[libavg-devel] v4l branch code review

[Ulrich von Zadow]

OXullo Intersecans schrieb:
> Yep,
> I read it.
> However I made a visual comparison between RGB, YUV422 and YUV420
> (interlaced stream).
> In the latter, vertical artifacts occur on saturated colour borders, but
> overall damage it's quite limited.

Ok, so we'll leave it as it is. No problem :-).

Also: I just got a USB webcam, did some tests and got a picture! Some
things happened, though:

First, I fixed a compile error (I think it depends on the kernel version
- I have 2.6.21 here) in linux/videodev2.h. The fix is comitted on the
branch. Please check if that doesn't break on your computer.

Then, the camera only supports V4L2_PIX_FMT_YUYV (not
V4L2_PIX_FMT_UYUV). I haven't fixed that yet (I will), but I can get a
picture with broken colors by just ignoring the PIX_FMT difference, so
in principle everything else works.

The next thing is that the current camera node uses the width and height
attributes as the camera image width and height for V4L. However, these
are also used as the size of the image on the screen :-(. We should
really change that and use new attribute names for the camera resolution.

Also, while everything works here using V4L2_FIELD_INTERLACED, can you
check if V4L2_FIELD_ANY works as well? That should work for more
cameras, right?

After that, I noticed that I didn't really need to buy a camera at all;
there is a test device you can enable in the kernel under Device
Drivers->Multimedia devices->Video Capture Adapters->Virtual Video
Driver. The test device also only supports V4L2_PIX_FMT_YUYV.

Still, I think we're very close to being done :-).

Regards,

  Uli