[pulseaudio-discuss] Is this possible? - 4.1 with filtered bass

[Lennart Poettering]

On Thu, 13.11.08 20:41, Dom H (speedsix.lists at googlemail.com) wrote:

> Hi all,
> 
> I believe I'm correct in saying Pulse doesn't support DD/DTS
> passthrough (yet) so what I want my system to pass the decoded output
> to my amps analogue inputs. I don't think this is a problem but I want
> it setup in a way that mimicks my amps decoder and I'd like to know if
> it's possible.
> 
> My amp is configured with 4 speakers (no centre) and each is set to
> what the amp calls 'small' i.e all bass output below the crossover
> frequency is passed to the sub ASWELL as the discrete LFE channel.
> Centre information is mixed into FL & FR speakers.
> 
> Now I know a 4.1 setup is possible in Pulse with a config line like;
> 
> load-module module-alsa-sink device_id=0 channels=5
> channel_map=front-left,front-right,rear-left,rear-right,lfe
> 
> 
> The problem is, I'm assuming this is passing full range signals to the
> main speakers and only the discrete LFE track to the sub, this also
> suggest to me that playing audio tracks that don't have a discrete LFE
> track (2ch music for example) would not output anything to the
> subwoofer?

In .13 we do not synthesize LFE anymore by default. Previously (and
still now if you enable some config option) we would mix LFE from all
other channels. We did never apply a lowpass however.

In .13 the LFE channel will thus only get silence if you play a stream
without LFE data and it is up to the hardware you have connected to
your sound card to synthesize it if it wants to.

Lennart

-- 
Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net         ICQ# 11060553
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