Re: [Linux-uvc-devel] uvcview videograbber with preview available for testing

[michel X. <mx...@ma...>]

Le Lundi 9 Janvier 2006 11:33, Laurent Pinchart a écrit :
> > Yes, I've made it to uncompress mjpeg data from an avi, and mov file for
> > my gallery program (photon) written in python. I known it's not the best
> > langage to play with bitstream, but it's working i recreate a full jpeg
> > header from the stream. Else, i dont' known how to decode jpeg data +
> > huffman table without the libjpeg.
>
> You definitely need a library to decode MJPEG. libjpeg might be a bit too
> big to do the job (MJPEG is a small subset of all possible JPEG formats),
> but it's the easiest to use for prototyping.

Why don't used the library from uvcview in utils.c 
int jpeg_decode(unsigned char **pic, unsigned char *buf, int *width,
		int *height);
If you need i can patch this function to accept jpeg data without huffman 
table  :)
> > I'll look Qt. For now, i only do conversion for the YVY2 format.
>
> The Qt patch I wrote modifies the Qt JPEG codec which uses libjpeg, so you
> will be able to reuse the code in Gnomemeeting. Be careful about licensing
> issues though. pwlib is licensed under the Mozilla Public License 1.1 and
> Qt under the GNU Public License. You can reuse my code in pwlib (I grant
> you the right to use it under the MPL), but not Qt code.
>
> > > Why did you need to modify the driver ?
> >
> > To support ENUM_STD. Only to not return -EINVAL. But it failed somewhere
> > after that ... This is why i don't send the patch. Here the patch use:
>
> Mmmmm... Shouldn't mplayer be fixed instead ? V4L2 v0.8 doesn't make it
> mandatory to support ENUM_STD:
>
> (1.7. Video Standards)
>
> "Here the driver shall set the std field of struct v4l2_input and struct
> v4l2_output to zero, the VIDIOC_G_STD, VIDIOC_S_STD, VIDIOC_QUERYSTD and
> VIDIOC_ENUMSTD ioctls shall return the EINVAL error code."
>
> Laurent Pinchart
-- 
Michel Xhaard
http://mxhaard.free.fr