Abstract:
The present invention is related to a method and an apparatus for processing audio signals, which uses two speakers to simulate audio sounds with wide and 3D effects. The method provides a structure for processing audio signals by a plurality of analog elements (filter, gain amplifier, delay processing unit). The present invention also improves the bass part and strengthens 3D effects of the audio sounds. Therefore, the audio sounds output from the audio devices are more natural and smooth.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention is a method and an apparatus for processing audio signals, especially relates to a method and an apparatus which comprises a plurality of amplifiers, filters and subtracters. It may also produce audio sound with wide and 3D effects.  
         [0003]     2. Descriptions of Related Arts  
         [0004]     With the progress of technology, requirements for family audio devices are more and more in recent years. Bass in audio sounds is enhanced and 3D effects are also simulated for high quality audio output devices. Prior art audio output devices includes a delay unit, a gain control unit, and other related audio processing units. A complicated audio device needs a powerful central processing unit, a digital signal processor and a memory with high capacity. It costs too much and is not practical for family application. Therefore, the present invention provides a simpler and effective algorithm structure to solve the above-mention problem.  
       SUMMARY OF THE INVENTION  
       [0005]     The present invention provides a method and an apparatus for processing audio signals. It uses two speakers to simulate 3D and wide effects for audio sounds. An algorithm structure in the present invention includes a plurality of gain amplifiers, substracters, delay processing unit, high-pass filters and low-pass filters. The high-pass filter is used to eliminate direct current (DC) gain, but it may also be saturated by audio signals. To prevent the high-pass filter from being saturated, a gain unit can be cascaded in front of the high-pass filter. A plurality of delay processing units and low-pass filters may compose a structure to produce audio signals with wide and 3D effects.  
         [0006]     The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing, in which: 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     The foregoing aspects and many of the attendant advantages of this invention will be more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, in which:  
         [0008]      FIG. 1  shows a block diagram of a first embodiment of the present invention;  FIG. 2  shows a block diagram of a second embodiment of the present invention; and  FIG. 3  shows a block diagram of a third embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0009]      FIG. 1  shows a block diagram of an apparatus for processing audio signal according to the first embodiment of the present invention, and the apparatus for processing audio signal comprises a first gain unit  100 , a first high-pass filter processing unit  102 , a first low-pass filter processing unit  104 , a first delay processing unit  106 , a second gain unit  101 , a second high-pass filter processing unit  103 , a second low-pass filter processing unit  105 , a second delay processing unit  107 , a first subtracter  111 , and a second subtracter  112 .  
         [0010]     The first low-pass filter processing unit  104  is connected to the first high-pass filter processing unit  102 . The second low-pass filter processing unit  105  is connected to the a second high-pass filter processing unit  103 . The first subtracter  111  is connected to the first high-pass filter processing unit  102  and the second delay processing unit  107 . The second subtracter  112  is connected to the second high-pass filter processing unit  103  and the first delay processing unit  106 .  
         [0011]     Audio signals inputted to the structure may be divided into a left and a right channel input signals. After the left channel input signal  11  is processed by the first gain unit  100  and the first high-pass filter processing unit  102 , it will be divided again into a first left channel input signal  110  and a second left channel input signal  113 ; and after a right channel input signal  12  is processed by the second gain unit  101  and the second high-pass filter processing unit  103 , it will be divided again into a first right channel input signal  120  and a second right channel input signal  121 . The first gain unit  100  and the second gain unit  101  can prevent the high-pass filter processing unit from being saturated. The first high-pass filter processing unit  102  and the second high-pass filter processing unit  103  also have an advantage of eliminating the direct current gain.  
         [0012]     Next, the second left channel input signal  113  is processed by the low-pass filter processing unit and the delaying processing unit, and the processed signal will be subtracted with the first right channel input signal  120  to produce a first right channel output signal  132 . The second right channel input signal  113  is processed by the low-pass filter processing unit and the delaying processing unit. The processed signal will then be subtracted with the first left channel input signal  110  to produce a first left channel output signal  131 . Finally, the first left channel output signal  131  and the first right channel output signal  132  compensate for each other. With the above-mentioned processing steps, output audio sounds will have wide effects.  
         [0013]      FIG. 2  shows a second embodiment of the present invention, and the apparatus for processing audio signal comprises: a first gain unit  100 , a first high-pass filter processing unit  102 , a first low-pass filter processing unit  104 , a first delay processing unit  106 , a second gain unit  101 , a second high-pass filter processing unit  103 , a second low-pass filter processing unit  105 , a second delay processing unit  107 , a first subtracter  111 , a second subtracter  112 , a third subtracter  213 , a fourth subtracter  214 , a fifth subtracter  215 , and a third gain unit  201 .  
         [0014]     The first low-pass filter processing unit  104  is connected to the first high-pass filter processing unit  102 . The second low-pass filter processing unit  105  is connected to the a second high-pass filter processing unit  103 . The first subtracter  111  is connected to the first high-pass filter processing unit  102  and the second delay processing unit  107 . The second subtracter  112  is connected to the second high-pass filter processing unit  103  and the first delay processing unit  106 . The third subtracter  213  is connected to the first subtracter  111  and the second subtracter  112 . The fourth subtracter  214  is connected to the first subtracter  111 . The fifth subtracter  215  is connected to the second subtracter  112 . The third gain unit  201  is connected to the third subtracter  213 . The fourth subtracter  214  is connected to the fifth subtracter  215 .  
         [0015]     Audio signals inputted to the structure may be divided into left and right channel input signals. After the a left channel input signal  11  is processed by the first gain unit  100  and the first high-pass filter processing unit  102 , it will be divided again into a first left channel input signal  110  and a second left channel input signal  113 ; and after a right channel input signal  12  is processed by the second gain unit  101  and the second high-pass filter processing unit  103 , it will be divided again into a first right channel input signal  120  and a second right channel input signal  121 . The first gain unit  100  and the second gain unit  101  can prevent the high-pass filter processing unit from being saturated. The first high-pass filter processing unit  102  and the second high-pass filter processing unit  103  also have a advantage of eliminating the direct current gain.  
         [0016]     Next, the second left channel input signal  113  is processed by the low-pass filter processing unit and the delaying processing unit, and the processed signal will be subtracted with the first right channel input signal  120  to produce a first right channel output signal  132 ; the second right channel input signal  113  is processed by the low-pass filter processing unit and the delaying processing unit, and then the processed signal will be subtracted with the first left channel input signal  110  to produce a first left channel output signal  131 . Finally, the first left channel output signal  131  and the first right channel output signal  132  compensate for each other. After the above-mentioned processing steps, output audio sounds will have wide effects. For obtaining better audio sounds, a gain processing sector is added behind the structure of the first embodiment, and comprises the third gain unit  201 , the third subtracter  213 , the fourth subtracter  214 , the fifth subtracter  215 . Parts of the first left channel output signal  131  will be processed by the third gain unit  201  and subtracted from the first right channel output signal  132  to produce a second left channel output signal  231 ; parts of the first right channel output signal  132  will be processed by the third gain unit  201  and subtracted from the first left channel output signal  131  to produce a second right channel output signal  232 . Therefore, 3D effects are strengthened in the output audio signals as well as wide effects.  
         [0017]      FIG. 3  shows a third embodiment of the present invention. The apparatus for processing audio signal comprises a first gain unit  100 , a first high-pass filter processing unit  102 , a first low-pass filter processing unit  104 , a first delay processing unit  106 , a second gain unit  101 , a second high-pass filter processing unit  103 , a second low-pass filter processing unit  105 , a second delay processing unit  107 , a first subtracter  111 , a second subtracter  112 , a third subtracter  213 , a fourth subtracter  214 , a fifth subtracter  215 , a third gain unit  201 , a fourth gain unit  301 , a fifth gain unit  302 , a first adder  311  and a second adder  312 .  
         [0018]     The first low-pass filter processing unit  104  is connected to the first high-pass filter processing unit  102 . The second low-pass filter processing unit  105  is connected to the a second high-pass filter processing unit  103 . The first subtracter  111  is connected to the first high-pass filter processing unit  102  and the second delay processing unit  107 . The second subtracter  112  is connected to the second high-pass filter processing unit  103  and the first delay processing unit  106 . The third subtracter  213  is connected to the first subtracter  111  and the second subtracter  112 . The fourth subtracter  214  is connected to the first subtracter  111 . The fifth subtracter  215  is connected to the second subtracter  112 . The third gain unit  201  is connected to the third subtracter  213 . The fourth subtracter  214  is connected to the fifth subtracter  215 . The fourth subtracter  214  is connected to the first subtracter  311 . The fifth subtracter  215  is connected to the second adder  312 . The fourth gain unit  301  is connected between a left channel input port (not labeled) and the first adder  311 . The fifth gain unit  302  is connected between a right channel input port (not labeled) and the second adder  312 .  
         [0019]     Audio signals inputted to the structure may be divided into left and right channel input signals. After the a left channel input signal  11  is processed by the first gain unit  100  and the first high-pass filter processing unit  102 , it will be divided again into a first left channel input signal  110  and a second left channel input signal  113 ; and after a right channel input signal  12  is processed by the second gain unit  101  and the second high-pass filter processing unit  103 , it will be divided again into a first right channel input signal  120  and a second right channel input signal  121 . The first gain unit  100  and the second gain unit  101  can prevent the high-pass filter processing unit from being saturated. The first high-pass filter processing unit  102  and the second high-pass filter processing unit  103  also have a advantage of eliminating the direct current gain.  
         [0020]     Next, the second left channel input signal  113  is processed by the low-pass filter processing unit and the delaying processing unit, and the processed signal will be subtracted with the first right channel input signal  120  to produce a first right channel output signal  132 ; the second right channel input signal  113  is processed by the low-pass filter processing unit and the delaying processing unit, and then the processed signal will be subtracted with the first left channel input signal  110  to produce a first left channel output signal  131 . Finally, the first left channel output signal  131  and the first right channel output signal  132  will be compensated for each other. With the above-mentioned processing steps, output audio sounds will have wide effects. For obtaining better audio sounds, a gain processing sector is added behind the structure of the first embodiment, and which comprises the third gain unit  201 , the third subtracter  213 , the fourth subtracter  214 , and the fifth subtracter  215 . Parts of the first left channel output signal  131  will be processed by the third gain unit  201  and subtracted from the first right channel output signal  132  to produce a second left channel output signal  231 ; parts of the first right channel output signal  132  will be processed by the third gain unit  201  and subtracted from the first left channel output signal  131  to produce a second left channel output signal  232 . Therefore, 3D effects are strengthened in the output audio signals as well as wide effects  
         [0021]     The fourth gain unit  301  and the fifth gain unit  302  are appended for strengthening the bass part in the audio sounds and connected to the left and right channel input port, respectively. The left channel input signal  11  is processed by the gain unit and added with the second left channel output signal  231  to produce a third left channel output signal  331 ; the left channel input signal  12  is processed by the gain unit and added with the second right channel output signal  232  to produce a third right channel output signal  332 . Hence, the bass parts in the third left channel output signal  331  and the third right channel output signal  332  are more powerful. Alto and treble voice parts are most important in audio sounds. With the strengthening of bass part, the alto and treble voice parts will not be too shrill and piercing and the output sound is thus natural and smooth. The fourth gain unit  301  and the fifth gain unit  302  may prevent the alto and treble voice parts from decay and keep the output signals from being saturated.  
         [0022]     Although the present invention has been described with reference to the preferred embodiment therefore, it will be understood that the invention is not limited to the details thereof. Various substitutions and modifications have suggested in the foregoing description, and other will occur to those of ordinary skill in the art. Therefore, all such substitutions and modifications are intended to be embrace within the scope of the invention as defined in the appended claims.