[mythtv-users] Switch to OSS in mythfrontend. How?

[Michael T. Dean]

On 03/08/2008 10:19 AM, Mark Hutchinson wrote:
> I am having NVP prebuffering pause, dropped video, audio issues.
> It was suggested to switch to OSS rather than ALSA.
> I am running F8 with Internal built in sound.  Alsa have an Audigy SB  
> card I can use.
>
> Anyway, how to switch to OSS rather than ALSA?
>   

Specify an OSS device name (i.e. /dev/dsp) for the "Audio output device" 
setting rather than an ALSA device name (i.e. ALSA:default).  You'll 
also have to specify an OSS mixer (i.e. /dev/mixer) for the "Mixer 
Device" setting.

> Should I shutdown alsa in the OS?
>   

No.  Anymore, when people say, "Use OSS," they tend to mean, "Use the 
applications OSS API code," rather than, "Use the OSS drivers."  The OSS 
drivers/API are actually a commercial product ( 
http://www.4front-tech.com/ ).  The OSS/free drivers/API ( 
http://www.4front-tech.com/usslite/ ), which are included in the Linux 
kernel, are terrible.  Funny enough, the ALSA OSS compatibility API (and 
the ALSA drivers OSS compatibility) are actually better "OSS" than the 
OSS/free drivers/API.

Though the "real" (commercial) OSS drivers/API are actually quite 
good--and have many benefits over the ALSA drivers/API (in many respects 
are significantly better than ALSA)--few free apps have had much effort 
put into taking advantage of them (because few users of free apps would 
pay for a commercial audio system).  Note, also, that the OSS/free 
drivers are basically a snapshot of an extremely old version of the 
commercial drivers with modifications--pretty much an unloved fork of an 
old, bad version.

Myth has pretty good support for analog audio through the OSS/free API's 
using ALSA OSS compatibility.  The ALSA (API) output code is newer (and 
tends to try to do more, so has more potential for bugs).

> What do I put in mythfrontend in the sound section in setup?  /dev/dsp?
>   

Yep.  Assuming you actually have a /dev/dsp device corresponding to the 
sound card output you want to use.  If not, you may need to load the 
ALSA OSS compatibility modules (snd_pcm_oss, snd_mixer_oss, 
and--optionally--snd_seq_oss).

> Assistance appreciated.

Hope the above was of assistance.  However, I would guess you'll find 
the prebuffering pauses are due to something else once you switch (i.e. 
I/O issues, video driver issues, Myth configuration issues, improper 
sound card configuration--which can affect you whether using ALSA or OSS 
API's, though it's generally easier to misconfigure the ALSA).  In other 
words, either should work fine once everything is properly configured.

Now, the $64M question, "What's misconfigured?"  That's much harder to 
say...

Good luck,
Mike