Patent Publication Number: US-2009235039-A1

Title: Digital Data Reproducing Apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of priority to Japanese Patent Application No. 2008-64674, filed Mar. 13, 2008, of which full contents are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a digital data reproducing apparatus. 
     2. Description of the Related Art 
     Audio and video digital data stored in a recording medium such as CD (Compact Disc) is converted into encoded data in the MP3 (MPEG Audio Layer-3) format, etc., and transferred to an encoded data reproducing apparatus such as a portable player through USB (universal Serial Bus), etc., in some cases. Such encoding of digital data for transfer to the external memory such as compression is called ripping. The ripping is performed not only for digital data stored in a recording medium such as CD but also for analog signals output from a tuner of a radio or analog signals input from the outside through a connection terminal, etc., (see, e.g., Japanese Patent Application Laid-Open Publication No. 2007-133955). 
     For example, while listening to reproduction of radio broadcast without ripping, one may want to start the ripping in the middle, when a song of a favorite singer begins. In such a case, since the instruction of the ripping is given at this point, a portion already reproduced cannot be ripped. The encoded data corresponding to the digital data already reproduced at the time of giving the instruction of the ripping cannot be transferred to the encoded data reproducing apparatus such as a portable player. 
     SUMMARY OF THE INVENTION 
     A digital data reproducing apparatus according to an aspect of the present invention, comprises: a reproducing unit configured to reproduce input digital data; an encoding unit configured to store encoded data obtained by encoding the digital data into a memory; a transferring unit configured to transfer the encoded data stored after a transfer address specified in the memory to an encoded data reproducing apparatus capable of reproducing the encoded data; and a control unit configured to specifies the transfer address in the transferring unit in accordance with a transfer instruction signal giving an instruction for transfer of the encoded data corresponding to the digital data already reproduced. 
     Other features of the present invention will become apparent from descriptions of this specification and of the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For more thorough understanding of the present invention and advantages thereof, the following description should be read in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a diagram of a configuration of a digital data reproducing apparatus that is one embodiment of the present invention; and 
         FIG. 2  is a flowchart of an example of a process when an instruction is given to retrospectively transfer MP3 data to a USB device  42 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     At least the following details will become apparent from descriptions of this specification and of the accompanying drawings. 
       FIG. 1  is a diagram of a configuration of a digital data reproducing apparatus that is one embodiment of the present invention. A digital data reproducing apparatus  10  includes a DSP (Digital Signal Processor)  20 , a system microcomputer  22 , and a USB (Universal Serial Bus) microcomputer  24 . 
     The DSP  20  rotates a CD-standard recording medium  30  with a spindle motor  31 , reads digital data (PCM (pulse Code Modulation) data) in the PCM format with a laser beam output from a pickup  32 , and reproduces the read PCM data to output audio from a speaker  34  based on the control of the system microcomputer  22 . Analog signals output from a tuner  35  for radio broadcast and analog signals output from an external input terminal (AUX)  36  are selected by a selector  37 , converted by an ADC (Analog to Digital Converter)  38  into, for example, PCM data, and input to the DSP  20 . The DSP  20  reproduces the PCM data input from the ADC  38  to output audio from the speaker  34 . The DSP  20  generates encoded data (MP3 data) obtained by encoding the PCM data from the recording medium  30 , the tuner  35 , and the external input terminal  36  into the MP3 format and stores the encoded data into SDRAM (Synchronous Dynamic Random Access Memory)  40  based on the control of the system microcomputer  22 . The DSP  20  sequentially outputs pieces of the MP3 data stored in the SDRAM  40  through the USB microcomputer  24  to a USB device  42  that is an encoded data reproducing apparatus capable of reproducing MP3 data based on the control of the system microcomputer  22 . The format conversion for transferring digital data stored in a recording medium or input from a tuner, etc., to an external memory such as a portable player is called ripping. A process of converting PCM data from the recording medium  30 , the tuner  35 , and the external input terminal  36  into MP3 data is the ripping in this embodiment. 
     The system microcomputer  22  (control unit) accepts instructions for reproducing the PCM data stored in the recording medium  30 , selecting a channel of the tuner  35 , selecting an input source, executing the ripping, transferring the MP3 data to the USB device  42 , etc., from a user to transmit data to and receive data from the DSP  20 , etc., depending on the instructions. The system microcomputer  22  may output various pieces of information associated with the reproduction of the PCM data, the ripping, etc., to a display  41 . For example, when a certain tune is reproduced, reproduction instruction data specifying the track number of the tune are transmitted to the DSP  20 . Control data about reproduction time, etc., are transmitted from the DSP  20  to the system microcomputer  22 , and information obtained from the control data is displayed on the display  41 . Alternatively, for example, when the PCM data from the tuner  35  is ripped during reproduction and transferred to the USB device, the transfer instruction data for the MP3 data is transmitted to the DSP  20  along with the reproduction instruction data for the PCM data output from the ADC  38 . Alternatively, for example, in the case where the transfer of the MP3 data to the USB device  42  is started retrospectively from the past time in which the reproduction had already been performed in the middle of the reproduction of the PCM data from the tuner  35 , a read address corresponding to the retrospective time is transmitted from the SDRAM  40  to the DSP  20 . 
     The USB microcomputer  24  is a processing circuit for transferring the data output from the DSP  20  to a USB device  42  such as a portable music player having a memory connected through a USB connector. For example, pieces of the MP3 data generated by the ripping are sequentially output to the USB microcomputer  24  at a speed in accordance with the specifications of the USB microcomputer  24  and the USB device  42  and are transferred to the USB device  42 . 
     Although the recording medium  30  conforms to the CD standard in this embodiment, the standard of the recording medium  30  is not limited to CD and may be any standards, for example, DVD (Digital Versatile Disc), as long as the stored digital data may be ripped. The digital data to be ripped is not limited to PCM data and the data generated by the ripping is not limited to MP3 data. For example, digital data in the DVD-Video format may be ripped to generate digital data in the MPEG format. The standard for transferring the digital data generated by the ripping to an external portable music player, etc., is not limited to USB. 
     A detailed configuration of the DSP  20  will be described. The DSP  20  includes a servo circuit  50 , a CD-DA (Compact Disc Digital Audio) processing circuit  52 , a DAC (Digital to Analog Converter)  54 , an MP3 encoder  56 , an external transfer circuit  58 , a PCM control register  60 , an MP3 control register  64 , a transfer control register  68 , and a register I/F (Interface)  70 . 
     The servo circuit  50  controls the spindle motor  31  to adjust the readout speed of the PCM data stored in the recording medium  30 . The servo circuit  50  controls the pickup  32  such that the laser beam output from the pickup  32  is applied to a proper position. 
     The CD-DA processing circuit  52  (reproducing unit) outputs control data for reading desired PCM data stored in the recording medium  30  to the servo circuit  50  based on the information set in the PCM control register  60  through the register I/F  70  if the PCM data stored in the recording medium  30  is reproduced. The CD-DA processing circuit  52  converts RF (Radio Frequency) signals output from the pickup  32  into digital signals to generate PCM data. If the analog signals from the tuner  35  or the external input terminal  36  are reproduced, the PCM data obtained by the digital conversion of the analog signals is input from the ADC  38  to the CD-DA processing circuit  52 . The PCM data from the recording medium  30 , the tuner  35 , and the external input terminal  36  is converted by the DAC  54  into the analog signals to be audio-output from the speaker  34 . The PCM data from the recording medium  30 , the tuner  35 , and the external input terminal  36  is also output to the MP3 encoder  56 . The CD-DA processing circuit  52  outputs control data for performing the focus control and the tracking control of the pickup  32  based on the RF signals from the pickup  32 . 
     The MP3 encoder  56  (encoding unit) encodes (compresses) the PCM data output from the CD-DA processing circuit  52  to generate MP3 data based on the information set in the MP3 control register  64  through the register I/F  70 , and store the generated MP3 data into the SDRAM  40 . It is assumed in this embodiment that the information is set in the MP3 control register  64  such that the PCM data output from the CD-DA processing circuit  52  is always converted into MP3 data to be stored in the SDRAM  40  regardless of the presence of the instruction for transfer to the USB device  42 . The MP3 encoder  56  stores the MP3 data into a predetermined area of the SDRAM  40  in a cyclic manner. The area storing the MP3 data is managed as a ring buffer and if pieces of the MP3 data are continuously generated without transferring to the USB device  42 , the pieces of MP3 data are sequentially overwritten in order of occurrence. Therefore, if the MP3 data is not transferred to the USB device  42 , the SDRAM  40  accumulates the MP3 data generated by encoding the reproduced PCM data. For example, assuming that a size of the area of the SDRAM  40  storing the MP3 data is 64 Mbit and that the bit rate of the MP3 data is 96 kbps (Kilobit per second), the SDRAM  40  may accumulate the MP3 data of the past about 11 minutes. The MP3 encoder  56  stores information about the write address of the MP3 data to the SDRAM  40  and the number of data (number of words) of the MP3 data stored in the SDRAM  40  and not transferred. 
     The external transfer circuit  58  (transferring unit) reads the MP3 data stored in the SDRAM  40  and outputs the data to the USB microcomputer  24  based on information such as the MP3 data transfer address set in the transfer control register  68  through the register I/F  70 . The MP3 data output to the USB microcomputer  24  is transferred to the USB device  40  such as a portable player. The external transfer circuit  58  may read the MP3 data stored at the read address set in the transfer control register  68  from the SDRAM  40  to store the data in the transfer control register  68 . 
     The digital data reproducing apparatus  10  may perform the ripping while reproducing the PCM data from the recording medium  30 , the tuner  35 , and the external input terminal  36  and may transfer the MP3 data generated by the ripping to the USB device  42  as above. Since the digital data reproducing apparatus  10  rips and stores the reproduced PCM data into the SDRAM  40  regardless of the presence of the instruction for transfer to the USB device  42 , the MP3 data may be transferred retrospectively from the past time if the instruction for transfer to the USB device  42  is made in the middle of the reproduction of the PCM data without transferring to the USB device  42 . 
       FIG. 2  is a flowchart of an example of a process when an instruction is given to retrospectively transfer MP3 data to a USB device  42 . It is assumed that the PCM data from the tuner  35  is reproduced without the instruction for transfer to the USB device  42  in the initial state and that the MP3 data generated by encoding the reproduced PCM data is stored in the predetermined area of the SDRAM  40  in a cyclic manner. 
     It is assumed that a user wants to transfer the part already reproduced to the USB device  42  when the PCM data is reproduced without transferring to the USB device  42 . In this case, an instruction (transfer instruction signal) for transferring the MP3 data ripped and stored in the SDRAM  40  to the USB device  40  retrospectively from a past arbitrarily time point, is input by a user (S 101 ). The system microcomputer  22  calculates the number of data (number of words) to be transferred corresponding to the retrospective time based on the bit rate of the MP3 data based on the retrospective time information included in the transfer instruction from the user (S 102 ). The retrospective time may preliminarily be determined instead of input from the user. All the MP3 data stored in the SDRAM  40  and not transferred may be data to be transferred without specifying the retrospective time. 
     The system microcomputer  22  calculates an address specifying the start position of the transfer based on the calculated number of data, the number of data (number of words) of the MP3 data accumulated in the SDRAM  40  and not transferred, and the information indicative of the write address, for which the MP3 control register  64  is set (S 103 ). The system microcomputer  22  sets an address preceding the calculated address by, for example, 16 bytes, as a search address for searching a delimiter of frames making up the MP3 data (S 104 ). 
     The system microcomputer  22  checks whether three-byte data from the search address of the SDRAM  40  indicate a synchronization code (0xFFF) corresponding to delimiter data indicative of the beginning of the frame (S 105 ). Specifically, information giving an instruction for reading data stored at the search address is set in the transfer control register  68  and the data read from the search address is stored in the transfer control register  68 . The system microcomputer  22  refers to the data stored in the transfer control register  68  to check whether the three-byte data from the search address indicate the synchronization code. 
     Until the three-byte data from the search address indicate the synchronization code (S 105 : NO), the system microcomputer  22  increments the search address by one at a time (S 106 ). If the three-byte data from the search address indicate the synchronization code (S 105 : YES), the system microcomputer  22  retains the search address as a transfer address (S 107 ). The system microcomputer  22  extracts header information of the MP3 data frame from the data read from the transfer address and calculates the frame size based on the header information (S 108 ). Specifically, assuming that the number of samplings per frame is 144, the frame size may be obtained on the basis of a bit rate, a sampling frequency, and a padding bit ( 0  or  1 ) included in the header information by calculation using the formula, (the frame size)=144×(bit rate)/(sampling frequency)+(padding bit). 
     After the frame size is calculated, the system microcomputer  22  adds an address corresponding to the frame size to the search address (S 109 ) and checks whether the three-byte data from the search address of the SDRAM  40  indicate the synchronization code (S 110 ). If the three-byte data from the search address do not indicate the synchronization code (S 110 : NO), the system microcomputer  22  determines that the transfer address is not the address indicative of the beginning of the frame, sets an address obtained by adding one to the transfer address as the search address (S 111 ), and goes back to the process of searching from the search address (S 105 ). If the three-byte data from the search address indicate the synchronization code (S 110 : YES), the system microcomputer  22  determines that the transfer address is the address indicative of the beginning of the frame, and sets the transfer control register  68  for information for controlling the external transfer circuit  58  so as to transfer the MP3 data after the transfer address to the USB device  42  through the USB microcomputer  24  (S 112 ). This starts the transfer of the MP3 data to the USB device  42  retrospectively from the past reproduction time. Since pieces of the MP3 data are stored in the SDRAM  40  in the cyclic manner, the MP3 data after the transfer address may include MP3 data stored at an address smaller than the transfer address. 
     The digital data reproducing apparatus  10  may transfer MP3 data to the USB device  42  retrospectively from the past reproduction time if a user wants to transfer the portion already reproduced to the USB device  42  while the PCM data is reproduced without transferring to the USB device  42 . 
     The digital data reproducing apparatus  10  may control the retrospective time in accordance with the specification from a user. Therefore, only the portion necessary for the user may be transferred to the USB device  42  in the MP3 data corresponding to the PCM data already reproduced. 
     The digital data reproducing apparatus  10  sets the search address as the transfer address if the synchronization code of frames making up the MP3 data is stored at the search address calculated based on the retrospective time. Therefore, the MP3 data may be transferred to the USB device  42  for each frame. 
     The digital data reproducing apparatus  10  determines that the transfer address is located at the beginning position of the frame if the synchronization code of the frame is stored at the address obtained by adding the frame size of the MP3 data to the transfer address. Therefore, the erroneous determination of the beginning position of the frame may be prevented. 
     As above, according to the embodiment, the encoded data obtained by ripping digital data may be transferred to an encoded data reproducing apparatus retrospectively from the past reproduction time. 
     The above embodiments of the present invention are simply for facilitating the understanding of the present invention and are not in any way to be construed as limiting the present invention. The present invention may variously be changed or altered without departing from its spirit and encompass equivalents thereof.