Method for determining audio coding/decoding mode and related product
A method for determining an audio coding mode and a related apparatus are provided. The method may include: determining a channel combination scheme for a current frame, where the determined channel combination scheme for the current frame is one of a plurality of channel combination schemes; and determining a coding mode of the current frame based on a channel combination scheme for a previous frame and the channel combination scheme for the current frame, where the coding mode of the current frame is one of a plurality of coding modes. The technical solutions provided in embodiments of this application help improve encoding quality.
1 . A method for determining a channel combination scheme, comprising:
obtaining a first signal type of a current frame of an audio signal, wherein the first signal type is either a near in phase signal or a near out of phase signal, and wherein the current frame includes a left channel signal and a right channel signal;
obtaining a previous channel combination scheme of a first previous frame of the audio signal, wherein the previous channel combination scheme is either an anticorrelated signal channel combination scheme corresponding to the near out of phase signal or a correlated signal channel combination scheme corresponding to the near in phase signal;
obtaining a first signal-to-noise ratio of the left channel signal and a second signal-to-noise ratio of the right channel signal;
determining whether the first signal-to-noise ratio is greater than a preset threshold;
determining whether the second signal-to-noise ratio is greater than the preset threshold; and
in response to determining that the first signal type of the current frame is the near in phase signal, the previous channel combination scheme is the anticorrelated signal channel combination scheme, and both the first signal-to-noise ratio and the second signal-to-noise ratio are less than the preset threshold, determining that an initial channel combination scheme of the current frame is the correlated signal channel combination scheme.
2 . The method according to claim 1 , further comprising:
determining whether the initial channel combination scheme needs to be modified; and
in response to determining that the initial channel combination scheme needs to be modified, obtaining a final channel combination scheme by modifying the initial channel combination scheme.
3 . The method according to claim 2 , wherein the determining whether the initial channel combination scheme needs to be modified comprises:
obtaining a channel combination ratio factor modification flag of the first previous frame;
determining whether the current frame meets a switching condition when the channel combination ratio factor modification flag indicates that a channel combination ratio factor does not need to be modified; and
determining the final channel combination scheme based on a result of determining whether the current frame meets the switching condition.
4 . The method according to claim 3 , wherein the determining whether the current frame meets a switching condition comprises:
obtaining a second signal type of a primary channel signal of the first previous frame;
obtaining a third signal type of a primary channel signal of a second previous frame prior to the first previous frame; and
determining that the current frame meets the switching condition when the second signal type is UNVOICED_CLAS and the third signal type is VOICED_TRANSITION.
5 . The method according to claim 3 , wherein the determining whether the current frame meets a switching condition comprises:
obtaining a fourth signal type of a secondary channel signal of the first previous frame;
obtaining a fifth signal type of a secondary channel signal of a second previous frame prior to the first previous frame; and
determining that the current frame meets the switching condition when the fourth signal type is UNVOICED_CLAS and the fifth signal type is VOICED_TRANSITION.
6 . An apparatus comprising:
at least one processor; and
one or more memories coupled to the at least one processor and storing programming instructions, which when executed by the at least one processor, cause the apparatus to:
obtain a first signal type of a current frame of an audio signal, wherein the first signal type is either a near in phase signal or a near out of phase signal, and wherein the current frame includes a left channel signal and a right channel signal;
obtain a previous channel combination scheme of a first previous frame of the audio signal, wherein the previous channel combination scheme is either an anticorrelated signal channel combination scheme corresponding to the near out of phase signal or a correlated signal channel combination scheme corresponding to the near in phase signal;
obtain a first signal-to-noise ratio of the left channel signal and a second signal-to-noise ratio of the right channel signal;
determine whether the first signal-to-noise ratio is greater than a preset threshold;
determine whether the second signal-to-noise ratio is greater than the preset threshold; and
in response to determining that the first signal type of the current frame is the near in phase signal, the previous channel combination scheme is the anticorrelated signal channel combination scheme, and both the first signal-to-noise ratio and the second signal-to-noise ratio are less than the preset threshold, determine that an initial channel combination scheme of the current frame is the correlated signal channel combination scheme.
7 . The apparatus according to claim 6 , wherein the programming instructions, when executed by the at least one processor, cause the apparatus further to:
determine whether the initial channel combination scheme needs to be modified; and
in response to determining that the initial channel combination scheme needs to be modified, obtain a final channel combination scheme by modifying the initial channel combination scheme.
8 . The apparatus according to claim 7 , wherein the programming instructions, when executed by the at least one processor, cause the apparatus further to:
obtain a channel combination ratio factor modification flag of the first previous frame;
determine whether the current frame meets a switching condition when the channel combination ratio factor modification flag indicates that a channel combination ratio factor does not need to be modified; and
determine the final channel combination scheme based on a result of determining whether the current frame meets the switching condition.
9 . The apparatus according to claim 8 , wherein the programming instructions, when executed by the at least one processor, cause the apparatus further to:
obtain a second signal type of a primary channel signal of the first previous frame;
obtain a third signal type of a primary channel signal of a second previous frame prior to the first previous frame; and
determine that the current frame meets the switching condition when the second signal type is UNVOICED_CLAS and the third signal type is VOICED_TRANSITION.
10 . The apparatus according to claim 8 , wherein the programming instructions, when executed by the at least one processor, cause the apparatus further to:
obtain a fourth signal type of a secondary channel signal of the first previous frame;
obtain a fifth signal type of a secondary channel signal of a second previous frame prior to the first previous frame; and
determine that the current frame meets the switching condition when the fourth signal type is UNVOICED_CLAS and the fifth signal type is VOICED_TRANSITION.
11 . A non-transitory computer-readable storage medium storing computer instructions, which when executed by one or more processors, cause the one or more processors to perform operations, the operations comprising:
obtaining a first signal type of a current frame of an audio signal, wherein the first signal type is either a near in phase signal or a near out of phase signal, and wherein the current frame includes a left channel signal and a right channel signal;
obtaining a previous channel combination scheme of a first previous frame of the audio signal, wherein the previous channel combination scheme is either an anticorrelated signal channel combination scheme corresponding to the near out of phase signal or a correlated signal channel combination scheme corresponding to the near in phase signal;
obtaining a first signal-to-noise ratio of the left channel signal and a second signal-to-noise ratio of the right channel signal;
determining whether the first signal-to-noise ratio is greater than a preset threshold;
determining whether the second signal-to-noise ratio is greater than the preset threshold; and
in response to determining that the first signal type of the current frame is the near in phase signal, the previous channel combination scheme is the anticorrelated signal channel combination scheme, and both the first signal-to-noise ratio and the second signal-to-noise ratio are less than the preset threshold, determining that an initial channel combination scheme of the current frame is the correlated signal channel combination scheme.
12 . The non-transitory computer-readable storage medium according to claim 11 , wherein the operations further comprise:
determining whether the initial channel combination scheme needs to be modified; and
in response to determining that the initial channel combination scheme needs to be modified, obtaining a final channel combination scheme by modifying the initial channel combination scheme.
13 . The non-transitory computer-readable storage medium according to claim 12 , wherein the determining whether the initial channel combination scheme needs to be modified comprises:
obtaining a channel combination ratio factor modification flag of the first previous frame;
determining whether the current frame meets a switching condition when the channel combination ratio factor modification flag indicates that a channel combination ratio factor does not need to be modified; and
determining the final channel combination scheme based on a result of determining whether the current frame meets the switching condition.
14 . The non-transitory computer-readable storage medium according to claim 13 , wherein the determining whether the current frame meets a switching condition comprises:
obtaining a second signal type of a primary channel signal of the first previous frame;
obtaining a third signal type of a primary channel signal of a second previous frame prior to the first previous frame; and
determining that the current frame meets the switching condition when the second signal type is UNVOICED_CLAS and the third signal type is VOICED_TRANSITION.
15 . The non-transitory computer-readable storage medium according to claim 13 , wherein the determining whether the current frame meets a switching condition comprises:
obtaining a fourth signal type of a secondary channel signal of the first previous frame;
obtaining a fifth signal type of a secondary channel signal of a second previous frame prior to the first previous frame; and
determining that the current frame meets the switching condition when the fourth signal type is UNVOICED_CLAS and the fifth signal type is VOICED_TRANSITION.