From: Ricard Wanderlof <ricardw@axis.com>
To: Amanda Ava Koci Pereira <arsoftware10@gmail.com>
Cc: "alsa-devel@alsa-project.org" <alsa-devel@alsa-project.org>
Subject: Re: How to downmix 5.1 and 7.1 channels to 2 channels
Date: Wed, 21 Oct 2020 15:57:50 +0200 [thread overview]
Message-ID: <alpine.DEB.2.21.2010211554200.22113@lnxricardw1.se.axis.com> (raw)
In-Reply-To: <CALAz8EWAKP-LaeDyQZW0BauwYBthSbgJgxRT8hypuXEWEOfPhA@mail.gmail.com>
On Tue, 20 Oct 2020, Amanda Ava Koci Pereira wrote:
> Hi guys...
>
> We need some clues about to downmix 5.1 and 7.1 channels to 2 channels
>
> for the moment we are using the following code ->
>
> It works but fails miserably if all channels have data at same time
>
Is the problem that you get clipping if there is audio on more than one
input channel?
In general, if you sum a number (N)( of digital channels which have a
maximum amplitude of M, then the maximum amplitude of the sum will be N *
M. So in this case you need to reduce the output amplitude by 1/N if you
want to keep the maximum amplitude of the sum at M.
So in your case you need to set
> #define AR_K_P_ATTENUATION_LEVEL 1.0
according to the number of channels being downmixed per output channel.
/Ricard
--
Ricard Wolf Wanderlof ricardw(at)axis.com
Axis Communications AB, Lund, Sweden www.axis.com
Phone +46 46 272 2016 Fax +46 46 13 61 30
next prev parent reply other threads:[~2020-10-21 13:58 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-20 2:32 How to downmix 5.1 and 7.1 channels to 2 channels Amanda Ava Koci Pereira
2020-10-21 13:57 ` Ricard Wanderlof [this message]
2020-10-22 9:11 ` Amanda Ava Koci Pereira
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