JP2008269745A - Reproducing device, program, and reproducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To save power consumption as much as possible in a reproducing device. <P>SOLUTION: The reproducing device is provided with a read-out means 12 reading out data of contents to be reproduced, a decoding means 13 decoding data read out from the read-out means, a buffer means 21 accumulating successively data already recorded which is obtained by the decoding means, a control means 23 controlling output of already recorded data accumulated in the buffer means, and a control means in which when the already recorded data is output by the control means, the read-out means and the decoding means are operated intermittently based on residual quantity of the buffer means output by control of the control means, and the read-out means and the decoding means are shifted to a stop state during non-operation in intermittent operation. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a playback apparatus that decodes and reproduces content data, a program that causes a computer to function as the apparatus, and a playback method that decodes and plays back content data.

  In a DAC (D / A converter), a data buffer necessary for receiving input data is usually provided, and digital data input to the data buffer is converted into analog data in synchronization with an input clock. Is converted and output. In the case of an MD player, a player using a hard disk, a flash memory, or the like, data to be reproduced is often compressed, and is decompressed before being input to the DAC. Many portable players have a data buffer so that the reproduced sound is not interrupted even if data cannot be temporarily read from the recording medium due to vibration or the like.

  FIG. 4 shows a conventional example of a reproducing apparatus having such a data buffer. However, in the figure, only the part related to the flow of the audio signal and the control microcomputer are shown. In the figure, 41 is a control microcomputer for controlling each part, 42 is a data reading part for reading data from an MD (mini disk) or the like, 43 is a data buffer for temporarily storing data from the data reading part 42, 44 is A decoder 45 is sequentially input to the data buffer 43 and sequentially reads and decodes the stored data, and 45 is a DAC that converts the data from the decoder 44 into an analog signal. The data buffer 43 is provided for the purpose of preventing sound skipping.

  In this configuration, when an instruction to start reproduction is given, the control microcomputer 41 starts an operation of reading data from the MD or the like by the data reading unit 42 and inputting it to the data buffer 43. When the amount of data stored in the data buffer 43 exceeds a predetermined value, conversion of the stored data by the data code by the decoder 44 and the DAC 45 is started. Usually, in such a reproducing apparatus, the reading rate by the data reading unit 42 is faster than the data conversion rate in the DAC 45, so that the data buffer 43 becomes full when the data reading unit 42 operates for a while.

  At this time, for the purpose of power saving, the control microcomputer 41 stops the operation of the data reading unit 42 and controls only the circuits after the data buffer 43 to operate. Thereafter, when the amount of data stored in the data buffer 43 decreases and reaches a predetermined value, the control microcomputer 41 resumes the reading operation by the data reading unit 42. In this manner, the control microcomputer 41 can perform the reproduction operation while intermittently operating the data reading unit 42 to save power.

  Here, in the configuration of FIG. 4, the data buffer 43 is provided in the preceding stage of the decoder 44, but this can be stored in the unit memory capacity by buffering the compressed data. This is because the actual reproduction time per data can be increased. For example, when the data from the data reading unit 42 is data obtained by compressing original data of 1.4 [Mbps] (44.1 [kHz] × 2 × 16 [bit]) to 320 [kbps], the decoder 44 Is stretched about 4.5 times. Therefore, according to the configuration of FIG. 4, about 4.5 times as much data can be stored in the data buffer 44 as the data after being decompressed by the decoder 44 is buffered.

  On the other hand, as a conventional example of a CD player using a CD drive connected by ATAPI or SCSI interface, a technique described in Patent Document 1 is also known. Since this technique is intended for a CD player, data read from the CD is not compressed and a decoder is not necessary. Therefore, the data buffer is located in front of the DAC. What is characteristic in this technique is that a first buffer and a second buffer are prepared, and the respective buffers are connected via an interface circuit.

JP 2002-260324 A

  However, according to the prior art of FIG. 4 described above, the decoder 44 continues to operate in addition to the data buffer 43 and the DAC 45 even after the data buffer 43 is full and the data reading unit 42 shifts to the sleep state. Yes. As the decoder 44, hardware corresponding to the codec corresponding to various data input from the data reading unit 42 may be prepared, respectively, but when implemented by software using a general-purpose DSP (Digital Signal Processor) There is also. Therefore, according to the configuration as shown in FIG. 4, in order to be able to cope with a codec that requires a large processing capacity, the redundancy is inevitably large. As a result, power from unnecessary circuits may be wasted inside the DSP.

  On the other hand, in the conventional technique in which the above-described first and second buffers are connected by an interface circuit, a decoder is not necessary, but a configuration in which an interface circuit or the like is provided is adopted, so that it is necessary to reduce power consumption. Not suitable for portable audio equipment.

  An object of the present invention is to reduce power consumption as much as possible in a reproducing apparatus in view of such problems of the prior art.

  In order to achieve this object, a playback apparatus according to a first aspect of the present invention includes a reading means for reading content data to be played back, a decoding means for decoding data read by the reading means, and a decoded data obtained by the decoding means. Buffer means for sequentially storing the data, control means for controlling the output of the decoded data stored in the buffer means, and when the decoded data is output by the control means, the reading means and the decoding means are controlled by the control means. Control means for intermittently operating based on the remaining capacity of the buffer means output by the control, and for causing the reading means and the decoding means to transition to a sleep state when not operating in the intermittent operation. . Here, the content corresponds to, for example, music content or video content. As the data, for example, compressed data in a format such as MP3 or WMA is applicable.

  In this configuration, the content data to be reproduced is read by the reading means, decoded by the decoding means, and then sequentially stored in the buffer means. The accumulated decoded data is sequentially output from the buffer means under the control of the control means. For example, the output data is converted into an analog signal by a DA conversion means and output as a reproduction signal. At that time, the reading means and the decoding means operate intermittently based on the remaining capacity of the buffer means, and shift to a dormant state when not operating. According to this, in addition to the reading means, the decoding means also operates intermittently and is in a pause state when not in operation, so that it is possible to further save power compared to the conventional case where the decoding means is always operating.

  According to a second aspect of the present invention, there is provided a reproducing apparatus according to the first aspect, wherein a first clock generation unit that generates an operation clock supplied to the control unit and a second operation clock that generates an operation clock supplied to the control unit Clock generation means, and the operation of the first clock generation means is stopped when the reading means and the decoding means are not in operation.

  According to a third aspect of the present invention, there is provided a reproducing apparatus according to the first aspect, further comprising clock generating means for generating an operation clock to be supplied to the control means and the control means, and to the control means when the reading means and decoding means are not operating. The operation clock supply is stopped, or the control means is shifted to a stopped state.

  A program according to a fourth invention causes a computer to function as each means in the playback device according to any one of the first to third inventions.

  According to a fifth aspect of the present invention, there is provided a reproducing method for reading content data to be reproduced by a reading unit, a decoding step for decoding data read by the reading unit by a decoding unit, and a decoded data obtained by the decoding unit. A buffering step for sequentially storing data by the buffer means, a control step for controlling the output of the decoded data stored in the buffer means by the control means, and at the time of outputting the decoded data by the control means, the reading means and The decoding means is operated intermittently based on the remaining capacity of the buffer means output by the control of the control means, and the reading means and the decoding means are put into a sleep state when not operating in the intermittent operation. Characterized by comprising a control step of shifting to.

  According to the present invention, since the reading means and the decoding means are intermittently operated and are shifted to a dormant state when not operating, it is possible to further save power compared to the conventional case where the decoding means is always operating. it can.

  FIG. 1 is a block diagram showing the configuration of a playback apparatus according to an embodiment of the present invention. In this reproducing apparatus, it is possible to pause the codec by buffering the data expanded by the decoder. Although a data buffer having a larger capacity than before is required as a data buffer, in recent years, the price of memory has been reduced, and a large-capacity data buffer can be prepared at low cost.

  As shown in the figure, the playback apparatus includes an intermittent operation block 10 that operates intermittently and a continuous operation block 20 that performs continuous operation. The intermittent operation block 10 includes: a control microcomputer 11 that controls each part of the apparatus; a data reading unit 12 that reads audio and image content data; a decoder 13 that decodes data from the data reading unit 12; A clock generation circuit 14 that supplies an operation clock and a display unit 15 that displays information provided from the control microcomputer 11 to the user are provided. As the data reading unit 12, any data can be used as long as it can store audio data and image data. For example, in addition to flash memory and hard disk drive, MD and the like are applicable.

  The constantly operating block 20 includes a data buffer 21 that temporarily stores the decoded data from the decoder 13, a DAC 22 that sequentially converts the data temporarily stored in the data buffer 21 into an analog signal, and a data storage amount in the data buffer 21. A memory controller 23 that monitors and controls data input from the decoder 13 to the data buffer 21, a DAC 22, an audio master clock generation circuit 24 that supplies an operation clock to the memory controller 23, and a control microcomputer 11 A key input unit 25 is provided for the user to give instructions. The master clock for audio supplied by the master clock generation circuit 24 has a frequency that is a multiple of the sampling frequency of the content data to be reproduced.

  For example, if this playback device is a portable playback device, it is often battery-powered, so it is necessary to reduce power consumption as much as possible. Therefore, a configuration in which the first and second buffers are connected via the interface circuit as described in the background art section is not employed. The data buffer 21 and the DAC 22 are always operated, and each circuit of the intermittent operation block 10 including the control microcomputer 11 is intermittently put into a sleep state to save power. The clock supply source is also divided into a clock generation circuit 14 for the control microcomputer 11 and an audio clock generation circuit 24, and only the audio clock generation circuit 24 is operated during the suspension of the clock generation circuit 14. I have to.

  In recent portable audio devices, the display unit is turned off when there is no key operation. Also in this embodiment, the portion of the intermittent operation block 10 operates intermittently as necessary. That is, when there is a key operation by the user at the key input unit 25, the control microcomputer 11 returns from the hibernation state based on the interrupt control signal from the key input unit 25 and turns on the display unit 15. When the remaining capacity of the data buffer 21 is reduced, the control microcomputer 11 resumes operation based on the interrupt control signal from the memory controller 23, reads the subsequent data by the data reading unit 12, and decompresses it by the decoder 13. The data is stored in the data buffer 21 via the memory controller 23. After all the data to be reproduced is read out, all the data in the data buffer 21 is output and the reproduction operation is terminated.

  FIG. 2 is a flowchart showing the operation of the playback apparatus. When receiving a reproduction instruction via the key input unit 25, the control microcomputer 11 starts reading data by the data reading unit 12 such as a flash memory or a hard disk drive (step S1). Next, the read data is decoded by the decoder 13, and an operation of buffering to the data buffer 21 via the memory controller 23 is started (step S2). Note that a clock for writing to the data buffer 21 by the memory controller 23 is supplied from the control microcomputer 11.

  The data sequentially stored in the data buffer 21 is sequentially read through the memory controller 23 at an actual reproduction speed slower than the storage speed, converted into an analog audio signal by the DAC 22, and output. That is, the operation in the constant operation block 20 is continuously performed so that the reproduction signal is not interrupted.

  Next, it is determined whether or not all reading has been completed for the data to be reproduced (step S3). If it is determined that the processing has not ended, it is determined whether or not the amount of data stored in the data buffer 21 is equal to or greater than a predetermined value (step S4). If it is determined that the value is not equal to or greater than the predetermined value, the process returns to step S3 and further buffering is continued.

  If it is determined in step S3 that all data has been read, and if it is determined in step S4 that the amount of accumulated data is greater than or equal to a predetermined value, the process proceeds to step S5, and the operation of each unit in the intermittent operation block 10 is performed. Pause. The operation of the clock generation circuit 14 is also stopped. This is to save power. While in the dormant state, the memory controller 23 monitors whether the capacity of the accumulated data in the data buffer 21 becomes equal to or less than a predetermined value (step S6).

  Even in the hibernation state, if there is a key operation by the user at the key input unit 25, the control microcomputer 11 together with the clock generation circuit 14 is in the hibernation state based on the interrupt control signal from the key input unit 25. The display unit 15 is turned on. Thereafter, when there is no key operation for a certain time, the display unit 15 is turned off.

  When it is detected that the capacity of the accumulated data has become equal to or less than the predetermined value, the memory controller 23 generates an interrupt control signal (step S7). Based on this, the control microcomputer 11 restarts the operation together with the clock generation circuit 14 ( In step S8, it is determined whether there is a continuation in the data to be reproduced (step S9). If it is determined that there is a continuation of data, the data reading unit 12 and the decoder 13 are set in an operating state (step S10), the process returns to step S1, and buffering is resumed in the same manner as described above. If it is determined that there is no continuation of data, it is monitored that there is no accumulated data in the data buffer 21 (step S11), and when there is no accumulated data, the processing in FIG.

  According to the present embodiment, the circuit in the intermittent operation block 10 including the control microcomputer 11 is paused when there is a key operation and when the capacity of the accumulated data in the data buffer 21 is not more than a predetermined value. Therefore, power consumption can be reduced. In particular, the decoder 13 has a redundant portion such as a decoding function for the WMA format not being decoded, in addition to a decoding function for the MP3 format being decoded. Therefore, the power saving can be effectively achieved by stopping the decoding 13.

  Further, since the constantly operating block 20 is operated with the master clock for audio generated by the master clock generation circuit 24, the clock for the control microcomputer 11 from the clock generation circuit 14 is intermittently stopped to further reduce power consumption. In addition, the quality of the output reproduction signal can be improved and the reproduction sound quality and reproduction image quality can be improved. That is, an audio master clock having an integer multiple of the sampling frequency (44.1 [kHz] × 256 or the like) can be used, which leads to improvement in sound quality. Even if an attempt is made to convert a clock for a microcomputer by a PLL circuit to generate a clock having such a frequency, there is an effect of jitter and the accuracy is not high, so that a good sound quality cannot be obtained. By using a clock source dedicated to audio, it is possible to supply a clock with no fluctuation in the time axis and improve sound quality.

  Further, since the clock generation circuit 14 for operating the microcomputer is also stopped when the intermittent operation block 10 is stopped, the sound quality can be further improved by the noise reduction effect.

  FIG. 3 is a block diagram showing the configuration of a playback apparatus according to another embodiment of the present invention. In this reproducing apparatus, the clock used in the constant operation block 20 is shared with the clock for the control microcomputer 11. In this case, when the operation in the intermittent operation block 10 is shifted to the sleep state (step S5 in FIG. 2), the control microcomputer 11 instructs the clock generation circuit 31 to stop supplying the clock to the control microcomputer 11. To do. In response to this, when the clock generation circuit 31 stops the supply of the clock to the control microcomputer 11, the intermittent operation block 10 enters a dormant state. When receiving an interrupt signal from the key input unit 25 or an interrupt signal from the memory controller 23 (step S7), the control microcomputer 11 instructs the clock generation circuit 31 to resume the supply of the clock, The lighting of the display unit 15 and the operation of the intermittent operation block 10 can be resumed. About another point, it is the same as that of the case of the above-mentioned embodiment.

  Note that the present invention is not limited to the above-described embodiment, and can be implemented with appropriate modifications. For example, in the above description, the data read by the data reading unit 12 is compressed, but it may be not only compressed data but also non-compressed data recorded by PCM (pulse code modulation). In this case, the decoder 13 does not perform data conversion in particular, but also in this case, the circuit such as the control microcomputer 11 can be paused by transferring the data to the data buffer 21 at a high speed.

  In the embodiment shown in FIG. 3 described above, the entire intermittent operation block 10 is shifted to the sleep state by stopping the clock supply from the clock generation circuit 31 to the control microcomputer 11. In addition, the CPU of the control microcomputer 11 may be shifted to the halt (stop) mode while the clock supply from the clock generation circuit 31 to the control microcomputer 11 is continued. This is because there are microcomputers that cannot receive an interrupt from the memory controller 23 when the clock supply is stopped. However, in this case, since the portion other than the CPU in the IC package constituting the control microcomputer 11 is operated by the supply of the clock, the power saving effect is lower than when the supply of the clock is stopped.

1 is a block diagram illustrating a configuration of a portable playback device according to an embodiment of the present invention. It is a flowchart which shows operation | movement of the apparatus of FIG. It is a block diagram which shows the structure of the reproducing | regenerating apparatus which concerns on other embodiment of this invention. It is a block diagram which shows the structure of the conventional reproducing | regenerating apparatus.

Explanation of symbols

  10: intermittent operation block, 11: control microcomputer, 12: data reading unit, 13: decoder, 14: clock generation circuit, 15: display unit, 20: always-on operation block, 21: data buffer, 22: DAC, 23: memory Controller: 24: Audio master clock, 25: Key input unit, 41: Control microcomputer, 42: Data reading unit, 43: Data buffer, 44: Decoder, 45: DAC.

Claims (5)

A reading means for reading data of content to be reproduced;
Decoding means for decoding data read by the reading means;
Buffer means for sequentially storing decoded data obtained by the decoding means;
Control means for controlling the output of the decoded data stored in the buffer means;
When the decoded data is output by the control means, the reading means and the decoding means are operated intermittently based on the remaining capacity of the buffer means output by the control of the control means, and the reading is performed when not operating in the intermittent operation. And a control means for causing the decoding means and the decoding means to shift to a pause state. First clock generation means for generating an operation clock to be supplied to the control means;
Second clock generation means for generating an operation clock to be supplied to the control means,
2. The reproducing apparatus according to claim 1, wherein when the reading unit and the decoding unit are not operating, the operation of the first clock generating unit is stopped. A clock generation means for generating an operation clock to be supplied to the control means and the control means;
2. The reproducing apparatus according to claim 1, wherein when the reading unit and the decoding unit are not operating, the supply of the operation clock to the control unit is stopped, or the control unit is shifted to a stopped state.   A program that causes a computer to function as each means in the playback apparatus according to claim 1. A reading process of reading content data to be played back by a reading unit;
A decoding step of decoding data read by the reading means by a decoding means;
A buffering step of sequentially storing decoded data obtained by the decoding means by the buffer means;
A control step of controlling the output of the decoded data stored in the buffer means by a control means;
When the decoded data is output by the control means, the reading means and the decoding means are operated intermittently based on the remaining capacity of the buffer means output by the control of the control means, and the reading is performed when not operating in the intermittent operation. And a control step of causing the decoding means to shift to a pause state.

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