A computer storage medium having stored instructions for instructing a computer device to perform the following steps: performing time-frequency transformation processing on a time-domain signal of a current audio frame, to obtain spectral coefficients of the current audio frame; acquiring an energy average of spectral coefficients that is located within a subband i and that is of the current audio frame and an energy average of spectral coefficients that is located within a subband j and that is of the current audio frame; and determining whether a quotient of dividing the energy average of the spectral coefficients that are located within the subband i and that is of the current audio frame by the energy average of the spectral coefficients that are located within the subband j and that is of the current audio frame is greater than or equal to a threshold T4; if the quotient of dividing the energy average of the spectral coefficients that are located within the subband i and that is of the current audio frame by the energy average of the spectral coefficients that are located within the subband j and that is of the current audio frame is greater than or equal to the threshold T4, coding spectral coefficients of the current audio frame based on a transform coded excitation algorithm; and if the quotient of dividing the energy average of the spectral coefficients that are located within the subband i and that is of the current audio frame by the energy average of the spectral coefficients that are located within the subband j and that is of the current audio frame is less than the threshold T4, coding spectral coefficients of the current audio frame based on a high quality transform coding algorithm. performing time-frequency transformation processing on a time-domain signal of a current audio frame, to obtain spectral coefficients of the current audio frame; acquiring an energy average of spectral coefficients that is located within a subband i and that is of the current audio frame and an energy average of spectral coefficients that is located within a subband j and that is of the current audio frame; and determining whether a quotient of dividing the energy average of the spectral coefficients that are located within the subband i and that is of the current audio frame by the energy average of the spectral coefficients that are located within the subband j and that is of the current audio frame is greater than or equal to a threshold T4; if the quotient of dividing the energy average of the spectral coefficients that are located within the subband i and that is of the current audio frame by the energy average of the spectral coefficients that are located within the subband j and that is of the current audio frame is greater than or equal to the threshold T4, coding spectral coefficients of the current audio frame based on a transform coded excitation algorithm; and if the quotient of dividing the energy average of the spectral coefficients that are located within the subband i and that is of the current audio frame by the energy average of the spectral coefficients that are located within the subband j and that is of the current audio frame is less than the threshold T4, coding spectral coefficients of the current audio frame based on a high quality transform coding algorithm. <EOS>