Em Terça-feira 21 Julho 2009, Antoine Jacquet escreveu:
> Hi,
Hi,
> > This patch implements changing resolution in zr364xx_vidioc_s_fmt_vid_cap
> > for zr364xx driver. This version is synced with v4l-dvb as of
> > 20/Jul/2009. Tested with Creative PC-CAM 880.
>
> Nice, I successfully tested your patch with 2 compatible webcams.
> From the users feedbacks I had before, it seems that some devices do
> not support the 640x480 resolution, but I was not able to verify this
> myself.
> This is the only concern I have, since some users may think the driver
> is not working if the application automatically switches to the maximum
> resolution with an incompatible device.
Maybe we should add a quirk list to prevent such cases or if
send_control_msg
returns error in such cases I can change the code to revert the change and
keep the old resolution.
> > OBS: I had to increase MAX_FRAME_SIZE to prevent a hard crash in my
> > notebook (caps lock blinking) when testing with mplayer, which
> > automatically sets resolution to the maximum (640x480). Maybe we should
> > add code to auto-detect frame size to prevent this kind of crash in the
> > future.
>
> Yes, I also had this issue before. I don't know what is the good
> approach to determine the best size with JPEG compression.
The driver reads data from USB port in 4096-bytes chunks, so before
adding
the data to frm->lpvbits we could verify if frm->lpvbits has enough space to
hold it. If there is no enough space we can dynamically increase frm->lpvbits.
In user space that can be done using realloc, I just do not know if there is a
similar function in kernel space. OBS: frm->lpvbits had be increased without
loosing the old data and of course we should have a upper limit, maybe 640 x
480 * 3 (3 bytes per pixel) = 921600 bytes.
> I will push your changes to my tree and send a pull request to Mauro later.
Ok, thanks.
--
Lamarque V. Souza
http://www.geographicguide.com/brazil.htm
Linux User #57137 - http://counter.li.org/
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