[mythtv-users] Just can't lick this sound issue

Joseph A. Caputo jcaputo1 at comcast.net
Tue Nov 25 12:14:33 EST 2003


On Tuesday 25 November 2003 01:08, Douglas Phillipson wrote:
> Joseph A. Caputo wrote:
> > On Monday 24 November 2003 11:02, Douglas Phillipson wrote:
> >>Joseph A. Caputo wrote:
> >>>On Monday 24 November 2003 02:46, Douglas Phillipson wrote:
> >>>>Douglas Phillipson wrote:
> >>>>>Installed MythTV from apt-get install mythtv-suite.  Using
> >>>>> Redhat 9, NVidia Gforce4, WinTV Go capture card.
> >>>>>
> >>>>>My backend is on the same machine as my frontend.  Recording is
> >>>>>taking place.  I can see the recordings in lower left of screen
> >>>>>when I'm in "Watch Recordings".  When I choose to play a
> >>>>> recording or try watching live TV I get a blank screen.  I have
> >>>>> "Video player" set to "mplayer -fs %s".
> >>>>>
> >>>>>Question:  What does MythTV use to play live TV and playback
> >>>>>recorded video?  Is it Mplayer?  What???  My xawtv works fine.
> >>>>>
> >>>>>What am I missing?
> >>>>>
> >>>>>Thanks
> >>>>>
> >>>>>Doug P
> >>>>
> >>>>I discovered I had to install Xine, sorry about that.  Now i can
> >>>>playback a recorded video (no sound yet)  I hear sound during the
> >>>>recording in the lineout jack of the WinTV Go board though.  But
> >>>> I still can't watch Live TV, screen goes black.  Any suggestions
> >>>> are appreciated...
> >>
> >>I saw xine, ogle mentioned in a step by step guide
> >>(http://pvrhw.goldfish.org/tiki-page.php?pageName=rh9pvr250) and
> >> just installed it.  When I did my playback (video only) started
> >> working so I thought...
> >>That was my problem, I thought...  Should my Hauppage 190 be
> >> similar to the PVR250 as far as this install is concerned?
> >
> > No, the WinTV-GO is just a regular V4L (Video4Linux) card with no
> > hardware encoding.
> >
> >>I'm curious, why was an "internal player" used/created instead of
> >> one of the many available?  I hope that's not a dumb question.
> >
> > Well, first of all, Myth records in a 'tweaked' NuppelVideo format
> > that isn't natively supported by external players, and second,
> > having an internal format & player allows better control over
> > playback features (bookmarks, commercial skip, etc).
> >
> >>>Whatever gave you the idea you needed to install Xine or mplayer?
> >>>Myth uses its own internal player to play back recorded programs.
> >>>You only need an external player if you want to play back non-Myth
> >>>content using the MythVideo plugin.
> >>>
> >>>The reason you can't watch LiveTV is likely because your sound
> >>> card or driver doesn't support (or isn't configured properly for)
> >>> full duplex.
> >>
> >>Is sound required to see the video?
> >
> > The frontend basically blocks on trying to open the sound device. 
> > If it can't open the sound device, it won't start playback, hence a
> > black screen.  There are two likely reasons why this might be
> > happening.  One reason (and the most common) is that you're running
> > Gnome or KDE and need to disable or kill the sound daemon (esd in
> > Gnome; artsd in KDE); other processes like mythfrontend can't
> > access the sound device for output while another app (esd/artsd)
> > already has it open for output. The other possibility is that your
> > sound card or driver doesn't support full duplex (i.e.,
> > simultaneous record & playback).  In LiveTV, what's happening is
> > the live feed is being recorded & encoded and then immediately
> > played back.  So, if your card isn't doing full duplex, then the
> > frontend can't open the device because the backend already has it
> > open for recording.
> >
> >>>The reason you have no sound when you play back a recording is
> >>>likely because your recordings have no sound (i.e., your sound is
> >>>mis-configured for Myth).
> >>
> >>I'm now hearing sound when I attempt live watching, so I thought I
> >>had sound licked...
> >
> > But is your sound out of sync, as in a couple of seconds ahead of
> > the video?
> >
> >>>Read the section in the docs about troubleshooting audio (http://
> >>>www.mythtv.org/docs/mythtv-HOWTO-7.html and
> >>>http://www.mythtv.org/docs/ mythtv-HOWTO-20.html#ss20.11 & try to
> >>>get your audio configured properly.
> >>>
> >>>-JAC
> >>>
> >>>PS- In future, it would be helpful to submit your system specs
> >>> when asking for help.  Include things like: motherboard, CPU,
> >>> sound card, video card, Linux distro, sound drivers, video card,
> >>> tuner card, version of Myth & source of Myth (i.e., RPM, Deb,
> >>> source tarball or CVS)
> >>
> >>OK, Thanks I'll keep plugging away at it and post my resulting
> >>successful procedure.  And thankyou VERY much for the support!  Are
> >>you the author of any of this great stuff?
> >
> > Sorry, I didn't see your specs at the top of your original post...
> > but you haven't indicated what kind of sound card you have or
> > whether you're using ALSA or OSS.  This is important information
> > when troubleshooting audio!
> >
> > -JAC
>
> Well I've jacked my sound all up.  I have VIA VT82xx audio on mobo.
> Does Redhat 9 use ALSA or OSS by default?  Anyway I installed
> alsa-drivers, alsa-lib, alsa-utils from source, no errors.  Changed
> /etc/modules.conf according to the alsa site's specs:

AFAIK, RedHat (& most distros) use OSS by default.  ALSA will become the 
new default for the 2.6 kernels, I believe.

>
> # ALSA portion
> alias char-major-116 snd
> alias snd-card-0 snd-via82xx
> # module options should go here
>
> # OSS/Free portion
> alias char-major-14 soundcore
> alias sound-slot-0 snd-card-0
>
> # card #1
> alias sound-service-0-0 snd-mixer-oss
> alias sound-service-0-1 snd-seq-oss
> alias sound-service-0-3 snd-pcm-oss
> alias sound-service-0-8 snd-seq-oss
> alias sound-service-0-12 snd-pcm-oss
>
> then did "modprobe snd-via82xx" and get: Initmodule: no such device.

Did you run the 'mksnddevices' script from the alsa-drivers source 
distro after you installed it?  Also, did you unload the OSS drivers 
before attempting to load ALSA?

> If RH 9 already used alsa should I have even installed alsa?

You really only need to try ALSA if the OSS drivers don't support 
features on your sound card that you need.

May I suggest that you try the KnoppMyth distro instead of RH9, as it is 
an easy install & I believe it will configure ALSA for you on 
installation.

-JAC



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