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From: James Courtier-Dutton <James@superbug.demon.co.uk>
To: alsa-devel@lists.sourceforge.net
Subject: Problems with snd_pcm_status_get_delay()
Date: Wed, 09 Oct 2002 02:25:40 +1000	[thread overview]
Message-ID: <3DA30704.3050000@superbug.demon.co.uk> (raw)

Hello

Can someone please explain to me the use of snd_pcm_status_get_delay()

If a buffer size is 16384, and avail=6384, should delay therefore equil 
10000 ? In all cases ?

I have found that in  SND_PCM_STATE_RUNNING, delay = buffer_size - avail.
I have found that in  SND_PCM_STATE_PREPARED, delay = 0

This causes problems. As one fills the buffer in SND_PCM_STATE_PREPARED 
, delay stays at 0, but when the buffer fills enough and moves to state 
 SND_PCM_STATE_RUNNING, the delay value suddenly jumps to delay = 
buffer_size - avail.

This causes problems with applications that need "delay" to be as 
accurate as possible at all times.
Is this a bug in alsa09, or should I ignore "delay" and just use the 
"buffer_size - avail" value.

Obviously, in  SND_PCM_STATE_XRUN, delay is invalid.with avail values 
sometimes becoming > buffer_size!
so should not be used.

Cheers
James




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             reply	other threads:[~2002-10-08 16:25 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-10-08 16:25 James Courtier-Dutton [this message]
2002-10-08 16:44 ` Problems with snd_pcm_status_get_delay() Takashi Iwai
2002-10-09  6:45   ` Jaroslav Kysela

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