JP4888955B2 - Content delivery method and apparatus - Google Patents

Description

  The present invention relates to a content distribution method and apparatus for distributing video content, and more particularly to a content distribution method and apparatus suitable for trick reproduction.

  2. Description of the Related Art Conventionally, a content distribution server that distributes video content is used for trick playback for fast forward playback / fast reverse playback separately from normal playback content in order to realize trick playback such as fast forward playback and fast reverse playback of moving images. Has content. Here, the normal playback content includes an intra-frame encoded picture (I picture), an inter-frame forward prediction encoded picture (P picture), and a bidirectional predictive encoded picture (B picture). The contents of the normal playback content are composed of only I pictures for high speed playback at a predetermined magnification.

  In such a configuration, if trick playback is requested during normal playback while distributing normal playback content, the content distribution server stops distributing normal playback content and then starts distributing trick playback content. Was. However, in such a conventional technique, there is a technical problem that the video is disturbed in a transition transition period in which the playback content is switched from the normal playback content to the trick playback content, or a long time lag occurs instead of the video switching.

In response to such a technical problem, Patent Document 1 discloses a technique for increasing the decoder frame rate during trick reproduction in order to enable smooth display during trick reproduction. That is, the frame rate that was 30 frames / second during normal playback is 60 frames / second during double-speed fast-forward playback.
JP 2001-54066 A

  In the prior art disclosed in Patent Document 1, the frame rate of the decoder must be increased in accordance with the trick playback speed. However, in high-quality playback that requires a high frame rate even during normal playback as in high-definition broadcasting, it is difficult to further increase the decoder frame rate during trick playback. Also, the higher the trick playback speed, the higher the frame rate required for the decoder. Therefore, it is difficult to apply when the trick playback speed is high.

  The object of the present invention is to solve the above-mentioned problems of the prior art, there is no restriction on the frame rate and trick playback speed during normal playback, and the video is disturbed during the transition period of content, or there is a long time lag in switching video. An object is to provide a content distribution device and a content reproduction device that do not occur.

  In order to achieve the above object, the present invention takes the following measures in a content distribution apparatus that receives and reproduces normal reproduction content and trick reproduction content distributed from a content distribution server by a reproduction apparatus. There is a feature in the point.

  (1) The content distribution server detects the normal reproduction request and trick reproduction request from the reproduction device, and distributes the normal reproduction content and trick reproduction content in parallel in response to the normal reproduction request. Content delivery means for delivering trick play content at a rate corresponding to the trick play speed in response to the play request, wherein the playback device sends a normal play request in response to a normal play instruction, Playback request means for transmitting a trick playback request in response to an instruction, trick playback buffer for storing trick playback content distributed in parallel with the normal playback content in response to the normal playback request, and streaming of received content Select playback of trick playback content stored in the playback or trick playback buffer And a content distribution server that selects a trick playback buffer in response to a trick playback instruction during streaming playback of normal playback content, and that responds to the trick playback request. When the trick playback content is received from, the streaming playback of the trick playback content being received is selected.

  (2) The trick playback content is distributed prior to the normal playback content.

  (3) The bandwidth of normal playback content distributed in parallel is wider than the bandwidth of trick playback content.

  (4) The normal playback content is composed of I slices, P slices, and B slices, the trick playback content is configured of I slices with a period corresponding to the trick playback speed, and the content distribution server Out of the I slices, the distribution of the I slices at the same or close timing on the timeline as the I slices of the normal playback content is thinned out, and the playback device performs normal playback corresponding to the I slices skipped from the trick playback content. Use the I slice of the playback content as the I slice of the trick playback content.

According to the present invention, the following effects are achieved.
(1) From the content distribution server, trick playback content is distributed in parallel with normal playback content even during normal playback. The playback device temporarily stores trick playback content in parallel with normal playback content playback. Is done. When trick playback is instructed, the temporarily stored trick playback content is read and played until the trick playback content can be streamed, and then trick playback content streaming playback is performed. Therefore, trick playback can be performed without a response delay immediately after the trick playback is instructed.
(2) Since the trick playback content is distributed in parallel with the normal playback content and before the normal playback content, trick playback can be started from the frame next to the frame being drawn during trick playback.
(3) In the content distribution server, among the I slices constituting the trick reproduction content, the distribution is thinned out for the I slice of the normal reproduction content at the same or close timing on the timeline, and the reproduction device Then, since the I slice of the normal playback content is stored as a part of the I slice of the trick playback content and used for trick playback, the bandwidth allocated to the trick playback content during normal playback can be reduced.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a main part of a content distribution system to which the present invention is applied. The content distribution side includes a normal reproduction content storage unit 1 in which normal reproduction content is stored, and fast-forward reproduction. A trick playback content storage unit 2 in which trick playback content such as fast reverse playback is stored, and a content distribution server 3 that distributes each video content to a playback device via a CDN (content delivery network) network 4 including. The content playback side includes a playback device 5 that receives and plays back video content from the CDN network 4 and a display device 6 that outputs the played back video content.

  FIG. 2 is a block diagram showing a configuration of a main part of the content distribution server 3, and the same reference numerals as those described above represent the same or equivalent parts.

  The normal playback content storage unit 1 includes normal playback content including an intra-frame encoded picture (I slice), an inter-frame forward prediction encoded picture (P slice), and a bidirectional predictive encoded picture (B slice). Is accumulated. The trick playback content storage unit 2 stores trick playback content for high-speed playback of normal playback content at a predetermined magnification. In this trick reproduction content, if the trick reproduction speed is 5 times, I slices are accumulated at a rate of one frame for every five frames of the normal reproduction content.

  In the content distribution server 3, the reproduction request detection unit 31 detects a normal reproduction request and a trick reproduction request transmitted from the user via the CDN network. When the reproduction request detecting unit 31 detects a normal reproduction request, the distribution switching unit 32 allocates most of the entire band (broadband) to the normal reproduction content, and the remaining bandwidth ( Narrow band).

  The content distribution unit 33 is configured to connect the normal reproduction content and the trick reproduction content in parallel, and so that the trick reproduction content precedes the normal reproduction content by a predetermined reproduction time on the timeline. The data is sent to the CDN network 4 via 34. At this time, if the trick playback speed is 5 ×, the trick playback content is delivered frame by frame every time 5 frames of normal playback content are delivered.

  In the present embodiment, among the I slices constituting the trick reproduction content, the I slice at the same or close timing on the timeline as the I slice of the normal reproduction content is thinned in advance and is not distributed. Predetermined identification information is added to the I slice of the normal playback content corresponding to the thinned I slice of the trick playback content.

  In the present embodiment, when a trick playback request is detected by the playback request detection unit 31, the distribution switching unit 32 allocates all the bands to trick playback content. The content distribution unit 33 transmits only the trick reproduction content at a rate corresponding to the trick reproduction speed. That is, if the trick playback speed is 5 times, the trick playback content is sent out at a speed 5 times that during the normal playback.

  FIG. 3 is a block diagram showing the configuration of the main part of the playback device 5, and the same reference numerals as those described above represent the same or equivalent parts.

  The reproduction request unit 51 includes a user interface 52, which transmits a normal reproduction request to the content distribution server 3 via the network interface 53 when a normal reproduction is requested by the user, and transmits a trick reproduction request when a trick reproduction is requested. To do. The content receiving unit 54 receives the video content (normal playback content and trick playback content) distributed from the content distribution server 3, and the normal playback content received in a wide band during normal playback and all during trick playback. The trick playback content received in the band is output to the primary storage buffer 55, and the trick playback content received in the narrow band during normal playback is stored in the trick playback buffer 56.

  In the present embodiment, among normal playback contents received in a wide band during normal playback, tricks are performed for I slices that are the same as or close to the timing of I slices thinned out for trick playback content on the timeline. Also stored in the reproduction buffer 56.

  The reproduction content selection unit 57 sequentially reads out the normal reproduction contents from the temporary storage buffer 55 and outputs them to the display device 6 if normal reproduction is designated by the reproduction request unit 51. Further, when trick playback is designated by the playback request unit 51, the playback content selection unit 57 sequentially calls trick playback content from the trick playback buffer 56 and sends it to the display device 6.

  FIG. 4 is a diagram schematically showing a content playback operation in the playback device 5, and FIG. 5 is a flowchart showing the operation. Here, the description will be given with particular attention to the operation of the playback content selection unit 57.

  During normal playback, normal playback content composed of B, P, and I slices from the content distribution server 3 and trick playback content composed of only I slices are used in parallel using a wide band and a narrow band, respectively. In addition, the trick reproduction content is distributed so that it precedes the normal reproduction content by several seconds on the timeline. At this time, each I slice distributed as trick playback content is an I slice (In, In + 1, In, which is separated from the normal playback content I slice on the timeline, as shown in FIG. +3 ...), and the I slice (In + 2) at the same timing as or close to the I slice of the normal playback content is replaced with the I slice of the normal playback content during trick playback. Not delivered.

  Therefore, in consideration of this decimation, when the trick playback speed is 5 ×, the trick playback content is delivered by a little less than one frame every time 5 frames of normal playback content is delivered. The content is sent out at a speed more than five times that of the normal playback.

  During normal playback, streaming playback is selected by the playback content selection unit 57, so that the received normal playback content is temporarily stored in the temporary storage buffer 55, and then sequentially by the playback content selection unit 57 at a predetermined timing. To be read and played. At this time, among the I slices of the normal playback content, the I slice at the same timing as or close to the I frame of the trick playback content is stored in the temporary storage buffer 55 and also stored in the trick playback buffer 56 for trick playback. Sometimes used as an I slice of trick play content. All trick playback content received in parallel with the normal playback content is stored in the trick playback buffer 56.

  Returning to FIG. 4, when the user instructs trick playback from the user interface 52 of the playback device 5 at time t <b> 1 during normal playback, a trick playback request is transmitted from the playback request unit 51 to the content distribution server 3. In response to the trick playback request, the content distribution server 3 stops the distribution of the normal playback content and the trick playback content at time t2, and further uses the entire band according to the trick playback speed. Start preparing for delivery at the specified rate. In the playback device 5, in response to the trick playback instruction, the playback content selection unit 57 selects the trick playback buffer 56, and the trick playback process of FIG. 5 is started.

  In FIG. 5, in step S1, the frame number Nfb currently being drawn is identified. In step S2, the frame number Nfc to be drawn now is identified. In step S3, a switching point Nfa for switching trick reproduction to streaming reproduction of trick reproduction content is obtained, for example, by adding the number N of frames corresponding to a predetermined response delay to the drawing frame number Nfb.

  In step S4, the frame number Nfd closest to the frame number Nfc to be drawn is identified among the frame numbers of each I slice stored in the trick reproduction buffer 56. Here, the frame number of each I slice stored in the trick playback buffer 56 is every fifth frame number if the trick playback speed is 5 ×, for example. In step S8 described later, the frame number Nfc to be drawn is 1. Updated frame by frame. Therefore, here, every time the frame number Nfc is updated by 5 frames, the frame number Nfd of a new I slice is sequentially identified.

  In step S5, it is determined which of the drawing frame number Nfb recognized in step S1 and the frame number Nfd identified in step S4 is closer to the frame number Nfc to be drawn next. In other words, it is determined whether to keep the current I slice to be displayed, or to switch to the next I slice (fast forward playback) or the previous I slice (fast reverse playback) by 5 frames. The

  If the interval between Nfd and Nfc is shorter than the interval between Nfb and Nfc, the process proceeds to step S6, and the I slice with the frame number Nfd is read from the trick playback buffer 56 and displayed. In step S7, the currently drawn frame number Nfb is updated to Nfd. On the other hand, if the interval between Nfb and Nfc is shorter than the interval between Nfd and Nfc, the current frame continues to be displayed.

  In step S8, the frame number Nfc to be drawn next is updated by one frame. In step S9, the switching frame number Nfa is compared with the frame number Nfc to be drawn next, and the above-described processes are repeated until the frame number Nfc to be drawn next reaches the switching frame number Nfa.

  Thereafter, distribution of trick play content is started from the content distribution server at time t3 in FIG. 4, and when this is received by the playback device 5, the received frame is accumulated in the temporary storage buffer 55. At time t4, the frame number Nfc to be drawn next coincides with the switching frame number Nfa, and when this is detected in step S9 in FIG. 5, the process proceeds to step S10. In step S 10, the trick playback system is switched from the playback of the I slice stored in the trick playback buffer 56 to the streaming playback of trick playback content input via the buffer 55.

  Thereafter, when the user instructs the end of trick playback from the user interface 52 of the playback device 5 at time t5 during the trick playback, the content distribution server 3 stops the distribution of trick playback content, and again for normal playback. Preparation for parallel distribution of content and trick reproduction content is started, and at time t6, switching to streaming reproduction of normal reproduction content is performed.

  In the above-described embodiment, the fast-forward playback has been described as an example. However, the present invention is not limited to this, and can be similarly applied to fast-rewind playback. That is, when fast reverse playback is instructed by the user during normal playback, the playback content selection unit 57 selects the trick playback buffer 56 immediately after that, and the stored I slice is played back in the reverse direction.

  At this time, the content distribution server 3 stops the distribution of the normal reproduction content and the trick reproduction content at time t2 in response to the trick reproduction request, and further uses the entire band to reproduce the trick reproduction content at the trick reproduction speed. Start preparation for reverse delivery at a rate according to. Thereafter, when distribution of trick playback content is started from the content distribution server 3, the primary storage buffer 55 is selected by the playback content selection unit 57, and switching to streaming playback of trick playback content is performed.

1 is a block diagram of a content distribution system to which the present invention is applied. It is the block diagram which showed the structure of the principal part of a content delivery server. It is the block diagram which showed the structure of the principal part of a reproducing | regenerating apparatus. It is the figure which represented typically the content reproduction operation in the reproducing device. It is the flowchart which showed the content reproduction operation in the reproducing device. It is the figure which expressed typically the thinning-out delivery method of the content for trick reproduction | regeneration.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Normal reproduction | regeneration content storage part, 2 ... Trick reproduction | regeneration content storage part, 3 ... Content distribution server, 4 ... CDN network, 5 ... Playback apparatus, 6 ... Display apparatus

Claims (8)

In a content distribution method for receiving and reproducing normal reproduction content and trick reproduction content distributed from a content distribution server by a reproduction device,
The content distribution server is
In response to a normal playback request from a playback device, a procedure for distributing normal playback content and trick playback content in parallel;
Stopping the parallel transmission in response to a trick playback request from a playback device, and delivering trick playback content at a rate corresponding to the trick playback speed,
The playback device is
A procedure for sending a normal playback request in response to a normal playback instruction;
Receiving normal playback content and trick playback content distributed in response to the normal playback request;
A procedure for streaming playback of the received normal playback content;
Storing the received trick play content;
Sending a trick play request in response to a trick play instruction;
In response to the trick playback instruction, a procedure for switching from streaming playback of normal playback content to playback of the stored trick playback content;
Receiving trick play content distributed in response to the trick play request;
And a procedure for switching from playing the stored trick playing content to streaming playing of the trick playing content being received when the trick playing content is received.   The content distribution method according to claim 1, wherein the trick reproduction content is distributed prior to the normal reproduction content.   The content distribution method according to claim 1 or 2, wherein a band of the normal reproduction content distributed in parallel is wider than a band of the trick reproduction content. The normal playback content is composed of an I slice, a P slice, and a B slice,
The trick playback content is composed of I slices with a period according to trick playback speed,
The content distribution server distributes I slices at the same timing or close to the I slice of the normal reproduction content on the timeline among the I slices of trick reproduction content distributed in parallel with the normal reproduction content. 4. The playback apparatus uses the I slice of the normal playback content corresponding to the I slice thinned out from the trick playback content as the I slice of the trick playback content. The content distribution method according to any one of the above. In a content distribution apparatus that receives and reproduces normal reproduction content and trick reproduction content distributed from a content distribution server by a reproduction apparatus,
The content distribution server is
Means for detecting a normal playback request and trick playback request from the playback device;
Content distribution means for distributing normal reproduction content and trick reproduction content in parallel in response to the normal reproduction request, and distributing trick reproduction content at a rate corresponding to the trick reproduction speed in response to the trick reproduction request; Including
The playback device is
A reproduction request means for transmitting a normal reproduction request in response to a normal reproduction instruction and transmitting a trick reproduction request in response to a trick reproduction instruction;
A trick playback buffer for storing trick playback content distributed in parallel with the normal playback content in response to the normal playback request;
Playback content selection means for selecting streaming playback of received content or playback of trick playback content stored in a trick playback buffer;
The playback content selection means selects a trick playback buffer in response to a trick playback instruction during streaming playback of normal playback content, and trick playback content is received from a content distribution server in response to the trick playback request. Then, the content distribution apparatus selects streaming reproduction of the trick reproduction content being received.   6. The content distribution apparatus according to claim 5, wherein the trick reproduction content is distributed prior to the normal reproduction content.   The content distribution apparatus according to claim 5 or 6, wherein a band of the normal reproduction content distributed in parallel is wider than a band of the trick reproduction content. The normal playback content is composed of an I slice, a P slice, and a B slice,
The trick playback content is composed of I slices with a period according to trick playback speed,
The content distribution server distributes I slices at the same timing or close to the I slice of the normal reproduction content on the timeline among the I slices of trick reproduction content distributed in parallel with the normal reproduction content. 8. The playback apparatus uses the I slice of the normal playback content corresponding to the I slice thinned out from the trick playback content as the I slice of the trick playback content. The content distribution device according to any one of the above.

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