a better v4l test application needed

[Peter Pregler]

On 18-Sep-99 sbertin@mindspring.com wrote:
> On 16 Sep, Peter Pregler wrote:
>> to test my v4l-module I would need a better v4l-application than xawtv.
>> Namely it should be possible to
>> 
>> - set brightness, color
>> - grab images
>> - pause
>> - any screen size handling (should be mapped to cif/qcif/...)
>> 
>> In other words it should be tailored playing with a camera not for
>> watching television. I have no idea if all listed above is really
>> covered
>> by the v4l-api. But in any case, if  your favoritve v4l-camera
>> application
>> supports those please give me a note so I can check things.
> 
> Have you had a look at gqcam?  http://cse.unl.edu/~cluening/gqcam/
> 
> I haven't tried it myself, but it looks like what you are looking for.

Yep, that was what I was looking for. Unfortunaly it is B&W only. I am
porting it to color.

About my v4l-stuff: normal capture already seems to work more or less
stable (memory mapped with xawtv, blocking read with gqcam, I'll add a
memory mapped mode to gqcam). Even changing brightness etc. seems to work
during capture though colors look strange but that might be a porting
failure (or the late hour ;). I will have to add some work for the
video-mode and size-settings though. This also affects the
decompession. So it is not really hard kernel work. After that I will
realease a first alpha. This v4l-driver is a bit more work than I
expected. :)

A comment/question about performance: memory mapped mode seems to be way
more efficient than a streaming read. This surprised me a bit since the
only real difference is a missing copy_to_user in the case of mmap. Sounds
this plausible? In both cases a interrupt driven kernel task does the
if_StreamRead/convert. To user-space go only decompressed frames.

About v4l2: I had a close look at the specification and I think as soon as
there is a reasonable appliation it is really worth to write the driver.
The core of my  v4l-stuff could be used. But the interface is soo much
cleaner (distinction between streaming mode, captuer, read, ...).

-Peter

-------------------------------
Email: Peter.Pregler@risc.uni-linz.ac.at
WWW:   http://www.risc.uni-linz.ac.at/people/ppregler
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