From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: "Rémi Denis-Courmont" <remi@remlab.net>
Cc: linux-media@vger.kernel.org
Subject: Re: UVC frame interval inconsistency
Date: Mon, 16 Apr 2012 14:40:53 +0200 [thread overview]
Message-ID: <1689657.5vs7Qpi9BC@avalon> (raw)
In-Reply-To: <c29fa93d58ec0a2289435bc92ac63e46@chewa.net>
Hi Rémi,
On Wednesday 11 April 2012 12:27:08 Rémi Denis-Courmont wrote:
> Hello guys,
>
> I have been reworking the V4L2 input in VLC and I hit what looks like a
> weird bug in the UVC driver. I am using a Logitech HD Pro C920 webcam.
>
> By default, VLC tries to find the highest possible frame rate (actually
> smallest frame interval in V4L2), then the largest possible resolution at
> that frame rate.
>
> When enumerating the frame sizes and intervals on the device, the winner
> is 800x600 at 30 f/s. But when setting 30 f/s with VIDIOC_S_PARM, the
> system call returns 24 f/s. Does anyone know why it is so? Is this a
> firmware bug or what?
The frame sizes and intervals returned by the uvcvideo driver during
enumeration come directly from the values advertised by the device. When you
set a frame rate using VIDIOC_S_PARM, the driver then negotiates the value
with the device, and returns the frame rate it received from the device to the
application. The device is free to adjust the frame rate (based on current
lightning conditions for instance, if auto-exposure is turned on).
--
Regards,
Laurent Pinchart
prev parent reply other threads:[~2012-04-16 12:41 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-11 10:27 UVC frame interval inconsistency Rémi Denis-Courmont
2012-04-16 12:40 ` Laurent Pinchart [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1689657.5vs7Qpi9BC@avalon \
--to=laurent.pinchart@ideasonboard.com \
--cc=linux-media@vger.kernel.org \
--cc=remi@remlab.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.