the downloading service (step S20).

0036Further, if there is no multi bit-rate media and the enhancement layer video in the original larger file (no is steps S12 and S13), the original file is not reduced (step S21) and transmitted as the original file (step S20).

0037As so far described, the apparatus and method for providing a high speed download service of multimedia contents of the present invention have the following advantages.

0038Because the large capacity multimedia file for streaming is converted into a smaller file, the time required for downloading the file is reduced, and the standby time for using the service is reduced. Further, because the file is reduced in size, the user's cost of the VOD is reduced.

0039This invention may be conveniently implemented using a conventional general purpose digital computer or microprocessor programmed according to the teachings of the present specification, as well be apparent to those skilled in the computer art. Appropriate software coding can readily be prepared by skilled programmers based on the teachings of the present disclosure, as will be apparent to those skilled in the software art.

0040The invention may also be implemented by the preparation of application specific integrated circuits or by interconnecting an appropriate network of conventional component circuits, as will be readily apparent to those skilled in the art. The present invention includes a computer program product which is a storage medium including instructions which can be used to program a computer to perform a process of the invention. The storage medium can include, but is not limited to, any type of disk including floppy disks, optical discs, CD-ROMs, and magneto-optical disks, ROMs, RAMs, EPROMs, EEPROMs, magnetic or optical cards, or any type of media suitable for storing electronic instructions. The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. The description of the present invention is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art.