1*4882a593Smuzhiyun.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2*4882a593Smuzhiyun.. c:namespace:: V4L 3*4882a593Smuzhiyun 4*4882a593Smuzhiyun.. _VIDIOC_ENUMAUDOUT: 5*4882a593Smuzhiyun 6*4882a593Smuzhiyun*********************** 7*4882a593Smuzhiyunioctl VIDIOC_ENUMAUDOUT 8*4882a593Smuzhiyun*********************** 9*4882a593Smuzhiyun 10*4882a593SmuzhiyunName 11*4882a593Smuzhiyun==== 12*4882a593Smuzhiyun 13*4882a593SmuzhiyunVIDIOC_ENUMAUDOUT - Enumerate audio outputs 14*4882a593Smuzhiyun 15*4882a593SmuzhiyunSynopsis 16*4882a593Smuzhiyun======== 17*4882a593Smuzhiyun 18*4882a593Smuzhiyun.. c:macro:: VIDIOC_ENUMAUDOUT 19*4882a593Smuzhiyun 20*4882a593Smuzhiyun``int ioctl(int fd, VIDIOC_ENUMAUDOUT, struct v4l2_audioout *argp)`` 21*4882a593Smuzhiyun 22*4882a593SmuzhiyunArguments 23*4882a593Smuzhiyun========= 24*4882a593Smuzhiyun 25*4882a593Smuzhiyun``fd`` 26*4882a593Smuzhiyun File descriptor returned by :c:func:`open()`. 27*4882a593Smuzhiyun 28*4882a593Smuzhiyun``argp`` 29*4882a593Smuzhiyun Pointer to struct :c:type:`v4l2_audioout`. 30*4882a593Smuzhiyun 31*4882a593SmuzhiyunDescription 32*4882a593Smuzhiyun=========== 33*4882a593Smuzhiyun 34*4882a593SmuzhiyunTo query the attributes of an audio output applications initialize the 35*4882a593Smuzhiyun``index`` field and zero out the ``reserved`` array of a struct 36*4882a593Smuzhiyun:c:type:`v4l2_audioout` and call the ``VIDIOC_G_AUDOUT`` 37*4882a593Smuzhiyunioctl with a pointer to this structure. Drivers fill the rest of the 38*4882a593Smuzhiyunstructure or return an ``EINVAL`` error code when the index is out of 39*4882a593Smuzhiyunbounds. To enumerate all audio outputs applications shall begin at index 40*4882a593Smuzhiyunzero, incrementing by one until the driver returns ``EINVAL``. 41*4882a593Smuzhiyun 42*4882a593Smuzhiyun.. note:: 43*4882a593Smuzhiyun 44*4882a593Smuzhiyun Connectors on a TV card to loop back the received audio signal 45*4882a593Smuzhiyun to a sound card are not audio outputs in this sense. 46*4882a593Smuzhiyun 47*4882a593SmuzhiyunSee :ref:`VIDIOC_G_AUDIOout <VIDIOC_G_AUDOUT>` for a description of struct 48*4882a593Smuzhiyun:c:type:`v4l2_audioout`. 49*4882a593Smuzhiyun 50*4882a593SmuzhiyunReturn Value 51*4882a593Smuzhiyun============ 52*4882a593Smuzhiyun 53*4882a593SmuzhiyunOn success 0 is returned, on error -1 and the ``errno`` variable is set 54*4882a593Smuzhiyunappropriately. The generic error codes are described at the 55*4882a593Smuzhiyun:ref:`Generic Error Codes <gen-errors>` chapter. 56*4882a593Smuzhiyun 57*4882a593SmuzhiyunEINVAL 58*4882a593Smuzhiyun The number of the audio output is out of bounds. 59