Patent Publication Number: US-2007107507-A1

Title: Mute processing apparatus and method for automatically sending mute frames

Description:
TECHNICAL FIELD  
      The present invention relates to mute processing apparatuses and methods, and particularly to a mute processing apparatus and method for automatically sending mute frames during a multi-person communication over a network.  
     GENERAL BACKGROUND  
      With the development of communication networks and the associated services, a multi-person communication has been introduced and regarded as one typical service in the communication networks, such as the Public Switched Telephone Network (PSTN) and the Voice Over Internet Protocol (VoIP) Network. Furthermore, the multi-person communication has been also pervasively applied in a network telephone conversation or a network TV conversation. Such multi-person communication can support multiple persons simultaneously to communicate, and deliver speech data from broadcaster(s) to the listeners.  
      In order to provide a friendly communication environment, it is critical for the multi-person communication to utilize system resources to reduce delay, namely to deliver the speech data to each person as soon as possibly. With respect to the delay problem, controlling a transferring amount of the speech data is an effective method to solve the delay problem. However, in the currently multi-person communication, it transfers all speech data regardless of sound data or soundless data over the communication network. In other words, the soundless data is send over the communication network as well as the sound data. As a result, the soundless data increases a loading of the communication network and the transferring amount of the speech data. Consequently, a delay phenomenon may appear due to the unnecessary soundless data, therefore, a service quality of the multi-person communication system may be weaken due to the delay phenomenon.  
      What is needed, therefore, is a mute processing apparatus and method used in the multi-person communication system, which can automatically send mute frames when there are no sound inputs from terminals of the multi-person communication system without sending unnecessary soundless data, thereby reducing the transferring amount of the speech data due to rather less sizes of the mute frames as compared to the soundless data.  
     SUMMARY  
      A mute processing apparatus is provided. The apparatus is capable of automatically sending mute frames when persons don&#39;t talk or keep mute during a multi-person communication over a network. The apparatus mainly includes a sampling unit, an energy calculating unit, a coding unit, a processing unit, and an output unit. The sampling unit is for collecting input signals from a microphone. The energy calculating unit is for calculating an energy level of input signals within a time span. The coding unit is for coding the input signals within the time span. The processing unit is for sending a mute frame within the time span if the energy levels of the input signals within previous continuous time spans are less than a predetermined energy level and the energy level of the input signals within the time span is still less than the predetermined energy level, otherwise, controlling the coding unit to code the input signals within the time span. The output unit is for outputting the mute frame from the processing unit or coded signals from the coding unit.  
      A mute processing method is also provided. The method includes the steps of: (a) collecting input signals from a microphone; (b) calculating an energy level of input signals within a time span; (c) sending a mute frame if the energy levels of the input signals within previous continuous time spans are less than a predetermined energy level and the energy level of the input signals within the time span is still less than the predetermined energy level, otherwise, coding the input signals within the time span; and (d) outputting the mute frame or coded signals.  
      Other advantages and novel features will be drawn from the following detailed description with reference to the attached drawing, in which: 
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       FIG. 1  is a schematic diagram of a hardware infrastructure of a mute processing apparatus for automatically sending mute frames during a multi-person communication over a network in accordance with a preferred embodiment of the present invention; and  
       FIG. 2  is a flowchart of a preferred mute processing method for automatically sending mute frames during a multi-person communication over a network by utilizing the apparatus of  FIG. 1 . 
    
    
     DETAILED DESCRIPTION  
       FIG. 1  is a schematic diagram of a hardware infrastructure of a mute processing apparatus (hereinafter, “the apparatus”) in accordance with a preferred embodiment of the present invention. The apparatus is used in a multi-person communication system, and preferably, is incorporated into each terminal of the multi-person communication system. The apparatus is capable of automatically sending mute frames when there are no sound inputs on any ends during the multi-person communication, thereby reducing a loading of a network responsible for transmitting data throughout the terminals. The apparatus includes a sampling unit  10 , an energy calculating unit  11 , a coding unit  12 , a counter  13 , an output unit  14 , a processing unit  15 , a volatile storage unit  16 , and a non-volatile storage unit  17 .  
      The sampling unit  10  is for collecting input signals from a microphone (not shown) connected to the apparatus.  
      The energy calculating unit  11  is for calculating an energy level of the input signals within a time span. That is, the energy calculating unit  11  regards the input signals within one time span as a sound unit, and calculates the energy level of each sound unit.  
      If the energy level of the sound unit is equal to or greater than a predetermined energy level, that means the terminal of the multi-person communication is inputting sound within the time span, therefore, a speech coding operation is required on the sound unit input signals to obtain coded signals to be sent out over the network.  
      If energy levels of several continuous sound units are a combination consisting of energy levels greater than (equal to) and less than the predetermined energy, that means the terminal of the multi-person communication may have one or more input pauses over several continuous time spans, therefore, the speech coding operation is required on each sound unit input signals over the several continuous time spans to obtain coded signals to be sent out over the network.  
      If the energy levels of several previous continuous sound units are less than the predetermined energy level, and the energy level of a following sound unit is still less than the predetermined energy level, that means there is no sound input from the terminal of the multi-person communication within the several previous continuous time span and the time span of the following sound unit, therefore, a mute frame is sent within the time span of the following sound unit instead of performing a speech coding operation on the following sound unit input signals.  
      The coding unit  12  is for performing the speech coding operation on the input signals within the time span, that is, for coding the sound unit input signals. The counter  13  provides a value for indicating a count of continuous sound units whose energy level is less than the predetermined energy level. Furthermore, an initial value of the counter  13  is zero. The output unit  14  is for outputting coded signals from the coding unit  13  or the mute frame.  
      The processing unit  15  is for controlling the components of the apparatus, i.e., the sampling unit  10 , the energy calculating unit  11 , the coding unit  12 , the counter  13 , the output unit  14 , the volatile storage unit  16 , and the non-volatile storage unit  17 .  
      The processing unit  15  resets the value of the counter  13  as the initial value and simultaneously signals the coding unit  12  to perform the speech coding operation on the sound unit input signals within the time span, if the energy level of the sound unit is equal to or greater than the predetermined energy level.  
      The processing unit  15  also signals the coding unit  12  to perform the sound coding operation on each sound unit input signals within the several continuous time spans, if the energy levels of several continuous sound units are the combination of energy levels greater than (equal to) and less than the predetermined energy level, or the energy levels of several continuous sound units are less than the predetermined energy level. The processing unit  15  further increases the value of the counter  13  by one while simultaneously performing the speech code operation on each sound unit input signals.  
      Moreover, the processing unit  15  sends the mute frame instead of performing the sound coding operation on the sound unit input signals and increasing the value of the counter  13 , if the energy levels of several previous continuous sound units are less than the predetermined energy level and the energy level of the following sound unit is still less than the predetermined energy level. That is, if the value of the counter  13  is equal to a predetermined value and the energy level of the following sound unit is less than the predetermined energy level, the processing unit  15  signals the output unit  14  to output the mute frame.  
      Therefore, in the case when the value of the counter  13  equals to the predetermined value and the energy levels of the several continuous sound units are still less than the predetermined energy, the apparatus simply sends the mute frame within each corresponding time span of the sound units. Otherwise, the apparatus sends coded signals within each corresponding time span. Because a size of the mute frame is rather less than a size of the sound unit coded signals, a transferring amount of the mute frame is consequentially less than a transferring amount of the sound unit coded signals. As a result, a loading of the network is available to be reduced due to less transferring amounts of mute frames, thereby eliminating delay phenomena.  
      Additionally, the volatile storage unit  16  is for storing the input signals of each sound unit and the energy level of the input signals of each sound unit. The non-volatile storage unit  17  is for storing the predetermined energy level and the predetermined value.  
       FIG. 2  is a flowchart of a preferred mute processing method for automatically sending mute frames during the multi-person communication over the network by utilizing the apparatus of  FIG. 1 . In step S 200 , the sampling unit  10  collects the input signals from the microphone connected thereto. In step S 201 , the energy calculating unit  11  calculates the energy level of the input signals within a current time span. In step S 202 , the processing unit  15  determines whether the energy level calculated is less than the predetermined energy level.  
      If the energy level calculated is not less than the predetermined energy level, in step S 203 , the processing unit  15  resets the value of the counter  13 . In step S 204 , the coding unit  12  performs the speech coding operation on the current sound unit input signals, and the output unit  14  sends out the coded signals from the coding unit  12  over the network. In step S 205 , the energy calculating unit  11  calculates the energy level of the input signals within a following time span, and the procedure goes to step S 202  described above.  
      If the energy level calculated is less than the predetermined energy level, in step S 206 , the processing unit  15  determines whether the value of the counter  13  is less than the predetermined value.  
      If the value of the counter  13  is less than the predetermined value, in step S 207 , the coding unit  12  performs the speech coding operation on the current sound unit input signals, and the output unit  14  sends out the coded signals from the coding unit  12  over the network. In step S 208 , the processing unit increases the value of the counter  13  by one. In step S 209 , the energy calculating unit  11  calculates the energy level of the input signals within a following time span, and the procedure goes to step S 202  described above.  
      If the value of the counter  13  is not less than the predetermined value, that means there is no sound input from the terminal of the multi-person communication within the current time span, in step S 210 , the processing unit  15  signals the output unit  14  to output the mute frame over the network, thereby reducing the loading of the network. In step S 211 , the energy calculating unit  11  calculates the energy level of the input signals within a following time span. In step S 212 , the processing unit  15  determines whether the energy level calculated is less than the predetermined energy level. If so, that means there is still no sound input from the terminal of the multi-person communication, and the procedure goes to step S 211  described above to output the mute frame again over the network. If not, that means the terminal of the multi-person communication is inputting sound, and the procedure goes to step S 203  described above.  
      Although the present invention has been specifically described on the basis of a preferred embodiment and preferred method thereof, the invention is not to be construed as being limited thereto. Various changes or modifications may be made to the embodiment and method without departing from the scope and spirit of the invention.