From: Clemens Ladisch <clemens@ladisch.de>
To: Metathronius Galabant <m.galabant@googlemail.com>
Cc: alsa-devel@alsa-project.org
Subject: Re: Frame-based access (via mmap) and cross-device synchronisation
Date: Tue, 21 Jul 2009 15:49:25 +0200 [thread overview]
Message-ID: <4A65C765.7040500@ladisch.de> (raw)
In-Reply-To: <1b270aae0907200703l50ddd108se3ad0f6801113540@mail.gmail.com>
Metathronius Galabant wrote:
> At any given time x0, x1, ... xn I'd like to take some kind of
> "snapshot" of both devices, ask them "how many frame do you have?".
> This MUST NOT be restricted to the period, but it should be like
> device1 has 80 frames, device2 only has 78 frames.
Call snd_pcm_avail(). The granlarity of its return value is device
specific; e.g., chips like Emu10k1 or DS-1 move data in blocks of 256
or 512 samples, and USB uses 1-ms frames. You are not guaranteed to
get a result that is more recent than the last period boundary,
although most devices can do better.
Best regards,
Clemens
prev parent reply other threads:[~2009-07-21 13:49 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-20 14:03 Frame-based access (via mmap) and cross-device synchronisation Metathronius Galabant
2009-07-21 13:49 ` Clemens Ladisch [this message]
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