19.07.2011 22:06, Mauro Carvalho Chehab wrote: >> Unless I am mistaken, this control is usually called a >> "Master Playback Switch" in the alsa world. > No, you're mistaken: on most boards, you have only one volume control/switch, > for capture. So, it would be a "master capture switch", Well, for such a cards we don't need to export the additional element, they are fine already. We can rename it to "Master Capture Switch", or may not. > but I don't think > that there's such alsa "generic" volume control. Even in the case where > you have a volume control for the LINE OUT pin[1], in general, you also need to > unmute the capture, so, it would be a "master capture and LINE OUT switch", > and, for sure alsa currently not provide anything like that. I think you can still call it a "Master Capture Switch", if it enables everything. >> So, am I right that the only problem is that it is not >> exported to the user by some drivers right now? > No, you're mistaken again. Such "master capture and LINE OUT switch" type of control > _is_exported_ via the V4L2 API as V4L2_CID_AUDIO_MUTE. Sorry, I meant the _alsa_ drivers here. So, to rephrase: So, am I right that the only problem is that it is not exported to the user by some _alsa_ drivers right now? > Some applications like mplayer don't use V4L2_CID_AUDIO_MUTE to unmute a video > device. They assume the current behavior that starting video also unmutes audio. > (mplayer is not symmetric with regard to the usage of this control, as it uses > V4L2_CID_AUDIO_MUTE to mute the device after the end of a capture). > > So, changing the logic at the drivers will break existing applications. I do not propose changing any V4L2 ioctls, my change concerns only the alsa driver. > It is probably doable to split the mute control for the LINE OUT pin from the > mute control of the PCM capture. Such patch would make sense, as the alsa > capture doesn't need to touch at the line out pin, but the patch should > let V4L2_CID_AUDIO_MUTE control to affect both LINE OUT and PCM capture > mutes, otherwise applications will break. That's exactly what I was talking about from the very beginning, saying that the single control currently controls way too much, and providing an examples about 2 separate controls. But... I haven't found the way to implement that, not sure of this is possible at all. :( -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
