[mythtvnz] No sound on videos

[Steve Hodge]

On Thu, Feb 18, 2010 at 1:59 PM, Nick Rout <nick.rout at gmail.com> wrote:


>  On Thu, Feb 18, 2010 at 3:53 PM, Steve Hodge <stevehodge at gmail.com>
> wrote:
> > On Thu, Feb 18, 2010 at 1:40 PM, Robin Gilks <g8ecj at gilks.org> wrote:
> >>
> >> > On Wed, 17 Feb 2010 19:17:55 +1300, you wrote:
> >> > Next problem: One of the files I want to be able to play has 24 kHz
> >> > audio, and that still does not play.  I am guessing that means that
> >> > the sound chip on the motherboard does not work below 32 kHz.  So does
> >> > anyone know how to tell Alsa to upsample anything below 32 kHz?  I
> >> > imagine what is needed is:
> >> >
> >> >   24 kHz => 48 kHz
> >> >   22.5 kHz => 44.1 kHz
> >> >
> >>
> >> Create (if you don't already have one) a file called .asoundrc in the
> home
> >> account of the user running mythtv with the following
> >>
> >> pcm.!default {
> >>    type plug
> >>    slave.pcm "spdif"
> >>    slave.rate 48000
> >> }
> >>
> >> Works for me....
> >
> > I've done it that way as well, but it's not quite ideal as it resamples
> > everything to 48kHz, regardless of what the hardware can actually take.
> Most
> > S/PDIF inputs take 32, 44.1, and 48kHz so ideally you don't want to
> resample
> > if the source is one of those rates. Anyone know if/how ALSA can be
> > instructed to leave 32kHz and 44.1kHz data alone and resample everything
> > else to 48kHz?
>
>
> Yes the standard says spdif should take a number of sample rates,
> however commonly the audio hardware in soundcards will only pass
> 48kHz. At least that's the way I understand it. So leaving 44.1 as
> 44.1 may not work, hardware dependent.
>
>

I believe almost all PC sound hardware will pass 44.1kHz - it's the standard
for CDs after all. I know the hardware I have certainly does. Many do not
support 32kHz though. The point is that if your hardware can do it, it's
desirable to pass 44.1kHz audio in particular with resampling so it'd be
great if ALSA could do that while resampling everything else to 48kHz.

Cheers,
Steve
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