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US 12,217,763 B2Granted
Transient detection with hangover indicator for encoding an audio signal
AssigneeTelefonaktiebolaget LM Ericsson (publ)
InventorsAnisse Taleb, Gustaf Ullberg
Life of this patent
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Abstract
A transient detector analyzes a given frame n of the input audio signal to determine, based on audio signal characteristics of the given frame n, a transient hangover indicator for a following frame n+1, and signals the determined transient hangover indicator to an associated audio encoder to enable proper encoding of the following frame n+1.
Claims17
An audio encoder apparatus, comprising:
- memory;
- and
- processing circuitry coupled to the memory, wherein the audio encoder apparatus is configured to perform an audio signal encoding process comprising:
- determining a short term energy value (E(m)) for a sub-frame m of a given frame n of the audio signal;
- determining a long term energy value (ELT(m)) using a previously determined long term energy value (ELT(m−1)), a predetermined factor (α), and the short term energy value (E(m)), wherein ELT(m)=αE(m)+(1−α)ELT(m−1);
- using the short term energy value and the long term energy value to determine whether a transient hangover condition exists for a frame n+1 of the audio signal, wherein frame n+1 of the audio signal follows frame n of the audio signal;
- and
- signaling a transient hangover indicator for frame n+1 as a result determining that the transient hangover condition exists for frame n+1 of the audio signal.
5 more elements
An audio encoder apparatus, comprising:
- memory;
- and
- processing circuitry coupled to the memory, wherein the audio encoder apparatus is configured to perform an audio signal encoding process comprising:
- analyzing a given frame n of an audio signal comprising a plurality of frames including frame n and a frame n+1, wherein frame n of the audio signal comprises at least a first sub-frame and a second sub-frame, and frame n of the audio signal is immediately followed by frame n+1 of the audio signal, to determine whether a transient hangover condition is satisfied for frame n+1;
- and
- triggering a transient for frame n+1 as a result of determining that the transient hangover condition for frame n+1 is satisfied, wherein
- analyzing the given frame n of the audio signal to determine whether the transient hangover condition is satisfied for frame n+1 comprises:
- i) determining a short term energy value for the first sub-frame of frame n(E(1)),
- ii) determining a long term energy value for the first sub-frame of frame n(ELT(1)) using the short term energy value, a previously determined long term energy value ELT(0), and a predetermined factor (α), wherein ELT(1)=αE(1)+(1−α)ELT(0), and
- iii) determining whether E(1)≥R×ELT(1), where R is a predetermined energy ratio threshold, and
- the audio encoder apparatus is configured such that the audio encoder apparatus determines that a transient is present in frame n of the audio signal as a result of determining that E(1) is greater than R×ELT(1).
8 more elements
An audio encoding method, the method comprising:
- obtaining a given frame n of an audio signal comprising a plurality of frames including frame n and a frame n+1, wherein frame n of the audio signal is immediately followed by frame n+1 of the audio signal;
- determining that a transient hangover condition is satisfied for frame n+1;
- and
- triggering a transient for frame n+1 as a result of determining that the transient hangover condition for frame n+1 is satisfied, thereby enabling proper encoding of frame n+1, wherein
- determining that the transient hangover condition is satisfied for frame n+1 comprises:
- determining a short term energy value (E(m)) for a sub-frame m of frame n;
- computing a long term energy value (ELT(m)) for the sub-frame m using a previously determined long term energy value ELT(m−1), a predetermined factor (α), and the short term energy value, wherein ELT(m)=αE(m)+(1−α)ELT(m−1);
- and
- determining that E(m)≥R×ELT(m), where R is a predetermined energy ratio threshold.
6 more elements
A transient detector, the transient detector comprising:
- memory;
- and
- processing circuitry, wherein the transient detector is configured to perform a process comprising:
- for a sub-frame m−1 of a frame n of an audio signal, obtaining a long term energy value (ELT(m−1)), wherein the frame n of the audio signal comprises an ordered set of M sub-frames, where m>1 and M>1;
- for a sub-frame m of the frame n of the audio signal, determining a short term energy value (E(m));
- for the sub-frame m of frame n of the audio signal, determining a long term energy value (ELT(m)), wherein ELT(m)=α×ELT(m−1)+(1−α)×E(m), where α is less than 1 and greater than or equal to 0;
- based on E(m) and ELT(m), determining whether a transient hangover condition exists for a frame n+1 of the audio signal, wherein frame n+1 of the audio signal follows frame n of the audio signal;
- and
- signaling a transient hangover indicator as a result determining that the transient hangover condition exists for frame n+1 of the audio signal.
6 more elements
A method for detecting a transient, the method comprising:
- obtaining a long term energy value (ELT(m−1)) for a given frame n of an audio signal, wherein the frame n of the audio signal comprises an ordered set of sub-frames, where m>1;
- for a sub-frame m of the given frame n of the audio signal, determining a short term energy value (E(m));
- for the sub-frame m, calculating a long term energy value (ELT(m)) by computing a weighted average of ELT(m−1) and E(m), such that ELT(m)=α×ELT(m−1)+(1−α)×E(m), where α is less than 1 and greater than or equal to 0;
- based on E(m) and ELT(m), determine whether a transient hangover condition exists for a frame n+1 of the audio signal, wherein frame n+1 of the audio signal follows frame n of the audio signal;
- and
- as a result determining that the transient hangover condition exists for frame n+1 of the audio signal, signal a transient hangover indicator to an audio encoder to enable proper encoding of frame n+1.
3 more elements
Dependencies are inferred from the claim text.