Abstract:
An information recording apparatus includes: a transferring device that separately and simultaneously receives at least two information supplied through at least two channels, and separately and simultaneously transfers the at least two information to a storing device at separate transfer rates, thereby storing the at least two information into the storing device; a recording device that alternately reads the at least two information from the storing device, and alternately records the at least two information read from the storing device onto a recording medium at a constant recording rate; and a transfer rate setting device that sets the respective transfer rates to make a total of the transfer rates smaller than the recording rate.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an information recording apparatus for recording information such as a picture image in a recording medium such as an optical disk. 
   2. Description of the Related Art 
   As an apparatus for recording a program broadcast from a TV broadcast station, a VTR (video tape recorder) is known. In general, analog system VTRs are used widely, but recently, digital system VTRs are spreading as well. It is characteristic of the digital system VTRs to provide a higher image quality compared with the analog system VTRs. 
   These days, with the number of channels of the TV broadcast increasing, it is very convenient if TV programs of a plurality of channels can be recorded at the same time. However, in the case of a VTR, only one program can be recorded at one time. That is, a VTR can record only one channel simultaneously. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to provide an information recording apparatus capable of recording the information of a plurality of channels at the same time. 
   An information recording apparatus in accordance with the present invention includes: a transferring device that separately and simultaneously receives at least two information supplied through at least two channels, and separately and simultaneously transfers the at least two information to a storing device at separate transfer rates, thereby storing the at least two information into the storing device; a recording device that alternately reads the at least two information from the storing device, and alternately records the at least two information read from the storing device onto a recording medium at a constant recording rate; and a transfer rate setting device that sets the respective transfer rates to make a total of the transfer rates smaller than the recording rate. 
   At least two information are separately and simultaneously supplied to the information recording apparatus through at least two channels. In the information recording apparatus, the transferring device separately and simultaneously receives these information, and separately and simultaneously transfers these information to the storing device to store the information into the storing device. Thus, the receiving operation, transferring operation and storing operation are performed in a parallel manner. 
   Furthermore, the transferring device transfers at least two information to the storing device at separate transfer rates. For example, if it is assumed that the transferring device transfers first information and second information to the storing device, the transferring device transfers the first information at a first transfer rate, and transfers the second information at a second transfer rate. The first transfer rate and the second transfer rate are separately set by the transfer rate setting device. 
   The recording device alternately reads the at least two information from the storing device, and alternately records these information onto a recording medium at a constant recording rate. For example, if it is assumed that the first information and the second information are stored in the storing device, the recording device firstly reads the first information from the storing device and records it onto the recording medium at the constant recording rate. The recording device next reads the second information from the storing device and records it onto the recording medium at the same recording rate. The recording device performed such reading and recording operations repeatedly. 
   The transfer rate setting device sets the respective transfer rates to make a total of the transfer rates smaller than the recording rate. As a result, the speed of reading information from the storing device is faster than the speed of storing information into the storing device. Therefore, it is possible to prevent overflow of the information in the storing device. 
   Thus, according to the information reproducing apparatus, simultaneous recording of a plurality of information can be substantially achieved. 
   In the aforementioned information recording apparatus, the transferring device may includes a compression device that separately compresses the at least two information at separate compression ratios, and the transfer rate setting device may includes a compression ratio setting device that sets the respective compression ratios to make the total of the transfer rates smaller than the recording rate. 
   In general, the amount of the information can be reduced by compression of the information. If the compression ratio is changed, the amount of the compressed information can be changed. If the compression ratio is changed, the quality of the information, such as the quality of image, the quality of sounds or the like, is also changed. 
   The compression device separately compresses the at least two information at separate compression ratios. Therefore, the quality of each information can be set separately. Here, it should be noted that there is a relation between the compression ratios of the information and the transfer rates of the information in the transferring device. So, when setting the compression ratios, it is needed to consider maintaining the state that the total of the transfer rates is smaller than the recording rate, in order to prevent overflow of the information in the storing device. Therefore, the compression ratio setting device sets the respective compression ratios to make the total of the transfer rates smaller than the recording rate. 
   Furthermore, in the aforementioned information recording apparatus, the recording device may includes: a selection device that alternately selects one of the at least two information stored in the storing device; a detection device that detects an amount of each of the at least two information stored in the storing device; a determination device that determines on the basis of a detection by the detection device whether or not the amount of the one of the at least two information selected by the selection device reaches a predetermined amount; a recording control device that records the one of the at least two information selected by the selection device onto the recording medium when the determination device determines that the amount of the one of the at least two information selected by the selection device reaches the predetermined amount. 
   Thus, the selected information is recorded onto the recording medium, each time the amount of the selected information reaches the predetermined amount in the storing device, and such an operation is alternately and repeatedly performed on the at least two information stored in the storing device. Therefore, equal amounts of at least two information are alternately recorded onto the recording medium, so that the efficiency of recording can be improved. 
   Furthermore, in the aforementioned information recording apparatus, the recording device may continuously arrange the at least two information read from the storing device on a recording medium in a reading order. Thus, the efficiency of recording can be improved. 
   Moreover, in the aforementioned information recording apparatus, the recording device may continuously arrange one of the at least two information read from the storing device on a first area on the recording medium, and continuously arrange another one of the at least two information read from the storing device on a second area on the recording medium. In this case, the first area and the second area are separately formed on the recording medium. Thus, the at least two information can be separately recorded in the separate areas, and in each area, only the information supplied through a single channel can be continuously arranged. Therefore, when reproducing the information from the recording medium, the reproduction of the information can be achieved by a simple reading operation, so that the efficiency of reading information can be improved. 
   The nature, utility, and further feature of this invention will be more clearly apparent from the following detailed description with respect to preferred embodiments of the invention when read in conjunction with the accompanying drawings briefly described below. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block diagram showing a recording/reproducing apparatus according to a first embodiment of the present invention; 
       FIG. 2  is a block diagram showing an MPEG encoder provided in the recording/reproducing apparatus according to the first embodiment of the present invention; 
       FIG. 3  is a block diagram showing a logical format buffer, a logical formatter, a physical format buffer, a physical formatter, and the like, according to the first embodiment of the present invention; 
       FIG. 4  is a flow chart showing a recording operation according to the first embodiment of the present invention; 
       FIG. 5  is a flow chart showing the transfer rate setting process according to the first embodiment of the present invention; 
       FIG. 6  is a flow chart showing a two channel simultaneous recording process according to the first embodiment of the present invention; 
       FIG. 7  is a graph for explaining the change of the picture image data in the logical format buffer according to the first embodiment of the present invention; 
       FIG. 8  is a graph for explaining the change of the picture image data in the physical format buffer according to the first embodiment of the present invention; 
       FIG. 9  is a diagram showing an example of a recording track position of picture image data according to the first embodiment of the present invention; 
       FIG. 10  is a diagram showing another example of a recording track position of picture image data according to the first embodiment of the present invention; 
       FIG. 11  is a flow chart showing a reproducing operation according to the first embodiment of the present invention; 
       FIG. 12  is a block diagram showing a recording/reproducing apparatus according to a second embodiment of the present invention; 
       FIG. 13  is a block diagram showing a recording/reproducing apparatus according to a third embodiment of the present invention; and 
       FIG. 14  is a diagram for explaining a compressed image according to the third embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Hereinafter embodiments of the present invention will be explained with reference to the accompanied drawings. In the embodiments described below, examples with a recording apparatus according to the present invention adopted in a DVD-R recording/reproducing apparatus will be presented. 
   1. First Embodiment 
     FIG. 1  shows a DVD-R recording/reproducing apparatus  100  according to the first embodiment of the present invention. The recording/reproducing apparatus  100  can receive two channel picture image signals A 1  and A 2  simultaneously so as to record image data D 1  and D 2  corresponding to the picture image signals A 1  and A 2  in a DVD-R  1  simultaneously. Moreover, the apparatus  100  can reproduce either one of the two channel picture image signals D 1  and D 2  selectively from the DVD-R  1  with the two channel picture image data D 1  and D 2  recorded. 
   The configuration of the recording/reproducing apparatus  100  will be explained with reference to FIG.  1 . The recording/reproducing apparatus  100  includes two analog-digital converters (hereinafter referred to as “A/D converters”)  11  and  12 , two MPEG encoders  13  and  14 , MPEG encoder buffers  15  and  16 , a logical format buffer  17 , a logical formatter  18 , a physical format buffer  19 , a physical formatter  20 , a signal processing circuit (S.P.C)  21 , and an optical pickup  22 . These elements comprise a recording section in the recording/reproducing apparatus  100 . 
   Furthermore, the recording/reproducing apparatus  100  includes a signal extraction circuit  23 , a physical decoder  24 , a buffer  25 , a logical decoder  26 , an MPEG decoder  27 , an MPEG decoder buffer  28 , and a digital-analog converter (hereinafter referred to as “D/A converter”)  29 . These elements comprise a reproducing section in the recording/reproducing apparatus  100 . 
   The A/D converter  11  is a device for converting an analog picture image signal A 1  to digital picture image data D 1 . The A/D converter  12  is a device for converting an analog picture image signal A 2  to digital picture image data D 2 . The two A/D converters  11  and  12  have the same configuration. The picture image signals A 1  and A 2  are, for example, video signals broadcast from a TV broadcasting station. The recording/reproducing apparatus  100  according to this embodiment can receive the two channel picture image signals A 1  and A 2  simultaneously. The signals broadcast from a TV broadcasting station include not only picture signals but also sound signals, however, the case of a picture image signal will be explained in this embodiment. 
   The MPEG encoder  13  is for compressing (encoding) picture image data output from the A/D converter  11  according to the MPEG (Moving Picture Experts Group) system. As shown in  FIG. 2 , the MPEG encoder  13  includes a subtraction portion  51 , a DCT portion  52 , a quantization portion  53 , a variable length encoding portion  54 , an inverse quantization portion  55 , an inverse DCT portion  56 , a motion compensation predicting portion  57 , a motion detecting portion  58 , a rate control portion  59 , and a buffer  15 . 
   The picture image data D 1  (D 2 ) are sectioned per frame, and the data pieces corresponding to individual picture images are assigned to respective frames. Specifically, in the picture image data D 1  (D 2 ), each of the data pieces assigned to the respective frames is pixel data representing the individual picture image. 
   The MPEG encoder  13  divides the picture image data D 1  into a plurality of blocks so as to execute a compression process per block. In this compression process, when the pixel data comprising one block of the picture image data D 1  are input to the MPEG encoder  13 , the subtraction portion  51  calculates the difference between the input pixel data and motion predicting data output from the motion compensation predicting portion  57  so as to output the result as the difference data. Then, the DCT portion  52  executes the discrete cosine transformation of the difference data output from the subtraction portion  51 . The quantization portion  53  quantizes the data applied with the discrete cosine transformation. The variable length encoding portion  54  applies the variable length coding process to the quantized data so as to output the obtained data to the buffer  15 . On the other hand, the inverse quantization portion  55  inversely quantizes the data quantized by the quantization portion  53 , and the inverse DCT portion  56  applies the inverse DCT to the inversely quantized data so as to output the same to the motion compensation predicting portion  57 . Moreover, the motion detecting portion  58  detects the motion vector of the image from the pixel data input to the subtraction portion  51  so as to output the same to the motion compensation predicting portion  57 . The motion compensation predicting portion  57  executes the frame prediction according to the MPEG system, using the inversely DTC data and the motion vector so as to produce prediction data and output the same to the subtraction portion  51 . Moreover, the rate control portion  59  is for controlling the quantization rate in the quantization portion  53  variably. The compression process executed in the MPEG encoder  13  itself is known by those skilled in the art, and the above-mentioned configuration of the MPEG encoder  13  is typical one for realizing the compression technique. 
   However, the MPEG encoder  13  according to the embodiment of the present invention further has a function of varying the quantization rate in the quantization portion  53  in addition to the above-mentioned typical function. That is, in the MPEG encoder  13 , the rate control portion  59  is connected with a CPU  30  described later. Accordingly, the MPEG encoder  13  according to the embodiment of the present invention can change the quantization rate in the quantization portion  53  according to a rate control signal RC 1  output from the CPU  30 . 
   The MPEG encoder  14  is for encoding (compressing) picture image data output from the A/D converter  12  according to the MPEG system with the configuration the same as the MPEG encoder  13 . Moreover, the MPEG encoder  14  can change the quantization rate in the quantization portion  53  provided in the MPEG encoder  14  according to a rate control signal RC 2  output from the CPU  30 . 
   As shown in  FIG. 3 , the logical format buffer  17  is a memory device for temporarily storing the picture image data D 1  and D 2  compressed and output by the MPEG encoders  13  and  14 . The logical format buffer  17  is, for example, a RAM (random access memory). A memory area  17 A for storing the picture image data D 1  and a memory area  17 B for storing the picture image data D 2  are formed in the logical format buffer  17 . The logical format buffer  17  is connected with the CPU  30  so as to store the picture image data D 1  output from the MPEG encoder  13  in the memory area  17 A and the picture image data D 2  output from the MPEG encoder  14  in the memory area  17 B according to a write control signal output from the CPU  30 . Moreover, the logical format buffer  17  outputs the picture image data D 1  stored in the memory area  17 A or the picture image data D 2  stored in the memory area  17 B to the logical formatter  18  according to a read control signal output from the CPU  30 . Whether to output the picture image data D 1  stored in the memory area  17 A or output the picture image data D 2  stored in the memory area  17 B is selected according to an address signal output from the CPU  30 . 
   The logical formatter  18  is for converting the formats of the picture image data D 1  and D 2  output from the logical format buffer  17  to the DVD standard logical format, respectively. 
   As shown in  FIG. 3 , the physical format buffer  19  is a memory device for temporarily storing the picture image data D 1  and D 2  each output from the logical formatter  18 . The physical format buffer is, for example, a RAM. A memory area  19 A for storing the picture image data D 1  and a memory area  19 B for storing the picture image data D 2  are formed in the physical format buffer  19 . The physical format buffer  19  is connected with the CPU  30  so as to store the picture image data D 1  output from the logical formatter  18  in the memory area  19 A and the picture image data D 2  output from the logical formatter  18  in the memory area  19 B according to a write control signal output from the CPU  30 . Moreover, the physical format buffer  19  outputs the picture image data D 1  stored in the memory area  19 A or the picture image data D 2  stored in the memory area  19 B to the physical formatter  20  according to a read control signal output from the CPU  30 . Whether to output the picture image data D 1  stored in the memory area  19 A or output the picture image data D 2  stored in the memory area  19 B is selected according- to an address signal output from the CPU  30 . Furthermore, the physical format buffer  19  outputs a data amount signal showing each amount of the picture image data D 1  and D 2  stored in the memory areas  19 A and  19 B to the CPU  30 . 
   The physical formatter  20  is for converting the formats of the picture image data D 1  and D 2  output from the physical format buffer  19  to the DVD standard physical format, respectively. 
   The signal processing circuit  21  is for converting the picture image data D 1  and D 2  output from the physical formatter  20  to NRZI (non return to zero inverse) signals and applying a waveform conversion process to the NRZI signals for improving the shape of a pit formed in the DVD-R  1 . 
   The optical pickup  22  is for irradiating a light beam to the DVD-R  1  so as to record the NRZI signals (picture image data D 1  and D 2 ) onto the DVD-R  1 . Moreover, the optical pickup  22  converts the light beam reflected by the DVD-R  1  into an electric signal so as to output the same as a read signal to the signal extraction circuit  23 . 
   The signal extraction circuit  23  extracts a reproduction signal and a control signal from the read signals output from the optical pickup  22 . The control signal is used for the focusing servo control and the tracking servo control. The reproduction signal is output to the physical decoder  24 . 
   The physical decoder  24  is for decoding a reproduction signal output from the signal extraction circuit  23  according to the decoding system corresponding to the above-mentioned physical formatter  20 . The logical decoder  26  is for decoding the data output from the physical decoder according to the decoding system corresponding to the above-mentioned logical formatter  18 . Furthermore, the MPEG decoder  27  is for decompressing the data output from the logical decoder  26  according to the decompressing (decoding) system corresponding to the above-mentioned MPEG encoders  13  and  14 . The digital-analog converter  29  is for converting the picture image data decoded and decompressed by the physical decoder  24 , the logical decoder  26  and the MPEG decoder  27  to an analog picture image signal and outputting the same. 
   The CPU  30  changes the “transfer rate of the picture image data D 1 ” and “the transfer rate of the picture image data D 2 ” independently, using the rate control signal RC 1  or RC 2  as described later. Moreover, the CPU  30  controls the selection of the memory area  17 A or  17 B in the logical format buffer  17 , the writing operation of the picture image data D 1  and D 2  in the memory areas  17 A and  17 B, and the reading operation of the picture image data D 1  and D 2  from the memory areas  17 A and  17 B, using an address signal, a write control signal and a read control signal. Furthermore, the CPU  30  controls the selection of the memory area  19 A or  19 B in the physical format buffer  19 , the writing operation of the picture image data D 1  and D 2  in the memory areas  19 A and  19 B, and the reading operation of the picture image data D 1  and D 2  from the memory areas  19 A and  19 B, using another address signal, another write control signal and another read control signal. Moreover, the CPU  30  receives a data amount signal output from the physical format buffer so as to monitor (detect) the amount of the image data D 1  and D 2  stored each in the memory areas  19 A and  19 B of the physical format buffer  19  based on the data amount signal. In addition thereto, the CPU  30  controls the logical formatter  17 , the physical formatter  20 , the signal extraction circuit  23 , the physical decoder  24 , the logical decoder  26 , the MPEG decoder  27 , or the like. 
   Then, the “transfer rate of the picture image data D 1 ”, the “transfer rate of the picture image data D 2 ” and a “recording rate” will be explained. 
   The “transfer rate of the picture image data D 1 ” stands for the amount of the picture image data D 1  written in the memory area  17 A of the logical format buffer  17  per unit time. The “transfer rate of the picture image data D 1 ” is determined on the whole by the quantization rate in the quantization portion  53  of the MPEG encoder  13 . Further specifically, since the compression ratio of the picture image data D 1  is reduced if the quantization rate in the quantization portion  53  is increased, the data amount of the picture image data D 1  output from the MPEG encoder  13  per unit time is increased. As a result, the “transfer rate of the picture image data D 1 ” is increased. On the other hand, since the compression ratio of the picture image data D 1  is increased if the quantization rate in the quantization portion  53  is reduced, the data amount of the picture image data D 1  output from the MPEG encoder  13  per unit time is reduced. As a result, the “transfer rate of the picture image data D 1 ” is reduced. 
   The “transfer rate of the picture image data D 2 ” stands for the amount of the picture image data D 2  written in the memory area  17 B of the logical format buffer  17  per unit time. The “transfer rate of the picture image data D 2 ” is determined on the whole by the quantization rate in the quantization portion  53  of the MPEG encoder  14 . 
   Moreover, as mentioned above, the “transfer rate of the picture image data D 1 ” and the “transfer rate of the picture image data D 2 ” can vary according to the control of the CPU  30 . The CPU  30  changes the quantization rate in the quantization portion  53  of the MPEG encoder  13 , using a rate control signal RC 1 . Accordingly, the “transfer rate of the picture image data D 1 ” is changed. Similarly, the CPU  30  changes the quantization rate in the quantization portion  53  of the MPEG encoder  14 , using a rate control signal RC 2 . Accordingly, the “transfer rate of the picture image data D 2 ” is changed. 
   Furthermore, the “transfer rate of the picture image data D 1 ” and the “transfer rate of the picture image data D 2 ” are controlled such that the upper limit of the total value thereof (hereinafter referred to as the “total upper limit value”) is the same as or less than the amount of the picture image data D 1  or D 2  read out from the logical format buffer  17  by the logical formatter  18  per unit time. This is for preventing the overflow of the logical format buffer  17 . The amount of the picture image data D 1  or D 2  read out from the logical format buffer  17  by the logical formatter  18  per unit time depends on the output rate (the amount of the output picture image data per unit time) of the logical formatter  18 . Since the output rate of the logical formatter  18  is, for example, about 10.08 Mbps, the “transfer rate of the picture image data D 1 ” and the “transfer rate of the picture image data D 2 ” are controlled so that the total upper limit value can be, for example, 10 M bit. 
   On the other hand, the “recording rate” stands for the amount of the picture image data recorded in the DVD-R  1  per unit time. The “recording rate” is determined on the whole by the output rate of the physical formatter  20 . Here, the amount of the picture image data D 1  or D 2  written in the physical format buffer  19  per unit time needs to be the same as or less than the amount of the picture image data D 1  or D 2  read out from the physical format buffer  19  by the physical formatter  20  per unit time in order to prevent the overflow of the physical format buffer  19 . The amount of the picture image data D 1  or D 2  read out from the physical format buffer  19  by the physical formatter  20  per unit time is determined on the whole by the output rate of the physical formatter  20 . Moreover, the amount of the picture image data D 1  or D 2  written in the physical format buffer  19  per unit time is determined by the output rate of the logical formatter  18 . Therefore, at least the output rate of the physical formatter  20  needs to be higher than the output rate of the logical formatter  18 . In consideration thereof, the output rate of the physical formatter  20  is, for example, about 11.08 Mbps. In this case, the “recording rate” becomes substantially 11.08 Mbps. 
   As a result, each rate is set in the recording/reproducing apparatus  100  such that the “transfer rate of the picture image data D 1 ” and the “transfer rate of the picture image data D 2 ” can always be lower than the “recording rate”. 
   The recording operation of the recording/reproducing apparatus  100  according to this embodiment will be explained with reference to  FIGS. 4  to  8 . 
     FIG. 4  shows the main program of the recording operation. When the recording operation starts, the CPU  30  executes the recording operation according to the main program. As shown in  FIG. 4 , the CPU  30  determines, first, whether or not to execute the two channel simultaneous recording (step  11 ). Whether or not to execute the two channel simultaneous recording is determined on the basis of the manual command by a user. For example, when the user operates an operation panel (not illustrated) provided in the recording/reproducing apparatus  100  for inputting the command of executing the two channel simultaneous recording, the CPU  30  continues the process to the step  12  so as to execute the transfer rate setting process. 
     FIG. 5  shows the transfer rate setting process program. The CPU  30  calls the transfer rate setting process program in the step  12  so as to execute the transfer rate setting process according to the transfer rate setting process program. As shown in  FIG. 5 , the CPU  30 , first, determines whether or not the “transfer rate of the picture image data D 1 ” is designated by the user, and whether or not the “transfer rate of the picture image data D 2 ” is designated by the user (steps  21  to  23 ). Here, the recording/reproducing apparatus  100  has the function that the user can set the image quality of the picture image to be recorded in recording a picture image in the DVD-R  1 . The image quality of the picture image is determined by the quantization rate (that is, the compression rate) in the quantization portion  53  of the MPEG encoder  13  ( 14 ). As mentioned above, since the “transfer rate of the picture image data D 1  (D 2 )” is determined by the quantization rate, setting of the image quality by the user stands for the designation of the “transfer rate of the picture image data D 1  (D 2 )”. 
   When only the “transfer rate of the picture image data D 1 ” is designated according to the result of the determination, the CPU  30  sets the “transfer rate of the picture image data D 1 ” at a designated value (step  24 ). Furthermore, the CPU  30  subtracts the value of the “transfer rate of the picture image data D 1 ” set in the step  24  from the total upper limit value, and sets the obtained value as the “transfer rate of the picture image data D 2 ” (step  25 ). 
   On the other hand, when only the “transfer rate of the picture image data D 2 ” is designated according to the result of the determination, the CPU  30  sets the “transfer rate of the picture image data D 2 ” at a designated value (step  26 ). Furthermore, the CPU  30  subtracts the value of the “transfer rate of the picture image data D 2 ” set in the step  26  from the total upper limit value, and sets the obtained value as the “transfer rate of the picture image data D 1 ” (step  27 ). 
   Moreover, when both the “transfer rate of the picture image data D 1 ” and the “transfer rate of the picture image data. D 2 ” are designated, or neither is designated according to the result of the determination, the CPU  30  sets the value obtained by dividing the total upper limit value by two as the “transfer rate of the picture image data D 1 ” and the “transfer rate of the picture image data D 2 ”, respectively. Then, the process returns to the main program of the recording operation. 
   As shown in  FIG. 4 , after finishing the transfer rate setting process, the CPU  30  commands commencement of the compression process to the MPEG encoders  13  and  14 . Accordingly, the MPEG encoders  13  and  14  start the compression process. Then, the CPU  30  outputs a write control signal to the logical format buffer  17  (step  13 ). Accordingly, the picture image data D 1  output from the MPEG encoder  13  are stored in the memory area  17 A of the logical format buffer  17 , and the picture image data D 2 ” output from the MPEG encoder  14  are stored in the memory area  17 B of the logical format buffer  17 . Then, the CPU  30  continues the process to the step  14  so as to execute the two channel simultaneous recording process. 
     FIG. 6  shows the two channel simultaneous recording process program. The CPU  30  calls the two channel simultaneous recording process program in the step  14  so as to execute the two channel simultaneous recording process according to the two channel simultaneous recording process program. As shown in  FIG. 6 , the CPU  30 , first, searches the tack for recording the picture image data D 1  (step  31 ). 
   Then, the CPU  30  outputs an address signal and a write control signal to the physical format buffer  19  for selecting the memory area  19 A. Then, the CPU  30  outputs an address signal and a write control signal to the logical format buffer  17  for selecting the memory area  17 A (step  32 ). Accordingly, the picture image data D 1  stored in the memory area  17 A of the logical format buffer  17  are transferred to the memory area  19 A of the physical format buffer  19  via the logical formatter  18 . In this step, the format of the picture image data D 1  is converted by the logical formatter  18 . 
   Then, the CPU  30  determines whether or not the picture image data D 1  transferred to the memory area  19 A of the physical format buffer  19  has reached a predetermined amount (step  33 ). In the case the picture image data D 1  have not reached the predetermined amount, the CPU  30  monitors the amount of the picture image data D 1  being stored in the memory area  19 A until the picture image data D 1  are stored to the predetermined amount. When the picture image data D 1  are stored to the predetermined amount, the CPU  30  outputs an address signal and a read control signal to the physical format buffer  19  for selecting the memory area  19 A (step  34 ). Accordingly, the picture image data D 1  stored in the memory area  19 A of the physical format buffer  19  are output to the optical pickup  22  via the physical formatter  20  and the signal processing circuit  21 . In this step, the format of the picture image data D 1  is converted by the physical formatter  20 , and furthermore, the picture image data D 1  are converted to an NRZI signal by the signal processing circuit  21 . Then, the picture image data D 1  reached to the optical pickup  22  are recorded in the DVD-R  1  by the optical pickup  22 . The above-mentioned predetermined amount is set not to exceed the upper limit value of the memory capacity of the physical format buffer  19 . 
   Furthermore, the CPU  30  outputs an address signal and a write control signal to the physical format buffer  19  immediately after executing the step  34  for selecting the memory area  19 B. Then, the CPU  30  outputs an address signal and a read control signal to the logical format buffer  17  for selecting the memory area  17 B (step  35 ). Accordingly, the picture image data D 2  stored in the memory area  17 B of the logical format buffer  17  are transferred to the memory area  19 B of the physical format buffer  19  via the logical formatter  18 . In this step, the format of the picture image data D 2  is converted by the logical formatter  18 . 
   Then, the CPU  30  determines whether or not the recording operation of the picture image data D 1  in the DVD-R  1  is finished (step  36 ). The recording operation of the picture image data D 1  in the DVD-R  1  is finished immediately after the output of all of the picture image data D 1  stored in the memory area  19 A of the physical format buffer  19 . When the recording operation of the picture image data D 1  in the DVD-R  1  is finished, the CPU  30  searches the track for recording the picture image data D 2  (step  37 ). 
   The CPU  30  determines whether or not the picture image data D 2  transferred to the memory area  19 B of the physical format buffer  19  has reached a predetermined amount (step  38 ). In the case the picture image data D 2  have not reached the predetermined amount, the CPU  30  monitors the amount of the picture image data D 2  being stored in the memory area  19 B until the picture image data D 2  are stored to the predetermined amount. When the picture image data D 2  are stored to the predetermined amount, the CPU  30  outputs an address signal and a read control signal to the physical format buffer  19  for selecting the memory area  19 B (step  39 ). Accordingly, the picture image data D 2  stored in the memory area  19 B of the physical format buffer  19  are output to the optical pickup  22  via the physical formatter  20  and the signal processing circuit  21 . In this step, the format of the picture image data D 2  is converted by the physical formatter  20 , and furthermore, the picture image data D 2  are converted to an NRZI signal by the signal processing circuit  21 . Then, the picture image data D 2  reached to the optical pickup  22  are recorded in the DVD-R  1  by the optical pickup  22 . 
   Furthermore, the CPU  30  outputs an address signal and a write control signal to the physical format buffer  19  immediately after executing the step  39  for selecting the memory area  19 A. Then, the CPU  30  outputs an address signal and a read control signal to the logical format buffer  17  for selecting the memory area  17 A (step  40 ). Accordingly, the picture image data D 1  stored in the memory area  17 A of the logical format buffer  17  are transferred to the memory area  19 A of the physical format buffer  19  via the logical formatter  18 . In this step, the format of the picture image data D 2  is converted by the logical formatter  18 . 
   Then, the CPU  30  determines whether or not the recording operation of the picture image data D 2  in the DVD-R  1  is finished (step  41 ). The recording operation of the picture image data D 2  in the DVD-R  1  is finished immediately after the output of all of the picture image data D 2  stored in the memory area  19 B of the physical format buffer  19 . When the recording operation of the picture image data D 2  in the DVD-R  1  is finished, the CPU  30  searches the track for recording the picture image data D 1  (step  42 ). 
   The CPU  30  repeats the process of the above-mentioned steps  33  to  42  until, for example, the user commands the finish of the recording operation. Accordingly, the picture image data D 1  and D 2  are recorded in the DVD-R  1 . 
   On the other hand, in the case the user inputs the command of not executing the two channel simultaneous recording, that is, the command of executing the one channel recording at the time of the determination in the step  11 , the CPU  30  continues the process to the step  15 . Then, in the step  15 , the recording operation is executed, for example, only for the picture image signal A 1 . 
   Here,  FIG. 7  shows the change of the amounts of the picture image data D 1  and D 2  stored in the memory areas  17 A and  17 B of the logical format buffer  17  while executing the above-mentioned two channel simultaneous recording. The period P 1  in  FIG. 7  is the period wherein the picture image data D 1  output from the MPEG encoder  13  are stored in the memory area  17 A of the logical format buffer  17 . Since the picture image data D 1  stored in the memory area  17 A are not transferred to the physical format buffer  19  in the period P 1 , the amount of the picture image data D 1  in the logical format buffer  17  increases gradually. The rate of the increase of the picture image data D 1  amount in this period is determined on the whole by the “transfer rate of the picture image data D 1 ”. 
   Moreover, the period P 2  is the period wherein the picture image data D 1  stored in the memory area  17 A are transferred to the physical format buffer  19 . In the period P 2 , although the picture image data D 1  output from the MPEG encoder  13  are written in the memory  17 A, since the picture image data D 1  stored in the memory area  17 A are transferred to the physical format buffer  19  at a higher rate, the amount of the picture image data D 1  in the logical format buffer  17  decreases gradually. The rate of the decrease of the picture image data D 1  amount in this period P 2  is determined on the whole by the “transfer rate of the picture image data D 1 ” and the output rate of the logical formatter  18 . 
   On the other hand, the period Q 1  is the period wherein the picture image data D 2  output from the MPEG encoder  14  are stored in the memory area  17 B of the logical format buffer  17 . Since the picture image data D 2  stored in the memory area  17 B are not transferred to the physical format buffer  19  in the period Q 1 , the amount of the picture image data D 2  in the logical format buffer  17  increases gradually. The rate of the increase of the picture image data D 2  amount in this period is determined on the whole by the “transfer rate of the picture image data D 2 ”. 
   Moreover, the period Q 2  is the period wherein the picture image data D 2  stored in the memory area  17 B are transferred to the physical format buffer  19 . In the period Q 2 , although the picture image data D 2  output from the MPEG encoder  14  are written in the memory  17 B, since the picture image data D 2  stored in the memory area  17 B are transferred to the physical format buffer  19  at a higher rate, the amount of the picture image data D 2  in the logical format buffer  17  decreases gradually. The rate of the decrease of the picture image data D 2  amount in this period Q 2  is determined on the whole by the “transfer rate of the picture image data D 2 ” and the output rate of the logical formatter  18 . 
   Accordingly, the amounts of the picture image data D 1  and D 2  are each increased and decreased periodically in the logical format buffer  17 . However, the increase and decrease pattern of the picture image data D 1  amount and the increase and decrease pattern of the picture image data D 2  amount are about out of phase by the half cycle with each other. Therefore, on the whole, when the picture image data D 1  amount is increased, the picture image data D 2  amount is decreased, and when the picture image data D 1  amount is decreased, the picture image data D 2  amount is increased. Thereby, the total amount F of the picture image data D 1  and D 2  in the logical format buffer  17  is always maintained without exceeding the upper limit of the memory capacity of the logical format buffer  17 . 
     FIG. 8  shows the change of the amounts of the picture image data D 1  and D 2  stored in the memory areas  19 A and  19 B of the physical format buffer  19 . The period S 1  in  FIG. 8  is the period wherein the picture image data D 1  transferred from the logical format buffer  17  are stored in the memory area  19 A of the physical format buffer  19 . Since the picture image data D 1  are not recorded in the period S 1 , the amount of the picture image data D 1  in the physical format buffer  19  increases gradually. The rate of the increase of the picture image data D 1  amount in this period S 1  is determined on the whole by the output rate of the logical formatter  18 . 
   Moreover, the period S 2  is the period wherein the picture image data D 1  stored in the memory area  19 A are recorded in the DVD-R  1 . In this period, since the picture image data D 1  stored in the memory area  19 A are only output to the optical pickup  22  side, the amount of the picture image data D 1  in the physical format buffer  19  decreases gradually. The rate of the decrease of the picture image data D 1  amount in this period S 2  is determined by the recording rate. 
   On the other hand, the period T 1  is the period wherein the picture image data D 2  transferred from the logical format buffer  17  are stored in the memory area  19 B of the physical format buffer  19 . Since the picture image data D 2  are not recorded in the period T 1 , the amount of the picture image data D 2  in the physical format buffer  19  increases gradually. The rate of the increase of the picture image data D 2  amount in this period T 1  is determined on the whole by the output rate of the logical formatter  18 . 
   Moreover, the period T 2  is the period wherein the picture image data D 2  stored in the memory area  19 B are recorded in the DVD-R  1 . In this period, since the picture image data D 2  stored in the memory area  19 B are only output to the optical pickup  22  side, the amount of the picture image data D 2  in the physical format buffer  19  decreases gradually. The rate of the decrease of the picture image data D 2  amount in this period T 2  is determined by the recording rate. 
   Accordingly, the amounts of the picture image data D 1  and D 2  are each increased and decreased periodically in the physical format buffer  19 . However, the increase and decrease pattern of the picture image data D 1  amount and the increase and decrease pattern of the picture image data D 2  amount are out of phase by the half cycle with each other. Therefore, on the whole, when the picture image data D 1  amount is increased, the picture image data D 2  amount is decreased, and when the picture image data D 1  amount is decreased, the picture image data D 2  amount is increased. Thereby, the total amount F of the picture image data D 1  and D 2  in the physical format buffer  19  cannot exceed the upper limit of the memory capacity of the physical format buffer  19 . 
   Furthermore, the rate of the decrease of the picture image data D 1  amount in the period S 2  is higher than the rate of the increase of the picture image data D 2  amount in the period T 1 . Thereby, the period H for searching the track can be set for preparing for recording the next picture image data. That is, the output rate and the recording rate of the logical formatter  18  are set such that the track searching period H can be set sufficiently and appropriately. 
   Then, the recording track positions of the picture image data D 1  and D 2  on the DVD-R  1  will be explained with reference to  FIGS. 9  and  10 .  FIG. 9  shows a spiral track formed on the DVD-R  1  illustrated linearly for the convenience of the explanation. As shown in  FIG. 9 , the recording/reproducing apparatus  100  according to this embodiment records the picture image data D 1  in the inner circumference side region R 1  of the DVD-R  1  and the picture image data D 2  in the outer circumference side area R 2  of the DVD-R  1 . Therefore, in the recording operation, whenever recording of the picture image data D 1  and recording of the picture image data D 2  are switched, the searching operation (track jump) is repeated between the inner circumference side area R 1  and the outer circumference area R 2  of the DVD-R. By completely separating the recording domains of the picture image data D 1  and D 2  accordingly, for example, in reproducing the picture image data D 1 , the inner circumference side area R 1  of the DVD-R  1  can be read out continuously. Therefore, the reproducing operation can be executed efficiently. 
   The present invention is not limited thereto but as shown in  FIG. 10 , the picture image data D 1  and the picture image data D 2  can be recorded alternately on the track. Accordingly, a long track jump in the recording operation can be avoided, and thus the efficiency of the recording operation can be improved. 
   The reproducing operation of the recording/reproducing apparatus  100  according to this embodiment will be explained with reference to FIG.  11 . 
     FIG. 11  shows a reproducing operation program. When the reproducing operation is started, the CPU  30  determines whether or not the DVD-R  1  to be reproduced is recorded by the two channel simultaneous recording (step  51 ). This can be realized by recording identity data of the two channel simultaneous recording in the DVD-R  1  as control data at the time of executing the two channel simultaneous recording, and detecting the identity data in this step  51 . 
   In the case the DVD-R  1  to be reproduced is recorded by the two channel simultaneous recording, the CPU  30  selects the picture data to be reproduced (step  52 ). The picture image data to be reproduced are determined on the basis of the manual command by the user. Then, the CPU  30  reproduced the selected picture image data (step  53 ). 
   As heretofore mentioned, the recording/reproducing apparatus  100  according to this embodiment can receive the two channel picture image signals A 1  and A 2  simultaneously and record the picture image data D 1  and D 2  corresponding to the picture image signals A 1  and A 2  simultaneously. Moreover, the image quality of the picture image to be recorded in the DVD-R  1  can be set freely by changing the quantization rate in the quantization portion  53  of the MPEG encoder  13  ( 14 ) under the control of the CPU  30 . 
   2. Second Embodiment 
   The second embodiment of the present invention will be explained with reference to FIG.  12 . In a recording/reproducing apparatus  200  according to this embodiment shown in  FIG. 12 , the components the same as those of the recording/reproducing apparatus  100  according to the first embodiment shown in  FIG. 1  are applied with the same numerals, and further explanation is not given here. 
   As shown in  FIG. 12 , it is characteristic of the recording/reproducing apparatus  200  according to this embodiment that an analog picture image signal A 3  is input as one of the two channel inputs, and a digital picture image signal D 4  is input as the other one. The digital picture image signal D 4  is, for example, transmitted from a digital satellite broadcast station. Moreover, since the picture image signal is a digital signal, unlike the recording/reproducing apparatus  100  according to the first embodiment, the A/D converter and the MPEG encoder are not required. Furthermore, since the MPEG encoder is not provided for the input of the digital picture image signal D 4 , the transfer rate of the digital picture image signal D 4  is fixed. That is, the transfer rate of the digital picture image signal D 4  is the transfer rate set by a digital satellite broadcast station. On the other hand, since the analog picture image signal A 3  is output to the logical format buffer  17  via the MPEG encoder  13  after being converted to picture image data D 3  by the A/D converter  11 , the “transfer rate of the picture image data D 3 ” can be changed under a predetermined limitation by controlling the quantization rate in the quantization portion of the MPEG encoder  13  by the CPU  30 , and thus the image quality of the picture image signal A 3  can be changed within a predetermined range. 
   In this embodiment with the above-mentioned configuration, the effect substantially the same as that of the above-mentioned first embodiment can be obtained. 
   3. Third Embodiment 
   The third embodiment of the present invention will be explained with reference to  FIGS. 13 and 14 . In this embodiment, the components the same as those of the recording/reproducing apparatus  100  according to the first embodiment shown in  FIG. 1  are applied with the same numerals, and further explanation is not given here. 
     FIG. 13  shows a recording/reproducing apparatus  300  according to this embodiment. In comparison with the above-mentioned recording/reproducing apparatus  100  according to the first embodiment, it is characteristic of the recording/reproducing apparatus  300  according to this embodiment that the recording section comprises image compression portions  301  and  302  and an image composition portion  303 , and the reproducing section comprises an image separation portion  304  and an image decompression portion  305 . 
   As shown in  FIG. 14 , the image compression portion  301  is a device for generating a compressed picture image  312  by compressing a picture image  310  corresponding to a digital picture image signal D 4  obtained by converting an analog picture image signal A 4  by the A/D converter  11  so as to have the length in the lateral direction (horizontal direction) to half. Similarly, the image compression portion  302  is a device for generating a compressed picture image  313  by compressing a picture image  311  corresponding to a digital picture image signal D 5  obtained by converting an analog picture image signal A 5  by the A/D converter  12  so as to have the length in the lateral direction (horizontal direction) to half. 
   The image composition portion  303  is a device for producing a synthesized image  314  by arranging the compressed picture images  312  and  313  produced by the image compression portions  301  and  302  side by side laterally for synthesizing the compressed picture images as shown in FIG.  14 . The synthesized picture image  314  is output to the MPEG encoder  13 . Hereinafter, substantially similarly to the recording/reproducing apparatus  100  according to the first embodiment, after executing the compression process according to the MPEG system, the format conversion by the logical formatter  18 , the format conversion by the physical formatter  20 , or the like, the synthesized picture image  314  is recorded in the DVD-R  1 . 
   In reproducing the DVD-R  1  with the picture image data recorded by the recording/reproducing apparatus  300  according to this embodiment, substantially similarly to the recording/reproducing apparatus  100  according to the first embodiment, a reproduced signal read out from the DVD-R  1  is applied with the decoding process by the physical decoder  24 , the decoding process by the logical decoder  26  and the decompressing process by the MPEG decoder  27 . Accordingly, as shown in  FIG. 14 , a synthesized picture image  321  including the two compressed picture images  322  and  323  compressed by half in the lateral direction can be obtained, and picture image data corresponding to the synthesized picture image  321  are output to the image separation portion  304 . 
   As shown in  FIG. 14 , the image separation portion  304  is a device for separating the synthesized picture image  321  including the compressed picture images  322  and  323  compressed by half in the lateral direction in two. Moreover, the image decompression portion  305  is a device for expanding each of the separated compressed picture images  322  and  323  by double in the lateral direction. Accordingly, the picture images  324  ( 310 ) and  325  ( 311 ) corresponding to the picture image data D 4  and D 5  can be reproduced. 
   According to the recording/reproducing apparatus  300  according to this embodiment with the above-mentioned configuration, the two channel picture image signals can be recorded simultaneously. 
   Although the cases of simultaneously recording the two channel picture image signals have been explained in the above-mentioned first to third embodiments, the present invention is not limited thereto, but may have a configuration for simultaneously recording the picture image of the three or more channels, for example, four, five, six or eight channels. 
   Moreover, although the cases of recording and reproducing the picture image signals (picture image data) as the information have been explained in the above-mentioned first to third embodiments, the present invention is not limited thereto, but may have a configuration for recording and reproducing another kind of information, such as a sound signal (sound data), or the like. 
   Furthermore, although the cases of using a DVD-R as the recording medium have been explained in the above-mentioned first to third embodiments, the present invention is not limited thereto, but other recording media, such as a CD-R can be used. 
   Moreover, although the present invention is adopted in the recording/reproducing apparatus  100  ( 200 ,  300 ) in the above-mentioned first to third embodiments, the present invention can be used also in a recording apparatus without a reproducing function. 
   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. 
   The entire disclosure of Japanese patent application no. 10-287030 filed on Oct., 8, 1998 including the specification, claims, drawings and summary is incorporated herein by reference in its entirety.