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| author | Mathias Agopian <mathias@google.com> | 2012-10-26 13:48:42 -0700 |
|---|---|---|
| committer | Mathias Agopian <mathias@google.com> | 2012-10-26 14:58:42 -0700 |
| commit | 3bd72cc23f74e750069a2943ad3d5c9af3be4b55 (patch) | |
| tree | aff530f634a7ce504d1e7b7926136f06bea481e4 /services/audioflinger/AudioResampler.cpp | |
| parent | 04b49594036f17bc260af711becd13924774caae (diff) | |
| download | frameworks_av-3bd72cc23f74e750069a2943ad3d5c9af3be4b55.zip frameworks_av-3bd72cc23f74e750069a2943ad3d5c9af3be4b55.tar.gz frameworks_av-3bd72cc23f74e750069a2943ad3d5c9af3be4b55.tar.bz2 | |
improve SINC resampler coefficients
- we increase the interpolation precision from 4 to 7 bits
this doesn't increase CPU power required, it only increases the
size of the filter table but significantly reduces the noise
introduced by the quantization of the impulse response.
- the parameters of the filter are set such that aliasing is
rejected at 80 dB below 20 KHz. Because we don't use a lot of
coefficient (to save compute power), there are quite a bit of
attenuation in the pass-band: starting at 9KHz for the
down-sampler (48 to 44.1), and starting at 13 KHz for the
up-sampler (44.1 to 48) -- the transition band is about 15 KHz.
Change-Id: I855548d2aab8a0fb0d2a2da3a364b6842d7d3838
Diffstat (limited to 'services/audioflinger/AudioResampler.cpp')
0 files changed, 0 insertions, 0 deletions