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From: Richard Cochran <richardcochran@gmail.com>
To: Henrik Austad <henrik@austad.us>
Cc: Takashi Sakamoto <o-takashi@sakamocchi.jp>,
	alsa-devel@alsa-project.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, Arnd Bergmann <arnd@linaro.org>,
	linux-media@vger.kernel.org
Subject: Re: [very-RFC 0/8] TSN driver for the kernel
Date: Sun, 19 Jun 2016 11:46:29 +0200	[thread overview]
Message-ID: <20160619094629.GC5853@netboy> (raw)
In-Reply-To: <20160618224549.GF32724@icarus.home.austad.us>

On Sun, Jun 19, 2016 at 12:45:50AM +0200, Henrik Austad wrote:
> edit: this turned out to be a somewhat lengthy answer. I have tried to 
> shorten it down somewhere. it is getting late and I'm getting increasingly 
> incoherent (Richard probably knows what I'm talking about ;) so I'll stop 
> for now.

Thanks for your responses, Henrik.  I think your explanations are on spot.

> note that an adjustable sample-clock is not a *requirement* but in general 
> you'd want to avoid resampling in software.

Yes, but..

Adjusting the local clock rate to match the AVB network rate is
essential.  You must be able to *continuously* adjust the rate in
order to compensate drift.  Again, there are exactly two ways to do
it, namely in hardware (think VCO) or in software (dynamic
resampling).

What you cannot do is simply buffer the AV data and play it out
blindly at the local clock rate.

Regarding the media clock, if I understand correctly, there the talker
has two possibilities.  Either the talker samples the stream at the
gPTP rate, or the talker must tell the listeners the relationship
(phase offset and frequency ratio) between the media clock and the
gPTP time.  Please correct me if I got the wrong impression...

Thanks,
Richard

  reply	other threads:[~2016-06-19  9:46 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-11 23:01 [very-RFC 0/8] TSN driver for the kernel Henrik Austad
2016-06-11 23:01 ` [very-RFC 1/8] TSN: add documentation Henrik Austad
2016-06-11 23:01 ` [very-RFC 2/8] TSN: Add the standard formerly known as AVB to the kernel Henrik Austad
2016-06-11 23:01 ` [very-RFC 3/8] Adding TSN-driver to Intel I210 controller Henrik Austad
2016-06-11 23:01 ` [very-RFC 4/8] Add TSN header for the driver Henrik Austad
2016-06-11 23:01 ` [very-RFC 5/8] Add TSN machinery to drive the traffic from a shim over the network Henrik Austad
2016-06-11 23:01 ` [very-RFC 6/8] Add TSN event-tracing Henrik Austad
2016-06-12 16:58   ` Steven Rostedt
2016-06-12 21:25     ` Henrik Austad
2016-06-13  2:22       ` Steven Rostedt
2016-06-13  7:20         ` Henrik Austad
2016-06-11 23:01 ` [very-RFC 7/8] AVB ALSA - Add ALSA shim for TSN Henrik Austad
2016-06-15 11:49   ` Richard Cochran
2016-06-15 12:13     ` Henrik Austad
2016-06-15 12:43       ` Richard Cochran
2016-06-11 23:01 ` [very-RFC 8/8] MAINTAINERS: add TSN/AVB-entries Henrik Austad
2016-06-13 11:47 ` [very-RFC 0/8] TSN driver for the kernel Richard Cochran
2016-06-13 13:00   ` Henrik Austad
2016-06-13 19:32     ` Richard Cochran
2016-06-14  9:30       ` Henrik Austad
2016-06-14 18:26         ` Richard Cochran
2016-06-14 20:38           ` Henrik Austad
2016-06-15  7:04             ` Richard Cochran
2016-06-15  7:50               ` Henrik Austad
2016-06-15 11:41               ` Richard Cochran
2016-06-15  7:11             ` Richard Cochran
2016-06-13 19:37     ` Richard Cochran
2016-06-13 13:12   ` Arnd Bergmann
2016-06-13 15:56   ` John Fastabend
2016-06-14  8:35     ` Henrik Austad
2016-06-13 19:51   ` Richard Cochran
2016-06-14 11:18     ` One Thousand Gnomes
2016-06-14 17:04       ` Richard Cochran
2016-06-15  3:15       ` Takashi Sakamoto
2016-06-15  8:06         ` Richard Cochran
2016-06-18  5:22           ` Takashi Sakamoto
2016-06-18 22:45             ` Henrik Austad
2016-06-19  9:46               ` Richard Cochran [this message]
2016-06-20  8:05                 ` Henrik Austad
2016-06-20 11:08               ` [alsa-devel] " Pierre-Louis Bossart
2016-06-20 11:49                 ` Henrik Austad
2016-06-20 12:18                 ` Richard Cochran
2016-06-20 12:31                   ` Richard Cochran
2016-06-20 15:21                     ` Richard Cochran
2016-06-21  5:54                       ` Takashi Iwai
2016-06-21  6:38                         ` Richard Cochran
2016-06-21  6:45                           ` Takashi Iwai
2016-06-21 17:18                     ` Pierre-Louis Bossart
2016-06-21 17:45                   ` Pierre-Louis Bossart
2016-06-21 19:40                     ` Richard Cochran
2016-06-22 12:36                       ` Pierre-Louis Bossart
2016-06-23 10:38                     ` Henrik Austad
2016-06-23 13:28                       ` Richard Cochran
2016-06-15  3:27       ` Takashi Sakamoto
  -- strict thread matches above, loose matches on Subject: below --
2016-06-11 22:22 Henrik Austad
2016-06-11 22:49 ` Henrik Austad

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