Hi Vladmir,
On Mon, 16 Jul 2007 15:19:53 +0400
Vladimir <kv11111@xxxxxxx> wrote:
> stan wrote:
> >> > Beyond that you could change the dmix6 to use only 4 channels, 0,
> >> > 1, 2, 3.
> >> I'll try this. Can I also just skip dmix6 and route the sound
> >> directly to hardware ?
> >>
> > I'm not sure, but I don't think so. I think the channels are being
> > defined by the dmix6 plugin, and so can't be used unless it is
> > there. I'm not familiar enough with the plugin system to know if
> > there are default channels defined, the 0-5 of the above ch51dup.
> > Just drop it and leave the channels slave there and it might be
> > enough to try # upmixing:
> > pcm.ch20dup {
> > type route
> > slave.channels 4
> > ttable.0.2 1
> > ttable.1.3 1
> > }
> When I'm changing channels count to 4 for both ch20dup and dmix6 it
> works well.
Good to hear.
>
> > This will be true if the channels slave is defining the channel
> > numbers. It might be, and if this works it would definitely be more
> > robust and less cpu load than the first version. It should give you
> > the identical output that you would get on the front channels.
> I've tried it. It works but still requires defining the channel
> number. It also requires different ttable:
>
> pcm.ch20dup {
> type route
> slave.pcm "hw:0"
> slave.channels 6
> ttable.0.4 1
> ttable.1.5 1
> }
>
> I've found one more strange problem: when the sound is played using
> dmix everything is good, but when playing it directly it plays
> slightly faster then it should - I've checked it with mplayer.
You've reached the limit of my knowledge. I believe that dmix adjusts
the stream so that the hardware gets frames at the rate it wants. And I
vaguely recall that the native speed of the rev5.1 is 48000. If you
are playing cd quality of 44,100, this might account for the increase
in speed of play. All conjecture though, I don't know. You could test
this by using audacity to resample to 48000 and try playing the
resulting file. If it sounds correct with the higher frame rate, then
this could be the explanation.
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