Research On Multi - Channel Broadcast Source Audio Processing Technology

The numerous source of the audio broadcast and the different standards of program make the huge difference of the signal levels or other parameters.The decreased efficiency of broadcasting center and bad quality of program is caused. The project is based on this situation that the set of multicast source audio processing system is developed in cooperation with a radio equipment company. The level and spectrum parameters of multi-channel audio input signal can be processed in real time and dynamically so as to balance the quality and loudness of program is the target of system. After the research and analysis of task, the main part of audio processing is all realized by software. So the designed algorithm is simulated by the MATLAB and programmed-by C, the host control software is achieved by VC++The system solution choose DSP+PC, the core processor is TM320VC5509A which has excellent ability of processing data,the codec chip is TLV320AIC23B which can sample audio signal efficiently. The data transmission uses USB which is provided by 5509A.In conclusion, the system posses the ability on balancing gparameters, controlling dynamic range and detecting frequency of multichannel input signal.The algorithm of Audio equalization is based on the combinations of HP or LP shelving filter and BP filter, the center frequency, gain and bandwidth of can be adjusted. The objective function test and actual audio alignment prove that promote or inhibit effect of equalizer on various frequency bands is great, the processed effect on audio is ideal.Dynamic range control algorithm is implemented by the combinations of its four forms, at the same time, a flat frequency response for four bands division is designed on the base of LR division, with two-way in amplitude and time control, the multiband dynamic range controller is accomplished.The practical audio program function test and the overall objective and subjective test shows that the precision of dynamic range controller is high,the processed output audio signal sound naturally and clearly.Frequency detection algorithm is based on the plural FFT algorithm and the center of gravity spectrum correction algorithm. The signal under the set threshold can be detected in real-time and provide the standard for noise suppression.The simulation and practical test shows that the measurement of signal frequency and amplitude is in the high and accuracy precision.