Date: Wed, 16 Dec 2009 16:10:02 GMT From: Marcin Wisnicki <mwisnicki+freebsd@gmail.com> To: freebsd-multimedia@FreeBSD.org Subject: Re: kern/140453: [sound] No sound inside Virtualbox on 50% volume Message-ID: <200912161610.nBGGA2wG066301@freefall.freebsd.org>
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The following reply was made to PR kern/140453; it has been noted by GNATS. From: Marcin Wisnicki <mwisnicki+freebsd@gmail.com> To: Ariff Abdullah <ariff@freebsd.org> Cc: bug-followup@freebsd.org Subject: Re: kern/140453: [sound] No sound inside Virtualbox on 50% volume Date: Wed, 16 Dec 2009 17:03:12 +0100 On Wed, Dec 16, 2009 at 02:57, Ariff Abdullah <ariff@freebsd.org> wrote: > Virtualbox (QEMU too) default to 5bit volume resolution, but it > appears through the volume resolution calibration process as > 6bit. Clearly, it is a "hardware" bug. Virtualbox doing > slightly a better job by "clamping" the results (the lower bits > written as '1') whenever there is a write attempt on 5th (or > 13th) bit, but _without_ resetting those high bit. As such, it > appears as a full 6-bit resolution result on the next codec > read. FreeBSD try to be honest here by doing supposed to be > correct calibration process and see/measure the result as is. > Others <insert whatever..> probably have their own static > mapping (think about vendor specific driver) or depends on > whatever magic marker, etc. > > You have two choices: > > 1) Fix virtualbox ac97 codec emulation (probably not for you > given the fact that your vbox runs on Windows). > Good to hear it's a known problem. Is there any reason why this patch was not submitted to virtualbox (at least I couldn't find a ticket there) ? I don't really care about it since workaround is so simple, but it would be nice to have it working correctly out of the box. > or > > 2) "Fix" FreeBSD ac97 volume resolution calibration by > accepting certain lower bits magic marker, ignoring the high bit. > >
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