JP2005037743A - Information processor, method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure that the exact reproduction time of data of a variable bit rate can be rapidly calculated. <P>SOLUTION: In processing of a step S 13, speech data is divided to blocks of any number of 8 to 32. In processing of a step S 15, the portions of amounts of data of any among 4 K bytes to 8 K bytes are extracted from each of the divided blocks. In processing of a step S 17, a bit rate index indicating a bit rater is read out of the respective header of the extracted portions. In processing of a step S 19, the reproduction time of the speech data is calculated from the average of the bit rates shown by the bit rate indices and the amount of the data over the entire part of the speech data. The method is applicable to a PDA which calculates the reproduction time of the speech data compressed and encoded by the variable bit rate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an information processing apparatus, method, and program, and more particularly, to an information processing apparatus, method, and program for calculating the reproduction time of compression-encoded data.

  Audio data that has been compression-encoded has been widely used.

  There are roughly two types of audio data compression coding methods: a fixed bit rate and a variable bit rate. In compression coding at a variable bit rate, the bit rate is changed based on the change in the audio signal at that time, the change in the audio signal before and after the change.

  When displaying the playback time of such variable bit rate audio data, all the audio data is read, the number of frames is obtained, and playback is performed from the number of samples stored in the frame, the number of frames, and the sampling frequency. You can ask for time.

  However, when displaying the playback time of variable bit rate audio data before playback, when trying to display the correct playback time, it is necessary to determine the number of frames included in the audio data from the entire audio data, There was a problem that it took time to display. In this case, it takes time to start reproduction.

  On the other hand, when promptly displaying the playback time, there is a problem that a playback time with a large error, which is greatly different from the actual playback time, is displayed.

  An information processing apparatus according to the present invention includes a dividing unit that divides data into a plurality of blocks, an extracting unit that extracts a predetermined amount of data from each of the plurality of blocks, and a bit rate from each of the extracted portions. And a calculating means for calculating the reproduction time of the data from the average bit rate indicated by the information and the data amount of the entire data.

  The dividing means can divide the data into any number of blocks from 8 to 32.

  The extracting means can extract a portion from each of the blocks other than the head block of the data.

  The extraction means can extract a portion having a data amount of 4 Kbytes to 8 Kbytes from each of the plurality of blocks.

  An information processing method according to the present invention includes a dividing step of dividing data into a plurality of blocks, an extracting step of extracting a predetermined amount of data from each of the plurality of blocks, and a bit rate from each of the extracted portions. And a calculation step of calculating a data reproduction time from the average bit rate indicated by the information and the data amount of the entire data.

  The program according to the present invention includes a dividing step for dividing data into a plurality of blocks, an extracting step for extracting a predetermined amount of data from each of the plurality of blocks, and a bit from each of the extracted portions. A read step for reading information indicating a rate, and a calculation step for calculating a data reproduction time from the average bit rate indicated by the information and the data amount of the entire data are executed.

  The information processing apparatus may be an independent apparatus, or may be a block that performs information processing of an audio player, for example.

  In the information processing apparatus, method, and program of the present invention, data is divided into a plurality of blocks, a portion having a predetermined data amount is extracted from each of the plurality of blocks, and a bit rate is calculated from each of the extracted portions. Is read out, and the data reproduction time is calculated from the average bit rate indicated by the information and the data amount of the entire data.

  Accurate playback time of variable bit rate data can be calculated quickly.

  Embodiments of the present invention will be described below. The correspondence relationship between the invention described in this specification and the embodiments of the invention is exemplified as follows. This description is intended to confirm that the embodiments supporting the invention described in this specification are described in this specification. Therefore, although there is an embodiment which is described in the embodiment of the invention but is not described here as corresponding to the invention, it means that the embodiment is not It does not mean that it does not correspond to the invention. Conversely, even if an embodiment is described herein as corresponding to an invention, that means that the embodiment does not correspond to an invention other than the invention. Absent.

  Further, this description does not mean all the inventions described in this specification. In other words, this description is for the invention described in the present specification, which is not claimed in this application, that is, for the invention that will be applied for in the future or that will appear and be added by amendment. It does not deny existence.

  The information processing apparatus according to claim 1 includes: a dividing unit that divides data into a plurality of blocks (for example, the CPU 11 in FIG. 1 that executes the process of step S13 in FIG. 2); Extraction means for extracting a portion of the data amount (for example, the CPU 11 of FIG. 1 that executes the process of step S15 of FIG. 2) and reading means for reading information indicating the bit rate from each of the extracted portions (for example, FIG. CPU 11 of FIG. 1 that executes the process of step S16 of 2), a calculation means for calculating the data reproduction time from the average of the bit rate indicated by the information and the data amount of the entire data (for example, step S19 of FIG. 2) And the CPU 11) of FIG.

  FIG. 1 is a block diagram showing a configuration of an embodiment of a PDA 1 according to the present invention. A CPU (Central Processing Unit) 11 executes various programs such as an operating system stored in an SDRAM (Synchronous Random Access Memory) 12 or a flash memory 13, or application programs and class libraries.

  The SDRAM 12 stores a program executed by the CPU 11 and parameters that appropriately change during the execution. The flash memory 13 is a kind of EEPROM (Electrically Erasable Programmable Read Only Memory), and generally stores basically fixed data among programs used by the CPU 11 and calculation parameters.

  A buffer 14 is connected to the CPU 11 via a bus common to the flash memory 13. The wireless LAN interface 15 is connected to the CPU 11 via the buffer 14. The wireless LAN interface 15 wirelessly communicates with other devices or access points based on standards such as IEEE (Institute of Electrical and Electronic Engineers) 802.11a, IEEE802.11b, or IEEE802.11g, and transmits and receives data or commands. To do. The buffer 14 temporarily stores data supplied from the CPU 11 and transmitted by the wireless LAN interface 15, or temporarily stores data received by the wireless LAN interface 15 and supplied to the CPU 11.

  The Bluetooth interface 16 wirelessly communicates with other devices based on the Bluetooth standard and transmits / receives data or commands.

  The display unit 17 includes an LCD (Liquid Crystal Display) 41 and a touch pad 42. The LCD 41 displays an image such as an icon, thumbnail, or text based on the data supplied from the CPU 11. The touch pad 42 is provided so as to be stacked on the LCD 41.

  For example, the display unit 17 reads data in a video memory area assigned to a specific address on the SDRAM 12 via the CPU 11 at a predetermined timing, and displays an image on the LCD 41 based on the read data.

  The display unit 17 is not limited to the LCD 41, and a thin display device such as an organic EL (Electro Luminescence) display device may be provided.

  The touch pad 42 supplies data (for example, data of coordinates indicating the instructed position) corresponding to the operation of instructing the position by pressing to the CPU 11. The user inputs predetermined data or operation instructions to the PDA 1 by pressing the touch pad 42 stacked on the LCD 41 with a finger or a pen.

  The display unit 17 is not limited to the touch pad 42 that senses pressure due to pressing, but may be provided with an input device that detects a position electromagnetically, such as a digitizer or a tablet. Alternatively, a mouse may be connected to the PDA 1 via a USB (Universal Serial Bus) interface 22, and the PDA 1 may acquire a position instruction using the mouse.

  The camera unit 18 is a camera that uses a CCD (Charge Coupled Device) or CMOS (Complementary Metal-Oxide Semiconductor) sensor as a light receiving element. Under the control of the CPU 11, the camera unit 18 captures a still image or a moving image, The obtained image data is supplied to the CPU 11.

  The audio encoding / decoding unit 19 decodes the encoded audio data supplied from the CPU 11 under the control of the CPU 11, converts it into an analog audio signal, and supplies the audio signal to a speaker or headphones. To do. Also, the audio encoding / decoding unit 19 converts the analog audio signal supplied from the microphone into digital data under the control of the CPU 11, encodes it, and supplies the audio data obtained as a result to the CPU 11. .

  The keyboard controller 20 controls the keyboard and supplies data for the signal supplied from the keyboard to the CPU 11. The power control unit 21 monitors the voltage of the power supplied from a battery (not shown) or a connected AC (Alternating Current) adapter, etc. To control the supply.

  The USB (Universal Serial Bus) interface 22 is an interface for connecting to a USB device based on the USB standard. For example, the USB interface 22 is connected to a drive 51, which is a USB device, as necessary, and inputs data or a program from the connected drive 51 and supplies the data supplied from the CPU 11 to the drive 51. .

  The drive 51 reads data or a program recorded in the magnetic disk 61, the optical disk 62, the magneto-optical disk 63, or the semiconductor memory 64 that is mounted as necessary, and the data or program is read through the USB interface 22. To the CPU 11 or the SDRAM 12. The drive 51 records data or a program on the magnetic disk 61, the optical disk 62, the magneto-optical disk 63, or the semiconductor memory 64 that is mounted.

  The memory card interface 23 acquires a program or data supplied from a memory card installed in a memory card slot (not shown), and supplies various data supplied from the CPU 11 to the installed memory card.

  The jog dial 24 supplies the CPU 11 with a signal corresponding to a rotation operation or a pressing operation by the user. For example, the jog dial 24 receives a rotation operation or a pressing operation to the main body when an icon, thumbnail, text, or the like displayed on the display unit 17 is selected by the user. For example, when the jog dial 24 is rotated while a plurality of icons are displayed on the display unit 17, a desired icon is selected from the plurality of icons and the jog dial 24 is pressed toward the main body. The selected icon is confirmed. If the determined icon corresponds to the application program, the application program is activated.

  The infrared communication unit 25 transmits the data supplied from the CPU 11 as an infrared signal to another device, receives the infrared signal transmitted from the other device, and supplies the CPU 11 with data for the received infrared signal. .

  Next, for example, in the PDA 1 that executes an MP3 (Moving Pictures Experts Group 1 Audio Layer 3) playback program, the playback time of the audio data compressed and encoded in the MP3 format by the calculation program that is a module of the MP3 playback program The calculation process will be described.

  FIG. 2 is a flowchart for explaining processing for calculating the performance time (reproduction time) of audio data compression-encoded by the MP3 method by the PDA 1 that executes the calculation program. In step S11, the calculation program reads an audio file. For example, the calculation program reads from the flash memory 13 an audio file that stores audio data that has been compression-encoded by the MP3 method.

  FIG. 3 is a diagram showing the structure of an MP3 audio file. In the audio file, a tag 112 is added before the audio data 101 and a tag 113 is added after the audio data 101.

  In step S12, the calculation program removes the tag from the audio file. For example, in order to extract audio data from the audio file, the calculation program removes the tag 112 and the tag 113 which are additional data added before or after the audio data from the read audio file.

  In step S13, the calculation program divides the audio data 101 into divided blocks. For example, as illustrated in FIG. 3, the calculation program equally divides the audio data 101 obtained by removing the tag 112 and the tag 113 into 16 to obtain divided blocks 111-1 to 111-16.

  Note that an appropriate value can be arbitrarily adopted as the number of the audio data 101 divided according to the actual use environment. In this case, if the number of divisions is too small, the accuracy will be insufficient, and if the number of divisions is too large, the speed will be insufficient. In particular, when dividing into any of 8 to 32, , Can quickly determine the exact playback time.

  In step S14, the calculation program discards the first divided block. That is, the calculation program discards the divided block 111 located at the head of the audio data 101 among the divided blocks obtained by the division.

  This is because the sound data of music usually has a silent part before the performance is started. In variable bit rate encoding, the silent part is compression encoded into less data, so the bit rate of the silent part is small. If the playback time is calculated including the bit rate of the silent part, it is impossible to calculate the correct playback time. Therefore, the reproduction time is calculated more accurately by removing a portion having a bit rate that is clearly smaller than the overall bit rate.

  For example, the divided block 111-1 in FIG. 3 is discarded, and the divided blocks 111-2 to 111-16 are subjected to the processing after step S15.

  In step S15, the calculation program extracts a header read block from each divided block. For example, the calculation program extracts a predetermined amount of data from each of the divided blocks 111-2 to 111-16 as a header read block 114-1 to a header read block 114-15. More specifically, for example, as shown in FIG. 3, the calculation program reads the header portion of the data amount portion of 8 Kbytes from the head of each of the divided blocks 111-2 to 111-16. 1 to header reading block 114-15 are extracted.

  Note that the data amount of the portion extracted from each of the divided blocks 111-2 to 111-16 is not limited to 8 Kbytes, and an appropriate value can be arbitrarily adopted according to the actual use environment. If the amount of data is too small, the accuracy will be lacking, and if the amount of data is too large, the speed will be lacking. Therefore, especially when extracting any part of the data amount from 4 Kbytes to 8 Kbytes. , Can quickly determine the exact playback time.

  Hereinafter, when it is not necessary to individually distinguish the header reading block 114-1 to the header reading block 114-15, they are simply referred to as a header reading block 114.

  In step S <b> 16, the calculation program reads the header from each header reading block 114.

  FIG. 4 is a diagram illustrating a header structure of audio data that has been compression-encoded by the MP3 method. A synchronization word composed of 12 bits “1” is arranged at the head of the header, and an ID of 1 bit “1” is arranged following the synchronization word. The header further stores data such as layer, protection bit, bit rate index, sampling frequency, padding bit, private bit, mode, mode extension, copyright, original / copy, and emphasis.

  In the 17th to 20th bits from the beginning of the header, a bit rate index indicating the bit rate of the AAU (Audio Access Unit) to which the header is attached is stored. AAU is an example of a frame. As shown in FIG. 5, when the 4-bit bit rate disk is 1 (binary number “0001”), the AAU bit rate is 32 Kbps and 2 (binary number “0010”). When the AAU bit rate is 40 Kbps and 3 (binary “0011”), the AAU bit rate is 48 Kbps and 4 (binary “0100”). The bit rate is 56 Kbps, and when it is 5 (binary “0101”), the AAU bit rate is 64 Kbps.

  Similarly, when the 4-bit bit rate in disk is 6 (binary “0110”), the AAU bit rate is 80 Kbps, and when 7 (binary “0111”), the AAU bit When the rate is 96 Kbps, 8 (binary number “1000”), the AAU bit rate is 112 Kbps, and when 9 (binary number “1001”), the AAU bit rate is 128 Kbps. And 10 (binary “1010”), the AAU bit rate is 160 Kbps.

  Further, when the 4-bit bit rate in disk is 11 (binary “1011”), the AAU bit rate is 192 Kbps, and when 12 (binary “1100”), the AAU bit rate. Is 224 Kbps, 13 (binary “1101”), the AAU bit rate is 256 Kbps, and 14 (binary “1110”), the AAU bit rate is 320 Kbps. is there.

  As described above, in step S <b> 16, the calculation program reads a header including information indicating the bit rate from each header reading block 114. For example, as shown in FIG. 3, the calculation program reads N headers 115-1-1 to 115-1-N from the header reading block 114-1. Similarly, the calculation program reads all the arranged headers from each of the header reading block 114-2 to the header reading block 114-15. The calculation program reads M headers 115-15-1 to 115-15-M from the header reading block 114-15.

  In this case, for example, the calculation program detects a 32-bit header by detecting a synchronization word composed of 12 bits of “1”, and reads the detected header.

  Returning to FIG. 2, in step S <b> 17, the calculation program acquires a bit rate index, which is an example of information indicating the bit rate, from each header. That is, for example, as described above, since the bit rate index is arranged at the 17th to 20th bits from the beginning of the header, the calculation program stores the data at the 17th to 20th bits from the beginning of the header. By extracting, a bit rate index is acquired.

  In step S18, the calculation program obtains the average bit rate. For example, the calculation program obtains the bit rate based on the correspondence between the bit rate index and the bit rate shown in FIG. 5 for each of the bit rate indexes obtained in the process of step S17, and obtains the obtained bit. Calculate the average rate.

  More specifically, for example, the calculation program converts each of the bit rate indexes having values of 0 to 15 acquired from the headers 115-11-1 to 115-15-M to 32 Kbps, 40 Kbps, and 48 Kbps. , 56 Kbps, 64 Kbps, 80 Kbps, 96 Kbps, 112 Kbps, 128 Kbps, 160 Kbps, 192 Kbps, 224 Kbps, 256 Kbps, or 320 Kbps, add all the bit rates obtained by the conversion, and the result The average bit rate is calculated by dividing by the number of headers.

  In step S19, the calculation program obtains the performance time (reproduction time) from the average bit rate obtained in the process of step S18 and the data amount of the audio data 101.

For example, the calculation program calculates a performance time (reproduction time) based on Expression (1).
Performance time (seconds) = amount of data (bytes) x 8 / average bit rate (Kbps) (1)

  In step S20, the calculation program displays the performance time obtained in the process of step S19 on the LCD 41 of the display unit 17, and the process ends.

  As described above, the PDA 1 can calculate the reproduction time of the audio data compressed and encoded at the variable bit rate from a part of the audio data, so that the reproduction time can be quickly obtained.

  Next, the results of comparison between the performance time (reproduction time) calculated by the present invention and the actual performance time (hereinafter referred to as actual performance time) are shown for three examples of audio data. In the example shown below, the sampling frequency of audio data is 44.1 KHz.

In the results shown below, the actual performance time was calculated by equation (2).
Actual performance time (seconds) = total number of frames x 1152/44100 (2)
In Equation (2), the number of frames corresponds to the number of AUUs, and 1152 indicates the number of samples per frame. In Expression (2), 44100 indicates a sampling frequency.

  The data amount of the first audio data was 4484110 bytes, and the total number of frames was 10832. The actual performance time of the first audio data was 282.958 seconds from Equation (2).

  On the other hand, the performance time (reproduction time) calculated according to the present invention was calculated to be 282.466 seconds from Equation (1) because the average bit rate was 127 Kbps. When this is compared with the actual performance time, from (282.958-282.466) /282.958 = 0.00173, it can be seen that the performance time error calculated by the present invention is 0.17%.

  The data amount of the second audio data was 5168491 bytes, and the total number of frames was 10845. The actual performance time of the second audio data was 283.298 seconds from the equation (2).

  On the other hand, the performance time (reproduction time) calculated according to the present invention was calculated as 279.377 seconds from the equation (1) because the average bit rate was 148 Kbps. When this is compared with the actual performance time, (283.298-279.377) /283.298 = 0.01384, it can be seen that the error in the performance time calculated by the present invention is 1.38%.

  The data amount of the third audio data was 5030774 bytes, and the total number of frames was 10671. The actual performance time of the third audio data was 278.753 seconds from Equation (2).

  On the other hand, the performance time (reproduction time) calculated according to the present invention was calculated as 275.541 seconds from Equation (1) because the average bit rate was 147 Kbps. When this is compared with the actual performance time, (278.753-275.541) /278.753 = 0.01152, it can be seen that the performance time error calculated by the present invention is 1.15%.

  As described above, in the present invention, it is possible to accurately and quickly obtain the reproduction time of the variable bit rate data.

  The audio data has been described as being compressed and encoded by the MP3 system. However, the audio data is not limited to the MP3 system, and is compressed and encoded at a predetermined bit rate for each predetermined unit (for example, a frame). If it is audio data of a system to which data indicating a rate is attached, the reproduction time can be calculated according to the present invention.

  The PDA 1 has been described as an example of the information processing apparatus. However, the PDA 1 is not limited to the PDA, but may be another type of apparatus that handles sound, such as a portable player, a personal computer, and a mobile phone.

  Note that the playback time of moving image data is not limited to audio data, and may be calculated.

  In this way, when the data reproduction time is calculated from the bit rate and the data amount of the entire data, the data reproduction time can be calculated. Further, the data is divided into a plurality of blocks, a portion having a predetermined data amount is extracted from each of the plurality of blocks, information indicating the bit rate is read from each of the extracted portions, and the bit rate indicated by the information When the data reproduction time is calculated from the average of the data and the data amount of the entire data, the accurate reproduction time of the variable bit rate data can be quickly calculated.

  The series of processes described above can be executed by hardware, but can also be executed by software. When a series of processing is executed by software, a program constituting the software may execute various functions by installing a computer incorporated in dedicated hardware or various programs. For example, it is installed from a recording medium in a general-purpose personal computer or the like.

  As shown in FIG. 1, the recording medium is distributed to provide a program to a user separately from the computer, and includes a magnetic disk 61 (including a flexible disk) on which the program is recorded, an optical disk 62 (CD- ROM (Compact Disc-Read Only Memory), DVD (including Digital Versatile Disc)), magneto-optical disk 63 (including MD (Mini-Disc) (trademark)), or semiconductor memory 64, etc. In addition, it is configured by a ROM, a hard disk, or the like that stores a program and is provided to the user in a state of being pre-installed in a computer.

  The program for executing the series of processes described above is installed in a computer via a wired or wireless communication medium such as a local area network, the Internet, or digital satellite broadcasting via an interface such as a router or a modem as necessary. You may be made to do.

  Further, in the present specification, the step of describing the program stored in the recording medium is not limited to the processing performed in chronological order according to the described order, but is not necessarily performed in chronological order. It also includes processes that are executed individually.

It is a block diagram which shows the structure of one Embodiment of PDA based on this invention. It is a flowchart explaining the process which calculates performance time. It is a figure explaining the header which a calculation program reads. It is a figure which shows the structure of the header of audio | voice data. It is a figure explaining a response | compatibility with a bit rate index and a bit rate.

Explanation of symbols

  1 PDA, 11 CPU, 12 SDRAM, 13 Flash memory, 15 Wireless LAN interface, 17 Display unit, 19 Audio encoding / decoding unit, 61 Magnetic disk, 62 Optical disk, 63 Magneto-optical disk, 64 Semiconductor memory, 101 Audio data, 111-1 thru | or 111-16 division | segmentation block, 114-1 thru | or 114-15 header read block, 115-1-1 thru | or 115-15-M header

Claims (6)

In an information processing apparatus for calculating the reproduction time of compression-encoded data,
Dividing means for dividing the data into a plurality of blocks;
Extraction means for extracting a predetermined amount of data from each of the plurality of blocks;
Read means for reading out information indicating the bit rate from each of the extracted portions;
An information processing apparatus comprising: calculating means for calculating the reproduction time of the data from an average of the bit rate indicated by the information and a data amount of the entire data. The information processing apparatus according to claim 1, wherein the dividing unit divides the data into any number of 8 to 32 blocks. The information processing apparatus according to claim 1, wherein the extraction unit extracts the portion from each of the blocks other than the first block of the data in the block. The information processing apparatus according to claim 1, wherein the extraction unit extracts the portion having a data amount of 4 Kbytes to 8 Kbytes from each of the plurality of blocks. In an information processing method for calculating a reproduction time of compression-encoded data,
A dividing step of dividing the data into a plurality of blocks;
An extraction step of extracting a predetermined amount of data from each of the plurality of blocks;
A reading step of reading information indicating a bit rate from each of the extracted portions;
An information processing method comprising: calculating the reproduction time of the data from an average of the bit rates indicated by the information and a data amount of the entire data. In a program for causing a computer to perform a process of calculating a reproduction time of compression-encoded data,
A dividing step of dividing the data into a plurality of blocks;
An extraction step of extracting a predetermined amount of data from each of the plurality of blocks;
A reading step of reading information indicating a bit rate from each of the extracted portions;
And a calculation step of calculating the reproduction time of the data from an average of the bit rate indicated by the information and a data amount of the entire data.

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