From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-oi0-f47.google.com ([209.85.218.47]:48930 "EHLO mail-oi0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751270AbaKCXQE convert rfc822-to-8bit (ORCPT ); Mon, 3 Nov 2014 18:16:04 -0500 Received: by mail-oi0-f47.google.com with SMTP id a3so8808285oib.6 for ; Mon, 03 Nov 2014 15:16:04 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20141102225704.GM3136@valkosipuli.retiisi.org.uk> References: <20141102225704.GM3136@valkosipuli.retiisi.org.uk> Date: Tue, 4 Nov 2014 01:16:03 +0200 Message-ID: Subject: Re: (bisected) Logitech C920 (uvcvideo) stutters since 3.9 From: Grazvydas Ignotas To: Sakari Ailus Cc: linux-media@vger.kernel.org, Laurent Pinchart , Hans Verkuil , Mauro Carvalho Chehab Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-media-owner@vger.kernel.org List-ID: Hi, On Mon, Nov 3, 2014 at 12:57 AM, Sakari Ailus wrote: > Hi Grazvydas, > > On Sun, Nov 02, 2014 at 04:03:55AM +0200, Grazvydas Ignotas wrote: >> There is periodic stutter (seen in vlc, for example) since 3.9 where >> the stream stops for around half a second every 3-5 seconds or so. >> Bisecting points to 1b18e7a0be859911b22138ce27258687efc528b8 "v4l: >> Tell user space we're using monotonic timestamps". I've verified the >> problem is there on stock Ubuntu 14.04 kernel, 3.16.7 from kernel.org >> and when using media_build.git . The commit does not revert on newer >> kernels as that code changed, but checking out a commit before the one >> mentioned gives properly working kernel. >> >> I'm using Logitech C920 which can do h264 compression and playing the >> video using vlc: >> cvlc v4l2:///dev/video0:chroma=h264:width=1280:height=720 > > I've got Logitech C270 here but I can't reproduce the problem. The frame > rate with the above command is really low, around 5. With a smaller > resolution it works quite smoothly. The reason might be that the pixel > format is still YUYV. The other option appears to be MJPG. I've tried lower resolution and YUYV with MJPG too, this has the same problem: cvlc v4l2:///dev/video0:chroma=h264:width=320:height=240 cvlc v4l2:///dev/video0:chroma=yuyv:width=320:height=240 > > My vlc is of version 2.0.3 (Debian). Which one do you have, and does it use > libv4l2? Mine is 2.1.4, my distro is Ubuntu 14.04. I can see libv4l2.so.0.0.0 in maps, but I have no idea what it's used for.. > Have you tried with a different application to see if the problem persists? Tried mplayer and cheese now, and it seems they are not affected, so it's an issue with vlc. I wonder why it doesn't like newer flags.. Ohwell, sorry for the noise. -- GraÅžvydas