Re: [ecasound] Problems with 24/96 over stdin

From: <kls.schlz@email-addr-hidden>
Date: Tue Apr 21 2009 - 14:38:54 EEST

The issue: "aplay" S24_LE can cope with the MPD output. MPD folks won't see
a problem here. Alsa is setting the scene.

I proposed to the MPD folks already to introduce S24_3LE as output format
or even just not to change the 3LE incoming format.

As I wrote yesterday, to me it seems, that there is a confusion in the
Linux world about the different 24bits formats.
At least brutefir and ecasound doesn't seem to be 100% compliant to todays
Alsa formats or terminology.
I'll have a look at Sox to check what these guys are doing.

Cheers Klaus

On Apr 21, 2009 12:42pm, Oliver Oli <oliver.oli+0815@email-addr-hidden> wrote:
> On Sun, Apr 19, 2009 at 7:05 PM, Kai Vehmanen kvehmanen@email-addr-hidden> wrote:

> > Hmm,

> >

> > On Sun, 19 Apr 2009, kls.schlz@email-addr-hidden wrote:

> >

> >> BUT: How do I get rid of the 8 extra bits when sending the stream to my

> >> 24 bit sound card? Currently it seems I have an 8bit attentuation

> >> ongoing.

> >

> > yikes. That suggests that mpd is using yet another encoding, ie 24bits

> > in 32bit words, but with most-significant 8bits padded to zero.

> >

> > Is volume ok with aplay..?

> >

> >> | ecasound -q -B:rt -b:64 -r:80 -f:s32_le,2,96000,i -i:stdin
> -f:s24_le,2,96000,i -o:alsaplugin,0,0 2>/dev/null

> >

> > If the above hypothesis is correct, adding "-ea:25600" should get the

> > volume back to its original level (effectively bitshifting each sample

> > left by 8). The real-fix would be to figure out what exact format

> > mpd is sending...

> If the above hypothesis is correct, I feel it should be reported as a

> bug in MPD. It doesn't make much sense to pad the most significant 8

> bits to zero, does it?

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Received on Tue Apr 21 16:15:03 2009

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