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Clicks and Pops in SBC Decoder
post May 7 2013, 08:23
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Hi All...

Currently i am working with SBC Decoder, while i run my decoder for the test case with 44.1Khz and 16blks and 8 sub bands it produces a output with clicks and pops. But no clicks and pops in output when i run the same testcase in reference SBC decoder in A2DP profile. Could any one guide me to solve this issue? The clicks and pops are occur in samples which has high amplitude.

Thanks and Regards,
Vigneshwaran V

This post has been edited by vigneshv55: May 7 2013, 08:24
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post May 7 2013, 09:02
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Don't know anything specific, but it sounds like clipping isn't properly handled, possibly if you're using integer mathematics. If you divide into subbands and reduce bit-depth then recombine (or other operations like filtering), you'll often get some peaks higher than the original (Gibbs phenomenon). You need to handle those properly to max them out to full scale positive or negative as appropriate rather than ignore cut-off the extra most significant bit that's required to represent them.

In decimal imagine I use 2-figure representation so 99 is my limit and that turns into 105. If I ignore the 3rd figure, that looks like 05, which is way different to 99. In 2's complement binary, it can even turn a positive into a negative. 01111111 is positive full scale +127 but 10000000 is negative full scale -128 in 8-bit 2's complement.

That's pure speculation but somethiing to look for given it occurs at high amplitudes only.
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