[mythtv-users] Switch to OSS in mythfrontend. How?
Michael T. Dean
mtdean at thirdcontact.com
Sat Mar 8 16:08:54 UTC 2008
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
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