Abstract:
An apparatus and method for improved processing of audio and video in the wireless multimedia communication. By setting a SNR estimator in the de-modulator and connecting a PLC trigger between the de-modulator and the PLC module in parallel. The SNR estimator can calculate the signal to noise ratio (SNR) of the wireless signal in the de-modulator directly. The PLC trigger can calculate the losing condition of the digital signal and make the decision whether proceeds the packet loss concealment (PLC) depend on the condition to make the PLC to the highest efficiency.

Description:
FIELD OF THE INVENTION 
       [0001]    The present disclosure relates to an apparatus and method for improved processing of audio and video in the wireless multimedia communication. 
       BACKGROUND 
       [0002]    A network packet is a formatted unit of data carried by a packet-switched network. And in the conventional wireless packet networks, sometimes transmitted packets are erased or lost, called packet erasure or loss. This will make the communication quality poor. Generally, the spurious packets made by the packets lost, bit error and noise are the main reason of errors in digital communications. 
         [0003]    In many multimedia communication systems, the packet loss concealment (PLC) logic is invoked at the decoder to try to conceal the quality-degrading effects of the lost packet or erasure, thereby avoiding substantial degradation in output quality, such as WIFI, Bluetooth use for audio and video device system. 
         [0004]    There are two conventional concealment methods: transmitter based method and receiver based method. The transmitter based recovery techniques, for example, the forward error correction (FEC) is adding the error correction code to the packets transmitted. And another example, automatic repeat-request is an error-control method for data transmission using acknowledgements and timeouts to achieve reliable data transmission over an unreliable service. If the sender does not receive an acknowledgment before the timeout, it usually re-transmits the frame/packet until the sender receives an acknowledgment or exceeds a predefined number of re-transmissions. 
         [0005]    The disadvantages of the above mentioned technologies are high power consumption and high bandwidth requirement. In poor signal conditions, they inherently lead to network congestion and delay. 
         [0006]    In addition to transmitter-based recovery techniques, a method concealing any remaining degradation left after the transmitter-based recovery techniques can be employed. In the applications of voice, a parameter commonly chosen for interpolation and/or extrapolation is the pitch period. A waveform with a length of the estimated pitch period or a multiple of the estimated pitch period is generated as a substitute for the degraded packet. 
         [0007]    And in video communications, the interpolation and/or extrapolation based techniques are commonly used. These techniques generate a replacement packet by interpolating the parameters from the packets on one or both sides (1D), pre-video line or post-video line (2D) or pre-video frame or post-video frame (3D) of the degraded packet. 
         [0008]    Referring to  FIG. 1  there is shown a schematic view of a concealment apparatus in wireless multimedia system in prior arts. The concealment apparatus in wireless multimedia system  100  includes a modulator  101 , a de-modulator  103 , an A/V-decoder  105 , a PLC module  107  and a gain controller  109 . 
         [0009]    The modulator  101  can send a wireless signal, and the de-modulator  103  can receive the wireless signal and transform it into a digital signal. The A/V-decoder  105  can receive the digital signal and transform it into a multimedia signal. The PLC module  107  can receive the multimedia signal. If the multimedia signal is intact, the PLC module  107  will transport the multimedia signal to the gain controller  109 . 
         [0010]    And if the multimedia signal has defects and/or loss, the PLC module  107  can conceal the defects and/or loss packets depend on the information of the previous and/or following intact packets, and transport the concealed multimedia signal to the gain controller  109 . The gain controller  109  can control the gain of the multimedia signal concealed. To achieve the purpose of concealing the defects and/or loss of the multimedia signal caused by wireless transportation and make the output audio and/or video more smooth and harmonious. 
       SUMMARY OF THE INVENTION 
       [0011]    It is a primary objective of the present invention to provide a signal to noise ratio concealment apparatus and method in wireless multimedia system. Because the damaged packets often contain information that can be used to improve the quality of the multimedia signal. An object of the present disclosure is to set a SNR estimator in the de-modulator and connect a PLC trigger between the de-modulator and the PLC module in parallel. The SNR estimator can calculate the signal to noise ratio (SNR) of the wireless signal in the de-modulator directly. The PLC trigger can calculate the losing condition of the digital signal and make the decision whether proceeds the packet loss concealment (PLC) depend on the condition to make the PLC to the highest efficiency. 
         [0012]    To achieve the aforementioned object, the present disclosure provides a signal to noise ratio concealment apparatus in wireless multimedia system comprising: a de-modulator, which includes a SNR estimator; an A/V-decoder, connecting to said de-modulator; a PLC module, connecting to said A/V-decoder; and a PLC trigger, one side connecting to said de-modulator, and the other side connecting to said PLC module. 
         [0013]    To achieve the aforementioned object, the present disclosure provides a signal to noise ratio concealment method in wireless multimedia system including a modulator, a de-modulator, a A/V-decoder, a PLC module, a PLC trigger and a gain controller, where the de-modulator includes a SNR estimator, the concealment method comprising the steps of: the modulator transmits a wireless signal to the de-modulator and the de-modulator transforms the wireless signal into a digital signal; the SNR estimator of the de-modulator estimates the signal to noise ratio of the wireless signal and generates a SNR value; the PLC trigger comprehensively analyzes and evaluates the integrity of the digital signal and generates a trigger value; the A/V-decoder transforms the digital signal into a multimedia signal and transmits it to the PLC module; the PLC module makes the decision whether proceeds the packet loss concealment depends on the trigger value; the PLC module conceals the multimedia signal and generates a comprehensively concealed multimedia signal; and the gain controller controls the gain of the multimedia signal or the comprehensively concealed multimedia signal. 
         [0014]    In one embodiment of this disclosure, further comprising a gain controller, connecting to said PLC module. 
         [0015]    In one embodiment of this disclosure, wherein said PLC trigger further comprising a SNR module. 
         [0016]    In one embodiment of this disclosure, wherein said PLC trigger further comprising a header information module. 
         [0017]    In one embodiment of this disclosure, wherein said PLC trigger further comprising a CRC module. 
         [0018]    In one embodiment of this disclosure, wherein said PLC trigger further comprising a packet information module. 
         [0019]    In one embodiment of this disclosure, wherein said PLC module further comprising an interpolator module. 
         [0020]    In one embodiment of this disclosure, wherein said PLC module further comprising an extrapolator module. 
         [0021]    In one embodiment of this disclosure, wherein said PLC module further comprising a pitch period module. 
         [0022]    In one embodiment of this disclosure, wherein said PLC module further comprising a maximum like module. 
         [0023]    In one embodiment of this disclosure, wherein said PLC module further comprising a signal character module. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0024]      FIG. 1  is a schematic view of a concealment apparatus in wireless multimedia system in prior arts. 
           [0025]      FIG. 2  is a schematic view of a signal to noise ratio concealment apparatus in wireless multimedia system in accordance with an embodiment of the present invention. 
           [0026]      FIG. 3  illustrates an example to a waveform of a packet. 
           [0027]      FIG. 4  is a flowchart of the signal to noise ratio concealment method of the present invention in wireless multimedia system. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0028]    In order to further understand the present disclosure, preferred embodiments are to be described such that variations and alterations thereto are readily apparent to a person skilled in the art. However, it will be realized that the scope of this disclosure is not confined or restricted to the details of the embodiments described below. Identical reference numerals always designate the same elements throughout all the figures of the drawing. 
         [0029]    First, referring to  FIG. 2  and  FIG. 3  there is shown a schematic view of a signal to noise ratio concealment apparatus in wireless multimedia system and an example to a waveform of a packet in accordance with an embodiment of the present invention. As shown, the signal to noise ratio concealment apparatus in wireless multimedia system  200  includes a modulator  201 , a de-modulator  203 , an AN-decoder  205 , a PLC module  207 , a gain controller  209  and a PLC trigger  211 , said de-modulator  203  includes a SNR estimator  2031 , said PLC module  207  includes an interpolator module  2071 , a pitch period module  2073 , a maximum like module  2075  and a signal character module  2077 , said PLC trigger  211  includes a SNR module  2111 , a header information module  2113 , a CRC module  2115  and a packet information module  2117 . 
         [0030]    The modulator  201  can transmit a wireless signal  2011  and the de-modulator  203  can receive the wireless signal  2011  and transform it into a digital signal  2033 . The SNR estimator  2031  of the de-modulator  203  can estimate the signal to noise ratio of the wireless signal  2011  and generate a SNR value  20311  then transmit the SNR value  20311  to the PLC trigger  211 . The SNR module  2111  of said PLC trigger  211  can generate a judgment value  21111  depend on the SNR value  20311 . A packet consists of a header and a payload. The properties of the packet are defined in the header, including the communications protocol, source/destination IP and source/destination communication port. Said header information module  2113  can estimate the integrity of the digital signal  2033  and generate a judgment value  21131  depend on the header information of the packets of digital signal  2033 . The cyclic redundancy check (CRC) is an error-detecting code used in digital networks to detect accidental changes to signal. Blocks of data entering these systems get a short check value attached, based on the remainder of a polynomial division of their contents. On retrieval the calculation is repeated, and corrective action can be taken against presumed data corruption if the check values do not match. The CRC module  2115  can estimate the integrity of the digital signal  2033  and generate a judgment value  21151  depend on the CRC value of the packets of digital signal  2033 . The packet information module  2117  can estimate the integrity of the digital signal  2033  and generate a judgment value  21171  depend on the information of the packets of digital signal  2033 . The PLC trigger  211  can comprehensively analyze and evaluate the judgment value  21111 ,  21131 , 21151  and  21171  to generate a trigger value  2119  and transmit the trigger value  2119  to the PLC module  207 . 
         [0031]    The A/V-decoder  205  can transform the digital signal  2033  into a multimedia signal  2051  and transmit it to the PLC module  207 . 
         [0032]    The PLC module  207  will make the decision whether proceeds the packet loss concealment (PLC) depend on the comprehensively evaluated trigger value  2119 . If the PLC module  207  decides not to conceal the multimedia signal  2051  depends on the trigger value  2119 . The PLC module  207  will transmit the multimedia signal  2051  to the gain controller  209  and the gain controller  209  can control the gain of the multimedia signal  2051 . 
         [0033]    If the PLC module  207  decides that the multimedia signal  2051  needs concealment depends on the trigger value  2119 . The PLC module  207  can use the interpolator module  2071  to conceal the damaged and/or loss packets of the multimedia signal  2051  by interpolation depend on the previous and/or following intact packets and generate a concealment signal  20711 . The pitch period module  2073  can detect the pitch period of the multimedia signal  2051  and repeat the waveform of the primitive period and generate a concealment signal  20731 . The maximum like module  2075  uses the pattern matching technique to search and use the previous maximum like intact multimedia waveform concealing the multimedia signal  2051  and generates a concealment signal  20751 . The signal character module  2077  conceals the multimedia signal  2051  depends on the signal character like tonal speech and generates a concealment signal  20771 . The PLC module  207  will comprehensively analyze the concealment signal  20711 ,  20731 ,  20751  and  20771  and generate a comprehensively concealed multimedia signal  2079 . And then the PLC module  207  transmits the comprehensively concealed multimedia signal  2079  to the gain controller  209 . The gain controller  209  can control the gain of the comprehensively concealed multimedia signal  2079  and make the output video and/or voice more smooth and harmonious. The signal to noise ratio concealment apparatus in wireless multimedia system  200  reduces the affect of the defects and/or loss of the multimedia signal caused by the wireless transport in this way. 
         [0034]    Therefore, the present disclosure can accurately estimate the signal to noise ratio of the wireless signal for the calculation in the PLC trigger. It can calculate the SNR, header information, CRC value of the packets more accurately and comprehensively evaluate the information to decide whether proceeds the packet loss concealment by setting the PLC trigger, and make the PLC to the highest efficiency, and improve the usage of the system resource. Also, it can improve the overall effect of the concealment by setting the interpolator module, pitch period module, maximum like module and signal character module in the PLC module and work with the PLC trigger making the overall concealment to the highest efficiency and quality. 
         [0035]    In another embodiment of the present invention, the interpolator module  2071  can be replaced by an extrapolator module. The PLC module  207  can use the extrapolator module to conceal the damaged and/or loss packets of the multimedia signal  2051  by extrapolation depend on the previous and/or following intact packets and generate a concealment signal. 
         [0036]    Referring to  FIG. 4 , there is shown a flowchart of the signal to noise ratio concealment method in wireless multimedia system. In one embodiment, the concealment method includes the following steps. In step  401 , the modulator  201  transmits a wireless signal  2011  to the de-modulator  203  and the de-modulator  203  transforms the wireless signal  2011  into a digital signal  2033 . In step  403 , the SNR estimator  2031  of the de-modulator  203  estimates the signal to noise ratio of the wireless signal  2011  and generates a SNR value  20311 . In step  405 , the PLC trigger  211  comprehensively analyzes and evaluates the integrity of the digital signal  2033  and generates a trigger value  2119 . In step  407 , the A/V-decoder  205  transforms the digital signal  2033  into a multimedia signal  2051  and transmits it to the PLC module  207 . In step  409 , the PLC module  207  makes the decision whether proceeds the packet loss concealment depends on the trigger value  2119 . If the PLC module  207  decides not to conceal the multimedia signal  2051 , then proceeds to step S 413 . If the PLC module  207  decides that the multimedia signal  2051  needs concealment, then proceeds to step S 411 . In step  411 , the PLC module  207  conceals the multimedia signal  2051  and generates a comprehensively concealed multimedia signal  2079 . In step  413 , the gain controller  209  controls the gain of the multimedia signal  2051  or the comprehensively concealed multimedia signal  2079 . 
         [0037]    The present disclosure, as discussed herein, is industrially applicable, novel, and of significant value in technology development. It is to be understood; however, that this disclosure is not limited to the embodiments set forth and illustrated hereinabove, but encompasses any and all variations falling within the spirit and scope of this disclosure as defined by the appended claims and their equivalents.