30 Aug
2010
30 Aug
'10
2:18 p.m.
On Mon, August 30, 2010 5:00 am, Kim Therkelsen wrote:
Hi,
I want to make is a DSP module that improves the sound quality
of the sound coming from the laptop builtin speakers by applying DSP
(FIR/IIR filters).
I want to route all audio played back (from for
instance an offline WAV or MP3 file, from a movie, or streamed from the
internet) to
pass through the
DSP plugin whenever headphones are NOT connected. When headphones are
connected no processing should be applied.
I
want to place the DSP module as close to the hardware as possible to
make sure all audio is really routed through the DSP plugin so I always
can enjoy
the DSP improvements made to the sound.
Where should I place this module/DSP code?
- As a plugin to PulseAudio?
- As a plugin to ALSA?
- As its own virtual sound card?
- In the audio driver for my built-in sound card?
- As a kernel module?
I have tried loading the LADSPA-module using the module-ladspa-sink in
PulseAudio but I am not sure this is the best solution.
It is the recommended solution if you are using PA for your sound server.
I need to remove some limitations in
module-ladspa-sink to get it working
properly ( multichannel audio, only DSP processing for internal speakers).
My requirements:
1) Must be able to detect if headphones are connected
IIUC, PA gets this info from ALSA
2) Must be able to process stereo and multichannel
(5.1/7.1) formats. I
need the multichannel formats to perform binaural downmixing to
stereo.
I'm not sure how the dolby multichannel support is in ALSA. It may depend
on the internal capabilities of the device.
So it is important that I can receive multichannel
audio and mix it down
to stereo and output it to a stereo soundcard.
This may better handled in app.
--
Patrick Shirkey
Boost Hardware Ltd.