From: Alan Young <consult.awy@gmail.com>
To: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
Takashi Iwai <tiwai@suse.de>
Cc: Raymond Yau <superquad.vortex2@gmail.com>, alsa-devel@alsa-project.org
Subject: Re: Improving status timestamp accuracy
Date: Tue, 7 Jun 2016 07:44:52 +0100 [thread overview]
Message-ID: <57566D64.1050400@gmail.com> (raw)
In-Reply-To: <51c7887a-db2f-ee88-8290-2f2d21d6435d@linux.intel.com>
On 06/06/16 15:53, Pierre-Louis Bossart wrote:
> I probably need more coffee but how is this patch helping track audio
> v. wallclock drift? The additional precision is based on wallclock
> deltas...
Of course, it wouldn't, due to being buggy. I think I needed more coffee
too.
But the basic point is that if the difference between tstamp and
(trigger_tstamp + audio_tstamp) varies over time, this will be the drift
between the audio output and wallclock time.
Depending upon the specific goal, a calculation based on tstamp + delay
may be appropriate.
This is true today with a granularity of about period time. The idea
behind my change is to make the granularity much smaller, preferably < ~1ms.
I'll work on developing and testing a patch for consideration before
coming back to the last. It will be easier to discuss the merits or
otherwise of my proposal with a concrete, working patch to consider.
Alan.
next prev parent reply other threads:[~2016-06-07 6:44 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-04 9:31 Improving status timestamp accuracy Alan Young
2016-06-04 10:17 ` Clemens Ladisch
2016-06-04 10:43 ` Alan Young
2016-06-04 15:59 ` Clemens Ladisch
2016-06-04 16:20 ` Alan Young
2016-06-05 16:27 ` Clemens Ladisch
2016-06-05 16:32 ` Alan Young
2016-06-05 1:14 ` Raymond Yau
2016-06-05 10:33 ` Alan Young
2016-06-06 1:24 ` Raymond Yau
2016-06-06 9:40 ` Alan Young
2016-06-06 8:34 ` Takashi Iwai
2016-06-06 9:42 ` Alan Young
2016-06-06 14:53 ` Pierre-Louis Bossart
2016-06-07 6:44 ` Alan Young [this message]
2016-06-07 18:01 ` Pierre-Louis Bossart
2016-07-08 15:03 ` Alan Young
2016-07-15 20:13 ` Pierre-Louis Bossart
2016-07-19 15:33 ` Alan Young
2016-07-19 15:58 ` Pierre-Louis Bossart
2016-07-20 6:59 ` Alan Young
2016-08-01 21:56 ` Pierre-Louis Bossart
2016-08-02 7:30 ` Alan Young
2016-08-02 7:55 ` Clemens Ladisch
2016-08-02 16:25 ` Pierre-Louis Bossart
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