[mythtv-users] No Alsa output without OSS emulation?

[Sage]

>Note, also, that using "--disable-audio-oss" doesn't "make a cleaner
>system that doesn't require installing OSS", it just tells Myth to
>compile only the parts that don't rely on calls that use the OSS API.

That's good to know, thanks for the explanation, Michael.

What I and apparently many others thought was that MythTV supported more
than one method of audio output, and that by disabling OSS, we were
disabling an unnecessary and unused output method, and therefore building a
smaller binary.  It would be good to note in the documentation that this is
not the case, and that OSS (or Alsa's OSS emulation) is a prerequisite for
MythTV.

It is interesting to note that even when I compiled with the
--disable-audio-oss flag, I could still hear sound, so long as I had the
alsa-oss package installed.

On 6/30/06, Michael T. Dean <mtdean at thirdcontact.com> wrote:
>
> On 06/29/2006 10:00 PM, Sage wrote:
> > On 6/29/06, Michael T. Dean <mtdean at thirdcontact.com> wrote:
> >
> >> On 06/29/2006 07:24 PM, Sage wrote:
> >>
> >>> I'm running MythTV 0.19-fixed, compiled from source, on Ubuntu 6.06
> >>> (Dapper Drake).  Despite the fact that I compiled MythTV with OSS
> >>> support disabled, I am unable to hear sound without the alsa-oss
> >>> emulation package installed.
> >>>
> >> http://www.gossamer-threads.com/lists/mythtv/users/185108#185108
> >> (whole message including quoted material--applies to more than just
> >> transcoding, BTW, including recording on some hardware)
> >>
> >> Or, for the short version:
> >> http://www.gossamer-threads.com/lists/mythtv/users/185111#185111
> >>
> >>> Is this a requirement of MythTV?  In the general settings, I have set
> >>> ALSA:default as my playback device, and I have a working .asoundrc,
> >>> and I disabled OSS support in MythTV before I compiled it.  Sound
> >>> didn't work until I installed the alsa-oss package (all other alsa
> >>> packages were already installed).  Why do I need OSS installed in
> >>> order to play sound?
> >>>
> >> You don't (and I would /never/ install OSS on /any/ system).  You just
> >> need OSS emulation support.
> >>
> >>>   Has anyone else run into this problem before?
> >>>
> >> Search the archives for "disable-audio-oss" (no quotes) and you'll see
> >> all the other people who tried to make a "cleaner" system by "not
> >> installing" OSS.
> >>
> > Thanks for the response.  So to clarify:
> >
> > 1. Even if ALSA is installed, MythTV does not work without OSS
> > emulation, and this is normal.
> >
>
> Myth uses OSS calls for recording audio (or writing audio in transcodes
> or ...).  Native ALSA can be used /only/ for playback.
>
> > 2. --disable-oss should *only* be used on systems that do not have OSS
> > or OSS emulation available, such as Mac OS X, because it cripples
> > MythTV's functionality in ways the user may not expect.
> >
> > Correct?
> >
>
> Exactly.  Some will tell you that it's OK to disable it on frontend
> systems, but you're on your own if you do so (it's not a supported
> configuration).  As Isaac said, "What's the big deal about keeping
> alsa's oss emulation turned on? It doesn't hurt _anything_." (
> http://www.gossamer-threads.com/lists/mythtv/users/128478#128478 )  And,
> a frontend system that was compiled with "--disable-audio-oss" cannot do
> certain jobs for you, so if you ever decide to let your frontend help
> with transcodes, you'd have to recompile.  A better approach is to
> compile with OSS support and if it really bugs you, don't load the ALSA
> OSS modules.  Then, if you later need them, you can just load them.
>
> Note, also, that using "--disable-audio-oss" doesn't "make a cleaner
> system that doesn't require installing OSS", it just tells Myth to
> compile only the parts that don't rely on calls that use the OSS API.
> Unless you really care to determine--every time you compile
> MythTV--whether those parts are required for your particular system, you
> should just /never/ specify "--disable-audio-oss".
>
> And, using "--disable-backend" and "--disable-frontend" are also not
> supported on GNU/Linux systems...
>
> Mike
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