Abstract: A method of pre-processing an audio signal transmitted to a user terminal via a communication network and an apparatus using the method are provided. The method of pre-processing the audio signal may prevent deterioration of a sound quality of the audio signal transmitted to the user terminal by pre-processing the audio signal, and by enabling a codec module, encoding the audio signal, to determine the audio signal as a speech signal. The method of pre-processing may include separating the audio signal into channels, measuring the channel energy for each of the channels, selecting a specific channel energy, and amplifying the specific channel energy. The method may include encoding an audio signal using a speech codec and/or decoding an encoded audio signal using the speech codec.

Abstract: A method of pre-processing an audio signal transmitted to a user terminal via a communication network and an apparatus using the method are provided. The method of pre-processing the audio signal may prevent deterioration of a sound quality of the audio signal transmitted to the user terminal by pre-processing the audio signal, and by enabling a codec module, encoding the audio signal, to determine the audio signal as a speech signal. Also, the method of pre-processing the audio signal may improve a probability that the codec module may determine a corresponding audio signal as a speech when the audio signal is transmitted via the communication network by pre-processing the audio signal using a speech codec.

Abstract: A method of pre-processing an audio signal transmitted to a user terminal via a communication network and an apparatus using the method are provided. The method of pre-processing the audio signal may prevent deterioration of a sound quality of the audio signal transmitted to the user terminal by pre-processing the audio signal, and by enabling a codec module, encoding the audio signal, to determine the audio signal as a speech signal. The method of pre-processing may include separating the audio signal into channels, measuring the channel energy for each of the channels, selecting a specific channel energy, and amplifying the specific channel energy. The method may include encoding an audio signal using a speech codec and/or decoding an encoded audio signal using the speech codec.

Abstract: A method of pre-processing an audio signal transmitted to a user terminal via a communication network and an apparatus using the method are provided. The method of pre-processing the audio signal may prevent deterioration of a sound quality of the audio signal transmitted to the user terminal by pre-processing the audio signal, and by enabling a codec module, encoding the audio signal, to determine the audio signal as a speech signal. Also, the method of pre-processing the audio signal may improve a probability that the codec module may determine a corresponding audio signal as a speech when the audio signal is transmitted via the communication network by pre-processing the audio signal using a speech codec.

Abstract: A method of pre-processing an audio signal transmitted to a user terminal via a communication network and an apparatus using the method are provided. The method of pre-processing the audio signal may prevent deterioration of a sound quality of the audio signal transmitted to the user terminal by pre-processing the audio signal, and by enabling a codec module, encoding the audio signal, to determine the audio signal as a speech signal. The method of pre-processing may include encoding the audio signal using a speech codec and decoding the encoded audio signal using the speech codec. A codec module, transmitting the decoded audio signal to the user terminal via the communication network, may determine whether a speech interval or a speechless interval with respect to at least one frame is included in the audio signal and transmit at least one parameter with respect to the at least one frame as a result of the determination.

Abstract: A method of pre-processing an audio signal transmitted to a user terminal via a communication network and an apparatus using the method are provided. The method of pre-processing the audio signal may prevent deterioration of a sound quality of the audio signal transmitted to the user terminal by pre-processing the audio signal, and by enabling a codec module, encoding the audio signal, to determine the audio signal as a speech signal. Also, the method of pre-processing the audio signal may improve a probability that the codec module may determine a corresponding audio signal as a speech when the audio signal is transmitted via the communication network by pre-processing the audio signal using a speech codec.

Abstract: Since music signals are encoded by a voice encoding method optimized to human voice signals such as EVRC (Enhanced Variable Rate Coding) in a cellular communication system, the music signals are often distorted by such encoding method, and listeners experience pauses in music caused by such voice-optimized encoding method. To improve the perceptual sound quality of music, a method for preprocessing digital audio data is provided in order to prevent the problem of pause in music signals in a cellular phone. In particular, AGC (Automatic Gain Control) preprocessing and PHE (Pitch Harmonics Enhancement) is performed to the digital audio data having low dynamic range. By this method, the number of pauses in music signal is reduced, and the perceptual sound quality of the music is improved.

Abstract: Recently, with the wider use of cellular phones, more and more users listen to music via their cellular phones, and thus, the sound quality of music provided via the cellular phones became more critical. Since music signals are encoded by a voice encoding method optimized to human voice signals such as EVRC (Enhanced Variable Rate Coding) in a cellular communication system, the music signals are often distorted by such encoding method, and listeners experience pauses in music caused by such voice-optimized encoding method. To improve the sound quality of music, a method for preprocessing audio data is provided in order to prevent the problem of pause in music signals in a cellular phone. In particular, AGC (Automatic Gain Control) preprocessing is performed to the audio data having low dynamic range. By this method, the number of pauses in music signal is reduced, and the sound quality of the music is improved.

Abstract: A method for producing a decoded signal approximate to an original signal upon decoding a quantized signal which is produced by vector-quantizing every block of an original signal or by vector-quantizing every block of a transform coefficient obtained after every block of the original signal is processed by a transform process such as a discrete cosine transform (DCT). The method includes the steps of determining a narrow vector quantization constraint set domain in which each vector or block divided from the decoded signal exists prior to the vector quantization at the transmitting site, and outputting a signal indicative of the determined narrow vector quantization constraint set domain, and performing a projection for returning a vector existing beyond the narrow vector quantization constraint set domain to its original domain, and repeating the projection for returning a vector existing beyond the narrow vector quantization constraint set domain to its original domain.