Abstract:
The apparatus and method for transferring audio data to a data recorder adopting a personal computer bus to receive audio data enters into data communication mode over a bus without conducting preparation steps for transferring data when a record request is received. The preparation steps include occupying the bus and issuing packet commands. Real-time data such as an audio signal are transferred with no delay to a general optical disk driver satisfying the personal computer (PC) bus interfacing requirement. This allows adoption of a general disk driver for data recording instead of an exclusive audio disk driver, thereby reducing manufacturing cost of a digital audio recorder and enabling the disk driver installed in a digital audio recorder to be used in other devices such as a PC.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an apparatus and method for transferring audio data to a data recorder using a personal computer bus to receive audio data. 
   2. Description of the Related Art 
   An optical disk driver for a rewritable optical disk such as a CD_RW uses the AT Attachment Packet Interface (ATAPI) bus standard developed for a personal computer (PC). Through the ATAPI bus, an optical disk driver receives data from other devices and records the received data on an optical disk. 
   The ATAPI protocol is a multi-to-multi device protocol, such that before a device connected to the bus transfers data through the bus, the device must conduct a preparation processes marked ‘A’ in FIG.  1 . The preparation processes include bus busy checking, bus occupying, and entering into communication standby mode which require issuing and executing necessary packet commands. After the preparation processes are done, two devices connected to the bus can transfer data therebetween. 
   If an audio data recording/reproducing device uses a general optical disk driver adopting the ATAPI standard, the data to be recorded should be provided for the disk driver in accordance with the sequence diagram of FIG.  1 . However, the above-explained preparation processes should be executed in advance for entering into a data communication mode in which data are effectively communicated between two devices, causing data transmission to be delayed. Therefore, the ATAPI standard has some disadvantages due to data transmission delays when applied in an audio data recorder in which audio data must be transferred with minimal delay. 
   Recently, in the field of ACDRs (Audio CD Recorders), an optical disk driver for consumer use has been developed. This optical disk driver has an exclusive audio channel for receiving audio signals and a channel protocol for the exclusive audio channel instead of adopting the ATAPI standard. The audio recording/reproducing device adopting the optical disk driver receives audio signals through the exclusive audio channel and then records them on an optical disk. Audio data in the optical disk driver is transferred as serial data. On the other hand, all data in the optical disk driver for a PC, e.g., a CD-RW are transferred as 16-bit bus data. 
   Therefore, the optical disk driver for consumer use cannot be used in a personal computer (PC) employing an ATAPI bus because the exclusive audio channel and the channel protocol of this optical disk driver are not compatible with the ATAPI standard used in a PC. Furthermore, for consumer use, the optical disk driver must be operated by user commands, not by commands from the PC. 
   Accordingly, the demand for such optical disk driver is much lower, and these optical drivers are more expensive than the widely popularized disk drivers using the ATAPI bus architecture. This causes an audio recording/reproducing device using such optical disk driver to be less cost competitive. 
   SUMMARY OF THE INVENTION 
   The present invention provides an audio data recording apparatus and audio data sending/receiving method for the apparatus which are capable of transferring inputted audio signals immediately on a transmission request without unnecessary preparation processes. 
   Further, the present invention provides an audio data recording apparatus for consumer use and audio data sending/receiving method thereof which are capable of transferring audio data through the ATAPI bus, such as CD-RW driver for PC. 
   The audio data receiving apparatus according to the present invention comprises a selecting means for selecting an audio signal source among a plurality of audio signal sources; a converting means for converting the selected audio signal into record-formatted audio data; and a connecting means for transferring the record-formatted audio data to a disk recording/reproducing device without passing through preparation steps for sending/receiving data when a record is requested through the disk recording/reproducing device, wherein the preparation steps are specified in the bus standard adopted in a personal computer. 
   The audio data sending/receiving method according to the present invention comprises the steps of entering into data communication mode without passing through preparation steps for transferring data when a record is requested, wherein the preparation steps include occupying the bus and entering into a communication standby mode which require issuing necessary packet commands and executing them; sending/receiving audio data in the data communication mode; escaping the data communication mode when a recording stop is requested; and interrupting the data transferring operation. 
   When a record command is received, an optical disk driver connected through said connecting means enters into the data communication mode directly without passing through the preparation steps, which are required to enter a communication standby mode, including bus occupation and packet command execution. Upon entering into the data communication mode, said converting means converts the audio data selected among a plurality of signal sources by said selecting means into record-formatted data, and said connecting means transmits the format-converted audio data to the optical disk driver with no delay in accordance with bus protocol adopted in a personal computer. The optical disk driver records the record-formatted audio data received from said connecting means on an optical disk. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are included to provide a further understanding of the invention, illustrate the preferred embodiments of the invention, and together with the description, serve to explain the principles of the present invention. 
     In the drawings: 
       FIG. 1  is a simplified conventional data transfer protocol of the ATAPI bus between a host and an optical disk driver; 
       FIG. 2  is a simplified block diagram of an audio data recorder to; which a data sending/receiving method according to the present invention is applied; 
       FIG. 3  shows the block diagram of  FIG. 2  in more detail; 
       FIG. 4  shows the block diagram of an audio data adaptor and the recording part of an optical disk driver; 
       FIG. 5  is a block diagram of an ATAPI interface installed in an audio data adaptor; and 
       FIG. 6  is a data transfer protocol of the present invention applied to an audio data recorder. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In order that the invention may be more fully understood, preferred embodiments thereof will now be described with reference to the accompanying drawings. 
     FIG. 2  is a simplified block diagram of an audio data recorder to which a data sending/receiving method according to the present invention is applied. The audio data recorder of  FIG. 2  comprises an adaptor  100  for converting inputted audio signals into data streams of a pre-determined audio recording format and transmitting the format-converted data streams through an Integrated Drive Electronics (IDE) or ATAPI bus  102  in accordance with transferring sequences compatible with the ATAPI protocol developed for the input/output (I/O) bus of a personal computer; and an optical disk driver  300  for commanding the audio data adapter  100  to enter into data communication mode immediately or to escape the mode when a record start or a stop key is entered via a command line  104 , and recording audio data streams transferred from the audio data adaptor  100  through the IDE bus on an inserted optical disk. 
     FIG. 3  shows the block diagram of  FIG. 2  in more detail. The optical disk driver  300  and an I/O port  200 , controlling input and output of audio signals, are depicted in FIG.  3 . Specifically, the I/O port  200  is shown connected by serial buses and an I/O control line to the optical disk driver  300 , and is shown connected to the adapter  100  by the serial bus. The disk driver  300  consists of a recording unit  301 ; a reproducing unit  302 ; and an user interface  303 . 
     FIG. 4  is a block diagram showing the audio data adaptor  100  and the optical disk driver  300 , from a recording point of view, in more detail. The audio data adaptor  100  of  FIG. 4  includes an A/D converter  10  for digitizing inputted an analog audio signal; a switch  20  for selecting one of the digitized audio data and digital audio data streams provided from an external source; an audio format converter  30  for converting the selected audio data into data streams of a predetermined audio recording format; and an ATAPI interface  40  for transferring the format-converted audio data streams to the optical disk driver  300  through a IDE bus  102  in accordance with the ATAPI protocol when a command is received. 
   The optical disk driver  300  of  FIG. 4  includes of an ATAPI interface  304  for connecting with the IDE bus  102  according to the ATAPI protocol; a digital recording signal processor  310  for converting digital audio data streams received through the ATAPI interface  304  into data frames of error-correctable format by adding error correction codes; a channel bit encoder  320  for encoding the data frames into eight-to-fifteen-modulated (EFM) bit streams; a writing power driver  330  for outputting a driving current whose intensity is proportional to the bit level; a pickup  331  for making a laser beam be incident to the optical disk  1  according to the driving current; a driver  360  for moving the pickup  331  and driving motors; a servo unit  350  for applying an adjusting signal to the driver  360  on the basis of a tracking error signal, a focussing error signal, and the rotation speed of the optical disk  1 ; and a microcomputer  340  for performing data transferring through the IDE bus by controlling the internal elements of the adaptor  100  and the disk driver  300 . 
     FIG. 5  is a detailed block diagram of the ATAPI interface  40  of the audio data adaptor  100 , which includes a serial-to-parallel converter  41 , a memory control  42 , a bus control  43 , and a clock divider  44 . 
     FIG. 6  shows data transferring procedures implemented by the audio data recorder according to the present invention. The data transferring procedures of  FIG. 6 , as carried out by the audio data recorder depicted in FIG.  4  and  FIG. 5 , will be explained in detail below. 
   First, an optical disk  1  for audio recording is inserted into the optical disk driver  300  for recording audio data received through the IDE bus  102 . When a record start key is entered, the microcomputer  340  transmits a ‘conversion start’ signal to the audio format converter  30  through a signal line (not shown in  FIGS. 4 and 5 ) that is different from the IDE bus  102 . At the same time, the microcomputer  340  sets a ‘START’ signal to the ATAPI interface  40  of the audio data adaptor  100  through the bus  102  by controlling the ATAPI interface  304  of the optical disk driver  300  (Step  1 ). As shown in  FIG. 6 , the ‘START’ signal is set directly without intermediate steps such as the bus checking and occupation steps, and a communication standby mode which require interchange of packet commands. The audio format converter  30  converts the received audio signal into record-formatted data as soon as the ‘conversion start’ signal is received. After detecting the setting of the ‘START’ signal, the ATAPI interface  40  continuously checks whether the format-converted data are received and whether transmission is possible (Step  2 ). 
   Meanwhile, the microcomputer  340  enables the A/D converter  10  of the audio data adapter  100  to digitize an input signal, and controls the switch  20  to select an audio signal source among audio signal sources provided from external devices based upon a user&#39;s choice. The switch  20  connects an audio signal at input terminal ‘a’ to the output terminal ‘c’ if a user selects an analog signal source, and connects an audio signal at input terminal ‘b’ if a user selects a digital signal source. 
   If an analog signal is inputted, the A/D converter  10  digitizes the analog signal into digital data by sampling the analog signal at 44 kHz. The switch  20  selects the digitized audio data if an analog signal source is selected, and selects digital audio data streams inputted directly from an external device through the I/O port  200  if a digital signal source is chosen by a user. The audio format converter  30  converts the digital audio data from the switch  20  into audio data streams of a pre-determined audio recording format, for example, the layer3 standard of MPEG1, after examining the format of the selected digital audio data and activating the corresponding format converting routine. 
   While the ATAPI interface  40  continuously checks whether any data to be transmitted is received (Step  2 ), if a data to be transmitted is outputted in serial format from the audio format converter  30 , the ATAPI interface  40  conducts a transmission of the received data immediately (Step  3 ) because the ‘START’ signal in the bus has been set, of which the detailed process is as follows. 
   Referring to  FIG. 5 , at first, the serial-to-parallel converter  41  of the ATAPI interface  40  converts the serial bits from the audio format converter  30  into 8-bit parallel data, and outputs the 8-bit parallel data to the memory control  42  together with a data writing signal synchronized with a writing clock of the clock divider  44 , which generates all clock signals necessary for data transfer. The above operation is performed whenever the ‘START’ signal in the bus is cleared. 
   The memory control  42  stores 8-bit data in the memory (SRAM)  45  whenever the data writing signal is applied from the serial-to-parallel converter  41 , and increases a writing address whenever data is stored. When the increased address reaches a limit address during the storing process, the memory control  42  transmits a ‘transfer-ready’ signal to the bus control  43 , and activates a data-valid signal if a data-hold signal is deactivated. The data-hold signal becomes activated by the bus control  43  if the ‘START’ signal in the IDE bus has been set, and becomes deactivated if the ‘START’ signal is cleared. Accordingly, the data is transferred through the IDE bus  102  according to the following process if the ‘START’ signal in the bus is set. 
   When the ‘transfer ready’ signal and the data-valid signal are activated, the data addressed by the memory control  42  are retrieved one by one, and then packed into 16-bit parallel data which are applied to the bus control  43  in accordance with a data reading clock of the clock divider  44 . At the same time, the memory control  42  increases the address of a read pointer. The bus control  43  transmits the read 16-bit data to the optical disk driver  300  through the IDE bus  102 . 
   If the data writing signal is applied to the memory control  42 , again during the above process, the memory control  42  releases the activated valid-data signal, and conducts the data storing process explained above after changing the data reading address to the data writing address. 
   The above data retrieving process of the memory control  42  shall be continued until data of desirable size are retrieved for a single; transmission. After the last data is read out, the memory control  42  releases the activated ‘transfer ready’ signal and the valid-data signal at the same time. 
   If the counter portion of the ATAPI interface  304  is delayed in data receiving during data transmission through the IDE bus  102 , the bus control  43  temporarily interrupts the data transmitting process by sending a data-hold signal to the memory control  42 , and when the delay condition is resolved, the data-hold signal is released so that the data transmission restarts. 
   According to the data transferring through the IDE bus connected to the ATAPI interfaces  40  and  304 , the ATAPI interface  304  of the optical disk driver  300  receives record-formatted audio data in accordance with the same protocol (Step  4 ). The optical disk driver  300  records the audio data received through the ATAPI interface  304  as explained below. 
   When the record-formatted audio data are applied to the digital recording signal processor  310  through the interface  304 , the digital recording signal processor  310  reconstructs the received data into error correction code (ECC) blocks to enhance data reliability by adding error correction parities and rearranging data. The channel bit encoder  320  generates a 15-bit modulated code, which is adequate for optical recording, for each 8-bit data outputted from the digital recording signal processor  310 , and then applies the modulated code to the writing power driver  330 . 
   The writing power driver  330  having been adjusted to output optimal writing power by the microcomputer  340 , generates a driving current whose magnitude is determined depending upon the binary level of codes. Driven by the driving current, the pickup  331  records the modulated codes in the program area of the optical disk  1  by making an internal laser beam be incident on the surface of the disk  1 . Thereby, the audio signal provided from another device is recorded on the optical disk. 
   If a record stop operation is requested to the microcomputer  340  during the recording of audio signals, the microcomputer  340  releases the activated ‘conversion start’ signal and deactivates the ‘START’ signal in the bus  102  by controlling the ATAPI interface  304  at the same time, for interrupting the data transmission. Accordingly, the audio format converter  30  of the audio data adapter  100  immediately stops converting the received data and the ATAPI interface  40  also stops transferring the converted data through the IDE bus (Step  5 ). That is, the data communication mode of the IDE bus  102  is stopped and the data transferring and recording is terminated. 
   The method and apparatus according to the present invention transfers real-time data such as an audio signal with no delay to a general optical disk driver satisfying the personal computer bus interfacing requirements, making it possible to use a general disk driver for a data recording means instead of an exclusive audio disk driver, thereby reducing manufacturing costs of a digital audio recorder and enabling the disk driver installed in a digital audio recorder to be used in other devices such as a PC. 
   The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.