JP5500649B2 - Video distribution server - Google Patents

Description

The present invention relates to a video distribution server, in particular, it relates to a video distribution server video distribution server distributes a zoom image by expanding the streaming video partly in response to a request from the video reproduction device.

  A so-called multi-screen service that enables viewing of content for a large screen such as a cable television on not only a TV but also a device such as a PC, a mobile phone, and a stylus portable terminal is becoming popular. Non-Patent Document 1 discloses a technology for distributing content for cable television to a PC. In such a multi-screen service, it is necessary to convert high-resolution content created for a television with a large display to a low resolution for a mobile phone with a small display.

  In a general multi-screen service, the entire content for a large screen is converted (transcoded) as it is and streamed to a mobile phone or the like. However, mobile phones and the like have a problem that the attractiveness of content cannot be fully exhibited because the display is small. Therefore, there has been a demand for a mechanism that allows the user to enlarge and view an arbitrary area that the user wants to view.

  As a technique for enlarging video content, Patent Document 1 discloses a digital zoom for trimming (cutting out) and presenting an arbitrary part in a video. However, such a digital zoom function is performed as a process at the time of video shooting, and does not take into consideration the bit rate limitation in video transmission and the low delay required for streaming in real time, and has a high load. Since processing is required, application to video streaming is difficult.

  As a method for solving such a technical problem, a method using real-time encoding in which an enlarged image desired by the user is encoded and transmitted in real time on the server side can be easily imagined. However, if the user always wants to encode and transmit the enlarged video, the load on the server increases, and the load increases in proportion to the number of users receiving the service. At the same time, it is not practical to provide services.

  Furthermore, as another solution to the above technical problem, Non-Patent Document 2 divides and encodes video content into tiles, and transmits a part of the entire tile from the server side, while receiving it at the client side. A method is disclosed in which an enlarged image is obtained by decoding an image for each tile and displaying the decoding result at the same time. However, in this method, it is necessary to individually decode the video divided into tiles on the client side and display it in synchronization. Therefore, it is not practical to install it on a terminal with low processing capability such as a portable terminal. No.

JP2008-316739

Fancast (http://www.fancast.com/) A Study on Multi-resolution Distribution Method for Interactive Panorama Video Distribution System (Information Processing Society of Japan Vol.2010-AVM-70 No.8)

  In this way, when video streaming distributed from the video distribution server is enlarged and reproduced in response to a request from the playback terminal side, extremely high processing capability is required on the video playback terminal side, or each user is requested by the server. In other words, video streaming cannot be enlarged and played in response to a request from the playback terminal.

The object of the present invention is to solve the above-mentioned problems of the prior art, and to make video streaming a request from the playback terminal in a form that does not require a high processing capacity on the playback terminal and can provide services to a large-scale user. Accordingly, it is to provide a video distribution server that can be enlarged and reproduced accordingly.

  In order to achieve the above object, the present invention is characterized in that the following means is taken in a video distribution server that switches a video distributed in a streaming format to a zoom video in response to a zoom request.

(1) For each video content, means for storing a non-zoom encoded file having a distribution resolution and at least one zoom encoded file having a resolution higher than the distribution resolution, and a zoom request in which a zoom magnification and a zoom position are described. Means for detecting, and when a zoom request for the encoded file being distributed is detected, the means for switching the encoded file to be distributed to a zoom encoded file having a resolution corresponding to the zoom magnification; Means for cutting out a zoom image at the distribution resolution from the zoom position of a zoom encoded file;
Means for delivering the cut-out zoom video in a streaming format.

  (b) The encoding file for zoom is composed of a plurality of divided video areas divided by logical boundary lines and is encoded for each divided video area, and each divided video area includes a plurality of sets corresponding to the zoom position. The position, shape, and size of the zoom image are defined so that the zoom image of the distribution resolution can be configured with a plurality of divided images corresponding to the zoom position from the switched zoom encoding file. A set of areas was cut out as a zoom image.

  (c) There is provided means for rewriting the macro block header information of a plurality of divided video areas cut out as a zoom video in accordance with the display position of each macro block in the zoom video.

  According to the present invention, the following effects are achieved.

  (1) In the video distribution server, a plurality of encoded files for zoom having different resolutions are prepared in advance according to the stage of zoom magnification that can be provided, and when a zoom request is detected, the requested zoom magnification Since the zoom position video is cut out from the zoom encoding file corresponding to the zoom video, the zoom video can be distributed with a low load in response to the zoom request.

(2) The encoding file for zoom is composed of a plurality of divided video areas divided by logical boundary lines and is encoded for each divided video area, and the zoom video can be configured as a set of a plurality of divided video areas. since, by setting the zoom position divided image area as a unit, cut out of the zoom image is facilitated.

  (3) The video header information of a plurality of divided video regions cut out from the zoom encoded file is rewritten in advance on the video distribution server side so that it can be reproduced at a low load even by a receiving terminal with low processing capability, and then distributed. Therefore, high-load processing is not necessary on the receiving terminal side when displaying the zoom video.

1 is a block diagram of a video distribution system according to a first embodiment of the present invention. It is the figure which showed the operation | movement outline | summary of 1st Embodiment. It is the figure which showed an example of the encoding file prepared for a video delivery server. It is the figure which expressed typically the method of cutting out a some slice from the encoding file for zoom, and delivering a zoom image | video. It is the figure which showed the method of cutting out several different slices according to a zoom position. It is the figure which showed the example of reproduction | regeneration of a zoom image | video. It is the figure which showed the rewriting method of video header information. It is the figure which compared before and after rewriting of video header information. It is the sequence flow which showed the operation | movement of an effect part. It is the figure which showed an example of the effect inserted at the time of video switching. It is the figure which showed the operation | movement outline | summary of 2nd Embodiment. It is the figure which showed the example of a movement of a zoom image | video. It is a figure showing an example of an effect inserted at the time of movement of a zoom position. It is the figure which showed the operation | movement outline | summary of 3rd Embodiment. It is a block diagram of the video delivery system which concerns on 3rd Embodiment. It is a block diagram of the video delivery system which concerns on 4th Embodiment. It is the figure which showed the rewriting method of an encoding parameter. It is the figure which showed an example of IDR frame information. It is the figure which showed another example of IDR frame information. It is the figure which showed an example of the zoom request message.

[First embodiment]
FIG. 1 is a block diagram showing the configuration of a video distribution system according to a first embodiment of the present invention, a video distribution server 1 that distributes video content in a streaming format, and a video that receives and reproduces the video content A playback terminal 2 is connected via a wide area network 3 such as the Internet.

  FIG. 2 is a diagram showing an outline of the operation of the first embodiment. The video distribution server 1 is a video content of high resolution (for example, 1440 × 1080 pixels) shot and edited for a large TV [the same figure] (a)] is converted into distribution resolution, that is, display resolution of the video playback terminal 2 (for example, 640 × 480 pixels) and distributed [FIG. (b)], and zoomed in response to a zoom request from the terminal user Distribute the video at the distribution resolution [(c)].

  In the present invention, as shown in FIG. 3, in order to achieve such zoom video distribution without adversely affecting the bit rate and transmission delay, and without requiring high processing capability on the video playback terminal 2 side. In addition, a plurality of encoded files Fb and Fc for zooming that can cut out a zoomed video having a distribution resolution from a part of the image area together with a non-zoom encoded file Fa having a distribution resolution are created for each video content in advance. 1 is accumulated.

  In the present embodiment, three types of zoom magnifications (no zoom, medium zoom ratio, large zoom ratio) can be set, and the resolution of the encoded file Fb [zoom ratio medium (b)] for the zoom ratio is for no zoom. The resolution of the encoded file Fa [Fig. (A)] is set higher than the distribution resolution of the encoded file Fa [Fig. (C)]. The resolution of the encoded file Fc [Fig. The resolution is set higher than the resolution of FIG.

  The grid lines shown in each of the zoom encoded files Fb and Fc represent slice boundaries to be described later. For example, when the terminal user requests enlargement reproduction during the zoom rate, an example is shown in FIG. In this way, only the video range (distribution resolution) of 2 rows and 2 columns partitioned by the slice boundary is cut out from the encoded file Fb for medium zoom ratio in accordance with the zoom position and distributed as a zoom image. The position, shape, and size of each slice are defined so that a zoom video having a distribution resolution can be configured by a plurality of sets according to the zoom position.

  In the present embodiment, as shown in FIG. 5, zoom reference points O1, O2, O3, O4,... Are preset for each zoom encoded file, and if it is a zoom encoded file Fb, Slices 1-1, 1-2, 2-1, 2-2 are associated with the zoom reference point O1, as slice targets, and slices 1-2, 1-3, 2-2, 2 are associated with the zoom reference point O2. -3 is associated as a clipping target. If the nearest zoom reference point from the requested zoom position is O1, four slices 1-1, 1-2, 2-1, 2-2 corresponding to the zoom reference point O1 are cut out. Zoomed image.

  That is, during playback of the non-zoom video shown in FIG. 4A, if enlargement playback is requested during the zoom ratio by designating the vicinity of the zoom reference point O1, as shown in FIG. A video area in the upper left area composed of two slices [1-1], [1-2], [2-1], and [2-2] is distributed as a zoom video. Further, when enlargement reproduction is requested during the zoom ratio by designating the vicinity of the zoom reference point O2, as shown in FIG. 4C, four slices [1-2], [1-3], The video area in the upper right area composed of [2-2] and [2-3] is distributed as a zoom video. Similarly, when the vicinity of the zoom reference point O3 is designated, as shown in FIG. 4D, four slices [2-1], [2-2], [3-1], [3 -2] is distributed as a zoom image, and when the vicinity of the zoom reference point O4 is designated, as shown in FIG. 4E, four slices [2-2] , [2-3], [3-2], and [3-3] are distributed as zoomed images in the lower right region.

  FIG. 6 is a diagram showing an example of playback of the zoom video. The video playback terminal 2 during decoding [FIG. 6 (a)] while decoding and playing back the non-zoom encoded file Fa received from the video distribution server 1. When the enlargement to the zoom ratio is requested [(b) in FIG. 2], the video distribution server 1 switches the distribution file from the non-zoom encoded file Fa to the intermediate zoom ratio encoded file Fb. Then, the zoom video clipped according to the zoom position from the encoded file Fb is distributed. As a result, the video playback terminal 2 plays back the video with the zoom ratio [(c)].

  If a further enlargement to a higher zoom ratio is requested during playback of the zoom video [(c)], the video distribution server 1 uses a larger zoom ratio from the encoded file Fb in the zoom ratio. Is switched to the encoded file Fc, and a zoom image cut out from the encoded file Fc according to the zoom position is distributed. As a result, the video playback terminal 2 plays back a video with a large zoom rate [(d)].

  When the encoded file Fa for non-zoom is being reproduced [FIG. (A)], when a request to switch to a large zoom rate is requested [(e)], the video distribution server 1 similarly distributes the file. Is switched from the encoded file Fa for non-zoom to the encoded file Fc for large zoom ratio, and a zoom video clipped from the encoded file Fc according to the zoom position is distributed. As a result, the video playback terminal 2 plays back video content with a large zoom rate [(d)].

  Next, the configuration of the present invention will be described in detail with reference to FIG. In the video distribution server 1, the video division encoding unit 101 encodes and compresses the video content 4 to be distributed. In this embodiment, the H.264 encoding method is adopted, information of the IDR frame that is the intra frame is accumulated in the IDR frame information DB 102, audio data is accumulated in the audio data storage DB 103, and video data is stored in the video data storage DB 104. Accumulated in. The IDR frame information is stored in the format shown in FIG. 18 when IDR frames are inserted at regular intervals. When the IDR frame information is not inserted at regular intervals, the frame numbers of all IDR frames are stored as shown in FIG. Accumulated in the manner listed.

  In the video data storage DB 104, a plurality of encoded files having different resolutions according to types of zoom magnifications that can be set are generated and stored for each video content. In the present embodiment, as shown in FIG. 3, there are a total of three encoded files, that is, an encoded file Fa for non-zoom, an encoded file Fb for medium zoom ratio, and an encoded file Fc for large zoom ratio. Is created and accumulated. With respect to the two encoded files Fb and Fc for zooming, for each predetermined divided video area (in this embodiment, since the H.264 encoding method is used, the video content is partitioned by logical boundary lines) In both processes of intra-frame prediction encoding (intra encoding) and inter-frame prediction encoding (inter encoding), prediction across slice boundaries is prohibited. Accordingly, as described with reference to FIG. 4, even when a zoom video is constructed by cutting out a plurality of different slices according to the zoom position, macroblocks in other slices are not decoded when each slice is decoded. Since there is no reference, there is no failure in decoding.

  However, there is a concern that if the prediction across the slice boundary is uniformly prohibited in this way, the encoding efficiency is lowered. On the other hand, as is clear from FIG. 4, for example, a zoom image is generated by cutting out 2 rows and 2 columns according to the zoom position from the zoom encoding file Fb in which the slice is set to 3 rows and 3 columns. In this case, when slice 1-1 is cut out, slices 1-2, 2-1, and 2-2 are also cut out. When slice 1-2 is cut out, slice 2-2 is also cut out. Therefore, if slices that are always cut out at the same time can be defined in advance, encoding efficiency can be improved by allowing prediction across slice boundaries in both intra-frame predictive coding and inter-frame predictive coding between the slices. It becomes possible to improve.

  Generalizing this, when the slice configuration of the zoom encoding file is Xnum rows and Ynum columns, and the slice configuration of the zoom video extracted from there is w rows and h columns, and the ID of the slice of interest is x-y,

  (1) Number of slices whose ID x-y slice can be predicted in the right direction Bright = w-x, (Bright = 0 and Bright ≤ Xnum-x if negative)

  (2) Slice area where ID x-y slice can be predicted in the left direction Bleft = w- (Xnum -x) -1, (Bleft = 0, Bleft ≤ x-1 if negative)

  (3) Number of slices whose ID x-y slice can be predicted and referenced in the upward direction Bup = h- (Ynum -y) -1, (However, if negative, Bup = 0, and Bup ≤ y-1)

(4) Number of slices whose ID xy slice can be predicted downward Bdown = hy, (However, if down, Bdown = 0, and Bdown ≤ Ynum-y)
These conditions are satisfied. Therefore, slices that can satisfy the above conditions (1) to (4) may be allowed to use prediction that crosses the slice boundary for encoding.

  The user operation receiving unit 105 receives the user operation transmitted from the video reproduction terminal 2, and if the user operation is a “zoom request” in which the zoom magnification Zf and the zoom position Zp are described, this is displayed as a video switching control unit. 106 is notified.

  The video switching control unit 106 switches the video read and distributed from the video data storage DB 104 to a zoom encoded file corresponding to the zoom factor Zf of the zoom request received by the user operation receiving unit 105. The switched zoom encoding file is output together with the audio data read from the audio data storage DB 103. That is, if the zoom request is in the zoom ratio, the encoded file Fb is switched to the medium zoom ratio, and if the zoom request is in the large zoom ratio, the encoded file Fc is switched to the large zoom ratio. Such video switching is all performed at the timing of an intra frame (in this embodiment, an IDR frame).

  As described in detail with reference to FIG. 4, the zoom video cutout unit 107 cuts out a plurality of slices corresponding to the zoom position Zp described in the zoom request from the switched zoom encoded file, and zooms in. The video is converted into video and stored in the slice data buffer 108. Note that such a cutout of the zoom image is performed by rewriting the image header information of the zoom encoding file to generate a zoom image having a single slice structure.

  FIG. 7 is a diagram schematically showing the video header information rewriting method. Here, four slices 1-1, 1-2, and 2 in the upper left area of the encoded file Fb in the zoom rate are shown. A case where a zoom image having a single slice structure is generated by cutting out -1 and 2-2 will be described as an example.

  In the encoded file Fb for zooming, as shown in (a) of the figure, all macroblocks are managed in raster order for each slice 1-1, 1-2, 2-1, 2-2. Has been. However, the video playback terminal 2 having a low processing capability cannot decode a video configured by combining slices having an arbitrary shape as it is. Therefore, in this embodiment, the video playback terminal 2 can decode the encoded file Fb as a single slice structure by renumbering all the macroblocks of each slice in the raster order in the single slice structure. I have to.

  FIG. 8 is a diagram comparing the video header of the encoded file Fb before rewriting with the video header of the zoomed video after rewriting. In the encoded file Fb in FIG. 8A, one frame includes a plurality of slices. An ordinal number starting from 1 is assigned to every macroblock for each slice. On the other hand, in the zoom image of FIG. 4B, one frame is composed of one slice obtained by concatenating the four slices, and a consistent serial number (1 to 1180) is assigned to all macroblocks. ing.

  Note that SPS (Sequence Parameter Set) is a header in which information related to the encoding of the entire video sequence is described. The type of tool (profile: profile_idc) used for encoding the video and the target decoder Information on the level (level_idc) representing the processing capacity of the image, the screen size (screen size expressed by the number of macroblocks: pic_width_in_mbs_minus1, pic_height_in_map_units_minus1), and the like. In the present embodiment, the SPS of the encoded file Fb is also added to the zoom video as it is for the information that does not depend on the image size such as the profile in this embodiment, but the values such as the encoding level and the image size are generated. Is rewritten to a value corresponding to the size of the zoom image to be displayed.

  Furthermore, PPS (Picture Parameter Set) is a header in which information related to frame encoding is described. The type of encoding method (entropy_coding_mode_flag) used for frame encoding and the number of slices constituting the frame ( num_slice_groups_minus1) and information such as slice arrangement (slice_group_map_type) are included. In the present embodiment, regarding this PPS, the encoded file Fb describes the arrangement and the number of slices for constituting one frame by a plurality of slices, but in a zoom image, a single slice is composed of one frame. Rewritten to be configured.

  Furthermore, when the value of the quantization parameter (QP) for quantizing the luminance component of the macroblock is controlled for each macroblock, the macroblock adjacent to the right of the slice boundary is used to derive the QP. It is also desirable to rewrite the difference information. For example, in H.264 encoding, the QPY of a macroblock in a slice is given by the following equation (1).

  Here, QPY and PREV are the QPY value of the macroblock located immediately before counting in the order of FIG. 7, mb_qp_delta is the QP difference information described in the macroblock, QpBdOffsetY is the offset value, In the first macroblock, QPY and PREV take initial values. Therefore, as shown in FIG. 17, assuming that the default QP value is 24 and the value described in the macroblock lattice in the figure is the QP of each macroblock, a single slice video from a video composed of a plurality of slices When converting to, the macroblock located immediately before is changed as the order of the macroblocks changes. Therefore, by converting the value of mb_qp_delta as follows, the QPY value of each macroblock can be maintained, and re-encoding of the macroblock can be made unnecessary.

  That is, when a certain macroblock has mb_qp_delta_old and the values of QPY and PREV referred to by the macroblock are changed from QPY and PREV_A to QPY and PREV_B, the mb_qp_delta_new is calculated by the following equation (2).

  By performing such a calculation on the macroblock located at the right end of the slice boundary, it is possible to reuse the already-calculated optimal quantization parameter with a minimum amount of processing. Of course, if all the macroblocks constituting the frame have the same value, this processing is unnecessary and need not be executed.

  In addition, when intra prediction encoding is used in which encoding is performed with reference to information on other macroblocks in the screen, the macroblock adjacent to the right end or upper end of the slice boundary is encoded. It is desirable to make necessary changes to the luminance signal and the color difference signal according to the position of the macroblock.

  That is, when the average value prediction of intra coding is performed, the signal of the macro block is usually obtained using the average value of 32 pixels (in the case of 16 × 16 macro block) adjacent to the top and left of the macro block. Encoding is performed, but the macroblock located at the upper end of the slice is encoded using only the average value of 16 pixels adjacent to the left. Therefore, as shown in FIG. 7, when converting a multi-slice video to a single-slice video, average value prediction of intra coding is used in a macroblock adjacent to the right end or the upper end of a slice boundary. In this case, it is desirable to change the average value used for the prediction and recalculate the luminance value in the macroblock. The same applies to the color difference signal.

  Such processing is performed only for the macroblock adjacent to the right end or the upper end of the slice boundary, and for the other macroblocks, the encoded luminance signal and color difference signal are used as they are to obtain a single slice. The amount of calculation involved can be minimized.

  When the effect unit 109 switches the zoom ratio of the video to be distributed in the streaming format, the effect unit 109 inserts the effect between the videos before and after the switching. When an effect is inserted, a decoded image frame as a base is required. Therefore, the next IDR frame is acquired as the nearest decoded image frame.

  FIG. 9 is a sequence flow showing the operation of the effect unit 109. When a zoom request is detected, the distribution video is displayed at the current zoom at time t1, which is the distribution timing of the (n-th) IDR frame. The non-video image is switched to the effect video image, and the distribution video image is switched from the effect video image to the zoom video image at time t2, which is the distribution timing of the next (n + 1) th IDR frame.

  FIG. 10 is a diagram showing an example of the effect displayed on the video playback terminal 2. When zoom playback is requested on the non-zoom video in FIG. 10 (a), the next IDR frame is delivered. At a certain time t1, as shown in the same figure (b), except the zoom area is mosaic processed, and as shown in the same figure (c), until the time t2, which is the delivery timing of the next IDR frame, The zoom area is enlarged step by step, and the distribution video is switched to the zoom video at the time t2. At this time, a sound effect may be generated in accordance with a change in the effect effect.

  The effect image is generated as a frame image that gradually changes from the nth IDR frame to the (n + 1) th IDR frame, encoded as video data, and written into the slice data buffer 108. The effect image in FIG. 10 gradually enlarges the area instructed to be enlarged by, for example, linear interpolation, while the other areas are divided into cells of a certain area, and the mother points of the cells are arranged at equal intervals, This can be realized by performing a process such as tiling step by step. The non-zoom video, the effect video, and the zoom video are distributed in a streaming format to the video reproduction terminal 2 via the multiplexing unit 110 and the distribution unit 111 that superimpose the effect sound.

  Returning to FIG. 1, in the video playback terminal 2, the video receiving unit 201 receives a video stream distributed in a streaming format. In this video stream, as a supplementary information, the zoom ratio of the video being transmitted and the coordinates of the area of the video being transmitted are transmitted as SEI (Supplemental Enhancement Information) of H.264.

  The display buffer 202 temporarily stores the received video, reads it at a predetermined bit rate, and outputs it to the display unit 203. The user operation accepting unit 204 accepts user operations related to a video content distribution request, a zoom request for a video being played back, a movement request related to a video being zoom played, and the like. If the display unit 203 has a touch panel function, the zoom request can be accepted by pinching out the area to be enlarged.

  The operation determination unit 205 determines whether or not the video distribution server 1 can respond to the accepted zoom request. For example, if the video currently being distributed is a streaming video related to the encoded file Fb for the zoom ratio, Since further zooming is possible, the zoom request is transmitted from the user operation transmission unit 206 to the video distribution server 1. Such zoom request is transmitted by describing the requested zoom magnification Zf and zoom position (coordinate) Zp in the SET_PARAMETER message of RTSP as shown in FIG.

  In the above-described embodiment, description has been made mainly on the switching at the time of zooming in from the image without zoom to the image with zoom. However, the present invention is not limited to this, and the image with zoom with different resolution is used. It can be applied in the same way when switching between and zooming out from an image with zoom to an image without zoom.

According to the present embodiment, the video distribution server 1 is prepared in advance with a plurality of zoom encoded files having different resolutions according to the stage of zoom magnification that can be provided, and when a zoom request is detected, Since the video at the zoom position Zp is cut out from the encoded file for zooming corresponding to the requested zoom magnification Zf and used as the zoom video, the zoom video can be distributed with a low load in response to the zoom request.
[Second Embodiment]

  Next, a second embodiment of the present invention will be described. In the above embodiment, the video switching when zooming the video being played back has been described. However, the present invention is not limited to this, and the zoom position can be changed without changing the zoom magnification during playback of the zoom video. The same can be applied to the case of moving only.

  FIG. 11 is a diagram showing an outline of the operation of the second embodiment. The video distribution server 1 displays high-resolution video content shot and edited for a large TV [the same figure (a)] as distribution resolution. That is, the image is converted to the display resolution of the video playback terminal 2 and distributed [FIG. (B)], and the zoom video of the distribution resolution is distributed [FIG. (C)] in response to a zoom request from the terminal user. In response to the movement request from the terminal user, the zoom image of the movement destination (also distribution resolution) is distributed [(d)].

  FIG. 12 is a diagram illustrating a zoom video moving method according to the second embodiment. Here, a case where the position of the zoom video cut out from the encoded file Fc with a large zoom ratio is moved will be described as an example. .

  The video distribution server 1 distributes in a streaming format the zoom video shown in FIG. 7C, which is generated by cutting out six slices of the area indicated by the black frame in FIG. In the video distribution server 1, during this distribution, when a movement request designating movement to the right side is received as shown in FIG. 4D, the video distribution server 1 responds to the movement request from the encoded file Fc. Six slices in the range indicated by the black frame in FIG. Then, a new zoom image shown in FIG. 5E is created from these six slices, and the distribution image is switched from the zoom image before the movement to the zoom image after the movement.

  In this embodiment as well, as shown in FIG. 13 as an example, when switching from the zoom image before movement [FIG. 13 (a)] to the zoom image after movement [FIG. It is desirable to insert the figure (b)]. Such an effect video can be generated by shifting the pixel value of the original data to the left and simultaneously copying the pixel value at the right edge boundary of the original image for the right edge of the screen.

According to this embodiment, the video distribution server 1 cuts out a slice corresponding to the zoom position of the movement destination in response to receiving a movement request describing the zoom position of the movement destination from the video playback terminal 2, and zooms in the video. Therefore, the zoom position can be easily moved.
[Third embodiment]

  Next, a third embodiment of the present invention will be described. In each of the above-described embodiments, the upper limit of the settable zoom rate depends on the resolution of the encoded file for zoom stored in the video distribution server 1 and requires playback at a zoom rate higher than that. I could not.

  On the other hand, in the present embodiment, when a zoom rate exceeding the zoom rate by the zoom encoded file stored in the video distribution server 1 is designated, the video playback terminal 2 detects this, and the well-known digital zoom function As a result, the video is tremmed on the display buffer 202 to realize an apparent high magnification zoom.

  FIG. 14 is a diagram for explaining the zoom method of the present embodiment. If zoom playback is not requested, the video distribution server 1 distributes the non-zoom encoded file Fa of FIG. The video playback terminal 2 plays back the non-zoom video shown in FIG.

  When zooming at the zoom rate is requested, the video delivery server 1 delivers the zoomed video clipped from the encoded file Fb at the zoom rate shown in FIG. ) Is played back at the zoom rate. When zoom with a large zoom rate is requested, the video distribution server 1 distributes the zoom image cut out from the encoded file Fc with the large zoom rate shown in FIG. The image with the large zoom factor (f) is played back.

  When zooming at a higher magnification is required, the video on the display buffer 202 is tremmed to the size corresponding to the required magnification around the zoom position Zp in the video playback terminal 2 as shown in FIG. Cut out. The trimmed tremming image is resized by raising its resolution to the distribution resolution by interpolation processing or the like, and is displayed as if it has been zoomed to a high magnification as shown in FIG.

  FIG. 15 is a functional block diagram of the present embodiment, and the same reference numerals as those described above represent the same or equivalent parts, and thus description thereof is omitted.

  When the local zoom unit 207 determines that the magnification of the zoom request accepted as a user operation exceeds the range that can be handled by cutting out the zoom video from the zoom encoded file prepared in the video distribution server 1, The zoom image developed in the display buffer 202 is tremmed with a size corresponding to the requested zoom ratio Zf with the designated zoom position Zp as the center, and the number of pixels of the tremming image matches the number of pixels of the distribution resolution. As described above, the tremming image is resized by performing an interpolation process or the like.

According to the present embodiment, zoom reproduction at a high magnification exceeding the zoom magnification that can be handled by cutting out a zoom video from a zoom encoded file prepared in advance in the video distribution server 1 becomes possible.
[Fourth embodiment]

  Next, a fourth embodiment of the present invention will be described. In the above embodiment, the effect image is described as being inserted on the video distribution server side. However, the present invention is not limited to this, and is stored in the display buffer 202 as shown in FIG. A local effect unit 208 is provided for processing an image being processed, and when a zoom request to the user operation receiving unit 204 is detected, the local effect unit 208 is stored in the display buffer 202 for a certain period of time immediately after that. On the other hand, by inserting an effect such as mosaicing, it may be easily understood that the operation has been accepted by the local processing.

  In each of the above embodiments, the VDO (Video On Demand) that distributes the content stored in the video distribution server 1 in response to a request from the user terminal has been described as an example. The present invention is not limited and can be similarly applied to real-time broadcasting.

  DESCRIPTION OF SYMBOLS 1 ... Video distribution server, 2 ... Video distribution terminal, 101 ... Video division | segmentation encoding part, 102 ... IDR frame information DB, 103 ... Audio data storage DB, 104 ... Video data storage DB, 105 ... User operation receiving part, 106 ... Video switching control unit 107 107 Zoom video cutting unit 108 Slice data buffer 109 Effect unit 110 Multiplexing unit 111 Distribution unit 201 Video receiving unit 202 Display buffer 203 Display unit , 204 ... User operation reception unit, 205 ... Operation determination unit, 206 ... User operation transmission unit, 207 ... Local zoom unit, 208 ... Local effect unit

Claims (9)

In a video distribution server that switches a video distributed in a streaming format to a zoom video in response to a zoom request,
Encoding means for generating, for each video content, a non-zoom encoded file having a distribution resolution and at least one zoom encoded file having a resolution higher than the distribution resolution;
Means for storing the non-zoom encoded file and the zoom encoded file for each video content;
Means for detecting a zoom request describing a zoom magnification and a zoom position;
When a zoom request for the encoded file being distributed is detected, means for switching the encoded file to be distributed to a zoom encoded file of another resolution corresponding to the zoom magnification;
Means for cutting out a zoom image at the distribution resolution from the zoom position of the switched zoom encoding file;
Means for delivering the cut-out zoom video in a streaming format,
The encoding means encodes the zoom encoding file for each of a plurality of divided video regions including a plurality of macroblocks partitioned by a logical boundary line,
The encoded file for zoom is encoded by the encoding method at the time of distribution for each of the divided video areas,
Each of the divided video areas is defined in position, shape, and size so that a zoom video of the distribution resolution can be configured by a plurality of sets according to the zoom position.
The video distribution server , wherein the means for cutting out the zoom video cuts out a set of a plurality of divided video areas corresponding to the zoom position from the switched zoom encoding file as a zoom video . The video distribution according to claim 1 , further comprising means for rewriting header information of macroblocks of a plurality of divided video areas cut out as the zoom video in accordance with display positions of the macroblocks in the zoom video. server. The means for rewriting the header information of the macroblock rewrites the ordinal number attached to each macroblock so that a plurality of divided video areas cut out as a zoom video become a single video area. 2. The video distribution server according to 2. The means for rewriting the header information of the macroblock, when the quantization parameter information possessed by each macroblock is stored as a difference from the quantization parameter information possessed by the immediately preceding macroblock in the decoding order of the macroblock, 3. The video distribution server according to claim 2 , wherein the difference information is rewritten in accordance with the converted new macroblock decoding order for the macroblock located on the right side of the logical boundary line. 2. The video distribution server according to claim 1 , wherein the encoding unit does not refer to a macroblock of another one divided region when encoding each macroblock of one divided video region. 3. When the encoding means encodes each macroblock of one divided video area, reference to macroblocks of other divided video areas that are always cut out simultaneously with the one divided video area and constitute a zoom video is 6. The video distribution server according to claim 5 , wherein the video distribution server is allowed. The video distribution server according to claim 5 or 6 , wherein the encoding is intra encoding or inter encoding. Video distribution server according to any one of claims 1 to 7, characterized in that further comprising an effect means for inserting an effect image between the switching of the front and rear zoom image. Video distribution server according to any one of claims 1 to 8, wherein the image switching is performed at the timing of the intra-frame.