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

[Luc S. <lu...@sa...>]

On Mon, Jan 09, 2006 at 11:04:59AM +0100, Laurent Pinchart wrote:
> Hi Luc,
> 
> > I hope that gnomemeeting is link to the jpeg library or something like that.
> 
> I don't think it will be a problem to link to libjpeg (even if Damien would 
> rather avoid it if possible). Remember that the MJPEG data doesn't contain 
> the Huffman tables, so you need to add them manually (see the Qt patch I 
> posted on this list).

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. I'll look Qt. For now, i only do conversion for the YVY2
format.
 
> 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:

/mnt/linux/srcs/usb/uvc/linux-uvc>LC_ALL=C svn diff
Index: uvcvideo.c
===================================================================
--- uvcvideo.c  (revision 8)
+++ uvcvideo.c  (working copy)
@@ -2071,12 +2071,34 @@
                return uvc_video_enable(video, 0);
        }
 
-       /* Analog video standards make no sense for digital cameras. */
-       case VIDIOC_ENUMSTD:
-       case VIDIOC_QUERYSTD:
+       /* Analog video standards make no sense for digital cameras, but some
+         * application need it (mplayer for example) */
        case VIDIOC_G_STD:
+       {
+         v4l2_std_id *std = arg;
+         *std = V4L2_STD_UNKNOWN;
+         return 0;
+       }
+
        case VIDIOC_S_STD:
+       {
+         v4l2_std_id *std = arg;
+         if (*std != V4L2_STD_UNKNOWN)
+           return -EINVAL;
+         return 0;
+       }
 
+       case VIDIOC_ENUMSTD:
+       {
+         struct v4l2_standard *std = arg;
+         if (std->index != 0)
+           return -EINVAL;
+         std->id = V4L2_STD_UNKNOWN;
+         strncpy(std->name, "webcam", sizeof(std->name));
+         return 0;
+       }
+       case VIDIOC_QUERYSTD:
+
        case VIDIOC_OVERLAY:
 
        case VIDIOC_ENUMAUDIO:

Wait ... i just receved a patch for pwc, to add these lines after the
strncpy.
                                                                                                                  
                std->frameperiod.numerator = 1;                 // NEW                                            
                std->frameperiod.denominator = pdev->vframes;   // NEW  

Luc