Non-synchronized ADPCM with discontinuous transmission
AssigneeDSP Group Ltd.
InventorArie Gur
Life of this patent
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Abstract
A method for coordinating an encoder and a decoder in a wireless communication system employing discontinuous transmission, the method comprising performing a syncless reset command on the encoder and the decoder, in order to bring the encoder and decoder into stable and compatible states. The syncless reset command can be implemented by setting the variables of the encoder and decoder into predetermined values, or by performing a normal reset command followed by encoding or decoding a predetermined number of predetermined sample values.
Claims20
In a communication system comprising a transmitting unit including an Adaptive Differential Pulse Code Modulation (ADPCM)-based encoder and a receiving unit including an ADPCM-based decoder, the communication system employing discontinuous transmission (DTX), a method for coordinating the ADPCM-based encoder and the ADPCM-based decoder after an end of a silence period during which the transmitting unit did not transmit, the method comprising:
- the ADPCM-based encoder performing a first syncless reset operation in response to a first reception of audio data after the end of the silence period;
- the ADPCM-based encoder operating on the audio data and setting at least one encoded value in a buffer of samples;
- the transmitting unit transmitting the content of the buffer of samples;
- the receiving unit receiving the content of the buffer of samples;
- the ADPCM-based decoder performing a second syncless reset operation in response to the reception of the content of the buffer samples;
- and the decoder decoding the received content;
- wherein said first syncless reset operation comprises setting internal variables of the ADPCM-based encoder into same values as would be obtained after performing, by the ADPCM-based encoder, a normal reset operation and encoding a predetermined number of ADPCM-based encoder samples having a predetermined ADPCM-based encoder sample value;
- wherein said second syncless reset operation comprises setting internal variables of the ADPCM-based decoder respectively into same values as would be obtained after performing, by the ADPCM-based decoder, a normal reset operation and decoding a predetermined number of ADPCM-based decoder samples having a predetermined ADPCM-based decoder sample value.
A communication system comprising a transmitting unit and a receiving unit, the communication system employing discontinuous transmission (DTX) between the transmitting side and the receiving side, the transmitting unit comprising:
- a voice activity detector (VAD) for identifying whether an input signal is voiced or silent and transmitting a VAD signal indicating whether the input signal is voiced or silent;
- wherein the transmitting unit is configured not to transmit during a silence period during which the input signal is silent;
- an Adaptive Differential Pulse Code Modulation (ADPCM)-based encoder, comprising a first syncless reset component for executing a first syncless reset operation when the VAD signal indicates that the input signal changed from silent to voiced;
- the receiving unit comprising:
- an ADPCM-based decoder, comprising a second syncless reset component for executing a second syncless reset operation when first receiving a content of buffer samples from the transmitter after an end of the silence period;
- and wherein said first syncless reset component is configured to set internal variables of the ADPCM-based encoder into same values as would be obtained after performing a normal reset operation and encoding a predetermined number of ADPCM-based encoder samples having a predetermined ADPCM-based encoder sample value;
- wherein said second syncless reset component is configured to set internal variables of the ADPCM-based decoder respectively into same values as would be obtained after performing, by the ADPCM-based decoder, a normal reset operation and decoding a predetermined number of ADPCM-based decoder samples having a predetermined ADPCM-based decoder sample value.
Dependencies are inferred from the claim text.