JP5011042B2 - Information processing device - Google Patents

Description

  The present invention relates to a content reproduction method and an information processing apparatus when using a removable content storage medium having a copyright protection function (security strength).

  In recent years, in digital broadcasting, from the viewpoint of copyright protection, contents are encrypted and provided with a restriction signal such as “copying is possible only once”. For this reason, the corresponding recorder encrypts the content independently and stores it on the hard disk to prevent the content from being leaked due to unauthorized use or human error. In addition, when content recorded on the HDD is written to a DVD or Blu-ray Disk, the content recorded on the HDD is deleted (move function), and it can be copied only once. I follow the rules.

  However, when content is stored on the hard disk, it is encrypted independently, so even if a removable hard disk cannot be used, it cannot be used on other devices, which is inconvenient for the user. There was also a face. Against this background, a removable hard disk “Secure-iVDR” equipped with a copyright protection function has appeared. Secure-iVDR has an independent management function for Usage Pass including encrypted content data and its decryption key, a function for protecting the stored Usage Pass from unauthorized access, and a Usage Pass transfer function with PKI-based bidirectional authentication. It realizes the copyright protection function of content. Furthermore, specifications for a music player for music content and a video player for video content are defined using this content copyright protection function. In the case of a video player, a continuous 3072-byte logical block obtained by dividing a video stream is called Aligned Unit (AU), and encryption is performed in units of AU. A logical block in which 512 consecutive AUs are grouped is called an Allocaiton Unit (ALU), and this unit is a minimum unit encrypted by one Usage Pass. When realizing the content move function, it is necessary to change the Usage Pass in 1 minute or less in Secure-iVDR, considering that the time allowed for content duplication is 1 minute or less. (Refer nonpatent literature 1).

Recording and Playback Device for iVDR-TV Recording specification (http://www.safia-lb.com/)

  Such a recorder using Secure-iVDR performs mutual authentication between the recorder main body and Secure-iVDR and plays an encrypted communication path using the Usage Pass transfer protocol between the recorder main body and Secure-iVDR. Establishing, safely reading the Usage Pass, decrypting the separately read encrypted content with the encryption key stored in the Usage Pass, and delivering the decrypted data to the decoder, thereby realizing normal playback. However, since the recorder main body and the Secure-iVDR use an embedded CPU, it may take a long time to safely read the Usage Pass. In this case, the Usage Pass may be read during normal playback. The screen may be disturbed in time. In addition, when Secure-iVDR is provided by a multi-vendor, the time required to read the Usage Pass safely may differ depending on the vendor. When special playback such as fast-forwarding or rewinding is realized, it is necessary to read the Usage Pass and content at a speed corresponding to the double speed. Terrestrial digital content is provided in an image format called MPEG2 TS. When special playback is performed, at least multiple (n) characteristic data called I pictures are displayed per minute, and a frame is displayed. Is extracted every certain time (if it is X speed, y frames in x minutes are selected every y / n so that the I picture after X minutes is displayed in 1 minute) There is a need. This needs to be performed in parallel with the reading of the Usage Pass that changes in less than one minute. If the time taken to read the Usage Pass is large, it is difficult to realize special reproduction.

  In order to solve this problem, there is a method of pre-reading the information of Usage Pass. However, even in this case, depending on the time required to acquire the Usage Pass, the faster the fast-forward / rewind speed, the shorter the time for pre-reading, resulting in fast-forward / rewind processing that smoothly changes the video. There was a problem that I could not.

  In the recorder using Secure-iVDR, the process for safely reading the Usage Pass corresponding to the key information is executed by the CPU built in the Secure-iVDR, so it takes time to acquire the Usage Pass. The video cannot be decoded in time for the content display, and the reproduced video stops. For example, if the acquisition time is about 1 second, normal playback is not a problem, but the key information necessary for decryption is not one for the content, but is changed at certain intervals. It is necessary to acquire and decode the Usage Pass corresponding to the position of the content in which the I picture is stored. For this reason, when the Usage Pass corresponding to the content played back at the time of content acquisition is acquired, there is a problem that smooth playback or special playback such as fast forward / rewind cannot be performed in time for content display.

  In addition, devices other than Secure-iVDR have similar problems if they require time for authentication and encryption / decryption processing.

  In order to solve the above problem, the content information to be processed and the key information corresponding to the information are stored in a temporary storage area such as a memory. The information stored in this area is used for decoding according to the playback speed, and the special display is realized by supplying the decoded display data to the decoder or display.

  Also, the key information acquisition time may vary depending on the operating load of the system. In order to absorb this change, the processing interval is adjusted by comparing the time of the displayed video and the next video to be displayed. The content information is read out and stored in the temporary storage area together with the key information. Perform the process. By these processes, it seems that special reproduction is performed smoothly from the viewpoint of the user.

  According to the present invention, it is possible to smoothly perform reproduction and special reproduction during reproduction of encrypted content in which key information is changed at certain intervals and special reproduction such as fast forward / rewind.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, this invention is not limited to a present Example.

  FIG. 1 is a hardware configuration and software configuration diagram of a recorder corresponding to a removable hard disk (Secure-iVDR) having a copyright protection function in an embodiment for realizing the present invention. Since the recorder may be built in the television or in the PC or DVD recorder, in the present embodiment, a recorder corresponding to Secure-iVDR will be described as an information processing apparatus. In addition, a removable hard disk (Secure-iVDR) for recording and storing content and a normal hard disk are described as information recording devices.

  The information processing apparatus 100 includes a content data acquisition processing unit 510 that reads out encrypted content as software, a decryption processing unit 550 that decrypts content, a key information acquisition unit 540 that acquires key information to temporarily store and use it, a high security In order to maintain the content data, the authentication processing unit 530 performs authentication between the information processing device 100 and the information recording devices 300 and 310, the reproduction operation unit 500 that accepts a request from the user, and the output device 140 such as a decoder. Content output processing unit 520 and a temporary storage area 560 for temporarily storing key information corresponding to the content data. In addition, although each process is implement | achieved by executing each software with CPU130, it can also implement | achieve by hardware, such as integrating-circuit as a process part which performs each process.

  The information processing apparatus 100 includes, as hardware, a CPU 130 that performs software processing, a tuner 120 for acquiring recording information, a decoder 140 for outputting acquired / recorded data as video / audio, In addition to a display unit 150 corresponding to a speaker or TV panel portion for actually expressing information output by the decoder, a recording device connection unit 160 for connecting an HDD as an information recording device, encryption / decryption processing The encryption processing unit 170 for assisting the user, the remote control receiving unit 180 for receiving the operation from the user, and the like. Note that the display unit 150 may be configured separately from the information processing apparatus 100.

The configuration of the information recording apparatuses 300 and 310 can be roughly divided into a control unit, a data storage unit, and a tamper resistant area. The control unit is a part that controls the information recording apparatuses 300 and 310, and includes a communication unit 610 that exchanges data and an authentication processing unit 600 that realizes a high security level such as Secure-iVDR. The information to be recorded is stored in the data storage unit, the content description information 720 that contains the encrypted content data 700 and information related to the content, the content / time information 730 that expresses the correspondence between the content and time, and the content There is content key information 710 that is used when acquiring key information necessary for decrypting. The key information 800 is also stored in the information recording devices 300 and 310, but the key information is stored in the tamper-resistant area because it is important and information that should not be acquired or changed. Even if it does not have a tamper-resistant area like a normal HDD, if it is content that does not require encryption, such as copy-free, or content that is encrypted independently, it is saved in the data storage area without regard to key information etc. It is possible to use it.
Here, for example, in the case of Secure-iVDR, Usage Pass including key information is stored in a tamper-resistant area provided in the information recording device, and corresponds to key information 800 in FIG. Further, in order to access the tamper-resistant area easily and to retrieve the key information by accessing this area, authentication between the information processing apparatus 100 and the information recording apparatus 300 or 310 is essential, and secure communication is performed. Exchanges take place after securing the road. This mechanism increases the security of the stored content.

  The communication unit used between the information processing apparatus 100 and the information recording apparatus 300 is generally not limited to an ATA interface or a SCSI interface in HDDs such as Secure-iVDR. In the future, the use of networks such as infrared communication, wired / wireless LAN, and Bluetooth ™ may be considered.

  The content reproduction process is realized by reading from the information recording device 300 or 310 if the content is not encrypted and sending the content data to the display unit 150 via the decoder 140. In the case of content that is encrypted and stored, the key information corresponding to the content and the position of the content is acquired, and the decrypted content data is transmitted to the output device while decrypting the content using the key. Is done.

  The TV recording specification used in Secure-iVDR stipulates that Usage Pass must be changed in one minute at the longest. In addition, when the copy information of the content being broadcast is changed, the Usage Pass must be changed.

  Therefore, it is necessary to read out the specific key information corresponding to the content and the reproduction position thereof and decrypt the content using the key information. That is, in Secure-iVDR, it is defined that the Usage Pass that is key information is changed for each of a plurality of ALUs. The plurality of ALUs are contents corresponding to a reproduced video of less than one minute, and one ALU is defined as 1.5 MB. In order to read the Usage Pass from the Secure-iVDR, the Usage Pass is encrypted and exchanged between the information processing apparatus and the information recording apparatus. However, when the embedded CPU mounted in the information recording device and the information processing device is used, it takes time for the encryption processing in the information recording device and the decryption processing in the information processing device, and the key information corresponding to the content is obtained when necessary. Even if it is acquired, the actual playback processing operation may not be in time.

  In particular, during normal playback, by providing a buffer inside the decoder 140 or a separate buffer on the memory 110, there may be a case where the playback processing operation can be performed without any problem even if the time required for key information acquisition is long. In special playback such as fast-forwarding and rewinding, when these buffers are used, the timing for displaying the video cannot be adjusted, special playback may not be realized, and the prepared buffer does not make sense There is. In this state, it is necessary to provide the data to the decoder 140 and the like without storing the data in the buffer. However, if it takes time to acquire the key information 800, the data cannot be provided at the timing for realizing the special reproduction, and the special reproduction processing is performed. Will collapse.

  Furthermore, the content capacity corresponding to “a certain time interval” in video content is constant over the long-term playback time, but the video data constituting the content is “I picture” in the case of current mainstream video formats such as MPEG. It consists of three types of data, “P picture” and “B picture”. The size of an I picture is significantly larger than that of a P picture or a B picture. Therefore, the content capacity to be read jumps up during I picture playback. For this reason, in Secure-iVDR, the number of ALUs encrypted with one Usage Pass cannot be specified.

  Considering these restrictions, the data is stored in a temporary storage area 560 prepared as a buffer immediately before the data is supplied to the decoding process or the decoder 140, and the stored data is processed at a timing at which special reproduction can be realized. This avoids the problem that it takes time to obtain the key information 800.

  Hereinafter, a process of storing a pair of Usage Pass and content data in the buffer in the case of special playback such as fast-forward / rewind when using Secure-iVDR will be described. However, as an information recording device with copyright protection, when a plurality of key information is changed in one content, the storing process of this embodiment can be applied. In addition, this process can be applied even when the decryption process takes a long time in addition to the key acquisition time (such as when there is no hardware support).

  FIG. 2 shows the reproduction process in the UML activity diagram, and FIG. 3 schematically shows the reproduction process.

  First, the user instructs the reproduction instruction unit to specify the content to be reproduced and to start reproduction by a remote controller or GUI operation (step S1000). In response to this instruction, the reproduction operation unit 500 receives the reproduction target content and its reproduction position information in the content data acquisition unit 510 if reproduction is started, and the speed and position information in the reproduction target content information in the case of a speed change or jump instruction. The operation of acquiring the data from the content data 700 is started (step S1100). The content data acquisition unit 510 that has received the name of the content data and the position or speed to read out reads the content data 1000 of the specified position and size from the content data 700 by actually performing file offset calculation or the like (step S1200). . However, since the read content data is encrypted and stored at the time of recording, the key information acquisition unit 540 is requested for key information corresponding to the content data for decoding the encryption (step S1300).

  The key information acquisition unit 540 reads the key information corresponding to the request and returns the key information 1100 as an internal process. The Usage Pass is normally changed by multiple ALUs, but the same Usage Pass can be used for a certain period of time, so that the key information acquisition unit 540 does not perform time-consuming key information acquisition processing each time a key information request is made. Save it temporarily. As shown in FIG. 3, the data 2000, 2010,... That associates the read content data 1000 with the corresponding key information 1100 is saved in the temporary storage area 560 as an amount that can avoid the time required to acquire the key information. The start of the decoding process is notified (step S1400).

  Thereafter, the data 2000, 2010,... Stored in the temporary storage area 560 are extracted at time intervals for realizing special reproduction such as fast forward / rewind, and the content data 1000 is combined in the decryption processing unit 550 using the acquired key information 1100. (Step S1500), and the content output processing unit 520 sends the data to the display panel 150 or the like via the decoder 140. With this series of processing, the content can be viewed (step S1600).

  The process described above is repeated until the end of the content data 700 is reached or a new user request is generated. The key information and the content data are stored in association with each other in the temporary storage area 560, and the associated information is acquired from the temporary storage area 560 at the timing of realizing fast forward / rewind, and processed by the decryption processing unit 550 to generate data. Thus, even if it takes a little time to obtain the corresponding key information from the key information 800, the special reproduction of the content can be performed without any problem.

  Fast forward / rewind is a method of browsing content at a speed equal to or higher than the normal speed. If you want to display such content in normal playback (1x speed) and T (sec), Information on the content that was scheduled to be displayed may be displayed in T / S (sec). In order to realize this, there is one that can instruct the decoder 140 to display content data for T (sec) at a time and display it in T / S (sec). However, even if the decoder 140 has the above-described mechanism, an upper limit value of processing such as “maximum F (sheets / sec)” exists. For this reason, as the value of S times increases, the amount of content data delivered at one time becomes enormous, and information that the decoder 140 cannot process is received, and the processing fails.

  In order to avoid this, it is possible to realize fast-forward / rewind by successfully picking up “information on one screen” present in the content data and providing the data to such an extent that the decoder 140 does not fail. In the case of MPEG data currently used in digital broadcasting or the like, an I picture corresponds to this information. If this I picture data is successfully acquired from the content and provided to the decoder 140 at an appropriate timing to output an image, it is possible to realize fast forward and backward rewind. This mechanism will be described with reference to FIG.

The content 3000 is MPEG data. In this data, I picture information exists in various places, and these are designated as I10, I20,. Here, as an example, assume that the hardware performance of the decoder 140 is 5 (sheets / sec), and T (sec) is required when normal reproduction is performed from the beginning of I10 to the position immediately before I100. At this time, since the hardware performance of the decoder 140 is 5 (sheets / sec), when reproducing at S-times speed, 5 out of I10, I20,..., I90 so that the reproduction time becomes T / S (sec). The sheet will be selected. For this reason, I10, I30, I50, I70, and I90 are selected and used. Also, assume that each I picture I10, I30, I50, I70, I90 is played back at T _d (sec) in order to play back at T / S (sec). _Td is basically required to be equidistant so that the user does not feel uncomfortable during special reproduction. In the case of FIG. 4, T _d = T / 5S (sec).

  Therefore, assuming that the number of I pictures per second is I and the maximum performance of the decoder 140 is F (sheets / sec), the following relationship is established.

When the content of T (sec) is played back at S-times speed, the maximum value of the number of I pictures displayed per second is S × I, so that the display interval of I pictures per frame is T _d. ,
When S × I <F,
T _d = 1 / SI (sec) (Equation 1)
When S × I ≧ F,
T _d = 1 / F (sec) (Equation 2)
This T _d is the minimum value that T _d can take, and if it is operated at this interval, the speed at which the image changes will change according to the double speed while S × I <F, and the speed will change from the user. It seems that double speed playback is performed. However, depending on the performance of the decoder 140, since the number of images that can be displayed per second is large, it may appear flickering when viewed from the user. In that case, the maximum performance may be set appropriately to determine _Td . In the present description, since the content of T (sec) is played back at S times speed, T _d ≦ T / S must be satisfied, so the maximum value of T _d is T / S (sec).

Further, depending on the conditions, more I picture data than the displayable number is targeted, so it is necessary to thin out the data up to the displayable number. Assuming that the interval for thinning out this I picture is T _S (sec), when S × I <F,
T _S = S / SI = 1 / I (sec) (Equation 3)
[Same as the original I picture interval = no blinking]
When S × I ≧ F,
T _S = S / F (sec) (Equation 4)
It becomes.

Therefore, it is sufficient to acquire the information of the I-picture locations spaced T _S distance from a certain reference point. For example, if T = 10, F = 5, I = 2, and S = 2, then T _d = 1 (sec) and T _S = 500 (ms). When S = 10, T _d = 200 ( ms), T _S = 2 (sec). In other words, as the double speed increases,
The minimum value of _Td is 1 / F, and the thinning interval increases. Based on this equation, an I picture for realizing the double speed is selected, and a predetermined speed reproduction is realized.

  In the case of Secure-iVDR, since it takes time to read the Usage Pass, content data cannot be read from the HDD. Therefore, if the content data is acquired from the HDD at the time of the request, the above formula for realizing special playback cannot be satisfied. For this reason, as described above, I picture information for realizing fast forward / rewind and the corresponding key information are stored in the temporary storage area 560 as a set. Here, it suffices to read the data 2000 that is a set of the content data 1000 and the key information 1100 held in the temporary storage area 560 as many as the time required for reading the Usage Pass. When this number is n, the following expression needs to be established in a portion corresponding to one Usage Pass. Note that the time required to acquire one I picture data is Ti, the time required for key information acquisition 1100 is Tk (sec), and the fluctuation at the time of key information acquisition is α (sec).

  By storing the amount of information satisfying n in the temporary storage area 560, the time Tk + α (sec) required to read the key information 1100 can be absorbed. By reading the content data 1000 and the key information 1100 from the HDD so as to always satisfy this relationship, smooth fast-forwarding and winding are not affected by the key information acquisition except when it takes time to acquire the key information 1100 first. It can be returned. The fluctuation time that occurs when acquiring key information is expressed as α (sec). This is because in Secure-iVDR, the time required to acquire the Usage Pass that is the key information 1100 is generally constant, but when other processing is performed in the information processing apparatus 100, processing other than acquisition of the key information 1100 is performed. You may be doing it. In this case, the processing may be delayed from the time which is “generally constant”, which is taken into consideration.

Also, there are cases where n data cannot be read within a range that can be covered by one Usage Pass, or even if n is obtained from the calculation formula, the memory for preparing the temporary storage area 560 may be compressed. In this case, if _Td is increased, the number of n can be made relatively small. That is, by reducing the number of images displayed on the screen per second, it is possible to increase _Td and decrease n. The specific value depends on the fast forward / rewind speed, the limit value F (sheets / sec) of the decoder 140, the amount of memory, and how it is shown to the user. (5) If the value is determined so as to satisfy the expression, the video can be updated smoothly within the range restricted by itself regardless of the Usage Pass acquisition time, and fast-forwarding / rewinding processing is performed without any problem from the user's point of view. looks like.

  However, in practice, it is not known whether the position at which fast-forwarding / rewinding is started can always obtain n pieces of I-picture data in the area corresponding to the Usage Pass. The process in this case will be described with reference to FIG.

  Assume that the content playback position is at a position indicated by 4000. When fast-forwarding is started from this state, only two pieces of I picture data exist thereafter. The Usage Pass, which is the key information 1500 within this range, should be used for reproduction, and has already been read. However, as soon as fast-forwarding is started, the Usage Pass of the next key information 1600 needs to be read. At this time, if the following formula (6) is not satisfied, a phenomenon occurs in which the video stops for a while after displaying the information of I80 and I90 for the key information 1600 acquisition process.

  In other words, if the inequality of equation (5) can be satisfied with n = 2, the fast-forward process can be performed without stopping the video even if the next key information 1600 is read.

  Therefore, when fast forward / rewind is started from a position that does not satisfy Expression (5), the range of the key information is determined from the content key information 710, and the remaining I at the specified position / speed / display interval is determined. When the number of picture data is n or less, processing from the first I picture data in the range corresponding to the next key information is started. In the example of FIG. 5, the fast-forward start position is moved to the position of 5000 which is the position of I100 where the first I picture data of the next key information 1600 is not the reproduction position 4000, and the fast-forward process is started from that position. By shifting the processing start position in this way, the fast-forward process can be performed so as to always satisfy Expression (5). Even in the rewinding process, only the direction of shifting the processing start position is reversed, and the same processing can be performed.

However, in this case, I80, 2T _d time only for displaying I90 would eventually shift. There is no problem if the time of 2T _d is short enough for human beings not to recognize, but depending on the speed and the number of displayed images per second, T _d becomes a considerably large value, which is higher than expected by the user. The fast forward / rewind process may end a few seconds earlier. In order to solve this problem, the processing time of each data is corrected up to a certain amount of time (for example, a time that cannot be recognized by humans) with respect to the time of _Td , which is the I picture display interval.

Specifically, processing such as adjusting the display interval by comparing the time of the actually displayed image with the information on the time to display the data to be processed next is performed. The flow of this process will be described with reference to FIGS. FIG. 6 explains step S1500 of FIG. 2 in detail. In the first process, the first data stored in the temporary storage area 560 is immediately acquired (step S2000), the composite process is performed (step S2100), and the data is provided to the content output processing unit 520 (step S2200). . In the second and subsequent processes, data is extracted from the temporary storage area 560 at intervals of T _d (sec) set in advance in order to realize fast forward / rewind (step S2300). The display interval T _d (sec) for displaying one I picture varies depending on the fast forward / rewind speed, the presence ratio of the I picture in the content, the performance of the decoder 140, and the like.

Next, a mechanism for correcting the display time interval _Td will be described with reference to FIG. First, the composite processing unit 550 refers to the oldest data (= data to be processed first) stored in the temporary storage area 560 and composites it as it is to provide to the content output processing unit 520. Finally, an image is displayed on the display unit 150 and shown to the user. In the second and subsequent processes, the oldest data 2000 stored in the temporary storage area 560 is referred to and “time to be displayed” is acquired. Subsequently, display time information is acquired from the decoder 140 from the current display unit or image data being processed by the decoder 140, and the timing for displaying the next data is calculated. For example, in the case of an MPEG2 stream, there is information related to display time such as DTS and PTS.

Here, “time to be displayed” is “0” in the case of the first data, and it is desirable to display it immediately. Thereafter, if the display interval is T _d (sec), it is sufficient that the m-th data can be displayed at a time after (m−1) × T _d (sec) from the top data, and T _d is determined. At the time, the “time to be displayed” of each data can be determined. This mth or “time to be displayed” and display interval information may be held inside the decoding processing unit 550, but as part of the data stored in the temporary storage area 560 as shown in FIG. You may keep it. In the case of FIG. 8, the time to be displayed corresponds to the display time information 6000, and the display interval corresponds to the processing time information 7000.

Considering in more detail, the image information is provided to the user over the following time.
1. 1. Time required for compounding 2. Time to pass data to the decoder 140 3. Time for the decoder 140 to process the data and generate an image 4. Time for the display unit 150 to receive and process image information from the decoder Number of waiting for processing after combined processing × T _d
Normally, the numerical values of 1 to 5 are generally considered to be fixed values, and when I picture data is provided in a timely manner as in this embodiment, there is no processing waiting data after the composite processing of 5 at first. The operation interval can be determined by the numerical value of 4 and the “current playback time” acquired from the decoder 140. Here, “next time for displaying next data” is T _next , “time of displayed data (relative value from the first data)” is T _disp , and time required for the above 1 to 5 is T _etc. When, since the display interval T _d, the magnitude relation of T _next -T _disp and T _{d +} T _etc, the amount of time to be adjusted can be determined as follows.
(1) When T _next −T _disp <T _d + T _etc , the processing interval of the signal processing unit 520 may be T _next −T _disp −T _etc (sec) (the processing interval is made smaller than T _d ).
(2) When T _next −T _disp = T _d + T _etc , the processing interval of the signal processing unit 520 remains T _d (sec), and there is no delay in processing.
(3) When T _next −T _disp > T _d + T _etc , the processing interval of the signal processing unit 520 may be T _next −T _disp −T _etc (sec) (the processing interval is made larger than T _d ).
However, if the time interval obtained from the above is large enough to be recognized by the user, the impression that “the image is clogged” or “the display interval is not constant” is displayed every time the image is displayed in the fast forward / rewind process. I will give it. For this reason, it is necessary to adjust within a range not noticed by the user. If T _d = 500 ms and the range is ± 100 ms, the processing interval is between 300 ms and 600 ms. Therefore, in this example, a time width corresponding to a maximum of 200 ms exists. By making this width incapable of being recognized by the user (or at a level that is difficult to recognize), it is possible for the user to notice that the display interval is changed and the processing is smoothly performed without being noticed. Further, if T _next −T _disp <T _d + T _etc is frequently satisfied, the composite processing unit 550 needs to operate at a time interval smaller than T _{d of the} display processing interval satisfying Expression (5). That is, as a result of composite processing or the like, “the processing is not in time”. Since the amount of adjustment of the processing interval is limited in order not to make the user aware of the video display interval, if this state continues frequently, “display delay” will be accumulated. As a result, the accumulated delay remains until the end, and it is not possible to realize exact double speed. In order to avoid this problem, a determination may be made to take out the data stored in the temporary storage area 560 and discard it without processing it. For example, when T _next −T _disp −T _etc (sec) is lower than T _d × 1/2, processing is performed with a threshold value that can be determined to discard the top data in the temporary storage area 560. After discarding the data, the processing time interval is determined with reference to the next data. Subsequent data may be performed in the same manner as the previous processing. By discarding one piece of data in this way, it is logically possible to earn time for T _d (sec) (= becomes a margin), so it is possible to process without accumulating “display delay”. In general, strict double-speed playback is possible.

  In addition, although this time demonstrated by the example which acquired the time information of the image currently reproduced | regenerated from the decoder 140, the content output process part 520 may acquire the time information which should scrutinize and display content data, When the processing target is information to which time information is added (Time Stamped TS or the like), the time information may be used. If the time information of the data to be processed first is held as a reference point, the “time to be displayed” may be a relative value from the reference point.

In addition, in the edited content or the content recorded when a reception failure occurs, the “time to be displayed” may be shifted more than _Td on the way. In that case, record the processing time up to the point of time when the deviation was found and the “number x display interval”, and record it from the original reference point in order to make the time greatly shifted as a new reference point. Add time information. A case where the time information acquired in this way is discontinuous can be dealt with.

  By adjusting the display interval in this way, the user can realize fast forward / rewind at a specified double speed without experiencing that the display interval of the image has changed. However, as expressed in the equation (5), when the key information 800 is acquired, it can be extracted in a substantially constant time, but there is a fluctuation in the acquisition time. For this reason, there are cases where the next Usage Pass acquisition process takes an unscheduled time even though all the I picture data in a certain Usage Pass compatible area has been processed. At this time, there is no data in the temporary storage area 560, and even if the acquisition of the I picture data itself has been completed, the key information 800 corresponding to them has not been acquired. Can not. At this time, the last processed video is displayed on the screen, and the video is stopped until the key information 800 is read and decrypted and displayed. Therefore, it does not appear to the user as if the fast forward / rewind processing is being performed smoothly.

  In order to deal with this problem, extra I picture data that was scheduled to be thinned out from the limit on the number of displayed sheets is read, and extra data is calculated from the number of data stored in the temporary storage area 560 and the time of the displayed data. Decide whether to use and proceed with the process. This is shown in FIG. Further, as shown in FIG. 10, in order to recognize that the data is extra data, information of type 8000 is added to the data stored in the temporary storage area 560, and information on the number of valid data is held in the temporary storage area 560. The effective number of data 9000 is prepared.

The equation (5), and that the I10 and I60 may be displayed at _{T d} determined at certain speed reproduction. Even in this case, for example, I90, which is the last I picture in the Usage Pass target range, is read and stored in the temporary storage area 560 as a pair with the key information 1500 which is the UsagaPass of that portion. The decryption processing unit 550 proceeds with the decryption process while adjusting the display interval from the information of the actually displayed video. After the I60 process, the decryption process unit 550 is effective when the reading of the key information 1600 corresponding to the next I100 is not completed. Recognizing that no I-picture data exists in the temporary storage area 560, decoding processing is performed using the I90 data stored in excess, and video data is provided. In this way, I picture data that was actually scheduled to be thinned out is stored in the temporary storage area 560 together with the key information, and is used when the data is insufficient or is likely to be insufficient. With this mechanism, the temporal width of the video data that is actually displayed changes, but since the “image switching interval” that can be seen by the user is maintained, fast forward / rewind can be realized without a sense of incongruity.

In the above example, the case of storing extra data at the end has been described. This is because the next key information can be read when exactly n processes are performed in the case of the minimum n for which equation (5) holds. If the time required to acquire the key information can be grasped each time, the same processing can be performed by reading the I picture data that was scheduled to be thinned out. In the state of FIG. 9, not only I90 but also I20, I30, I40, I50, I70, and I80 are read and marked so as to be understood as “extra data”. In the temporary storage area 560, the “number of valid data” is also counted and held at the number of valid data 9000 in FIG. In the case of FIG. 9, since two data of I10 and I60 are used, “the number of valid data = 2”. When determining whether to read the next data after processing this valid data, the “number of valid data × T _d ” is compared with the “remaining time necessary for obtaining the key information”. You can determine whether to use extra data. When the number of effective data 9000 is n or more, sufficient data for special reproduction is accumulated in the temporary storage area 560, so that it is not necessary to use extra data. At this time, only the valid data is processed without processing extra data.

  This depends on how much the value of α, which is an unpredictable time, is taken, and how many times the time of α that is provided in excess is exceeded. In the first place, since this processing is performed when the error that has been accepted as α is exceeded, the number of extra data to be read cannot be uniquely determined. Therefore, if the system operation cannot be predicted completely, it is desirable to read a certain number as insurance. For example, if you read the data at half the interval to be thinned out, if it is not a still image scene, you can expect that there will be some change in the image compared to valid data, and the user will also change the image You can feel as if you are fast-forwarding and rewinding correctly. However, since it leads to excessively reading I picture data from the HDD, it is important to consider how many numbers are read. It should be noted that when the maximum value of α is reliably obtained at the time of design, Equation (5) always holds, so that it is possible to perform fast forward / rewind processing while maintaining a constant image switching interval without having to perform this processing. is there.

Further, this method cannot be used when data is not skipped (≈when the double speed is low), but at this time, since the display interval _Td is a relatively large value, it can be generally solved by adjusting the display interval. In the first place, α is a value for giving a margin, so it is important to design so that this value is not exceeded.

Expression (5) is an expression that should hold within the range covered by one Usage Pass. If this equation does not hold at a certain speed, it may be avoided by adjusting the number of sheets displayed per second. Specifically, the number of displayed images per second is changed by changing it to T / S (sec) which is the maximum value of _Td .

However, there may be a case where equation (5) does not hold even if the number n to be read and _Td of the display interval are adjusted. That is, it takes a long time (T / S seconds or more) to acquire the Usage Pass. In this case, since it cannot be covered within the range of one Usage Pass, it is necessary to acquire information for fast forwarding / rewinding from the range of a plurality of Usage Pass compatible areas, which satisfies an expression different from Expression (5). There is a need. Here, when fast-forwarding / rewinding is performed at S-times speed, the time required to acquire the Usage Pass corresponding to the start position is T _k , and the playback time when each Usage Pass-compatible area is normally played is Tc _i , The range of n Usage Pass corresponding areas in which the following equation is satisfied is targeted, and the process is advanced by skipping n−1 areas. An image when n = 3 is shown in FIG.

Further, if the number of sheets to be displayed is, and the time for reading one I picture is (average) TI _-Picture , it can be obtained from Expression (7) and the following expression.

The display interval _Td is as follows.

  Further, if it is desired to keep the number of displayed sheets per second to some extent, the reciprocal number of equation (9) corresponds to the number of displayed sheets per second. Therefore, the number m to be displayed after determining this value and expression (7) are satisfied. Thus, the number of areas to be skipped after the first Usage Pass corresponding area is determined. However, the maximum number of display sheets per second is as follows.

Here, _{N i} is the number of I-pictures included in up to the processing starting position from the beginning of the first of the Usage Pass corresponding region. Specifically, it is the number of I pictures included from the beginning of I10 to position 4000 in FIG.

As described above, when special playback cannot be realized in one Usage Pass compatible area, processing is performed by associating information in the first Usage Pass compatible area among a plurality of Usage Pass compatible areas with a plurality of times. That is, to display the I picture in the range of Tc _n is "displayable section" in FIG. 11 does not utilize _{Tc n + 1, Tc n +} 2 of the information later. In the next processing, fast forward / rewind is realized using I picture data of Tcn _{+ 3} . In the case of rewinding, the content search direction is only reversed.

  In addition, depending on the start position of fast-forward / rewind, the maximum number of displays per second obtained by Expression (10) may be a value that is not intended by the designer. In that case, the display interval may be adjusted by proceeding from the beginning of the next Usage Pass compatible range. Also, there may be a case where the information of the I picture is clearly insufficient near the end / top of the content. In this case, it is possible to treat it as arriving at the end / top and finish the fast forward / rewind processing.

  In this embodiment, since the case where the key acquisition process takes time is taken as an example, the process is as shown in FIG. 3, but there may be a case where the decryption process takes time. In this case, the operation interval is adjusted by the content output processing unit as shown in FIG. 12, but the processing can be performed in exactly the same way as described above. Also, it may take time to read the first Usage Pass. In this case, by combining the prefetch processing described in Patent Document 1, the processing time of the next Usage Pass reading can be ignored, so that the processing can be performed more smoothly. There is no need to shift the processing start position to the beginning of the Usage Pass compatible area.

Hardware / software configuration diagram Overview of playback / special playback processing Key information reading and temporary storage processing overview Example of trick play operation Correspondence diagram of key information and content data Special playback process overview Display interval adjustment process overview Diagram of the data structure stored in the temporary storage area (1) Overview of display interval adjustment processing using excess data Diagram of the data structure stored in the temporary storage area (2) Overview of processing when key acquisition processing time is long Overview of processing when adjusting the operation interval in the content output processing section

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Information processing apparatus 110 ... Memory 120 ... Tuner 130 ... CPU
140: Decoder (output device)
150 ... Display unit 160 ... Recording device connection unit 170 ... Encryption processing unit 180 ... Remote control receiving unit 300, 310 ... Information recording device 400 ... Remote control 500 ... Playback operation unit 510 ... Content data acquisition unit 520 ... Content output processing unit 530 ... Authentication Processing unit 540 ... Key information acquisition unit 550 ... Decryption processing unit 610 ... Communication unit 600 ... Authentication processing unit 700 ... Content data 710 ... Content ⇔ key information 720 ... Content description information 730 ... Content ⇔ Time information 800 ... Key information 900 ... Processing Start notification 1000 ... content data (part of content data 700)
1100, 1400, 1500, 1600, 1700, 1800 ... key information (part of key information 800)
2000, 2010: Data that is a set of key information corresponding to content data 3000 ... Content data 4000 ... Reproduction start position 5000 ... Reproduction start position (Usage Pass start position)
6000 ... Display time information of this data 7000 ... Processing time information of this data (operation interval of decoding process)
8000... Data 9000... Expressing whether the data including the key information corresponding to the content data is valid or invalid 9000... The number of valid data I10 to I110.

Claims (3)

An information processing apparatus for playing back content obtained by decrypting encrypted content stored in an information storage device,
The content includes a plurality of partial contents including content information used for special playback of the content,
The encrypted content includes a plurality of partially encrypted contents obtained by encrypting each of the partial contents based on key information changed for each of the one or more consecutive partial contents.
As the copyright protection function, and the ability to decrypt the encrypted Kako content,
In association with the key information corresponding to the encrypted partial contents and the partial encryption content, the ability to store in the information storage device,
A function of determining the content information used for special playback and a display interval of the content information according to the playback speed and key information acquisition time of the specified content ;
A function of reading the partially encrypted content including the determined content information and the corresponding key information from the stored encrypted content and key information ;
The read portion encrypted content decrypted by using the corresponding key information, the function of acquiring the content information included,
Using the acquired content information, a function of performing special playback of the content at the specified playback speed, Ru with a
An information processing apparatus characterized by that . The information processing apparatus according to claim 1,
And time of the content being displayed, time required for key acquisition, from the amount of the read partial encryption content, a function of determining the fluctuation of the display interval of the content information,
A function of reading the excess portion encrypted content in consideration of the fluctuations,
Decrypts needed extra read partial encrypted contents, by using a function of performing special playback at the specified playback speed, Ru with a
An information processing apparatus characterized by that . The information processing apparatus according to claim 1, wherein:
When the same key information can be used for decrypting a plurality of partially encrypted contents, the reading function combines one piece of the partially encrypted content and the key information corresponding to the partially encrypted content. And store it in another storage area,
The decryption function reads the partially encrypted content and key information from the other storage area and performs the decryption.
An information processing apparatus characterized by that.

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