18c2ecf20Sopenharmony_ci.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 28c2ecf20Sopenharmony_ci.. c:namespace:: V4L 38c2ecf20Sopenharmony_ci 48c2ecf20Sopenharmony_ci.. _VIDIOC_ENUMAUDOUT: 58c2ecf20Sopenharmony_ci 68c2ecf20Sopenharmony_ci*********************** 78c2ecf20Sopenharmony_ciioctl VIDIOC_ENUMAUDOUT 88c2ecf20Sopenharmony_ci*********************** 98c2ecf20Sopenharmony_ci 108c2ecf20Sopenharmony_ciName 118c2ecf20Sopenharmony_ci==== 128c2ecf20Sopenharmony_ci 138c2ecf20Sopenharmony_ciVIDIOC_ENUMAUDOUT - Enumerate audio outputs 148c2ecf20Sopenharmony_ci 158c2ecf20Sopenharmony_ciSynopsis 168c2ecf20Sopenharmony_ci======== 178c2ecf20Sopenharmony_ci 188c2ecf20Sopenharmony_ci.. c:macro:: VIDIOC_ENUMAUDOUT 198c2ecf20Sopenharmony_ci 208c2ecf20Sopenharmony_ci``int ioctl(int fd, VIDIOC_ENUMAUDOUT, struct v4l2_audioout *argp)`` 218c2ecf20Sopenharmony_ci 228c2ecf20Sopenharmony_ciArguments 238c2ecf20Sopenharmony_ci========= 248c2ecf20Sopenharmony_ci 258c2ecf20Sopenharmony_ci``fd`` 268c2ecf20Sopenharmony_ci File descriptor returned by :c:func:`open()`. 278c2ecf20Sopenharmony_ci 288c2ecf20Sopenharmony_ci``argp`` 298c2ecf20Sopenharmony_ci Pointer to struct :c:type:`v4l2_audioout`. 308c2ecf20Sopenharmony_ci 318c2ecf20Sopenharmony_ciDescription 328c2ecf20Sopenharmony_ci=========== 338c2ecf20Sopenharmony_ci 348c2ecf20Sopenharmony_ciTo query the attributes of an audio output applications initialize the 358c2ecf20Sopenharmony_ci``index`` field and zero out the ``reserved`` array of a struct 368c2ecf20Sopenharmony_ci:c:type:`v4l2_audioout` and call the ``VIDIOC_G_AUDOUT`` 378c2ecf20Sopenharmony_ciioctl with a pointer to this structure. Drivers fill the rest of the 388c2ecf20Sopenharmony_cistructure or return an ``EINVAL`` error code when the index is out of 398c2ecf20Sopenharmony_cibounds. To enumerate all audio outputs applications shall begin at index 408c2ecf20Sopenharmony_cizero, incrementing by one until the driver returns ``EINVAL``. 418c2ecf20Sopenharmony_ci 428c2ecf20Sopenharmony_ci.. note:: 438c2ecf20Sopenharmony_ci 448c2ecf20Sopenharmony_ci Connectors on a TV card to loop back the received audio signal 458c2ecf20Sopenharmony_ci to a sound card are not audio outputs in this sense. 468c2ecf20Sopenharmony_ci 478c2ecf20Sopenharmony_ciSee :ref:`VIDIOC_G_AUDIOout <VIDIOC_G_AUDOUT>` for a description of struct 488c2ecf20Sopenharmony_ci:c:type:`v4l2_audioout`. 498c2ecf20Sopenharmony_ci 508c2ecf20Sopenharmony_ciReturn Value 518c2ecf20Sopenharmony_ci============ 528c2ecf20Sopenharmony_ci 538c2ecf20Sopenharmony_ciOn success 0 is returned, on error -1 and the ``errno`` variable is set 548c2ecf20Sopenharmony_ciappropriately. The generic error codes are described at the 558c2ecf20Sopenharmony_ci:ref:`Generic Error Codes <gen-errors>` chapter. 568c2ecf20Sopenharmony_ci 578c2ecf20Sopenharmony_ciEINVAL 588c2ecf20Sopenharmony_ci The number of the audio output is out of bounds. 59