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path: root/services/audioflinger/audio-resampler/filter_coefficients.h
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* Fix build warningsGlenn Kasten2013-01-081-2/+2
| | | | Change-Id: I79f4d7052a4c0a9fde144063f44a9c8c9dd575d5
* change how we store the FIR coefficientsMathias Agopian2012-11-051-36/+260
| | | | | | | | | | | | | | | | | The coefficient table is now transposed and shows much better its polyphase nature: we now have a FIR per line, each line corresponding to a phase. This doesn't change at all the results produced by the filter, but allows us to make slightly better use of the data cache and improves performance a bit (although not as much as I thought it would). The main benefit is that it is the first step before we can make much larger optimizations (like using NEON). Change-Id: Iebf7695825dcbd41f25861efcaefbaa3365ecb43
* new coefficients for the vhq resamplerMathias Agopian2012-11-011-0/+61
previous coefficients were provided by a 3rd party and didn't have a way to re-generate them. we're now using the 'fir' utility. the performance of the filter is virtually identical, except for the down-sampling case which seems slightly better now: It looks like both the previous and new coefficients are generating some sort of clipping for full-scale signals in the down-sampling case (although the new ones seem better), the reason for that is unknown (see bug: 7453062) Also updated the HQ coefficients for the down-samplers, previous ones were a little bit too conservative -- the new ones push the cut-off frequency up by about 1 KHz. Change-Id: I54a827b5c707c7cc41268ed01283758dce1d7647