From: Clemens Ladisch <clemens@ladisch.de>
To: Kai Vehmanen <kvehmanen@eca.cx>
Cc: alsa-devel@alsa-project.org,
Ujfalusi Peter <peter.ujfalusi@nokia.com>,
ext-eero.nurkkala@nokia.com
Subject: Re: snd_pcm_delay, hw buffers and driver api (v2)
Date: Fri, 14 Aug 2009 14:13:00 +0200 [thread overview]
Message-ID: <4A8554CC.2060009@ladisch.de> (raw)
In-Reply-To: <alpine.DEB.1.10.0908140023240.3417@ecabase.localdomain>
Kai Vehmanen wrote:
> ...
> In both cases, this value (hw_ptr) shows the status of sending data to an
> separate entity, and one that has its own buffer (multiple ms) before the
> actual DAC/ADC.
>
> So when application developer uses snd_pcm_delay(), the result is not
> quite what the ALSA API says: ...
snd_pcm_avail() returns the free part of the buffer.
snd_pcm_delay() returns the filled part of the buffer plus
the additional delay imposed by the device.
The additional delay can be set by the driver in
pcm_substream->runtime->delay. (Currently, only
the USB audio driver bothers to set this.)
HTH
Clemens
next prev parent reply other threads:[~2009-08-14 12:13 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-08-13 21:35 snd_pcm_delay, hw buffers and driver api (v2) Kai Vehmanen
2009-08-13 21:57 ` Kai Vehmanen
2009-08-14 10:38 ` James Courtier-Dutton
2009-08-14 22:02 ` Kai Vehmanen
2009-08-14 12:13 ` Clemens Ladisch [this message]
2009-08-14 23:27 ` Kai Vehmanen
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