On 2016-03-01 15:44, Tanu Kaskinen wrote: > On Tue, 2016-03-01 at 14:40 +0100, Klaus Jaensch wrote: >> Am 01.03.2016 um 11:19 schrieb Tanu Kaskinen: >>> On Mon, 2016-02-29 at 17:33 +0100, Klaus Jaensch wrote: >>>> I'm wondering why it is the default to mix the channels. >>> If there's a device with channel map "front-left,front-right", and a >>> capture stream appears that has channel map "mono", do you wish that >>> pulseaudio would by default take audio only from the left channel? Why >>> would that be more likely what the user wants, rather than taking audio >>> from all channels the device has, or only from the right channel? >> Yes. If the user wants only the left channel he has no chance to do so. >> (Without changing the configuration.) >> You can't split the mixed channels later. The only way is to record >> stereo and split the channels later. >> >> If you want a mix of both channels it is always possible to record >> stereo and mix it later. >> >> Another problem with mixing is that the level meter of applications like >> audacity show the amplitude of the mix. If you do not know that the >> level meter shows only half of the dynamic range (-6dB) if only one >> microphone is plugged to the left channel it is likely that you overmodulate >> the recording. >> >> And as far as I know it is the default on Windows and Mac OS X to record >> only the left channel. I've checked this with some of our USB audio devices. > > It could be also argued that if the recording application wants to pick > just one specific channel, it should set the stream channel map > accordingly. But after pondering this for a bit, I think I agree it > would probably good to map mono recording streams only to the first > channel (usually left) of the device by default. But - now every mono recording of, e g, line in, will only record the left channel instead of both. Also, what about dual-channel internal laptop microphones with high background noise? By not mixing the channels, won't your S/N ratio decrease by 6 dB? This sounds like fixing one problem but causing other problems. -- David Henningsson, Canonical Ltd. https://launchpad.net/~diwic
