| .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later |
| .. c:namespace:: V4L |
| |
| .. _VIDIOC_OVERLAY: |
| |
| ******************** |
| ioctl VIDIOC_OVERLAY |
| ******************** |
| |
| Name |
| ==== |
| |
| VIDIOC_OVERLAY - Start or stop video overlay |
| |
| Synopsis |
| ======== |
| |
| .. c:macro:: VIDIOC_OVERLAY |
| |
| ``int ioctl(int fd, VIDIOC_OVERLAY, const int *argp)`` |
| |
| Arguments |
| ========= |
| |
| ``fd`` |
| File descriptor returned by :c:func:`open()`. |
| |
| ``argp`` |
| Pointer to an integer. |
| |
| Description |
| =========== |
| |
| This ioctl is part of the :ref:`video overlay <overlay>` I/O method. |
| Applications call :ref:`VIDIOC_OVERLAY` to start or stop the overlay. It |
| takes a pointer to an integer which must be set to zero by the |
| application to stop overlay, to one to start. |
| |
| Drivers do not support :ref:`VIDIOC_STREAMON` or |
| :ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` with |
| ``V4L2_BUF_TYPE_VIDEO_OVERLAY``. |
| |
| Return Value |
| ============ |
| |
| On success 0 is returned, on error -1 and the ``errno`` variable is set |
| appropriately. The generic error codes are described at the |
| :ref:`Generic Error Codes <gen-errors>` chapter. |
| |
| EINVAL |
| The overlay parameters have not been set up. See :ref:`overlay` |
| for the necessary steps. |
