Encoding method and apparatus
Present disclosure provide an audio signal encoding method and communication terminal, which relate to the communications field. The method and communication terminal are used to obtain an analog audio signal and encoding the analog audio signal to obtain a bitstream representing the analog audio signal, in which a proper bit allocation for spectral coefficients can be performed.
1. An audio signal encoding method, comprising:
obtaining, by a communication terminal, an analog audio signal;
converting, by the communication terminal, the analog audio signal into a digital audio signal;
obtaining, by the communication terminal, initial quantized energy envelope for each of a plurality of subbands of a current frame of the digital audio signal, wherein each of the subbands includes a plurality of spectral coefficients;
adjusting, by the communication terminal, quantized energy envelopes of some subbands of the plurality of subbands;
allocating, based on the adjusted quantized energy envelopes of the some subbands and the initial quantized energy envelope of each subband besides the some subbands in the plurality of subbands, by the communication terminal, bits to at least one subbands of the plurality of subbands;
quantizing, based on the allocated bits, by the communication terminal, at least a part of spectral coefficients included in the at least one subbands; and
obtaining, by the communication terminal, a bitstream includes the quantized spectral coefficients,
wherein the some subbands includes a first subband, wherein the quantized energy envelope of the first subband is adjusted according to an adjustment factor for the first subband,
wherein the adjustment factor for the first subband is determined according to a flag indicates signal type of the first subband,
wherein the adjustment factor for the first subband is further determined according to reference information of a previous frame adjacent to the current frame, and
wherein the reference information of the previous frame indicates whether two consecutive subbands in the previous frame are allocated with bits.
2. The audio signal encoding method according to claim 1 , wherein quantity of the some subbands is two.
3. The audio signal encoding method according to claim 1 , wherein the signal type of the first subband is either harmonic or not harmonic.
4. The audio signal encoding method according to claim 3 , wherein the adjustment factor the first subband is no less than 1, when the signal type of the first subband is harmonic.
5. A communication terminal, comprising:
at least one microphone, configured to obtain an analog audio signal;
an analog-digital convertor coupled to the at least one microphone, configured to convert the analog audio signal into a digital audio signal; and
an encoder coupled to the analog-digital convertor, configured to:
obtain initial quantized energy envelope for each of a plurality of subbands of a current frame of the digital audio signal, wherein each of the subbands includes a plurality of spectral coefficients;
adjust quantized energy envelopes of some subbands of the plurality of subbands;
allocate, based on the adjusted quantized energy envelopes of the some subbands and the initial quantized energy envelope of each subband besides the some subbands in the plurality of subbands, bits to at least one subbands of the plurality of subbands;
quantize, based on the allocated bits, at least a part of spectral coefficients included in the at least one subbands; and
obtain a bitstream includes the quantized spectral coefficients,
wherein the some subbands includes a first subband, wherein the quantized energy envelope of the first subband is adjusted according to an adjustment factor for the first subband,
wherein the adjustment factor for the first subband is determined according to a flag indicates signal type of the first subband,
wherein the adjustment factor for the first subband is further determined according to reference information of a previous frame adjacent to the current frame, and
wherein the reference information of the previous frame indicates whether two consecutive subbands in the previous frame are allocated with bits.
6. The audio signal encoder according to claim 5 , wherein quantity of the some subbands is two.
7. The audio signal encoder according to claim 5 , wherein the signal type of the first subband is either harmonic or not harmonic.
8. The audio signal encoder according to claim 7 , wherein the adjustment factor the first subband is no less than 1, when the signal type of the first subband is harmonic.