On Monday 05 April 2010 20:11:13 Hans Verkuil wrote: > Another option would be to set aside a range of IDs at the end of each control > class that could be used as a 'remap' area. > > For example: the IDs for user class controls go from 0x980000-0x98ffff. Of > which anything >= 0x981000 is a private control (i.e. specific to a driver). > We could set aside 0x98f000-0x98ffff for remapped controls. > > So if you want to make a subdev's volume control available as a secondary > control you can do something like this: > > v4l2_ctrl_add_ctrl_remap(struct v4l2_ctrl_handler *hdl, > struct v4l2_ctrl_info *cinfo, > const char *fmt); > > The framework will pick a new ID from the remap range and add this control > with the name created using snprintf(fmt, sz, cinfo->name). Since this control > is remapped as a private control it will be seen by old applications as well > since they just iterate from V4L2_CID_PRIVATE_BASE, and the framework handles > that transparently. > > It is even possible to do this for all controls from a subdev, e.g.: > > v4l2_ctrl_add_handler_remap(struct v4l2_ctrl_handler *hdl, > struct v4l2_ctrl_handler *add, > const char *fmt); > > Every control in 'add' that already exists in 'hdl' would then be remapped > and a new name is generated.
I implemented this scheme in this tree: http://linuxtv.org/hg/~hverkuil/v4l-dvb-fw-remap/ I also hacked vivi to use this. After creating a second handler with volume, mute and saturation controls I added this line to merge the two: v4l2_ctrl_add_handler_remap(&dev->hdl, &dev->hdl2, "Secondary %s"); The end result is this: $ v4l2-ctl --list-ctrls User Controls brightness (int) : min=0 max=255 step=1 default=127 value=127 flags=slider contrast (int) : min=0 max=255 step=1 default=16 value=16 flags=slider saturation (int) : min=0 max=255 step=1 default=127 value=127 flags=slider hue (int) : min=-128 max=127 step=1 default=0 value=0 flags=slider volume (int) : min=0 max=255 step=1 default=200 value=200 flags=slider mute (bool) : default=1 value=1 integer_test_control (int) : min=-2147483648 max=2147483647 step=1 default=0 value=0 toggle_text_color (bool) : default=0 value=0 press_me (btn) : flags=write-only menu_test_control (menu) : min=0 max=5 default=1 value=1 integer64_test_control (int64): value=0 string_test_control (str) : min=0 max=100 step=2 value='' secondary_volume (int) : min=0 max=128 step=1 default=20 value=20 flags=slider secondary_saturation (int) : min=100 max=200 step=1 default=150 value=150 flags=slider So mute was added unchanged while volume and saturation were remapped automatically. And they showed up in xawtv as well. Regards, Hans -- Hans Verkuil - video4linux developer - sponsored by TANDBERG -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
