METHOD FOR DETERMINING NEW SID FRAME OF CNG IN VOICE ENCODER

摘要

PURPOSE: A method for determining a new SID(Silence Insertion Descriptor) frame of CNG(Comfortable Noise Generator) in a voice encoder is provided to be capable of decreasing the complexity and a lot of calculation required to LPC(Linear Predictive Coefficient) filter calculation by using a ZCR(zero crossing rate) parameter which can approximately represent a G.723.1 spectrum feature. CONSTITUTION: First, a first frame of a bundle section appeared next to a voice activity section is determined as an SID frame. Then, a ZCR extracted from a first bundle section is obtained. Next, it is determined whether a compared value between the ZCR and a ZCR of the SID frame is within a predetermined range. Then, it is determined whether the index value of energy quantized using energy value provided in COD-CNG has a difference over a predetermined value if the compared value isn't within the predetermined range. In this state, a current frame is set as a new SID frame by determining that a noise signal of the current frame was changed.