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From: Jan Stary <>
Subject: Re: Loopback latency issue
Date: Mon, 13 Jul 2020 13:49:27 +0200
Message-ID: <> (raw)
In-Reply-To: <139b163f-9192-436a-8fd4-5c3715927e5c@Spark> <> <9148e80a-8af7-4545-af62-bf4f3512aace@Spark>

On Jul 10 20:40:09, wrote:
> We are trying to build a Sox based real-time sound altering app, and we’ve got everything working on our LUbuntu 16.04 stations except for an issue w latency.
> When we test it on actual hardware, we are having a latency of about 2 seconds, when we test it on our virtual machine the latency is more like 250ms.
> sox -t pusleaudio default -t pulseaudio null pitch n

I don't use pulseaudio, but I assume that "default"
and "null" are names of pulseaudio (pseudo)devices.

How can you tell the delay when writing to a null device?
(If that means what I think it means: dropping the pulseaudio,
would it be what sox -d -n does?) I just tried

	sox -d -d pitch 1000

an OpenBSD current/amd64, and there is indeed
about a half second of delay.

> Whenever we add the null loopback or aloop, we experience a delay.

I don't understand: what does your application do
that you need to "add a null loopback"?

On Jul 11 14:12:13, wrote:
> Some effects have additional internal buffers.

It seems there is a delay even when just playing
default input to default output; even without the effects:

	sox -d -d

(So I don't think it's the effect processing
that introduces the delay.)


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Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <0713c9d8-7bdf-4b97-99b4-12e219e94d45@Spark>
2020-07-10 17:40 ` Maxim Doumkine
2020-07-10 18:08   ` Darryl Lewis
2020-07-11 16:04     ` Maxim Doumkine
2020-07-11 13:12   ` Måns Rullgård
2020-07-11 15:59     ` Maxim Doumkine
2020-07-11 16:12     ` Steve Masters
2020-07-13 11:49   ` Jan Stary [this message]
2020-07-13 12:05     ` Jan Stary
2020-07-13 15:09     ` Maxim Doumkine
2020-07-13 20:52     ` Måns Rullgård
2020-07-13 22:20       ` Rafal Maszkowski

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