[linux-dvb] Start thinking about potential Google Summer of Code Projects we could run

Markus Rechberger markus.rechberger at AMD.COM
Wed Dec 19 18:40:45 CET 2007


Hans Verkuil wrote:
> On Wednesday 19 December 2007 18:23:55 Richard Atterer wrote:
>   
>> On Wed, Dec 19, 2007 at 05:36:09PM +0100, Hans Verkuil wrote:
>>     
>>> I think that this might be an ideal opportunity to develop a v4l2
>>> library that can be used by applications to access v4l devices.
>>>       
>> Oh yes, very much agreed!
>>
>> The library should
>>  - provide a single API to access both v4l1 and v4l2
>>  - maybe allow non-v4l devices (network cams)
>>  - make it easy to get a picture from any detected cam in a
>> particular format (and e.g. perform MJPEG decoding or resolution
>> rescaling along the way)
>>  - provide a standard plug-in API (maybe gstreamer-like) for the
>> video stream. This is necessary to support stuff like software
>> autofocus for some Logitech webcams, or for turning the picture
>> upside down (necessary for some webcams built into notebooks)
>>  - extend the plugin API to controls, e.g. allow automatic framerate
>> (i.e. shutter speed) selection by user-supplied software as well as
>> framerate selection by the webcam's firmware.
>>  - provide a standard way for controls like brightness, focus, motor
>>    controls. Emulate controls like brightness in software
>>     
>
> - standard API to scan for channels (TV & radio), preferably also 
> setting a standard config format containing the channel info.
> - simple video format conversions for the various YUV/RGB formats.
> - storing and retrieving card preferences (e.g. recording volume, 
> brightness, MPEG encoder settings, etc.)
>
> The biggest initial problem is deciding how low or high level the 
> library will be. I actually think that it might be a good idea to have 
> perhaps two libraries: one for low-level stuff (i.e. just a relatively 
> thin layer on top of v4l) and a high-level library allowing format 
> conversions, etc.
>
>   
since applications need to be changed in that case it might go hand in 
hand with following BSD project:
http://www.nabble.com/Updated-cx88-snapshot-td14358084.html
finally only one API might serve support for both and maybe more OSes

Markus
> 	Hans
>
>   
>> The following is a start, but AFAICT nothing has happened WRT an
>> implementation (?):
>> <http://linuxtv.org/v4lwiki/index.php/V4L2UserspaceLibrary>
>>
>> This is a start from a different perspective, quite a bit more
>> low-level, not enough for many of my requirements above:
>> <http://www.quickcamteam.net/software/libwebcam>
>>
>> Cheers,
>>
>>   Richard
>>     
>
>
>
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