| 摘要 |
PURPOSE:To obtain excellent sound signals which are not deteriorated in tone quality even when the sound signals are applied to a highly erroneous usage of a transmission line by performing error controlling encoding to codes having important transmitting information in accordance with the importance. CONSTITUTION:A multi-pulse sound source calculating circuit 300 finds the amplitude and position of a prefixed number of multi-pulse trains by using sound signals and LPC coefficients and a pulse quantizer 350 quantizes the maximum value of the pulses as normalizing information with a prefixed bit number and, after normalizing the amplitude of each pulse by using the normalizing information, quantizes each pulse with the prefixed bit number and encodes the position of each pulse. An error controlling encoding circuit 400 inputs the LPC coefficients, normalized information of sound source pulses, and codes of the amplitude and position of sound source pulses and performs one kind or plural kinds of error controlling encoding in accordance with the importance of the code of each transmitting information and the sensitiveness to transmission line errors. Then the circuit 400 adds redundancy bits to the information to be protected in accordance with the kind of error controlling encoding. Therefore, deterioration of tone quantity can be eliminated even if a transmission line error is high and, as a result, excellent sounds can be reproduced. |
