media/v4l/audio.rst

11 each. Radio devices have no audio inputs or outputs. They have exactly
12 one tuner which in fact *is* an audio source, but this API associates
14 these. [#f1]_ A connector on a TV card to loop back the received audio
15 signal to a sound card is not considered an audio output.
18 source also selects an audio source. This is most evident when the video
19 and audio source is a tuner. Further audio connectors can combine with
21 and two audio inputs exist, there may be up to four valid combinations.
22 The relation of video and audio connectors is defined in the
26 number, starting at zero, of one audio input or output.
34 status information applicable when the current audio input is queried.
38 audio input and output, respectively.
47 To select an audio input and change its properties applications call the
48 :ref:`VIDIOC_S_AUDIO <VIDIOC_G_AUDIO>` ioctl. To select an audio
52 Drivers must implement all audio input ioctls when the device has
53 multiple selectable audio inputs, all audio output ioctls when the
54 device has multiple selectable audio outputs. When the device has any
55 audio inputs or outputs the driver must set the ``V4L2_CAP_AUDIO`` flag
60 Example: Information about the current audio input
65     struct v4l2_audio audio;
67     memset(&audio, 0, sizeof(audio));
69     if (-1 == ioctl(fd, VIDIOC_G_AUDIO, &audio)) {
74     printf("Current input: %s\\n", audio.name);
77 Example: Switching to the first audio input
82     struct v4l2_audio audio;
84     memset(&audio, 0, sizeof(audio)); /* clear audio.mode, audio.reserved */
86     audio.index = 0;
88     if (-1 == ioctl(fd, VIDIOC_S_AUDIO, &audio)) {