[vlc-devel] Doubts on VLC audio handling

[Kaarlo Räihä]

Assim Deodia kirjoitti 20.03.2009 kello 22:12:
> On Fri, Mar 20, 2009 at 8:09 PM, Kaarlo Räihä <agent_007 at luukku.com>
>  wrote:
> 
> > Assim Deodia kirjoitti 20.03.2009 kello 10:29:
> > > Hi All,
> > >
> > > I making a panning module for VLC as my final year project. I am having
> > > following doubts regarding VLC audio handling.
> > >
> > > 1) In aout_filter_sys_t: I can see int's for every channel (i.e. i_left,
> > > i_right etc) but not for LFE. does VLC handle in different way? I tried
> > > adding i_lfe to the structure and also to output buffer, and played
> > >  a 6ch
> > > file. Still there was no sound in lfe. I have attached the code
> > >  which i was
> > > testing.
> > >
> > > 2) I wish to determine the number of channel my system support. I
> > >  have a 5.1
> > > system but
> > > aout_FormatNbChannels( &p_filter->output ) was giving the number of
> > >  channel
> > > in file. Nor the values p_filter->input.i_physical_channels,
> > > p_filter->input.i_original_channels,
> > >  p_filter->output.i_physical_channels,
> > > p_filter->output.i_original_channels are corresponding to number of
> > > channels.
> > >
> >
> > output.i_physical_channels should be set by audio output module. So
> results
> > might vary if you for example try both DirectSound and Waveout outputs
> (APIs
> > aren't same nor the device driver stuff).
> >
> 
> So how do i determine number of channels supported? Can i manually
>  set the
> number of output channels in output.i_physical_channels?
> 

Both directx.c and waveout.c have Probe function that tries to figure out which speaker setups (or output modes) are supported. They don't test all possible modes, just few pre-selected ones. 

> >
> > > 3) I need to do is to upmix a stream manually to the max supported
> > >  channel.
> > > Vista seems to do it atomically but i produce a 6ch stream from a 2ch
> > > stream?
> > >
> >
> > IIRC upmixing is done by device drivers. So it shouldn't be automatic from
> > OS side.
> >
> > > Looking forward to hear soon.
> > >
> > > --
> > > Regards
> > > Assim
> >
> >
> > ...................................................................
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> 
> 
> 
> -- 
> Regards
> Assim Deodia | http://nsitonline.in/assim
> Undergraduate Student, Netaji Shubhas Institute of Technology


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