JP4398850B2 - Content playback apparatus and playback control program - Google Patents

Description

  The present invention relates to a content playback apparatus used in a mobile phone, a PDA (Personal Digital Assistants), a digital broadcast receiving terminal, and the like, and in particular, a function of playing back video content compressed and encoded by MPEG4 (Motion Picture Experts Group 4). The present invention relates to a content reproduction apparatus including the above and a reproduction control program used in the apparatus.

  In recent years, an increasing number of devices have a function of reproducing video content compressed and encoded by MPEG4 or ITUT H.264 in a mobile phone or a digital broadcast receiving terminal. When this type of device is used, video telephone communication and video content reproduction can be performed with good quality even in a mobile communication environment.

  However, in this type of conventional apparatus, various problems arise when trying to reproduce encoded data at a variable speed. For example, if the stored video content is to be fast-forwarded or reverse-fed at double speed, the playback bit rate of the decoder must be set high. For this purpose, a large-capacity memory and a decoder with a high processing capacity are required, and the price of the apparatus cannot be avoided.

  On the other hand, as a means for avoiding an increase in the reproduction bit rate of the decoder, it is known to perform a frame thinning process on encoded data. However, the conventional data reproduction method using the frame thinning process generally decodes each frame of the encoded data, performs the thinning process on each decoded frame, and reproduces it. For this reason, the amount of processing required for data decoding is very large, and a large-capacity memory and a high-speed processor are required for this processing. Therefore, in this case as well, the cost of the apparatus cannot be avoided.

  The present invention has been made paying attention to the above circumstances, and its object is to enable variable-speed reproduction of compression-coded video data without requiring a high-speed processor or a large-capacity memory. Accordingly, an object of the present invention is to provide a content reproduction apparatus and a reproduction control program that are inexpensive and capable of multi-function reproduction.

To achieve the above object, the present invention provides a coded stream data composed of an intra-frame compressed frame and an inter-frame compressed frame, and a frame indicating a position in the stream data of the intra-frame compressed frame included in the stream data. A video data reproducing apparatus that decodes and reproduces a stream file composed of position information and a header portion including marker information including size information indicating the data amount of the inter-frame compressed frame by a decoder having a predetermined reproduction bit rate. In response to the input of the playback instruction, based on the frame position information included in the marker information , extract the data of the intra-frame compressed frame included in the unit time starting from the input time of the playback instruction , designated reproduction speed prior to reproduction, reproduction bit rate 及 of the decoder Based on the size information included in the marker information, selects a frame to be reproduced from within the compressed frame frame of the extracted. Then, a time stamp corresponding to the set playback speed is given to the selected intra-frame compressed frame to be played back, and the selected intra-frame compressed frame to be played back according to the given time stamp. The decoder is made to decode .
Further, the selection process of the frame to be reproduced calculates the total frame size of the intra-frame compressed frames included in the extracted unit time based on the size information of the corresponding frame included in the marker information. The amount of data that can be decoded within the unit time is determined based on the set playback speed and the playback bit rate of the decoder, and this is set as a threshold, and the total value of the calculated frame sizes is When the total value of the frame sizes exceeds the threshold value as compared with the set threshold value, it is performed by thinning out the intraframe compressed frames included in the unit time in units of frames.

  Therefore, according to the present invention, for example, when performing double-speed playback, if the data amount of the intra-frame compressed frame per unit time exceeds the playback capability of the decoder, playback from the intra-frame compressed frame per unit time is performed. The target intra-frame compressed frame is selected. Then, a time stamp corresponding to the designated reproduction speed is reapplied to the selected intra-frame compressed frame, and the intra-frame compressed frame is decoded and reproduced according to the time stamp. Therefore, it is possible to perform double speed reproduction without increasing the reproduction bit rate of the decoder.

  In addition, the selection of an intra-frame compressed frame to be reproduced is first performed, and a time stamp is given to the intra-frame compressed frame after the selection, and the decoded frame is used for decoding. For this reason, the signal processing amount required for the data decoding process is reduced as compared with the case where the decimation process is performed after decoding all the frames of the encoded data, thereby eliminating the need for a large-capacity memory and a high-speed processor. Cost reduction. This effect is particularly useful in portable terminal devices such as mobile phones and PDAs that are difficult to increase the processor speed and increase the memory capacity easily from the viewpoints of miniaturization and weight reduction and battery life extension.

In short, in the present invention, the total value of the frame sizes of the intra-frame compressed frames included in the unit time is compared with the amount of data that can be decoded within the unit time, and the total value of the frame sizes exceeds the threshold value. The intra-frame compressed frame included in the unit time is thinned out in units of frames to select the intra-frame compressed frame to be reproduced from the intra-frame compressed frames included in the unit time. A time stamp corresponding to the designated reproduction speed is re-applied to the compressed frame, and the compressed frame is used for decoding reproduction.
Therefore, according to the present invention, even when the data amount of the intra-frame compressed frame per unit time exceeds the playback capability of the decoder , the compressed and encoded video data is not required without requiring a high-speed processor or a large-capacity memory. Thus, it is possible to provide a content playback apparatus and a playback control program that are capable of variable speed playback, thereby enabling inexpensive and multi-function playback.

FIG. 1 is a block diagram showing a configuration of a mobile terminal device which is an embodiment of a content reproduction apparatus according to the present invention.
In the figure, a radio signal transmitted from a base station (not shown) is received by an antenna 1 and then transmitted through an antenna duplexer (DUP) 2, a receiving circuit (RX) 3, and a CDMA signal processing unit 6. It is converted into a format and becomes received packet data. The received packet data is input to a compression / decompression processor (hereinafter referred to as a compander) 7.

  In the compander 7, the received packet data output from the CDMA signal processing unit 6 is separated for each medium by the demultiplexing unit, and decoding processing is performed for each media data. For example, if audio data is included in the received packet data, the audio data is decoded by a speech codec. If the received packet data includes video data, the video data is decoded by a video codec. The digital audio signal obtained by this decoding process is input to the PCM code processing unit (hereinafter referred to as the PCM codec) 8 and the digital video signal is input to the control unit 12A. Further, when the received packet data includes text data such as mail or application, the text data is input to the control unit 12A.

  The digital audio signal output from the compander 7 is output from the speaker 10 via the PCM codec 8 and the reception amplifier 9.

  On the other hand, the digital video signal output from the compander 7 is displayed on an LCD (Liquid Crystal Devise) of the display unit 15 via the video RAM. The control unit 12A displays not only the received video data but also the video data captured by the camera 19 on the LCD of the display unit 15 via the video RAM. Further, text data such as mails and applications is stored in the storage unit 13. Then, it is read from the storage unit 13 and displayed on the LCD of the display unit 15 according to the display operation in the input unit 14. Note that the audio data and video data are also stored in the storage unit 13 as necessary.

  On the other hand, the voice signal of the speaker input to the microphone 11 is transmitted to the transmission amplifier 20 and the PCM codec 8 compander 7, and the video signal output from the camera 19 is digitized by the controller 12 A and then the compander 7. , The CDMA signal processing unit 6 performs spread spectrum processing and transmits the signal to the base station via the transmission circuit (TX) 5, the antenna duplexer 2, and the antenna 1.

  In addition to the dial keys, the input unit 14 is provided with function keys such as a transmission key, an end key, a power key, a volume adjustment key, and a mode designation key. The display unit 15 is provided with an LCD and an LED. On the LCD, the above-described transmission / reception data and data representing the operation mode of the apparatus are displayed. In addition, phone book data, transmission / reception history, and the like are also displayed. Further, the LED is used for notifying incoming calls and displaying the state of charge of the battery 16. Reference numeral 17 denotes a power supply circuit, which generates a predetermined operating power supply voltage Vcc based on the output of the battery 16 and supplies it to each circuit unit. The battery 16 is charged by a charging circuit (not shown).

  By the way, the control unit 12 includes, for example, a microcomputer as a main control unit, and has a frame information analysis function 12a, a frame selection processing function 12b, and a time stamp giving function 12c as control functions according to the present invention. ing. All of these functions are realized by causing the microcomputer to execute a program.

  First, the frame information analysis function 12a analyzes the structure of the encoded video data when a reproduction request for the encoded video data stored in the storage unit 13 is input. For example, video content compressed and encoded by MPEG4 is composed of a header portion 5a and a stream data portion 5b as shown in FIG. 5, for example. In the header portion 5a, video track information 5c, frame position / time / size information 5d, and I frame position information 5e are inserted as marker information. In the stream data portion 5b, an intra-frame compressed frame (hereinafter referred to as I frame) and an inter-frame compressed frame (hereinafter referred to as P frame) are inserted. The frame information analysis function 12a extracts I frames per unit time based on the I frame position information 5e inserted in the header portion 5a.

  The frame selection processing function 12b calculates the total frame size of I frames per unit time extracted by the frame information analysis function 12a based on the frame position / time / size information 5d inserted in the header 5a. calculate. At the same time, the average that can be decoded by the compression / decompression processing unit 7 per unit time based on the reproduction speed designated by the user when reproducing the video content and the reproduction bit rate of the compression / decompression processing unit 7 The amount of data is obtained and set as a threshold value. Then, the calculated data amount is compared with the set threshold value, and when the data amount exceeds the threshold value, the I frame included in the unit time is thinned out in frame units.

  The time stamp assigning function 12c reassigns a time stamp corresponding to the designated and input reproduction speed to the I frame remaining after the thinning process of the frame selection processing function 12b. Then, the I frame to which the time stamp is reassigned is given to the compression / decompression processing unit 7 for decoding processing.

Next, a video content reproduction operation by the apparatus configured as described above will be described. FIG. 2 is a flowchart showing the control procedure and control contents of the control unit 12.
When the reproduction request for the video content stored in the storage unit 13 is input, the control unit 12 first determines whether or not the reproduction speed and the reproduction direction are changed in step 2a. Then, when the user designates and inputs an arbitrary reproduction speed and reproduction direction different from the currently set reproduction speed and reproduction direction through the input unit 14, the reproduction speed and reproduction direction designated and inputted in step 2b are set. Change to playback direction. The example shown in FIG. 3 shows a case where “1.5 times speed” is set as the playback speed. If the operation for changing the reproduction speed and the reproduction direction is not performed, the process goes to step 2c as it is through step 2b.

  When the playback instruction is input, the control unit 12 proceeds from step 2c to step 2d, where the control unit 12 first refers to the marker information included in the video content to be played back and is included per unit time (for example, 1 sec). I frame is extracted. Next, the control part 12 calculates the total value (for example, data amount) of the frame size of the said extracted I frame by step 2e. At the same time, in step 2f, the compression / expansion processing unit 7 within the unit time uses the reproduction speed set in step 2b (for example, 1.5 times speed) and the reproduction bit rate of the compression / expansion processing unit 7 in the unit time. An average amount of data that can be decrypted is obtained and set as a threshold value.

  Subsequently, in step 2g, the control unit 12 compares the calculated data amount with the set threshold value, and determines whether or not the calculated data amount is larger than the threshold value. If the amount of data exceeds the threshold value as a result of this comparison, the I frame included in the unit time is thinned out in units of frames in step 2h. For example, as shown in FIG. 3, if the I frames I1 to I4 are included in the unit time T1 of interest and the total value of the frame sizes exceeds the threshold value, as shown in FIG. Of the I frames I1 to I4 included in the unit time T1, the last I frame I4 located in the playback direction is deleted. On the other hand, when the data amount is equal to or smaller than the threshold value, the I frame thinning process is not performed.

  Subsequently, the control unit 12 proceeds to step 2i, and here, for the I frames I1 to I3 after the thinning process, a time stamp corresponding to the reproduction speed (for example, 1.5 times speed) set in the step 2b, Similarly, the reproduction direction is reassigned in the step 2b. For example, if “forward direction” is set as the playback direction, time stamps t1 to t3 are given to the I frames I1 to I3 to be played back in the same direction as the stream direction as shown in FIG. On the other hand, if “reverse direction” is set as the reproduction direction, the time stamps t3 to t1 are given to the reproduction target I frames I1 to I3 in the direction opposite to the stream direction.

  Next, the control unit 12 reads out the I frames I1 to I3, to which the time stamps have been reassigned in step 2j, from the storage unit 13 and gives them to the compression / decompression processing unit 7. As a result, the compression / decompression processing unit 7 performs the decoding process on each of the I frames I1 to I3 according to the time stamp. Then, the decoded video data is supplied to the LCD of the display unit 15 via the LCD driver in the control unit 12 and thereby displayed on the LCD.

  Thereafter, similarly, the control unit 12 repeatedly executes the processing from step 2a to step 2i for each unit time until the end of content reproduction is detected in step 2k. Thus, the video content is fast-forwarded and played in the forward direction at the playback speed (1.5 times speed) designated by the user.

  If the user changes the playback speed again during playback, the playback speed is reset to the newly specified playback speed in step 2b. Similarly, when the user changes the playback direction to “reverse direction” during playback, the playback direction is reset to the newly specified playback direction in step 2b. Thereafter, the video content playback process is continued at the playback speed and playback direction that have been reset.

  As described above, in this embodiment, when a reproduction request for the encoded video data stored in the storage unit 13 is input, first, I frames per unit time are extracted with reference to the marker information. Then, the total frame size of the extracted I frames per unit time is calculated, and compression is performed per unit time based on the reproduction speed designated by the user and the reproduction bit rate of the compression / decompression processor 7. An average data amount that can be decoded by the decompression processing unit 7 is obtained and set as a threshold value. Then, the calculated data amount is compared with the set threshold value, and when the data amount exceeds the threshold value, the I frame included in the unit time is thinned out in frame units. Further, a time stamp corresponding to the designated reproduction speed is reassigned to the designated reproduction direction with respect to the I frame after the thinning process, and the I frame to which the time stamp is reassigned is compressed and expanded. 7 for decoding.

  Therefore, according to this embodiment, for example, when performing double-speed playback, if the data amount of the intra-frame compressed frame per unit time exceeds the playback capability of the compression / decompression processing unit 7, the I frame per unit time is After the thinning process, a time stamp corresponding to the playback speed is given again. Therefore, double speed reproduction can be performed without increasing the reproduction bit rate of the compression / decompression processing unit 7.

  In addition, the I frame to be reproduced is first thinned out, and a time stamp is given to the I frame after the thinning out process for decoding and reproduction. For this reason, the signal processing amount required for the data decoding process is reduced as compared with the case where the decimation process is performed after decoding all the frames of the encoded data, thereby eliminating the need for a large-capacity memory and a high-speed processor. Cost reduction.

  Therefore, according to this embodiment, a portable terminal device capable of variable-speed playback of video content can be provided at low cost, and the highly useful portable terminal capable of reducing the size and weight of the device and extending the battery life. Equipment can be provided.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, when the total value of the frame sizes of the I frames I1 to I4 included in the unit time T1 of interest exceeds a threshold value, as shown in FIG. The I frame I4 located at the end in the reproduction direction is deleted. However, the present invention is not limited to this, and the last I frame I4 may be shifted into the subsequent unit time T2 as shown in FIG. In this way, high-quality fast-forward playback is possible as compared with the case where the I frame I4 is deleted.

  In the above embodiment, one of the plurality of I frames included in the unit time is deleted or shifted to the subsequent unit time. However, the total value of the frame sizes of the I frames included in the unit time. Depending on the relationship between and the processing capability of the compression / decompression processing unit 7, a plurality of I frames may be deleted or shifted to the subsequent unit time. Further, in this case, when deleting a plurality of I frames, it is preferable to delete frames at regular intervals without deleting consecutive frames.

  Further, the bit rate may be extracted from the video track information 5c inserted in the header portion 5a, and the threshold value may be calculated based on this bit rate, or the frame inserted in the header portion 5a. It is also possible to calculate the data size of the I frame based on the position / time / size information 5d.

  For example, if the playback bit rate of the content is 384 kbps, the threshold value is set to 48 kbytes. Here, if an attempt is made to play back a content that has an I-frame of 30 kbytes in 8 seconds at 8 times speed, there is only one I-frame of 30 kbytes per second. Without being decoded. On the other hand, if the playback speed is set to 16 times speed, there are two 30 kbyte I frames per second, so the total value of the data size is 60 kbytes. As a result, the second I frame is thinned out. Then, the I frame after the thinning process is decoded and reproduced.

In addition, the playback speed value and playback direction, the type and configuration of the mobile terminal device, the content playback control procedure and its contents, and the like can be variously modified without departing from the scope of the present invention.
In short, the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

The block diagram which shows the structure of the portable terminal device which is one Embodiment of the content reproduction apparatus concerning this invention. The flowchart which shows the content reproduction | regeneration control procedure and control content which are performed in the apparatus shown in FIG. The figure shown for demonstrating the content reproduction | regeneration control shown in FIG. The figure for demonstrating the content reproduction | regeneration control in other embodiment of this invention. The figure which shows an example of a structure of a stream file.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Antenna, 2 ... Antenna duplexer (DUP), 3 ... Reception circuit (RX), 4 ... Frequency synthesizer (SYN), 5 ... Transmission circuit (TX), 5a ... Header part, 5b ... Stream data part, 5c ... Video track information, 5d ... frame position / time / size information, 5e ... I frame position information, 6 ... CDMA signal processing unit, 7 ... compression / decompression processing unit, 8 ... PCM code processing unit (PCM codec), 9 ... receiving amplifier DESCRIPTION OF SYMBOLS 10 ... Speaker, 11 ... Microphone, 12 ... Control part, 12a ... Frame information analysis function, 12b ... Frame selection processing function, 12c ... Time stamp giving function, 13 ... Storage part, 14 ... Input part, 15 ... Display part, 16 ... battery, 17 ... power supply circuit, 18 ... transmission amplifier.

Claims (6)

The encoded stream data composed of the intra-frame compressed frame and the inter-frame compressed frame, the frame position information indicating the position in the stream data of the intra-frame compressed frame included in the encoded stream data, and the inter-frame compressed frame A content playback device that decodes and plays back a stream file including a header portion including marker information including size information indicating a data amount by a decoder having a predetermined playback bit rate,
Means for setting the playback speed according to the user's designated operation;
Means for extracting data of an intra-frame compressed frame included in a unit time starting from the input time point of the reproduction instruction based on the frame position information included in the marker information in response to the input of the reproduction instruction ;
Means for selecting a playback target frame from the extracted intra-frame compressed frames based on the set playback speed , the playback bit rate of the decoder, and the size information included in the marker information ;
Means for giving a time stamp corresponding to the set reproduction speed to the selected intra-compression frame to be reproduced;
Means for causing the decoder to decode the selected intra-frame compressed frame to be reproduced according to the given time stamp;
And means for selecting the frame to be played back,
Means for calculating a total value of the data amount of the intra-frame compressed frames included in the extracted unit time based on the size information included in the marker information ;
Means for setting, based on the reproduction bit rate of the set reproduction speed and the decoder, this as a threshold seeking the amount of data that can be decoded in the unit time,
Means for comparing the calculated total amount of data with the set threshold;
Means for performing a thinning process on a frame-by-frame basis for an intra-frame compressed frame included in the unit time when it is determined that the total value of the calculated data amount exceeds the threshold value as a result of the comparison; A content playback apparatus comprising: The means for selecting the frame to be reproduced, when performing the thinning process on the intra-frame compressed frame included in the unit time, selects the intra- frame compressed frame located at the end in the reproduction direction within the unit time. The content reproduction apparatus according to claim 1 , wherein the content reproduction apparatus is deleted. Means for selecting the reproduced frame, when performing the thinning process with respect to intra-frame compression frames included in the unit time, the intra-frame compression frame located rearmost respect reproducing direction within the unit time 2. The content reproduction apparatus according to claim 1 , wherein the content reproduction apparatus is moved within a subsequent unit time. The encoded stream data composed of the intra-frame compressed frame and the inter-frame compressed frame, the frame position information indicating the position in the stream data of the intra-frame compressed frame included in the stream data, and the inter-frame compressed frame This is a playback control program used in a content playback apparatus that decodes and plays back a header portion and a stream file including marker information including size information indicating the amount of data by a decoder having a predetermined playback bit rate under the control of the processor. And
Processing to set the playback speed according to the user's specified operation,
In response to an input of a playback instruction, based on frame position information included in the marker information , a process of extracting an intra-frame compressed frame existing within a unit time starting from the input time of the playback instruction ;
Based on the set playback speed, the playback bit rate of the decoder, and size information included in the marker information, a process of selecting a playback target frame from the extracted intra-frame compressed frames;
A process of giving a time stamp corresponding to the set reproduction speed to the selected intra-compression frame to be reproduced;
Causing the processor to execute a process of causing the decoder to decode the selected intra-frame compressed frame to be reproduced according to the assigned time stamp,
And the process of selecting the frame to be reproduced is
A total value of frame sizes of intra-frame compressed frames existing within the extracted unit time is calculated based on size information included in the marker information ,
Based on the reproduction bit rate of the set reproduction speed and the decoder, which is set as a threshold seeking the amount of data that can be decoded in the unit time,
The calculated total frame size value is compared with the set threshold value, and when the total frame size value exceeds the threshold value , the intra-frame compressed frame existing within the unit time is determined in frame units. A reproduction control program characterized by selective thinning. The process of selecting the frame to be played back includes an intra-frame compression located at the end in the playback direction within the unit time when the intra-frame compressed frame existing within the unit time is selectively thinned out in the frame unit. 5. The reproduction control program according to claim 4, wherein the frame is deleted. The process of selecting the frame to be played back includes an intra-frame compression located at the end in the playback direction within the unit time when the intra-frame compressed frame existing within the unit time is selectively thinned out in the frame unit. 5. The reproduction control program according to claim 4 , wherein the frame is moved within a subsequent unit time.

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