Abstract:
An image processor has an image decoder for decoding compressed image data. The image processor also has a central processing unit for controlling the operation of the image processor, including the image decoder, in accordance with a control program. The central processing unit performs, immediately after power ON, the startup operation to cause the image decoder to decode compressed control data (i.e., compressed control program) and acquire the control program.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to an image processor having an image decoder, such as an MPEG decoder.  
         [0003]     2. Description of the Related Art  
         [0004]     A DVD recorder can be considered to be an image processor. In the DVD recorder, CPU (Central Processing Unit) executes the control program comprised of an OS (Operating System) and application software, to implement various operations, such as recording operation, reproducing operation and editing operation.  
         [0005]     After power is turned ON in the DVD recorder, the startup operation is performed. During this startup operation under the control of the startup program, the CPU reads compressed control data from ROM, writes the compressed control data into RAM, sequentially decodes the compressed control data, writes it again to RAM, and creates a control program on the RAM. Then the CPU executes the control program to perform the actual operation of the DVD recorder.  
         [0006]     It takes time until the actual operation of the DVD recorder, such as the recording operation, becomes possible since the startup operation is executed immediately after power is turned ON. This is not limited to a DVD recorder, but is the same for other image processors that have the CPU to execute the control program.  
       SUMMARY OF THE INVENTION  
       [0007]     It is one object of the present invention to provide an image processor that can decrease the time required for the startup operation immediately after power ON.  
         [0008]     According to one aspect of the present invention, there is provided an image processor that includes an image decoder for decoding compressed image data, and a central processing unit for controlling the operation of the image processor including the image decoder in accordance with a control program. The central processing unit performs, immediately after power ON, a startup operation to cause the image decoder to decode compressed control data in which the control program is compressed, and acquire the control program.  
         [0009]     According to a second aspect of the present invention, there is provided an image processor that includes a decoding unit and a central processing unit for controlling an operation of the image processor in accordance with a control program. A decoding speed of the decoding unit is faster than a decoding speed-of the central processing unit. The central processing unit performs a startup operation to cause the decoding unit to decode compressed control program and obtain the control program. The central processing unit may perform the startup operation immediately after power ON of the image processor.  
         [0010]     According to a third aspect of the present invention, there is provided a method of making a control program to be used by a central processing unit of an image processor. The image processor has the central processing unit, a memory and a decoding unit. A decoding speed of the decoding unit is faster than a decoding speed of the central processing unit. The method includes reading compressed control program from the memory, and causing the decoding unit to decode the compressed control program to obtain the control program. The reading may be performed immediately after power ON of the image processor. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a block diagram depicting the configuration of the disk recorder according to one embodiment of the present invention; and  
         [0012]      FIG. 2  is a flow chart depicting the startup operation to be executed by the CPU. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0013]     Embodiments of the present invention will now be described with reference to the drawings.  
         [0014]     Referring to  FIG. 1 , an embodiment of a disk recorder  20  will be described. This disk recorder  20  includes a TV tuner  1 , A/D converter  2 , MPEG encoder  3 , CPU  4 , display section  5 , operation section  6 , HDD (Hard Disk Drive) device  7 , optical disk drive device  8 , ROM  9 , RAM  10 , MPEG decoder  11  and D/A converter  12 .  
         [0015]     The TV tuner  1  is connected to the antenna input terminal  21 , and selectively receives TV broadcast waves via an antenna (not illustrated) connected thereto, under the control of the CPU  4 . The TV tuner  1  demodulates the incoming signals and generates analog video signals and audio signals. The output of the TV tuner  1  is connected to the A/D converter  2 . The A/D converter  2  digitizes the analog video signals and audio signals which are supplied from the TV tuner  1 . The A/D converter  2  is connected to the external video and audio input terminals  22  and  23 , and digitizes the analog video signals and audio signals supplied thereto. The output of the A/D converter  2  is connected to the encoder  3 . The encoder  3  converts the digitized video signals and audio signals into compressed data in MPEG format, for example.  
         [0016]     The encoder  3 , CPU  4 , HDD device  7 , optical disk drive device  8 , ROM  9 , RAM  10  and decoder  11  are connected to the common bus  16 .  
         [0017]     The CPU  4  is a microcomputer, for example, and controls the entire disk recorder according to the predetermined control program. When the power of the disk recorder is turned ON, the CPU  4  performs the startup operation according to the predetermined startup program. The CPU  4  and the TV tuner  1  are connected by a control line (not illustrated), and the channel of the TV tuner  1  is controlled by the CPU  4 .  
         [0018]     The display section  5  and operation section  6  are connected to the CPU  4 . The display section  5  displays the recording/reproducing status of the signal-receiving channel of the TV tuner  1 , the HDD device  7 , and the optical disk drive device  8  according to a display instruction from the CPU  4 . The operation section  6  receives an input operation by the user and supplies an instruction to the CPU  4  according to the input operation.  
         [0019]     The HDD device  7  is a storage device having a reloadable (rewritable, re-recordable) fixed disk (not illustrated), and writes the compressed data, which is supplied from the encoder  3  according to the write instruction of the CPU  4 , to the internal fixed disk at an address position indicated by the write instruction. According to the read instruction of the CPU  4 , the HDD device  7  reads the compressed data at a storage position, of which address is specified by the read instruction, from the fixed disk, and sends it to the bus  16 .  
         [0020]     The optical disk drive device  8  is a removable storage device, and can write the compressed data from the encoder  3  or the HDD device  7  to the optical disk  15  according to the write instruction of the CPU  4 . The optical disk  15  is a DVD-R or DVD-RW, for example. The optical disk drive device  8  can also read the compressed data from the optical disk  15  according to the read instruction of the CPU  4 .  
         [0021]     In the ROM  9 , the startup program has been written in advance, and compressed control data, which is compressed in MPEG format, has been written in advance. In the RAM  10 , the control program, comprised of an OS (Operating System) and application software for this disk recorder  20 , is written. The startup program is a program which the CPU  4  executes when the power of the disk recorder  20  is turned ON. The control program is a program acquired by decompressing the compressed control data stored in ROM  9 .  
         [0022]     The decoder  11  decompresses the compressed data which is supplied from the encoder  3 , CPU  4 , HDD device  7  or optical disk drive device  8  via the bus  16 , and restores the data to the digital video and audio signals. The restored digital video and audio signals are supplied to the D/A converter  12 . The D/A converter  12  converts the digital video and audio signals into analog vide and audio signals, and supplies them to the video and audio output terminals  24  and  25 . A TV monitor (not shown) is connected to the video and audio output terminals  24  and  25 . The decoder  11  decodes the compressed control data, which has been compressed in MPEG format, at the startup operation.  
         [0023]     When the power supply button in the operation section  6  of the disk recorder  20  is operated, the CPU  4  starts the startup operation according to the startup program which is written in the ROM  9 .  
         [0024]     As shown in  FIG. 2 , the CPU  4  reads the compressed control data from the ROM  9  in the startup operation (step S 1 ), and writes the compressed control data to the RAM  10  (step S 2 ).  
         [0025]     The CPU  4  reads the compressed control data from the RAM  10  for a predetermined volume (step S 3 ), and supplies the compressed control data to the decoder  11  such that the decoder  11  decompress (decodes) it (step S 4 ). The decoder  11  decodes the predetermined volume of compressed control data, and generates the decoded control data. When the decoded control data is output from the decoder  11 , the CPU  4  writes (sends) the decoded control data to the RAM  10  (step S 5 ). The decoded control data is written to an area (second storage area) which is different from the storage area (first storage area) of the compressed control data in the RAM  10 . The CPU  4  determines whether unread compressed control data remains in the RAM  10  (step S 6 ). If compressed control data remains, the CPU  4  returns to step S 3  and repeats steps S 3  to S 6 .  
         [0026]     If the data volume of the final part of the unread compressed control data that remains in the RAM  10  is smaller than the predetermined volume, this data is read in step S 3 . The reading and writing operations of the compressed control data in step S 1  and step S 2  are executed while the decoder  11  is performing the decoding operation until all the compressed control data is written to the RAM  10 .  
         [0027]     When all the compressed control data in the RAM  10  is read, the decoded control data repeatedly written in the RAM  10  in step S 5  creates the control program. Therefore the CPU 4  reads the control program from the beginning, and starts control of the disk recorder  20  according to the control program (step S 7 ).  
         [0028]     In this way, in the startup operation until the control of the disk recorder  20  actually starts, not the CPU  4  but the MPEG decoder  11 , installed in the disk recorder  20 , executes the decoding of the compressed data stored in the ROM  9 . The MPEG decoder  11  is hardware dedicated to decoding, and the decoding speed of the MPEG decoder  11  is faster than that of a general purpose CPU. Since the CPU  4  should execute only the data transfer between the ROM  9  and the RAM  10 , and between the RAM  10  and the decoder  11 , the time required for the startup operation can be decreased.  
         [0029]     It should be noted that the mode of the MPEG decoder  11  when the MPEG decoder  11  decodes the compressed control data may be different from a mode of the MPEG decoder  11  when the MPEG decoder  11  decodes the video signals and audio signals.  
         [0030]     It should also be noted that the CPU may not read the compressed control data from the ROM and may not write it to the RAM. Instead of the CPU, the MPEG recorder may perform this processing.  
         [0031]     In the above described embodiment, the present invention is applied to a disk recorder, such as a DVD recorder, but the present invention can also be applied to an image processor other than a disk recorder, such as a PDA and portable telephone.  
         [0032]     As described above, according to the present invention, the CPU executes the startup operation for causing the image decoder to decode the compressed control data (i.e., the compressed control program) so as to obtain the control program immediately after power ON. Therefore, the time required for the startup operation after power ON can be reduced, and the actual operation of the image processing is enabled quickly after power ON.  
         [0033]     This application is based on Japanese Patent Application No. 2005-101553 filed on Mar. 31, 2005, and the entire disclosure thereof is incorporated herein by reference.