Friday, July 6, 2012

Testing your disks using dd utility and time.

You can execute copies a large block of data to and from disk.

This will minimize disk caching.

Next is one example if our test system has 1GB of RAM.

It is easy ( 1GB = 250,000 blocks ).

$ time sh -c "dd if=/dev/zero of=bigfile bs=8k count=250000 && sync"
250000+0 records in
250000+0 records out
2048000000 bytes (2.0 GB) copied, 37.0113 s, 55.3 MB/s

real 0m40.910s
user 0m0.172s
sys 0m12.641s

It's very hard to argue with this dd test.

Thursday, July 5, 2012

Using DIGITAL PEN CAMERA eheV1-USB-II with mplayer

It's not my camera, I take it just to try to make working on Linux OS.
This is the device.

The dmesg tell me about this camera:
uvcvideo: Found UVC 1.00 device USB2.0 Camera
If you want to see and not to take frames, then use :
mplayer tv:// driver=v4l2:width=640:height=480:device=/dev/video0 -vo null
You can try to take some frames. I use this:
mplayer tv:// -frames 10 -tv fps=20:driver=v4l2:width=640:height=480:device=/dev/video0 -vo jpeg
The result is ten frames.
On this image I draw one line to see how working default.

And using the zoom ...