Re: support MJPEG based webcams

[Ioannis Nousias <s0238762 sms ed ac uk>]

> yeah, we are doing such a probing, but we do not insert a decodebin
> element. if you want, you can have a look into cheese-webcam.c and see
> if you are able to add your device somehow!
>
>   
Thanks, I did. My distro (ubuntu gutsy) doesn't meet cheese's 
prerequisites, so I've installed hardy on a VM, but usb is flaky (I can 
rarely get it to map on the VM). By the way I've met a segfault (why 
does it start from index 1 when looking for available webcams?). I'll do 
some tests later.

As far as I understand, 'decodbin' is non-intrusive when the stream is 
uncompressed. It simply forwards it. It probably is cleaner to simply 
add a 'decodebin' (and probably an 'ffmpegcolorspace' as well) in the 
pipe rather than having explicit checks for possible cases, since these 
are already done by the 'decodbin'. Similarly why I didn't suggest using 
'jpegdec'. Mind you, I doubt there is a webcam with some other form of 
compression. In fact, mine is not even a webcam. It's a regular camera 
with a webcam mode of operation. However, my rule of thumb is to make as 
little assumptions as possible.

Anyway, I'll play with it and see how it behaves on different devices.

regards,
Ioannis