1 .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2 .. c:namespace:: V4L 3 4 .. _VIDIOC_ENUMAUDOUT: 5 6 *********************** 7 ioctl VIDIOC_ENUMAUDOUT 8 *********************** 9 10 Name 11 ==== 12 13 VIDIOC_ENUMAUDOUT - Enumerate audio outputs 14 15 Synopsis 16 ======== 17 18 .. c:macro:: VIDIOC_ENUMAUDOUT 19 20 ``int ioctl(int fd, VIDIOC_ENUMAUDOUT, struct v4l2_audioout *argp)`` 21 22 Arguments 23 ========= 24 25 ``fd`` 26 File descriptor returned by :c:func:`open()`. 27 28 ``argp`` 29 Pointer to struct :c:type:`v4l2_audioout`. 30 31 Description 32 =========== 33 34 To query the attributes of an audio output applications initialize the 35 ``index`` field and zero out the ``reserved`` array of a struct 36 :c:type:`v4l2_audioout` and call the ``VIDIOC_G_AUDOUT`` 37 ioctl with a pointer to this structure. Drivers fill the rest of the 38 structure or return an ``EINVAL`` error code when the index is out of 39 bounds. To enumerate all audio outputs applications shall begin at index 40 zero, incrementing by one until the driver returns ``EINVAL``. 41 42 .. note:: 43 44 Connectors on a TV card to loop back the received audio signal 45 to a sound card are not audio outputs in this sense. 46 47 See :ref:`VIDIOC_G_AUDIOout <VIDIOC_G_AUDOUT>` for a description of struct 48 :c:type:`v4l2_audioout`. 49 50 Return Value 51 ============ 52 53 On success 0 is returned, on error -1 and the ``errno`` variable is set 54 appropriately. The generic error codes are described at the 55 :ref:`Generic Error Codes <gen-errors>` chapter. 56 57 EINVAL 58 The number of the audio output is out of bounds.
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