JP2010171712A - Device and method for controlling reproduction speed, device for reproducing content, and program for controlling reproduction speed - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for controlling a reproduction speed for controlling the reproduction speed to reproduce, at speed higher than a normal reproduction speed, content data received in a period in which a reception state of a radio wave is improper. <P>SOLUTION: The device 100 for reproducing content data (device for controlling a reproduction speed) includes: a determination part 112 for determining the reception state of the content data; and a reproduction speed control part 114 for changing a value of the PTS of the content date received in a period in which the reception state is improper to set the reproduction speed higher than that in the case that the reception state is determined to be not improper when the reception state of the content data is improper, and a volume of data stored in a buffer 113 is not smaller than a predetermined value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a playback speed control apparatus that controls a playback speed when playing back content transmitted via digital broadcasting, and a playback speed control method in the playback speed control apparatus.

  In recent years, digital broadcasting systems such as terrestrial digital broadcasting and digital satellite broadcasting have been operated in place of conventional analog broadcasting.

  Since digital broadcasting can transmit content with high compression, the digital broadcasting content can be reproduced on a mobile device such as a mobile phone or a portable game device. However, problems arise because the content is highly compressed. For example, if the radio wave condition for transmitting digital broadcast content deteriorates before it exceeds a certain level, the reproduced content may be extremely deteriorated. In particular, a portable mobile device or a car navigation system is not always able to receive a signal with a good radio wave condition, so such a phenomenon is likely to occur frequently. When the content to be played deteriorates, the video is disturbed or the sound skips, so that the user feels uncomfortable.

  As a method for preventing deterioration of content depending on the reception state of radio waves, for example, the method described in Patent Document 1 can be cited. In the receiving device described in Patent Document 1, the received content data is stored in a buffer, the content data stored in the buffer is read during playback, and the content is slowly played back when the radio wave reception state deteriorates. ing.

JP 2008-5085 A (published January 10, 2008)

  As described above, when data received during a period in which the reception state of the radio wave is poor is reproduced, the video is frozen or a sound skips. However, since the apparatus described in Patent Document 1 does not process data received during a period in which the reception state of radio waves is poor, the data received during this period is normal or slow playback. For this reason, the apparatus described in Patent Document 1 has a problem that the user may be forced to view unpleasant content for a long time.

  In particular, when playing back video content, the user is likely to feel uncomfortable by being exposed to a frozen video for a long time.

  The present invention has been made in view of the above problems, and its main purpose is to reproduce content data received during a period in which the reception state of radio waves is poor at a speed higher than the normal reproduction speed. A reproduction speed control device for controlling the reproduction speed is provided.

In order to solve the above problems, a playback speed control device according to the present invention provides:
A playback speed control device including a memory for storing content data,
A determination unit for determining the reception state of the content data;
A detection unit for detecting the amount of content data stored in the memory;
Period in which the reception state of the content data is poor when the content data reception state is determined to be bad by the determination unit and the amount of data stored in the detection unit is determined to be greater than or equal to a predetermined amount A control unit that controls the playback speed so that the content represented by the received content data is played back faster than the playback speed when it is determined that the reception state is not bad;
It is characterized by having.

  The reproduction speed control device according to the present invention determines that the reception state of content data is bad and the content data stored in the memory when the stored data amount is a predetermined amount or more. A control unit that controls the playback speed so that the content represented by the content data received during the period in which the reception state is poor is played back faster than the playback speed when it is determined that the reception state is not bad. ing.

  Thereby, in the playback speed control device according to the present invention, the playback speed is changed so that the playback speed is higher than the normal playback speed for the content in the period in which the reception state of the content data is bad. become. That is, in the playback speed control device according to the present invention, the playback speed of the portion where the content to be played deteriorates (the portion where the video freezes or the sound skips) can be played back at a higher speed than usual. it can. In other words, in the playback speed control device according to the present invention, when the normal playback speed is the normal speed, the playback speed is set to be higher than the normal speed, and when the normal playback speed is the double speed. The reproduction speed can be higher than the double speed.

  Furthermore, in the playback speed control device according to the present invention, the content playback speed is made higher than the normal playback speed when it is determined that the amount of data stored in the detection unit is greater than or equal to a predetermined amount. In other words, the reproduction speed is increased only when the content to be reproduced has a predetermined delay. Therefore, it is necessary to reproduce the content data before the real time (that is, the future), and it is possible to prevent the content from being unable to be reproduced.

  Therefore, the playback speed control device according to the present invention has an effect of reducing the time that the user is exposed to deteriorated content.

  Further, in the playback control apparatus according to the present invention, the playback speed can be dynamically changed according to the content reception state and the amount of data in the memory, so that the user has to change the playback speed of the content as appropriate. There is no forced operation.

  In the playback speed control device according to the present invention, the control unit further displays the presentation time information given to the content data received during a period in which the reception state is bad when the content data is stored in the memory. It is preferable to change.

  According to said structure, when storing content data in memory, the presentation time information provided to content data is changed. That is, in the playback speed control apparatus according to the present invention, the content data to which the changed presentation time information is added is stored in the memory without changing the format. Therefore, it is not necessary to provide a special function on the playback device that plays back the content data stored in the memory.

  Thus, if the content data is processed using the playback speed control device according to the present invention, it is possible to reduce the time that the user is exposed to the deteriorated content even if the conventional playback device is used.

  That is, it is possible to reduce the time of exposure to deteriorated content even for a user having a conventional playback device. In addition, since it is not necessary to greatly modify the conventional playback device, the burden on the manufacturer of the playback device can be reduced.

  In the playback speed control device according to the present invention, the control unit further adds the amount of data stored in the memory to the presentation time information given to the content data received during the period in which the reception state is bad. It is preferable to change the presentation time information by adding the delay value calculated based on the information.

In the reproduction speed control apparatus according to the present invention, furthermore, the delay value is represented by the following formula _{(1) T buff = T max} + T high ··· (1)
(In the above equation (1), T _buff is a delay value (> 0), T _max is a reference value determined according to the amount of data stored in the memory, and T _high is an arbitrary value less than 0) (It is a fixed value)
It is preferable to calculate using

In the reproduction speed control device according to the present invention, the delay value is further expressed by the following formula (2):
_{T buff = T max + (T} 1 -T 2) + α ··· (2)
(In the above equation (2), T _buff is a delay value (> 0), T _max is a reference value determined according to the amount of data stored in the memory, and T ₁ is the first presentation time) Information, T ₂ is second presentation time information satisfying T ₁ <T ₂ , and α is an arbitrary fixed value)
It is preferable to calculate using

  According to the above configuration, when the reception state is bad for a long period of time, it is possible to skip the content data portion received during the period when the reception state was bad. That is, the playback speed control device according to the present invention can connect the content data before and after the content data portion that has failed to be received.

  As a result, even when content data cannot be acquired for a long period of time, there is an effect that it is possible to reduce the time that the user is exposed to deteriorated content.

  In particular, when the content data is video data, it is particularly effective because it is possible to eliminate the fact that the video to be played freezes and causes discomfort to the user.

  The playback speed control device according to the present invention preferably further includes a reading unit that reads content data to which presentation time information matching the reference time information generated in the device itself is added from the memory.

  According to said structure, there exists an effect which can save the troublesome time at the time of connecting another reproducing | regenerating apparatus to the reproducing speed control apparatus which concerns on this invention.

  In the playback speed control device according to the present invention, reference time information used for reading content data from the memory is generated, and content data to which presentation time information matching the generated reference time information is assigned is stored in the memory. The control unit changes the reference time information generated in the read unit during a period in which the reception state is bad, and the read unit is changed in the control unit. It is preferable to read the content data from the memory based on the reference time information.

  According to said structure, in order to change the reference | standard time information in an own apparatus, the processing capability of a control part does not need to be as high as the case where the information provided for every content data is changed.

  As a result, even in a playback speed control device in which the processing capability of the control unit is not high, there is an effect that it is possible to reduce the time that the user is exposed to deteriorated content.

  In addition, since the performance of the control unit does not have to be high, power consumption can be suppressed as compared with a playback speed control device using a high-performance control unit.

  In the playback speed control device according to the present invention, the control unit further calculates the reference time information generated in the control unit based on the amount of data stored in the memory during a period in which the reception state is bad. It is preferable to change the reference time information by subtracting the delayed value.

In the reproduction speed control device according to the present invention, the delay value is further expressed by the following equation (3) T _buff = T _max + T _high (3)
(In the above equation (3), T _buff is a delay value (> 0), T _max is a reference value determined according to the amount of data stored in the memory, and T _high is an arbitrary value less than 0) (It is a fixed value)
It is preferable to calculate using

  In the reproduction speed control device according to the present invention, it is preferable that the determination unit determines a reception state of the content data based on information included in the content data.

  According to said structure, the reception state of the content data from the received content data can be determined. That is, the playback speed control apparatus according to the present invention can determine the suitability of the reception state only from the content data.

  As a result, the playback speed control device according to the present invention does not need to be provided with a receiving unit such as an antenna for receiving a digital broadcast wave, so that the cost required for manufacturing the playback control device according to the present invention can be reduced. Play.

  Also, for content data acquired from an external recording medium that stores content data extracted from digital broadcast waves, the playback speed can be controlled so as to increase the playback speed during periods of poor reception. Play.

In order to solve the above problems, a playback speed control method according to the present invention provides
A content playback speed control method in a playback speed control device including a memory for storing content data,
A determination step of determining the reception state of the content data;
A detection step of detecting a data amount of the content data stored in the memory;
Period in which the reception state of the content data is poor when the reception state of the content data is determined to be bad in the determination step and the data amount stored in the detection step is determined to be greater than or equal to a predetermined amount A playback speed control step for controlling the playback speed so that the content represented by the received content data is played back faster than the playback speed when it is determined that the reception state is not bad;
It is characterized by including.

  According to said structure, there exists an effect similar to the reproduction speed control apparatus based on this invention.

  In addition, the content reproduction apparatus includes a reading unit that reads out content data to which presentation time information that matches the reference time information generated in the device itself is provided, and the reading unit provides a presentation that matches the generated reference time information. A content playback device that reads content data to which time information is added from the memory provided in the playback control device is also included in the scope of the present invention. However, the playback speed control device including the memory to be read by the content playback device changes the presentation time information given to the content data received during the period in which the reception state is bad when storing the content data in the memory. The control part which performs is provided.

  A program for operating a computer including a memory for storing content data according to the present invention, the computer comprising: a determination unit that determines a reception state of the content data; and a content data stored in the memory. When the detection means for detecting the data amount and the determination means determine that the reception state of the content data is bad and the data amount stored in the detection means is determined to be greater than or equal to a predetermined amount Control means for controlling the playback speed so as to play back the content represented by the content data received during the period in which the reception state is poor, faster than the playback speed when it is determined that the reception state is not bad; A program for causing the function to function as is also included in the scope of the present invention.

  As described above, the playback speed control device according to the present invention is stored in the memory when it is determined that the reception state of the content data is bad and the stored data amount is equal to or greater than the predetermined amount. Of the content data that is received during the period in which the reception state is poor, and the playback speed is set to be faster than the playback speed when the reception state is determined not to be bad. A control unit for controlling is provided.

  As a result, it is possible to reduce the time that the user is exposed to the deteriorated content when reproducing the content.

FIG. 2 is a block diagram illustrating a main configuration of the content data playback device according to the first embodiment. It is a figure which shows an example of the TS packet header in a TS packet. It is a figure which shows an example of the header in a PES packet. 6 is a flowchart showing a content data reproduction processing operation in the content data reproduction apparatus according to the first embodiment. It is a figure which shows the relationship between the reproduction speed in the content data reproduction apparatus which concerns on Embodiment 1, and the data amount in a buffer. 6 is a flowchart showing details of a speed-up process in the content data reproducing apparatus according to the first embodiment. It is a figure which shows the change of the value of PTS in the high-speed event in the content data reproduction apparatus which concerns on Embodiment 1. FIG. It is a figure which shows the change of the value of PTS in the skip event in the content data reproduction apparatus which concerns on Embodiment 1. FIG. It is a figure which shows the change of the value of PTS in the speed-lowering process in the content data reproduction apparatus which concerns on Embodiment 1. FIG. It is a block diagram which shows the principal part structure of the content data reproduction apparatus which concerns on Embodiment 2. FIG. 10 is a flowchart showing processing operations up to a PES packet storage portion in the content data reproducing apparatus according to the second embodiment. 10 is a flowchart showing processing operations from changing the STC value to content playback in the content data playback apparatus according to the second embodiment. It is the figure which showed typically the change of the reproduction speed of the content in the content data reproduction apparatus which concerns on Embodiment 2. FIG. It is a figure which shows typically the content data reproduction apparatus which concerns on this invention. FIG. 11 is a block diagram showing a content data reproduction device when each block of the content data reproduction device shown in FIG. 1 or FIG. 10 is realized by hardware.

[Embodiment 1]
An embodiment of a content data reproducing apparatus according to the present invention will be described below with reference to FIGS. In the present embodiment, a case where MPEG2-TS used in a currently operated digital broadcasting system is reproduced will be described as an example.

(Outline of MPEG2-TS)
Prior to the description of the content data reproducing apparatus according to the present invention, an outline of TS (Transport Stream) defined in the MPEG2 system will be described below.

  The TS in the MPEG2 system defined by ISO / IEC13818-1 is a stream obtained by multiplexing (MUX) video, audio, and additional data (for example, data broadcasting). The TS is composed of a sequence of 188-byte fixed-length packets (TS packets) to facilitate transmission. Each TS packet constituting the TS is composed of a 4-byte header, a variable-length adaptation field, and a payload.

  In the header (hereinafter also referred to as a TS packet header), as shown in FIG. 2, a PID (Packet Identifier) and various flags are defined. FIG. 2 is a diagram illustrating an example of a header of a TS packet.

  The adaptation field includes PCR (Program Clock Reference) necessary for synchronously reproducing video, audio, etc., and dummy data for making the TS packet a fixed length of 188 bytes.

  The payload includes ES (Elementary Stream) such as video, audio, and additional data. A stream (video, audio, caption, etc.) reproduced in synchronization with time is stored in the payload portion as a PES (Packetized Elementary Stream) obtained by packetizing an ES. The PES packet is composed of a PES packet header part and a PES data part. As shown in FIG. 3, the PES packet header portion is provided with a PTS (presentation time stamp) of each PES packet. FIG. 3 is a diagram illustrating an example of the PES packet header.

  Since the payload portion needs to be 184 bytes at the maximum, if the PES does not fit in 184 bytes, it is divided into a plurality of TS packets. Therefore, in order to restore the PES packet from the received TS packet, it is necessary to connect the payloads on the receiver (content reproduction device) side. The leading PES when connecting is identified by a PUSI (Packet Unit Start Indicator) flag (see FIG. 3) in the TS packet header.

(Outline of PES packet playback processing)
Next, an outline of the PES packet reproduction process will be described below. As described above, each ES is packetized into PES, and presentation time information (that is, PTS) indicating the time for reproducing (presenting) the ES in the PES is added to the header part of the PES packet. Yes. Therefore, the receiver can synchronize the video and the audio by presenting the video and the audio based on the PTS. At this time, in order to perform reproduction at the same timing in all the receivers, it is necessary to make the reference time information common to all the receivers.

  Therefore, the receiver interprets the time at which the PCR is received as the time indicated by the PCR. In other words, the receiver uses the transmitted PCR to match reference time information (STC: System Time Clock) generated in its own device with the reference time information on the transmitter side. PCR is calibration data for establishing synchronization of the reference clock. As a result, the receiver can reproduce the video and audio of the PES packet at the time indicated by the PTS with the PCR as the reference time. The STC is a clock composed of a 9-bit lower counter that operates at 27 MHz and a 33-bit upper counter that operates at 90 kHz.

  From the above, in order to change the playback speed of content in the receiver, it is only necessary to change the PTS value assigned to each PES packet or the STC value generated in the own device.

(Configuration of content data reproducing apparatus 100)
Next, the configuration of the content data reproducing apparatus according to the present embodiment will be described below with reference to FIG. FIG. 1 is a block diagram showing a main configuration of the content data reproducing apparatus 100. As shown in FIG. As shown in FIG. 1, the content data playback apparatus 100 includes a reception unit 110, a DEMUX processing unit 111, a determination unit 112, a buffer unit 113, a playback speed control unit 114, a playback control unit 115, and an output unit 116. These members will be described below.

(Receiver 110)
The receiving unit 110 receives a digital broadcast wave transmitted in a predetermined frequency band at an antenna provided in the receiver 110, and video data, audio data, and the like are multiplexed from the received digital broadcast wave. TS (Transport Stream) is extracted.

(DEMUX processing unit 111)
A DEMUX (Demultiplexing) processing unit 111 separates and extracts individual data such as video data and audio data multiplexed in the TS extracted by the receiving unit 110. The DEMUX processing unit 111 restores a PES packet by setting a PID (packet identifier) to be a DEMUX target in the PID filter and connecting the payload portions of TS packets having the same PID.

(Determination unit 112)
The determination unit 112 determines whether or not the reception state of the digital broadcast wave is good. More specifically, the determination unit 112 refers to the header in the TS packet separated and restored by the DEMUX processing unit 111 to determine the reception state. That is, when the value of the Transport Error Indicator in the TS packet header shown in FIG. 2 is “1”, the determination unit 112 determines that the TS packet is incorrect (an error has occurred in the TS packet). In other words, when the value of Transport Error Indicator in the TS packet header is “1”, it is determined that the reception state of the digital broadcast wave is not good. Conversely, when the value of Transport Error Indicator in the TS packet header is “0”, the determination unit 112 determines that the TS packet is correct.

  Of course, the determination of the TS packet error in the determination unit 112 is not limited to this, and the determination unit 112 determines the suitability of the TS packet based on the value of Continuity Count in the TS packet header. Also good.

  The determination unit 112 preferably includes a counter that counts the number of TS packets determined to be correct. The counter is initialized when a TS packet determined to be incorrect is received. The counter value is incremented every time a TS packet determined to be correct by the determination unit 112 is received. When the counter value becomes equal to or greater than a predetermined value (threshold value), the determination unit 112 has a poor reception state. It is determined that the state has been recovered from a good state.

  Further, the determination unit 112 may determine the reception state of the digital broadcast wave using the CN ratio (signal to noise ratio) or the bit error rate. That is, the determination unit 112 determines that the reception state is good when the CN ratio is equal to or less than a predetermined value, and the reception state is bad when the CN ratio is equal to or higher than the predetermined value. May be determined.

  Note that the determination unit 112 may determine the reception state using any one of the determination methods described above, or may determine the reception state by appropriately combining these.

(Buffer 113)
The buffer unit 113 is a memory that temporarily stores the PES packets separated and restored by the DEMUX processing unit 111. The buffer unit 113 is not particularly limited as long as it can store a PES packet. A non-volatile memory such as a flash memory, a volatile memory such as a DRAM, or the like can be used. As the buffer unit 113, an external memory such as an SD card may be used, or a magnetic recording medium such as a hard disk may be used.

(Reproduction speed control unit 114)
The playback speed control unit 114 changes the value of the PTS assigned to the PES packet based on the reception state of the digital broadcast wave determined by the determination unit 112 and the data amount of the PES packet stored in the buffer unit 113. To do. Since the change of the PTS value in the playback speed control unit 114 will be described in detail below, the description thereof is omitted here.

(Reproduction control unit 115)
The playback control unit 115 controls the entire content playback process. The reproduction control unit 115 generates an STC, and reads out from the buffer unit 113 a PES packet provided with a PTS that matches the value of the generated STC. Then, the reproduction control unit 115 decodes the read PES packet and instructs the output unit 116 to output the decoded video data or audio data.

(Output unit 116)
The output unit 116 outputs the video represented by the video data instructed to be output from the reproduction control unit 115 and the voice represented by the audio data. The device serving as the output unit 116 differs depending on data instructed to be output.

  That is, when outputting video data or caption data, the output unit 116 is an image output device such as a liquid crystal display, an organic EL display, a surface electric field display, and the like. Such an audio output device is obtained. Of course, the output unit 116 is not limited to only one of these, and may include both a speaker device and an image output device.

  In FIG. 1, the output unit 116 is illustrated as being included in the content data playback device 100, but of course the present invention is not limited to this, and the output unit 116 is separate from the content data playback device 100. It may be a device.

(Content data reproduction processing in the content data reproduction apparatus 100)
Next, content data playback processing in the content data playback apparatus 100 will be described below with reference to FIG. FIG. 4 is a flowchart showing an operation of content data playback processing in the content data playback device 100.

  First, when receiving a digital broadcast wave, the receiving unit 110 extracts a TS from the received digital broadcast wave (step S1). Subsequently, the DEMUX processing unit 111 restores the PES packet from the TS packet in the extracted TS (step S2).

  At this time, the determination unit 112 determines whether an error has occurred in reception of the TS packet based on the header of the TS packet (step S3). If the determination unit 112 determines that an error has occurred in reception of the TS packet (Yes in step S3), the determination unit 112 initializes the value of the counter (step S4). Subsequently, the playback speed control unit 114 sets a skip flag (step S5). In this case, since the TS packet determined to have an error is discarded, the restoration of the PES packet in step S2 is not executed. Therefore, the storage process of the restored PES packet in the buffer unit 113 is not performed.

  On the other hand, when determining unit 112 determines that there is no error in receiving the TS packet (No in step S3), determining unit 112 increments the value of the counter (step S6). Then, the determination unit 112 determines whether or not the incremented counter value has reached a predetermined value (step S7).

  When it is determined that the value of the counter is less than the predetermined value (No in step S7), determination unit 112 determines that the state in which the reception state of radio waves is poor continues. Subsequently, the reproduction control unit 114 determines whether or not the data amount of the PES packet stored in the buffer unit 113 is equal to or greater than a predetermined amount (step S8). When the playback control unit 114 determines that the data amount of the PES packet stored in the buffer unit 113 is greater than or equal to the predetermined amount (Yes in step S8), the playback speed control unit 114 increases the playback speed of the content. Processing is executed (step S9). That is, the playback speed control unit 114 changes the value of the PTS given to the PES packet so that the playback speed of the content is increased. Then, the playback speed control unit 114 stores the PES packet whose PTS value has been changed in the buffer unit 113 (step S10).

  When the determination unit 112 determines that the counter value has reached the predetermined value (Yes in step S7), the determination unit 112 determines that the reception state of the radio wave has recovered to a good state, and is added to the PES packet. The PTS value is recorded in a memory (not shown) (step S11). Subsequently, similarly to step S8, the reproduction control unit 114 checks whether or not the data amount of the PES packet stored in the buffer unit 113 is greater than or equal to a predetermined amount (step S12).

  When the playback control unit 114 determines that the data amount of the PES packet stored in the buffer unit 113 is less than the predetermined amount (No in step S12), the playback speed control unit 114 performs a process for reducing the playback speed of the content. Execute (Step S13). That is, the value of the PTS assigned to the PES packet is changed so that the content playback speed is slow. In addition, also when it determines with the data amount of a PES packet being less than predetermined amount in the above-mentioned step S8 (in step S8 No), the speed reduction process of step S13 will be performed. Then, the playback speed control unit 114 stores the PES packet whose PTS value has been changed in the buffer unit 113 (step S10).

  Finally, when the playback control unit 114 determines that the data amount of the PES packet stored in the buffer unit 113 is less than the predetermined amount (Yes in step S12), the playback speed control unit 114 changes the playback speed of the content. Without doing so, the PES packet is stored in the buffer unit 113 (step S10).

  Note that while the processing from step S1 to step S13 is executed, the playback control unit 115 in the content data playback apparatus 100 reads out the PES packet having the PTS that matches the generated STC value from the buffer unit 113 (step S14). . The playback control unit 115 decodes the read PES packet and outputs it to the output unit 116 (step S15). That is, in the content data reproducing apparatus 100, the PES packet is stored (queued) in the buffer unit 113, and at the same time, the PES packet is read (dequeued) from the buffer unit 113.

(Changes in playback speed due to changes in the amount of data stored in the buffer)
Here, a change in the content reproduction speed due to a change in the amount of data stored in the buffer unit 113 will be described below with reference to FIG. FIG. 5 is a diagram illustrating a change in the amount of data stored in the buffer unit 113 based on a change in content playback speed. In FIG. 6, it is determined that the reception state is bad in the period from time t2 to t3, and the PES packet stored in the period in which the reception state stored in the buffer unit 113 is good disappears at time t3. An example will be described.

  First, when content playback is started, the content data playback apparatus 100 stores the restored PES packet in the buffer unit 113 (buffering period in FIG. 5). At time t0 to t1, the content data reproducing apparatus 100 does not reproduce the content.

  When the amount of data stored in the buffer unit 113 reaches a predetermined amount, the content data playback apparatus 100 reads the PES packet stored in the buffer unit 113 and plays back the content. At this time, the content playback speed is a normal speed. Therefore, the processing at time t1 to t2 corresponds to the processing when the Yes option is selected in step S12 in FIG. Note that a delay value corresponding to the amount of data stored in the buffer unit 113 is added to the PTS assigned to the PES packet. Since the specific calculation of the PTS value will be described below, the description thereof is omitted here.

  Note that “normal speed” in this specification and the like refers to the playback speed of the content represented by the content data when the content data can be normally received. Accordingly, if the playback speed of the content represented by the normally received content data is the same speed, the normal speed is also the same speed, and if the playback speed is the speed of 2, the normal speed is also the double speed.

  Next, when it is determined that the reception state of the radio wave is poor at time t2, a PES packet that cannot be restored due to the deterioration of the reception state is generated, and is read out from the amount of PES packets stored (queued) ( The amount of PES packets that are dequeued is greater. Therefore, the amount of PES packets stored in the buffer unit 113 is reduced. The content data reproducing apparatus 100 changes the value of the PTS so that the reproduction speed of the PES packet received at this time is high. That is, the process at time t2 to t3 corresponds to the speed-up process (step S9) in FIG. However, the playback speed of the content during this period depends on the PTS of the PES packet to be read, and therefore remains at the normal speed.

  Subsequently, when the radio wave reception state returns to good at time t3, the content data reproduction device 100 changes the value of the PTS so that the reproduction speed of the stored PES packet becomes low. That is, the process at time t3 to t4 corresponds to the speed reduction process (step S13) in FIG.

  Further, after time t3, PES packets stored in a period in which the reception state is good disappear, and PES packets in which the PTS is changed so that the playback speed of the content becomes high are read out. The content playback speed is increased. In the case of high-speed playback, the amount of PES packets dequeued from the buffer unit 113 is much larger than the amount of PES packets queued. Therefore, the amount of reduction in the amount of data stored in the buffer unit 113 is further increased.

  When high-speed playback ends at time t4, a PES packet in which the PTS has been changed so that the content playback speed is low is read out, so the content playback speed after time t4 is low. At the same time, when low-speed playback is performed, the amount of PES packets dequeued from the buffer unit 113 is smaller than the amount of PES packets queued, so the amount of data stored in the buffer unit 113 increases. Therefore, the content data reproduction device 100 increases the data amount stored in the buffer unit 113 by reducing the content reproduction speed until the data amount stored in the buffer unit 113 reaches a predetermined amount at time t7. to continue.

  Finally, when the amount of data stored in the buffer unit 113 reaches a predetermined amount at time t7, the content data playback apparatus 100 returns the playback speed of the content to the normal speed and plays back.

(Details of processing to increase content playback speed)
Next, details of the processing for increasing the content reproduction speed in the content data reproduction apparatus 100 will be described below with reference to FIG. FIG. 6 is a flowchart showing the processing operation in the processing for increasing the content playback speed.

  When the content data playback apparatus 100 enters the content playback speed acceleration processing mode (Yes in step S8 in FIG. 4), the playback speed control unit 114 determines whether or not to execute a skip event (step S20). That is, the playback speed control unit 114 checks whether or not a skip flag is set. If the skip flag is set (Yes in step S20), the playback speed control unit 114 executes a skip event (step S21). When the execution of the skip event is completed, the skip flag is canceled (step S22).

  On the other hand, when the skip flag is not set (No in step S20), the playback speed control unit 114 executes a high speed event (step S23).

  The flag for executing the skip event is raised when the determination unit 112 determines that the TS packet has an error (step S5 in FIG. 4). Therefore, the content data reproducing apparatus 100 that has once executed the skip event does not execute the skip event and executes only the high-speed event until the reception state is recovered.

(Change of PTS value in high-speed event)
Next, details of the method for changing the value of the PTS in the high-speed event will be described below with reference to FIG. FIG. 7 is a diagram illustrating a change in the value of the PTS in the high-speed event. Each circle in FIG. 7 indicates a PES packet, and a ☆ -type PES packet indicates a PES packet that could not be restored. The numerical values in the circles or ☆ indicate the PTS values assigned to each PES packet.

  The upper row in FIG. 7 shows the PTS before the value is changed, the middle row shows the change in the value of the PTS when stored in the buffer unit 113, and the lower row shows the value after the value is changed. PTS is shown. That is, the upper stage in FIG. 7 is a received PES packet, the middle stage is a PES packet when stored in the buffer unit 113, and the lower stage is a PES packet when read from the buffer unit 113.

In the high-speed event, the changed PTS value is expressed by the following formula (1).
PTS '= PTS + T <buff> (1)
Can be used to calculate. Here, “PTS ′” is the PTS value after the change, “PTS” is the PTS value before the change, and “T <buff>” is the delay value (> 0). That is, the changed PTS value (PTS ′) can be calculated by adding the delay value T <buff> to the PTS value (PTS) before the change.

The delay value T <buff> is expressed by the following equation (2).
T <buff> = T <max> + T <high> (2)
Can be used to calculate. Here, “T <max>” is a reference value corresponding to the amount of data stored in the buffer unit 113, and “T <high>” is a predetermined correction value (negative value). Therefore, the delay value T <buff> is actually a value obtained by subtracting the correction value T <high> from the reference value T <max>.

  Here, since the reference value T <max> is a value corresponding to the amount of data stored in the buffer unit 113, the value decreases as the amount of data stored in the buffer unit 113 decreases. That is, when the amount of data stored in the buffer unit 113 decreases (or is expected to decrease), the value of the reference value T <max> decreases by the correction value T <high>. Therefore, the value of the delay value T <buff> also becomes smaller as the reference value T <max> decreases. That is, a decrease in the reference value T <max> and a decrease in the delay value T <buff> correspond to a decrease in the amount of data stored in the buffer unit 113.

  Hereinafter, the change of the PTS value using a specific numerical example will be described. In this section, the reference value T <max> corresponding to the amount of data stored in the buffer unit 113 is “50”. The case where the correction value T <high> is “−5” and the counter value that is determined to be good in the radio wave reception state is “3” will be described as an example. In this section, when the threshold value of the counter is “3”, that is, when three restored PES packets continue (when three circles in FIG. 7 continue), the execution of the high-speed event ends. (Yes is selected in step S7 in FIG. 4). In this section, in order to facilitate understanding of high-speed events, skip event execution is not considered for convenience.

  In the PES packet of PTS10 and the packet of PTS20 in FIG. 7, T <buff> = T <max>, so that the PTS is changed from 10 → 60 and 20 → 70, respectively. That is, the PTS packets of PTS′60 and PTS′70 are stored in the buffer unit 113. Note that the processing for the PES packet of PTS10 and the packet of PTS20 is normal processing when the answer is Yes in step S12, and is not processing at the time of a high-speed event. Here, in order to facilitate understanding of the high-speed event, it is described together with the processing of the high-speed event.

  Next, as shown in FIG. 7, it is assumed that the PES packet of the PTS 30 is damaged and cannot be restored. Since the PES packet of the PTS 30 is discarded, the high-speed event process is executed when changing the PTS value of the PES packet of the next PTS 40 (the flow of steps S6, S7, S8, and S23 in FIG. 4).

The delay value T <buff> to be added to the PES packet of the PTS 40 is in accordance with the above equation (2).
T <buff> = T <max> + T <high> = 50-5 = 45
It becomes.

Therefore, the value of PTS ′ in the PES packet of PTS 40 is in accordance with the above equation (1).
PTS '= PTS + T <buff> = 40 + 45 = 85
(See FIG. 7).

Similarly, the delay value T <buff> of the PES packet of the PTS 50 is
T <buff> = T <max> + T <high> = 45-5 = 40
The value of PTS ′ in the PES packet of PTS50 is
PTS ′ = PTS + T <buff> = 50 + 40 = 90
(See FIG. 7).

Since the PES packet of the next PTS 60 is damaged and cannot be restored in the same manner as the PES packet of the PTS 30, the counter is initialized again. Therefore, the high-speed event is continuously executed even in the PES packet of the next PTS 70. That is, the delay value T <buff> of the PES packet of the PTS 70 is
T <buff> = T <max> + T <high> = 40−5 = 35
The value of PTS ′ in the PES packet of PTS 70 is
PTS ′ = PTS + T <buff> = 70 + 35 = 105
(See FIG. 7).

Similarly, the delay value T <buff> of the PES packet of the PTS 80 is
T <buff> = T <max> + T <high> = 40−5 = 35
The value of PTS ′ in the PES packet of PTS80 is
PTS ′ = PTS + T <buff> = 80 + 35 = 105
(See FIG. 7).

  As described above, the content data playback apparatus 100 plays back the content so that the PTS is synchronized with the clock in the content data playback apparatus 100 after the interval of the PES packets is narrowed by changing the value of the PTS.

  In FIG. 7, the PES packet of the PTS 70 can be restored, and three PES packets marked with “○” are continuous. That is, since the value of the counter is “3”, the result in Step S7 is Yes, and the high-speed event ends. That is, a high-speed event is executed for the PES packet in the portion surrounded by a broken line in FIG.

  When the amount of data stored in the buffer unit 113 is less than a predetermined amount, that is, when the value of the delay value T <buff> is less than the predetermined value, the PES packet of the PTS 90 has a low speed. Will be processed. Since the speed reduction processing will be described in detail below, the description thereof is omitted here.

  If the PES packet of the PTS 90 is damaged and cannot be restored, the high-speed event is continued. However, when the delay value T <buff> is 0 or less, the value of PTS ′ becomes smaller than the value of PTS. That is, the PES packet is reproduced before the real time. Therefore, a threshold is provided for the value that the delay value T <buff> can take, and when the value of the delay value T <buff> is equal to or less than the predetermined threshold, the high-speed event is forcibly terminated and the speed is reduced. It is preferable that the processing is executed. The threshold value of the delay value T <buff> is not particularly limited as long as the PTS ′ value is not smaller than the PTS value.

(Change of PTS value in skip event)
Next, details of the method of changing the value of the PTS in the skip event will be described below with reference to FIG. FIG. 8 is a diagram illustrating a change in the value of the PTS in the skip event. Each circle in FIG. 8 indicates a PES packet, and a ☆ -type PES packet indicates a PES packet that could not be restored. In addition, the numerical values in the circles or ☆ indicate the value of the PTS assigned to each PES packet.

  As in FIG. 7, the upper part in FIG. 8 shows the PTS before the value is changed, the middle part shows the change in the value of the PTS when stored in the buffer unit 113, and the lower part shows the value. The PTS after the change is shown. That is, as in FIG. 7, the upper stage in FIG. 8 is the received PES packet, the middle stage is the PES packet when stored in the buffer unit 113, and the lower stage is the PES packet when read from the buffer unit 113.

In the skip event, the changed PTS value can be calculated using the above equation (1), as in the case of the high-speed event. However, in the skip event, the delay value T <buff>(> 0) is expressed by the following equation (3).
T <buff> = T <max> − (pre_PTS−PTS) + α (3)
Calculate using. Here, “T <max>” is a reference value corresponding to the amount of data stored in the buffer unit 113, and “pre_PTS” is the value of the PTS assigned to the PES packet restored immediately before (that is, FIG. 4), “PTS” is the PTS value assigned to the PES packet for changing the PTS value, and “α” is a predetermined correction value. That is, the correction value T <high>, which is a predetermined value in the high-speed event, is calculated by “(pre_PTS−PTS) + α” in the skip event.

  Hereinafter, the change of the PTS value using a specific numerical example will be described. In this section, the reference value T <max> corresponding to the amount of data stored in the buffer unit 113 is “100”. A case where α is “10” will be described as an example.

  In the PES packet of the PTS 10 in FIG. 8, T <buff> = T <max>, so the PTS is changed from 10 to 110. That is, the PES packet of PTS10 is stored in the buffer unit 113 as a PES packet of PTS′110. Note that the processing for the PES packet of the PTS 10 is described together with the processing of the skip event in order to facilitate understanding of the explanation of the skip event, but is a normal processing when it becomes Yes in step S12, and skip It is not processing at the time of an event. At this time, the playback speed control unit 114 stores “10”, which is the PTS value of this PES packet, in step S11 of FIG. 4 as pre_PTS.

  As shown in FIG. 8, the subsequent PES packets of PTS20, PTS30, and PTS40 cannot be restored. In the case of video content, when a portion (indicated by a broken line in FIG. 8) where PES packets that cannot be restored in this manner are reproduced at a normal speed, the video freezes for a long period of time. This is especially true for slow playback. At this time, the playback speed control unit 114 sets a skip flag in step S5 of FIG.

Subsequently, as shown in FIG. 8, when the PES packet of the PTS 50 can be restored, the playback speed control unit 114 executes a skip event (step S21 in FIG. 6). That is, the delay value T <buff> to be added to the PES packet of the PTS 50 is in accordance with the above equation (2).
T <buff> = T <max> − (pre_PTS−PTS) + α = 100− (10−50) + 10 = 70
It becomes.

Therefore, the value of PTS ′ in the PES packet of PTS 40 is in accordance with the above equation (1).
PTS ′ = PTS + T <buff> = 50 + 70 = 120
(See FIG. 8).

  In addition, when the PTS ′ of the PES packet of the PTS 60 is a normal process (Yes option in step S12 in FIG. 4), the delay value T <buff> is “70”, so PTS ′ = 130. Become. When a high-speed event is executed, PTS ′ = 125 (when the correction value T <high> is “−5” as described above).

(Change of PTS value in low-speed processing)
Next, details of the speed reduction processing for reducing the content reproduction speed will be described below with reference to FIG. FIG. 9 is a diagram illustrating a change in the PTS value in the speed reduction process. Each circle in FIG. 9 indicates a PES packet, and a numerical value in each circle indicates a PTS value assigned to each PES packet.

  7 and 8, the upper part in FIG. 9 shows the PTS before the value is changed, the middle part shows a change in the value of the PTS when stored in the buffer unit 113, and the lower part shows The PTS after changing the value is shown. That is, the upper stage in FIG. 9 is a received PES packet, the middle stage is a PES packet when stored in the buffer unit 113, and the lower stage is a PES packet when read from the buffer unit 113.

In the speed reduction process, the changed PTS value (PTS ′) can be calculated using the above equation (1) as in the case of the high speed event. In the speed reduction process, the delay value T <buff>(> 0) is expressed by the following equation (4).
T <buff> = T <max> + T <low> (4)
Can be used to calculate. Here, “T <max>” is a reference value corresponding to the amount of data stored in the buffer unit 113, and “T <low>” is a predetermined correction value (positive value). Therefore, the delay value T <buff> is a value obtained by adding the correction value T <low> to the reference value T <max> as described in the above equation (4).

  In the low-speed processing, contrary to the high-speed event described above, when the amount of data stored in the buffer unit 113 increases (or is expected to increase), the value of the reference value T <max> is The correction value increases by T <low>. Therefore, the delay value T <buff> also increases as the reference value T <max> increases. That is, an increase in the reference value T <max> and an increase in the delay value T <buff> correspond to an increase in the amount of data stored in the buffer unit 113.

  In the following, the change of the PTS value using a specific numerical example will be described. In this section, the reference value T <max> corresponding to the amount of data stored in the buffer unit 113 is “0”. The case where the correction value T <low> is “2” will be described as an example.

  As shown in FIG. 9, the PES packet of the PTS 10 is processed at a low speed because the amount of data stored in the buffer unit 113 is less than a predetermined amount (the flow of steps S7, S11, S12, and S13 in FIG. 4). ).

The delay value T <buff> to be added to the PES packet of the PTS 10 is in accordance with the above equation (4).
T <buff> = T <max> + T <low> = 0 + 2 = 2
It becomes.

Therefore, the value of PTS ′ in the PES packet of PTS 40 is in accordance with the above equation (1).
PTS ′ = PTS + T <buff> = 10 + 2 = 12
(See FIG. 9).

Subsequently, the delay value T <buff> of the PES packet of the PTS 20 is
T <buff> = T <max> + T <high> = 2 + 2 = 4
The value of PTS ′ in the PES packet of PTS20 is
PTS ′ = PTS + T <buff> = 20 + 4 = 24
(See FIG. 9).

  Similarly, since the delay value T <buff> of the PES packet of the PTS 30 is “6”, the value of PTS ′ in the PES packet of the PTS 30 is “36”, and the delay value T of the PES packet of the PTS 40 is Since <buff> is “8”, the value of PTS ′ in the PES packet of the PTS 40 is “48”, and the delay value T <buff> of the PES packet of the PTS 50 is “10”. The value of PTS ′ in the PES packet is “60”.

When the above-described speed reduction processing is applied to the PES packet of the PTS 90 in FIG. 7, the delay value T <buff> of the PTS packet of the PTS 90 is
T <buff> = T <max> + T <high> = 30 + 2 = 32
The value of PTS ′ in the PES packet of PTS90 is
PTS ′ = PTS + T <buff> = 90 + 32 = 122
It becomes.

(Advantages of Embodiment 1)
As described above, in the content data playback apparatus 100, the playback speed is changed so that the playback speed of the PES packet during the period in which the reception state of the radio wave is bad is faster than the normal playback speed. That is, in the content data playback apparatus 100, the playback speed of the portion where the TS to be played is deteriorated (the portion where the video freezes or the sound skips) can be made faster than the normal playback speed. .

  Therefore, the content data reproducing apparatus 100 can reduce the time that the user is exposed to deteriorated content.

  In addition, since the content data playback apparatus 100 can dynamically change the playback speed according to the reception state of radio waves and the amount of data in the buffer unit 113, the user needs to change the playback speed of the content as appropriate. There is no forced operation.

  Further, the PES packet to which the changed PTS (PTS ′) is added is stored in the buffer unit 113 in the content data reproducing apparatus 100. Therefore, the reproduction control unit 115 does not need to have a special function.

  Therefore, even if the playback control unit 115 has not been specially modified, it is possible to reduce the time that the user is exposed to deteriorated content. Therefore, the burden on the manufacturer can be reduced.

  Further, even when the radio wave reception state is poor for a long period of time, it is possible to skip the portion of the PES packet received during the period in which the reception state was poor. That is, the content data reproducing apparatus 100 can connect the PES packets before and after the PES packet portion that has failed to be received.

  As a result, even when content data cannot be acquired for a long period of time, there is an effect that it is possible to reduce the time that the user is exposed to deteriorated content. In particular, when the content data is video data, it is particularly effective because it is possible to eliminate the fact that the video to be played freezes and causes discomfort to the user.

  Further, since the content data playback apparatus 100 includes the playback control unit 115 that executes playback of content, the content data playback apparatus 100 can execute playback of content. Therefore, it is possible to save troublesome work when connecting a separate playback device.

(Modification 1)
In the present embodiment, the content data playback apparatus 100 including the playback control unit 115 has been described as an example. However, the playback control unit 115 may be provided in a separate device. In this case, the configuration for reproducing the PES packet stored in the buffer unit 113 based on the PTS value of each PES packet is separated from the content data reproducing apparatus 100.

  Since the PES packet whose PTS value has already been changed is already stored in the buffer unit 113, the playback apparatus that reproduces the PES packet stored in the buffer unit 113 does not need to have a special function. Therefore, as long as the PES packet stored in the buffer unit 113 is used, it is possible to reduce the time that the user is exposed to the deteriorated content regardless of the playback device.

  That is, it is possible to reduce the time of exposure to deteriorated content even for a user having a conventional playback device. In addition, since it is not necessary to greatly modify the conventional playback device, the burden on the manufacturer of the playback device can be reduced.

(Modification 2)
The receiving unit 110 may be provided in a device separate from the content data reproducing device 100. In this case, the content data playback device is provided with an acquisition unit that acquires a TS from an external storage device that stores the TS extracted in a separate device, instead of the reception unit 110.

  In this case, since it is not necessary for the playback speed control device 100 to include the receiving unit 110 that receives digital broadcast waves, the cost required for manufacturing the playback control device 100 can be reduced. Also, the playback speed can be controlled so as to increase the playback speed during a period of poor reception even for content data acquired from an external recording medium that stores content data extracted from digital broadcast waves.

(Additional notes)
In the present embodiment, the case where both the skip event and the high-speed event are executed has been described as an example, but only one of them may be performed.

  Further, as described above, the skip event has a special effect when PES packets that cannot be restored continue, so that a flag is set when the number of consecutive PES packets that cannot be restored exceeds a predetermined value. Also good. In this case, the determination unit 112 includes a counter that counts the number of consecutive TS packet errors, and each time the determination unit 112 determines a TS packet error (Yes in step S3 in FIG. 4), the counter value is set. Increment. Then, the playback speed control unit 114 determines whether or not the value of the counter is a predetermined value before step S5 in FIG. The playback speed control unit 114 sets a skip event flag if the value of the counter that counts the number of consecutive TS packet errors is greater than or equal to a predetermined value, and does not set a skip flag if the value is less than the predetermined value.

  Note that the counter for counting the number of consecutive TS packet errors may be initialized when no TS packet error occurs (No in step S3 in FIG. 4).

  In this embodiment, whether or not a skip event is executed is managed using a flag, but a high-speed event may be managed using a flag. As with the skip event, the high-speed event flag may be raised when a TS packet error occurs and lowered when the radio wave condition becomes good.

[Embodiment 2]
In the first embodiment, the case has been described in which when the PES packet restored by the content data playback device is stored in the buffer unit 113, the playback speed of the content is changed by changing the PTS attached to the PES packet. The method for changing the content playback speed is not limited to this. As described above, the content playback speed can be changed by changing the STC value in the content data playback apparatus.

  Therefore, a content data playback apparatus that changes the playback speed of content by changing the STC in the content data playback apparatus will be described below as Embodiment 2 with reference to FIGS. In addition, about the member similar to Embodiment 1, the same referential mark is attached | subjected and the detailed description is abbreviate | omitted.

(Configuration of content data reproducing apparatus 100b)
The configuration of the content data reproducing apparatus according to the present embodiment will be described below with reference to FIG. FIG. 10 is a block diagram showing a main configuration of the content data reproducing apparatus 100b.

  As shown in FIG. 2, the content data playback device 100b includes a reception unit 110, a DEMUX processing unit 111, a determination unit 112, a buffer unit 113, a playback speed control unit 114b, a playback control unit 115, and an output unit 116. Since the reception unit 110, the DEMUX processing unit 111, the determination unit 112, the buffer unit 113, the reproduction control unit 115, and the output unit 116 have been described in the first embodiment, description thereof will be omitted. Therefore, in the present embodiment, only the reproduction speed control unit 114b will be described below.

(Reproduction speed control unit 114b)
The playback speed control unit 114b changes the STC value generated by the content data playback device 100b based on the reception state determined by the determination unit 112 and the amount of data stored in the buffer unit 113. The change of the STC value in the playback speed control unit 114 will be described in detail below, and the description thereof is omitted here.

(Content Reproduction Process in Content Data Reproducing Device 100b)
The content playback processing operation in the content data playback apparatus 100b will be described below with reference to FIGS. FIG. 11 is a flowchart showing the processing operation up to the storage portion of the PES packet in the content data playback apparatus 100b, and FIG. 12 is a flowchart showing the processing operation until the content playback.

(Process until storing PES packet)
First, as shown in FIG. 11, when the receiving unit 110 receives a digital broadcast wave, the receiving unit 110 extracts a TS packet from the received digital broadcast wave (step S30). Subsequently, the DEMUX processing unit 111 restores the PES packet from the TS packet in the extracted TS (step S31).

  At this time, the determination unit 112 determines whether there is an error in receiving the TS packet based on the header of the TS packet (step S32). If the determination unit 112 determines that an error has occurred in receiving the TS packet (Yes in step S32), the determination unit 112 initializes the value of the counter (step S33). In this case, since the TS packet determined to have an error is discarded, the restoration of the PES packet in step S31 is not executed. Therefore, the restored PES packet is not stored in the buffer unit 113. Note that the processing so far is the same processing as steps S1 to S4 in the first embodiment.

  Next, the playback speed control unit 114b determines whether or not the content data playback device 100b is executing a high speed event (step S34). When the reproduction speed control unit 114b determines that the high-speed event is not being executed (No in step S34), the reproduction control unit 114b sets the STC value at which the high-speed event is started (step S35). At this time, the reproduction control unit 114b sets the value of the PTS assigned to the immediately preceding PES packet as the high-speed event start STC (STAR_HIGH_STC). If the reproduction speed control unit 114b determines that the high-speed event is not being executed (Yes in step S34), the reproduction control unit 114b proceeds to the next process without performing any special process.

  On the other hand, when determining unit 112 determines that there is no error in receiving the TS packet (No in step S32), determining unit 112 increments the value of the counter (step S36). Subsequently, the determination unit 112 determines whether or not the value of the counter has reached a predetermined value (step S37). When it is determined that the value of the counter is less than the predetermined value (No in step S37), that is, when the determination unit 112 determines that the state in which the radio wave reception is poor continues, the DEMUX processing unit 111 The restored PES packet is stored in the buffer unit 113 (step S41).

  When it is determined that the counter value is equal to or greater than the predetermined value (Yes in step S37), that is, when the determination unit 112 determines that the reception state of the radio wave has been recovered, the playback speed control unit 114b The value of PTS is stored (step S38). The stored PTS value is the high-speed event start STC set in step S35.

  Next, the playback speed control unit 114b determines whether or not a high-speed event is being executed (step S39). When the playback speed control unit 114b determines that the high-speed event is not being executed (No in step S39), the DEMUX processing unit 111 stores the restored PES packet in the buffer unit 113 (step S41). On the other hand, when the playback speed control unit 114b determines that the high speed event is being executed (Yes in step S39), the playback speed control unit 114b sets the PES value added to the restored PES packet to the high speed event. It is set as an event end STC (END_HIGH_STC) (step S40). Then, the DEMUX processing unit 111 stores the restored PES packet in the buffer unit 113 (step S41).

(Reproduction processing of PES packet)
Next, a playback processing operation in which the content data playback device 100b reads and plays back the PES packet stored by the above-described processing will be described with reference to FIG. FIG. 12 is a flowchart showing a processing operation in which the content data playback apparatus 100b plays back a PES packet.

  First, the playback speed control unit 114b determines whether or not a high-speed event is being executed (step S50).

  When the playback speed control unit 114b determines that the high speed event is not being executed (No in step S50), the playback speed control unit 114b determines whether to start the high speed event (step S51). Specifically, the playback speed control unit 114b determines whether the STC value generated by the playback control unit 115 has reached the PTS value set in step S35 of FIG. 11 (that is, has reached START_HIGH_STC). Determine.

  When the playback speed control unit 114b determines that a high-speed event is started (Yes in step S51), that is, when the STC value reaches the PTS value set in step S35 of FIG. 11, the playback speed control unit 114b It is determined whether the amount of data stored in the buffer unit 113 is equal to or greater than a predetermined amount (step S52).

  When the playback speed control unit 114b determines that the amount of data stored in the buffer unit 113 is greater than or equal to the predetermined amount (Yes in step S52), the playback speed control unit 114b executes a high speed event (step S53). That is, the playback speed control unit 114b changes the STC value generated by the playback control unit 115 so as to increase the content playback speed (high-speed playback processing). Note that the details of the method of changing the STC value will be described below, so the description thereof is omitted here.

  On the other hand, when the playback speed control unit 114b determines that the high-speed event is not being executed (Yes in step S50), the playback speed control unit 114b determines whether or not to end the high-speed event (step S54). Specifically, the playback speed control unit 114b determines whether the STC value generated by the playback control unit 115 has reached the PTS value set in step S40 of FIG. 11 (that is, END_HIGH_STC has been reached). Determine.

  When the playback speed control unit 114b determines that the high-speed event is to be ended (Yes in step S54), that is, when the STC value reaches the PTS value set in step S35 of FIG. 11, the playback speed control unit 114b It is determined whether the amount of data stored in the buffer unit 113 is equal to or greater than a predetermined amount (step S55). If the playback speed control unit 114b determines that the high-speed event is not terminated (No in step S54), the high-speed event continues and the playback speed control unit 114b executes the processing from step S52 described above. Will do.

  When the playback speed control unit 114b determines that the amount of data stored in the buffer unit 113 is less than the predetermined amount (No in step S55), the playback speed control unit 114b executes low speed playback processing (step S56). . That is, the playback speed control unit 114b changes the STC value generated by the playback control unit 115 so as to slow down the content playback speed. On the other hand, when the playback speed control unit 114b determines that the amount of data stored in the buffer unit 113 is equal to or greater than the predetermined amount (No in step S55), the playback speed control unit 114b executes normal playback processing (step S55). S57). That is, the playback speed control unit 114b plays back the content without changing the playback speed of the content.

  The playback control unit 115 reads the PES packet stored in the buffer unit 113 based on the STC value changed by the playback speed control unit 114b (step S58). The reproduction control unit 115 decodes the read PES packet and outputs it to the output unit 116 (step S59).

  As described above, in the content data playback apparatus 100b, the high-speed event is executed after the STC value generated by the playback control unit 115 reaches START_HIGH_STC until it reaches END_HIGH_STC. Therefore, the process for determining whether or not a high-speed event is being executed (step S34 in FIG. 11 and step S50 in FIG. 12) may be paraphrased as determining whether or not START_HIGH_STC <STC ≦ END_HIGH_STC is satisfied. it can.

(How to change STC value)
Next, details of the STC value changing method will be described below. The STC generated in the playback control unit 115 is expressed by the following formula (5).
STC '= STC-T <buff> (5)
Can be used to change. Here, “STC ′” is the STC value after the change, “STC” is the STC value before the change, and “T <buff>” is the delay value (> 0). In other words, the STC value (STC ′) after the change can be calculated by subtracting the delay value T <buff> from the STC value (STC) before the change.

In the case of high-speed playback processing, the delay value T <buff> is expressed by the following equation (6).
T <buff> = T <max> + T <high> (6)
Can be used to calculate. Here, “T <max>” is a reference value corresponding to the amount of data stored in the buffer unit 113, and “T <high>” is a predetermined correction value (negative value). Therefore, the delay value T <buff> is actually a value obtained by subtracting the correction value T <high> from the reference value T <max>.

  As in the case of the first embodiment, the reference value T <max> is a value corresponding to the amount of data stored in the buffer unit 113, and thus the value is reduced due to a decrease in the amount of data stored in the buffer unit 113. Decrease. That is, also in this embodiment, the decrease in the reference value T <max> and the decrease in the delay value T <buff> correspond to the decrease in the amount of data stored in the buffer unit 113.

On the other hand, in the case of low speed reproduction processing, the delay value T <buff>(> 0) is expressed by the following equation (7).
T <buff> = T <max> + T <low> (7)
Can be used to calculate. Here, since “T <low>” is a predetermined correction value (positive value), the delay value T <buff> is actually the reference value T <max> as represented by the above equation (7). To the correction value T <low>.

(Change content playback speed)
Here, changing the STC value by changing the content playback speed will be described below with reference to FIG. FIG. 13 is a diagram schematically showing a change in content playback speed in the content data playback apparatus 100b. Each circle in FIG. 13 indicates a PES packet, and each ☆ indicates a PES packet that could not be restored. The numerical value inside the circle mark or the star mark indicates the value of the PTS assigned to each PES packet.

  13 shows the relationship between the STC value and the PTS value when no change is made to the STC value. As described in the overview of the PES packet reproduction process, the STC on the receiver side is matched with the STC on the transmitter side, and therefore the upper part can be rephrased as the STC in the transmitting apparatus that transmits TS packets. it can. The lower part of FIG. 13 shows the relationship between the changed STC value (STC ′) and the PTS value. That is, the lower row is the STC value in the content data playback device 100b.

  In the following, change of the PTS value using a specific numerical example will be described. In this section, the reference value T <max> is “20” and the correction value T <high> is “−5”. A case where the correction value T <low> is “2” and the threshold value of the counter that determines that the reception state has been recovered is “2” will be described as an example.

  As shown in FIG. 13, the PES packets of PTS10, PTS20, and PTS30 can be normally restored, and thus are reproduced by the reproduction process at the normal speed. Therefore, T <buff> = T <max> = 20 for PTS10, PTS20, and PTS30.

  Here, since the reproduction control unit 115 reads a PES packet having a PTS value that matches the changed STC value (STC ′), the PES packet of the PTS 10 is read at the time of STC′10. Based on the above equation (5), the STC value can be calculated using “STC ′ + T <buff>”.

  Therefore, the PTS packet of PTS10 is actually read at STC30. In other words, the playback speed control unit 114b in the content data playback apparatus 100b impersonates the STC value generated by the playback control unit 115. Then, the playback control unit 115 reads out the PES packet using the camouflaged STC value (STC ′).

  Similarly, since the PES packet of PTS20 is read at STC'20, the actual STC is "40", and the PES packet of PTS30 is read at STC'30, so the actual STC is "50". It is. In FIG. 13, the actual STC value is described in parentheses below the STC ′ value.

  Subsequently, since the PES packet of the PTS 40 cannot be restored, it is discarded. At this time, the playback speed control unit 114b sets “30”, which is the PTS value assigned to the PES packet restored immediately before, as START_HIGH_STC.

When the STC ′ value reaches “30”, the playback speed control unit 114b starts a high-speed event. Therefore, the restored PES packet of the PTS 50 is read based on the value of STC ′ calculated by the high-speed playback process. That is, the delay value T <buff> for calculating STC ′ is calculated according to the above equation (6).
T <buff> = T <max> + T <high> = 20−5 = 15
Therefore, the STC value in the STC ′ 50 from which the PES packet of the PTS 50 is read is “65”.

Similarly, in the case of the PES packet of PTS70,
T <buff> = T <max> + T <high> = 15−5 = 10
Therefore, the STC value in the STC ′ 70 from which the PES packet of the PTS 70 is read is “80”.

For PTS90 PES packets:
T <buff> = T <max> + T <high> = 10−5 = 5
Therefore, the STC value in the STC '90 from which the PES packet of the PTS 90 is read is “95”.

  Next, since the PES packet of the PTS 100 can be restored following the PES packet of the PTS 90, the value of the counter becomes “2”, and the determination unit 112 determines that the radio wave reception state has been recovered. Therefore, the playback speed control unit 114b sets “100” given to the restored PES packet as END_HIGH_STC. Therefore, the playback speed control unit 114b ends the execution of the high-speed event when STC ′ = 100 is reached.

Here, at STC'100, the PES packet of PTS100 is read. At this time, the PES packet of the PTS 100 is
T <buff> = T <max> + T <high> = 5-5 = 0
Therefore, the STC'100 from which the PES packet of the PTS 100 is read is the same STC 100 as the actual time. Thus, when the delay value T <buff> = 0. The value of STC ′ and the value of STC match.

  As described above, the content data reproduction device 100b reproduces content so that the PTS is synchronized with the clock after the clock interval in the content data reproduction device 100b is narrowed.

Subsequently, since the PES packet of the PTS 110 has completed the high-speed event and the amount of data stored in the buffer unit 113 is “0”, low-speed playback processing is performed. That is, the delay value T <buff> for calculating STC ′ is calculated according to the above equation (7).
T <buff> = T <max> + T <low> = 0 + 2 = 2
Therefore, the STC value in the STC ′ 110 from which the PES packet of the PTS 110 is read is “112”.

  As shown in FIG. 13, during the period in which the reception state of the radio wave is bad, when STC is not changed, 100-30 = “70”, but in STC ′ whose STC value is changed, 100-50 = “50”. That is, by changing the STC value, it is possible to reduce the time that the viewer is exposed to the content in the period in which the reception state of the radio wave is poor.

(External view of content data playback device)
A schematic diagram of the content data reproducing apparatus 100 (100b) is shown in FIG. A broadcast station 200 in FIG. 14 is a base station that distributes MPEG2-TS (content data). The portable terminal 210 corresponds to the content data playback device 100 (100b), and the memory 220 corresponds to the buffer unit 113. In FIG. 14, for convenience, the memory 220 is illustrated outside the mobile terminal 210, but of course, an internal memory provided inside the mobile terminal 210 may be used.

  As described in the first modification of the first embodiment, when the playback control unit 115 and the output unit 116 are separate devices, the recorder 230 in FIG. 14 corresponds to the playback control unit 115, and the television 240 Corresponds to the output unit 116. In this case, the recorder 230 may read the content data directly from the memory 220, or may acquire the content data by data communication with the portable terminal 210.

  In FIG. 14, a case where the recorder 230 corresponding to the reproduction control unit 115 and the television 240 corresponding to the output unit 116 are separated is described as an example. However, the function of the recorder 230 and the television 240 are described. It may be a PC (Personal Computer) having the above functions.

(Content data playback device realized by hardware)
Here, FIG. 15 shows an example in which each block in the content data reproducing apparatus 100 (100b) according to the present invention is realized by hardware. FIG. 15 is a block diagram showing a case where each unit in the content data reproducing apparatus 100 is realized by hardware. In this section, the case where the content data reproducing apparatus 100 is a mobile phone is described as an example.

  15 includes a wireless unit 301, a communication control unit 302, a control unit 303, a tuner module 304, a media decoder 305, a display unit 306, a speaker 307, a B-CAS 308, and a memory 309. .

  The wireless unit 301 is used when the content data reproducing apparatus 100 performs wireless communication processing such as a telephone call. The communication control unit 302 controls overall communication control in the content data reproducing apparatus 100.

  The control unit 303 governs overall control in the content data playback apparatus 100, and controls processing when the content data playback apparatus 100 receives a digital broadcast. That is, the control unit 303 corresponds to the reproduction speed control units 114 and 114b in FIGS.

  The tuner module 304 is a tuner module for receiving digital broadcasting. In this section, a case where the tuner module 304 can switch between the one-segment reception mode and the full-segment reception mode is illustrated. The tuner module 304 corresponds to the reception unit 110 and the determination unit 112 in FIGS. 1 and 10.

  The media decoder 305 separates video, audio, data broadcast, PSI / SI, and the like from the TS input from the tuner module 304, and performs video / audio decoding and output.

  The media decoder 305 includes a TSDEMUX processing unit 350, an H.264 medium, An H.264 decoder 351, a descrambling processing unit 352, an MPEG2 decoder 353, an AAC decoder 354, a display processing unit 355, and an audio playback unit 356 are provided.

  The TSDEMUX processing unit 350 separates TS input from the tuner module 304. In addition, the descrambling processing unit 352 decrypts the video data and the audio data based on the key provided from the B-CAS 308 when the content data reproducing apparatus 100 is in the full segment reception mode. The TSDEMUX processing unit 350 and the descrambling processing unit 352 correspond to the DEMUX processing unit 111 in FIGS. 1 and 10.

  H. The H.264 decoder 351 decodes video data when the content data reproducing apparatus 100 is in the one-segment reception mode. The MPEG2 decoder 353 decodes video data when the content data reproducing apparatus 100 is in the full segment reception mode. The AAC decoder 354 decodes the audio data. H. The H.264 decoder 351, the MPEG2 decoder 353, and the AAC decoder 354 correspond to the reproduction control unit 115 in FIGS.

  The display processing unit 355 outputs the decoded video data to the display unit 306. The display unit 306 displays the input video data. Also, the audio playback unit 356 outputs the decoded audio data to the speaker 307. The speaker 307 outputs the input sound. That is, the display processing unit 355, the audio playback unit 356, the display unit 306, and the speaker 307 correspond to the output unit 116 in FIGS.

  The B-CAS 308 provides a descrambling key to the descrambling unit 352.

  The memory 309 is a memory that temporarily stores PES packets, and corresponds to the buffer unit 113 in FIGS. 1 and 10. Note that data other than the PES packet may be recorded in the memory 309.

(Program and recording medium)
Finally, a DEMUX processing unit 111, a determination unit 112, a playback speed control unit 114, and a playback control unit 115 (hereinafter, these members are collectively referred to as a content data playback unit) included in the content data playback device 100 (100b). ) May be configured by hardware logic. Alternatively, it may be realized by software using a CPU (Central Processing Unit) as follows.

  In other words, the content data playback unit includes a CPU such as an MPU that executes instructions of a program that realizes each function, a ROM (Read Only Memory) that stores the program, and a RAM (Random Access) that expands the program into an executable format Memory) and a storage device (recording medium) such as a memory for storing the program and various data.

  The object of the present invention is not limited to the case where the program is stored in the program memory of the content data reproducing unit, but the program code (execution format program, intermediate code program, or source program) of the above program is recorded. This can also be achieved by supplying the recording medium to the content data reproducing apparatus 100 (100b), and reading and executing the program code recorded on the recording medium by the content data reproducing apparatus 100 (100b).

  The recording medium is not limited to a specific structure or type. That is, the recording medium includes, for example, a tape system such as a magnetic tape and a cassette tape, a magnetic disk such as a floppy (registered trademark) disk / hard disk, and an optical disk such as a CD-ROM / MO / MD / DVD / CD-R. System, a card system such as an IC card (including a memory card) / optical card, or a semiconductor memory system such as a mask ROM / EPROM / EEPROM / flash ROM.

  The object of the present invention can also be achieved by configuring the content data playback unit (or content data playback device 100 (100b)) to be connectable to a communication network. In this case, the program code is supplied to the content data reproducing unit via the communication network. The communication network is not limited to a specific type or form as long as it can supply the program code to the content data reproducing unit. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication network, etc. may be used.

  The transmission medium constituting the communication network may be any medium that can transmit the program code, and is not limited to a specific configuration or type. For example, even with wired lines such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL (Asymmetric Digital Subscriber Line) line, infrared rays such as IrDA and remote control, Bluetooth (registered trademark), 802.11 wireless, HDR, mobile phone It can also be used by radio such as a telephone network, a satellite line, and a terrestrial digital network. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The playback speed control device according to the present invention can be widely used as a mobile phone, a portable game device, and a television receiver capable of playing back content transmitted by digital broadcast waves.

100 content data playback device (playback speed control device)
110b Content data playback device (playback speed control device)
110 receiving unit 111 DEMUX processing unit 112 determining unit 113 buffer unit (memory)
114 Playback speed control unit (detection unit, control unit)
114b Playback speed control unit (detection unit, control unit)
115 Playback control unit (reading unit)
116 Output unit

Claims (13)

A playback speed control device including a memory for storing content data,
A determination unit for determining the reception state of the content data;
A detection unit for detecting the amount of content data stored in the memory;
Period in which the reception state of the content data is poor when the content data reception state is determined to be bad by the determination unit and the amount of data stored in the detection unit is determined to be greater than or equal to a predetermined amount A control unit that controls the playback speed so that the content represented by the received content data is played back faster than the playback speed when it is determined that the reception state is not bad;
A playback speed control device comprising:   The said control part changes the presentation time information provided to the content data received during the period when the reception state was bad, when storing content data in the said memory. Playback speed control device.   The control unit adds the delay value calculated based on the amount of data stored in the memory to the presentation time information given to the content data received during a period in which the reception state is bad, The reproduction speed control apparatus according to claim 2, wherein the presentation time information is changed. The playback speed control apparatus according to claim 3, wherein the delay value is calculated using the following equation (1).
T _buff = T _max + T _high (1)
(In the above equation (1), T _buff is a delay value (> 0), T _max is a reference value determined according to the amount of data stored in the memory, and T _high is an arbitrary value less than 0) (It is a fixed value) The playback speed control apparatus according to claim 3, wherein the delay value is calculated using the following equation (2).
T _buff = T _max + (T ₁ −T ₂ ) + α (2)
(In the above equation (2), T _buff is a delay value (> 0), T _max is a reference value determined according to the amount of data stored in the memory, and T ₁ is the first presentation time) Information, T ₂ is second presentation time information satisfying T ₁ <T ₂ , and α is an arbitrary fixed value)   6. The reading apparatus according to claim 2, further comprising a reading unit that reads from the memory content data to which presentation time information that matches the reference time information generated in the device itself is added. Playback speed control device. It further includes a reading unit that generates reference time information used for reading content data from the memory, and reads the content data provided with presentation time information that matches the generated reference time information from the memory,
The control unit changes the reference time information generated in the reading unit during a period in which the reception state is bad,
The playback speed control apparatus according to claim 1, wherein the reading unit reads content data from the memory based on the reference time information changed in the control unit.   The control unit subtracts the delay value calculated based on the amount of data stored in the memory from the reference time information generated in the control unit during a period in which the reception state is bad, thereby 8. The reproduction speed control apparatus according to claim 7, wherein the information is changed. The playback speed control apparatus according to claim 8, wherein the delay value is calculated using the following equation (3).
T _buff = T _max + T _high (3)
(In the above equation (3), T _buff is a delay value (> 0), T _max is a reference value determined according to the amount of data stored in the memory, and T _high is an arbitrary value less than 0) (It is a fixed value)   The playback speed control apparatus according to claim 1, wherein the determination unit determines a reception state of the content data based on information included in the content data. A content playback speed control method in a playback speed control device including a memory for storing content data,
A determination step of determining the reception state of the content data;
A detection step of detecting a data amount of the content data stored in the memory;
Period in which the reception state of the content data is poor when the reception state of the content data is determined to be bad in the determination step and the data amount stored in the detection step is determined to be greater than or equal to a predetermined amount A playback speed control step for controlling the playback speed so that the content represented by the received content data is played back faster than the playback speed when it is determined that the reception state is not bad;
A playback speed control method comprising: A content playback device including a reading unit that reads content data provided with presentation time information that matches reference time information generated in the device itself,
3. The content playback apparatus according to claim 2, wherein the reading unit reads content data to which presentation time information that matches the generated reference time information is provided from the memory provided in the playback speed control device according to claim 2. . A program for operating a computer having a memory for storing content data, the computer
Determining means for determining the reception state of the content data;
Detecting means for detecting the amount of content data stored in the memory;
Period in which the reception state of the content data is bad when it is determined that the reception state of the content data is bad in the determination means and the amount of data stored in the detection means is greater than or equal to a predetermined amount A program for functioning as a control means for controlling the playback speed so that the content represented by the received content data is played back faster than the playback speed when it is determined that the reception state is not defective.

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