The present technology relates to a signal processing device, method, and program that may obtain audio at a higher audio quality when decoding an audio signal.An envelope information generating unit 24 generates envelope information representing an envelope form of high frequency components of an audio signal to be encoded. A sine wave information generating unit 26 extracts a sine wave signal from the high frequency components of the audio signal, and generates a sine wave information representing an emergence start position of the sine wave signal. An encoding stream generating unit 27 multiplexes the envelope information, the sine wave information, and low frequency components of the audio signal that have been encoded, and outputs an encoding stream obtained as the result. As a result, the high frequency components included in the sine wave signal may be predicted at a higher accuracy from the envelope information and the sine wave information at the receiving side of the encoding stream. The present invention may be applied to a signal processing device.