Hi! Hui and I have been working on some LFE filter patches lately, and this is our first draft for review/feedback. First, I have greedily stolen the math from CRAS, because CRAS is BSD and as I understand we don't have a problem with merging more liberal licenses. The LFE filter is implemented in the resampler, which means it is done for every sink-input rather than every sink - this might mean some additional CPU processing if many different streams play back at the same time, but putting it on the sink side would disable the possibility to mix a 2.0 stream with a 2.1 stream. The rewind part is very drafty and untested, and I'm not sure I choose the best design here. But at least this is something that could act as base for discussion. Also, while testing we noticed that flat volumes acts a bit weird, making it impossible to have a high subwoofer volume level but at the same time low front speaker volume, but I'm not sure if that's a bug or just the (ahem) normal weirdness of flat volumes. David Henningsson (4): lfe-filter: Import code from the Chrome OS audio server lfe-filter: Enable LFE filter in the resampler lfe-filter: Add rewind support resampler: Make some basic functions for rewinding Hui Wang (2): daemon-conf: enable the lfe remixing by default lfe-filter: change the crossover frequency as a parameter LICENSE | 3 + man/pulse-daemon.conf.5.xml.in | 7 +- src/Makefile.am | 3 + src/daemon/daemon-conf.c | 5 +- src/daemon/daemon-conf.h | 1 + src/daemon/daemon.conf.in | 3 +- src/daemon/main.c | 1 + src/modules/module-virtual-surround-sink.c | 2 +- src/pulsecore/core.c | 1 + src/pulsecore/core.h | 1 + src/pulsecore/filter/LICENSE.WEBKIT | 27 +++ src/pulsecore/filter/biquad.c | 368 +++++++++++++++++++++++++++++ src/pulsecore/filter/biquad.h | 57 +++++ src/pulsecore/filter/crossover.c | 263 +++++++++++++++++++++ src/pulsecore/filter/crossover.h | 76 ++++++ src/pulsecore/filter/lfe-filter.c | 187 +++++++++++++++ src/pulsecore/filter/lfe-filter.h | 39 +++ src/pulsecore/resampler.c | 49 +++- src/pulsecore/resampler.h | 7 + src/pulsecore/sink-input.c | 6 +- src/pulsecore/source-output.c | 4 +- src/tests/remix-test.c | 3 +- src/tests/resampler-test.c | 7 +- 23 files changed, 1106 insertions(+), 14 deletions(-) create mode 100644 src/pulsecore/filter/LICENSE.WEBKIT create mode 100644 src/pulsecore/filter/biquad.c create mode 100644 src/pulsecore/filter/biquad.h create mode 100644 src/pulsecore/filter/crossover.c create mode 100644 src/pulsecore/filter/crossover.h create mode 100644 src/pulsecore/filter/lfe-filter.c create mode 100644 src/pulsecore/filter/lfe-filter.h -- 1.9.1
