Patent Publication Number: US-2007110261-A1

Title: Audio processing system with function of automatic gain control and method thereof

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to an audio processing system with function of automatic gain control and method thereof, especially to an audio processing system with function of automatic gain control according to a time period to which a current time belongs and method thereof.  
      2. Description of Related Art  
      Compared to before, there is a significant increase of the work pace and living pace of people. Living in a fast pace society often puts a person under high pressure, thus more easily become discontent. Enjoying music has become one of the most common activity to relax and relieve the high pressure and people are often seen enjoying music while working, commuting, and when resting.  
      In addition, people generally have regular working schedules and living habits. I.e, the time a person wakes up, works, eats, sleeps, exercises, and so on usually remains somewhat habitual. A person may enjoy listening to different style of music when waking up, working, exercising . . . etc. For example, while at work, a person may prefer to listen to light music at a low volume and listen to music with a fast beat while exercising. Additionally, a person&#39;s hearing sensitivity may change according to different time periods of the day. During morning hours, a person&#39;s listening sensitivity may be more sensitive after waking up, and less sensitive in the afternoon.  
      Therefore, what is needed is an system capable of automatically controlling a gain value corresponding to different times of the day, which can automatically play appropriate music at a suitable volume during different time period, thereby making it convenient for people to enjoying music. Especially to drivers that listen music simultaneously, the system can lower the risks of accidents of the people who manually adjust the music volume while driving. Furthermore, if a listener prefers enjoying music at a desired volume corresponding to certain time periods of the day, for example, while waking up, the listener can wake up to soothing music comfortably.  
      Therefore, a heretofore unaddressed need exists in the industry to overcome the aforementioned deficiencies and inadequacies.  
     SUMMARY OF THE INVENTION  
      In order to solve said problems, the present invention provides an audio processing system with function of automatic gain control and method thereof. The audio processing system automatically adjusts a gain value of a gain amplifier according to a time period to which a current time belongs, thereby audio energy of analog audio signals amplified by the gain amplifier is proper to a user&#39;s hearing.  
      The audio processing system includes a storage unit, a processing unit, a decoding unit, a digital/analog converter and a gain managing unit. The storage unit stores a default gain value, a plurality of audio files and a gain setting table, the gain setting table being configured for listing a plurality of time period each referencing a predetermined gain value. The processing unit fetches an audio file from the storage unit after receiving a playing command for playing the audio file. The decoding unit decodes the audio file fetched to generate digital audio signals. The digital/analog converter converts the digital audio signals to analog audio signals. The gain managing unit includes a time processing module, an obtaining module, an updating module and a gain adjusting module. The time processing module reads a current time from a timer and determining a time period corresponding to the current time. The obtaining module reads a predetermined gain value referenced by the time period in the gain setting table. The updating module updates the default gain value with the predetermined gain value referenced by the time period. The gain adjusting module signals a gain amplifier to amplify the analog audio signals received from the digital/analog converter by the predetermined gain value referenced by the time period.  
      The audio processing system includes a storage unit, a processing unit, a decoding unit and a digital/analog converter. The storage unit stores a default gain value, a plurality of audio files and a gain setting table, the gain setting table being configured for listing a plurality of time period each referencing a predetermined gain value. The processing unit fetches an audio file from the storage unit after receiving a playing command for playing the audio file. The decoding unit decodes the audio file fetched to generate digital audio signals. The digital/analog converter converts the digital audio signals to analog audio signals. The processing unit includes a time processing module, an obtaining module, an updating module and a gain adjusting module. The time processing module reads a current time from a timer and determining a time period corresponding to the current time. The obtaining module reads a predetermined gain value referenced by the time period in the gain setting table. The updating module updates the default gain value with the predetermined gain value referenced by the time period. The gain adjusting module signals a gain amplifier to amplify the analog audio signals received from the digital/analog converter by the predetermined gain value referenced by the time period.  
      The automatic gain control method includes the steps of: receiving a gain adjusting command for adjusting the default gain value; adjusting the default gain value to an adjusted gain value; signaling a gain amplifier to amplify analog audio signals received from a digital/analog converter by the adjusted gain value; updating the default gain value with the adjusted gain value; updating the time period corresponding to a new current time thereby yielding an updated time period; reading a predetermined gain value referenced by the updated time period in the gain setting table; calculating an integrated gain value according to the predetermined gain value referenced by the updated time period and the adjusted gain value; and updating the predetermined gain value referenced by the updated time period in the gain setting table with the integrated gain value.  
      Other systems, methods, features, and advantages will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a block diagram of a hardware infrastructure of an audio processing system in accordance with a preferred embodiment of the present invention;  
       FIG. 2  is a schematic diagram of main function modules of a gain managing unit of  FIG. 1 ;  
       FIG. 3  is a flowchart of a preferred automatic gain control method by utilizing the audio processing system of  FIG. 1 ;  
       FIG. 4  is a flowchart of a preferred method of regenerating a predetermined gain value referenced by a time period by utilizing the audio processing system of  FIG. 1 ;  
       FIG. 5  is a block diagram of a hardware infrastructure of an audio processing system in accordance with an alternative preferred embodiment of the present invention; and  
       FIG. 6  is a schematic diagram of main function modules of a processing unit of  FIG. 5 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      The automatic gain control function of the present invention can be incorporated in an audio processing system, such as a car stereo system and other electric device. The other electric device includes an MP3 (Moving Picture Experts Group Audio Layer 11) player, an electronic book, a mobile telephone, a radio, a television set, and so on. The following detailed description of preferred embodiments is made with reference to the attached drawings.  
       FIG. 1  is a block diagram of a hardware infrastructure of the audio processing system  10  in accordance with the preferred embodiment of the present invention. The audio processing system  10  includes a processing unit  11 , a storage unit  12 , a decoding unit  13 , a digital/analog (D/A) converter  14 , a gain amplifier  15 , a sound output device  16 , a timer  18 , and a command input unit  19 .  
      The storage unit  12  stores a plurality of audio files, a default gain value of the gain amplifier  15 , a decoding program, and a gain setting table. The gain setting table lists a plurality of time periods each referencing a predetermined gain value. The storage unit  12  can be a flash storage, a hard disk, and the like. The processing unit  11  controls components of the system  10 . The processing unit  11  can be a digital signal processor (DSP), a central processing unit (CPU), and the like.  
      The command input unit  19  generates control commands after receiving operational inputs. The control commands include a playing command and a gain adjusting command for playing an audio file and for signaling the gain amplifier  15  to adjusting a gain value respectively thereof. After receiving the playing command, the processing unit  11  fetches/reads the audio file from the storage unit  12 .  
      The decoding unit  13  invokes the decoding program stored in the storage unit  12 , decodes the audio files fetched to generate digital audio signals. The D/A converter  14  converts the digital audio signals received from the decoding unit  13  to analog audio signals.  
      The gain amplifier  15  amplifies the analog audio signals received from the D/A converter  14  by the default gain value stored in the storage unit  12 . The sound output device  16  produces sounds corresponding to the analog audio signals amplified by the gain amplifier  15 . The sound output device  16  can be an earphone or a speaker.  
      The audio processing system  10  further includes a gain managing unit  17  integrated with the processing unit  11 . Referring to  FIG. 2 , the gain managing unit  17  includes a time processing module  170 , an obtaining module  171 , an adding module  172 , a gain adjusting module  173 , a calculating module  174 , and an updating module  175 .  
       FIG. 3  is a flowchart of a preferred automatic gain control method by utilizing the audio processing system  10  of  FIG. 1 . Referring to  FIG. 2 , in step S 30 , the processing unit  11  signals a request command to the gain managing unit  17  after receiving the playing command.  
      In step S 31 , the time processing module  170  determines a time period corresponding to a current time obtained from the timer  18 .  
      In step S 32 , the obtaining module  171  reads the gain setting table stored in the storage unit  12 .  
      In step S 33 , the obtaining module  171  determines whether the gain setting table contains a predetermined gain value referenced by the time period determined by the time processing module  170 .  
      If the gain setting table does not contain the predetermined gain value referenced by the time period, in step S 38 , the obtaining module  171  reads the default gain value stored in the storage unit  12  as a current gain value.  
      In step S 39 , the adding module  172  inserts the default gain value into the gain setting table as the predetermined gain value referenced by the time period, and then the procedure goes to step S 35 .  
      In step S 33 , if the gain setting table contains the predetermined gain value referenced by the time period, in step S 34 , the obtaining module  171  reads the predetermined gain value referenced by the time period in the gain setting table, and the updating module  175  updates the default gain value stored in the storage unit  12  with the predetermined gain value referenced by the time period.  
      In step S 35 , the gain adjusting module  173  signals the gain amplifier  15  to amplify the analog audio signals received from D/A converter  14  by the predetermined gain value.  
      In step S 36 , the time processing module  170  updates the time period corresponding to a new current time obtained from the timer  18  thereby yielding an updated time period.  
      In step S 37 , the time processing module  170  determines whether the updated time period is the same as the time period.  
      If the updated time period is to the same as the time period, the procedure goes to step S 36 ; otherwise, the procedure goes to step S 32 . The step S 32  to step S 37  is performed recursively until the audio signal processing system  10  is turned-off.  
       FIG. 4  is a flowchart of a preferred method of retrieving the predetermined gain value referenced by the time period by utilizing the audio processing system  10  of  FIG. 1 . Referring to  FIG. 2 , in step S 40 , the gain managing unit  17  receives the adjusting command for adjusting the default gain value.  
      In step S 41 , the gain adjusting module  173  adjusts the default gain value stored in the storage unit  12  to an adjusted gain value, and signals the gain amplifier  15  to amplify the analog audio signals received from the D/A converter  14  by the adjusted gain value.  
      In step S 42 , the updating module  175  updates the default gain value stored in the storage unit  12  with the adjusted gain value.  
      In step S 43 , the time processing module  170  updates the time period corresponding to a new current time obtained from the timer  18  thereby yielding an updated time period.  
      In step S 44 , the obtaining module  171  reads the predetermined gain value referenced by the updated time period.  
      In step S 45 , the calculating module  174  assigns a weight value to the predetermined gain value and the adjusted gain value correspondingly, multiplies the predetermined gain value and the adjusted gain value by the weight value assigned correspondingly, thereby obtaining two products, and totals the two products to obtain an integrated gain value.  
      In step S 46 , the updating module  175  updates the predetermined gain value referenced by the updated time period in the gain setting table with the integrated gain value.  
      In an alternative embodiment, the updating module  175  directly updates the predetermined gain value referenced by the time period in the gain setting table with the adjusted gain value.  
       FIG. 5  is a block diagram of a hardware infrastructure of an audio processing system  100  in accordance with an alternative embodiment of the present invention. The audio processing system  100  of the alternative embodiment is the same as that of the preferred embodiment, except that the gain managing unit  17  is integrated in the processing unit  51 .  
      Therefore, in this alternative embodiment, the processing unit  51  further has the function as well as the gain managing unit  17  does in  FIG. 1 . That is, the processing unit  51  has a time processing module  510 , an obtaining module  511 , an adding module  512 , a gain adjusting module  513 , a calculating module  514 , and an updating module  515 , which respectively performs the same functions as the time processing module  170 , an obtaining module  171 , an adding module  172 , a gain adjusting  173 , a calculating module  174 , and an updating module  175  of the gain managing unit  17 .  
      It is understood that the invention may be embodied in other forms without departing from the spirit thereof. Thus, the present examples and embodiments are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.