From: Clemens Ladisch <clemens@ladisch.de>
To: Jean-Yves Avenard <jyavenard@gmail.com>
Cc: alsa-devel@alsa-project.org
Subject: Re: Calculated average playback latency
Date: Tue, 14 Dec 2010 17:20:47 +0100 [thread overview]
Message-ID: <4D07995F.6020900@ladisch.de> (raw)
In-Reply-To: <AANLkTikcrTA4hRp9AvOfZPGN0FrkKwYS3SaFq0W25NdE@mail.gmail.com>
Jean-Yves Avenard wrote:
> By default, Myth uses mmap access
Why?
> Problem, turned out his was using a USB audio device, and
> snd_pcm_hw_params_set_access didn't return any error.
USB audio devices do support mmap.
> ... I decided to stop using mmap and instead use snd_pcm_writei.
>
> Now on my system, this has added quite a bit of latency and the A/V
> sync isn't perfect anymore...
Using mmap neither reduces latency, nor does it improve synchronization.
> Is there an official way to calculate an average system latency
> (doesn't need to be perfectly accurate).
Not the average, but try snd_pcm_delay().
Regards,
Clemens
prev parent reply other threads:[~2010-12-14 16:20 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-14 12:30 Calculated average playback latency Jean-Yves Avenard
2010-12-14 16:20 ` Clemens Ladisch [this message]
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