>>>When an application opens a mono substream, the sound has to >>>be sent to one channel only or must the low level driver >>>transparently convert it to stereo ? >>> >>> >> >>one channel only. >> >>in ALSA, low level drivers do not do any kind of format >>conversion. that is accomplished (if necessary) by code running in >>user-space, typically part of alsa-lib. the low level driver simply >>advertises the capabilities of the hardware, provides ways to use >>those capabilities, and lets the midlevel code and alsa-lib do the rest. >> >> > >...but, if you are doing mono playback, your sound driver has to setup >your soundcard to playback on both channels the same mono channel. The >Vortex >driver (still not in the main branch) for example splits the mono signal >on its internal >mixer into 2 identical signals which are feed one into each CODEC channels.
that's a driver author's design decision. if the "hw" PCM device is opened with a single channel, it would be equally valid to play on one channel only. if the h/w can't handle that, it should not advertise itself to be capable of mono operation. IMHO. --p ------------------------------------------------------- This SF.net email is sponsored by: The Definitive IT and Networking Event. Be There! NetWorld+Interop Las Vegas 2003 -- Register today! http://ads.sourceforge.net/cgi-bin/redirect.pl?keyn0001en _______________________________________________ Alsa-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/alsa-devel
