[vlc-devel] [PATCH 2/2] es: replace i_original_channels with i_stereo_mode

[Rémi Denis-Courmont]

On mardi 11 juillet 2017 15:58:08 EEST Thomas Guillem wrote:
> On Tue, Jul 11, 2017, at 15:29, Rémi Denis-Courmont wrote:
> > On mardi 11 juillet 2017 10:01:34 EEST Thomas Guillem wrote:
> > > The i_original_channels value (that is now i_stereo_mode) should not be
> > > used by aout modules, and shouldn't be set by input if there is no
> > > special stereo mode.
> > > 
> > > If accepeted, this commits will be splitted in the following way:
> > >  - One commit per module that remove the usage of i_original_channels
> > >  when
> > > 
> > > not needed at all.
> > > 
> > >  - One big commit that replace i_original_channels with i_stereo_mode
> > >  and
> > > 
> > > that changes few modules (mpg/a52/dca/dts/filters/core).
> > 
> > I have tried to move the original channels to a proper set of flags
> > already.
> > But I failed everytime, because I never understood what the channel mask
> > within original channels was exactly meant to be. As far as I could tell,
> > it
> > was simply three flags with the channels identical to the physical mask
> > 
> > :(
> > 
> > Also, if you want to rationalize this, there is really only one flag that
> > belongs there (Dolby). Reverse stereo could just as well be fixed by
> > reordering
> > in the decoder (easy). And in principles, dual-mono should be two
> > separate
> > audio ES's (less easy).
> 
> You mean, reodering in the audio_output code, just between the filters
> and the output ?

I don't understand the question.

> I have a branch that allow users to force a stereo-mode even with non
> stereo input.

I don't see how forced downmixing relates to my comment at all, nor how it 
relates to the current stereo modes.

> Some people asked this feature, I guess some content are
> better downmixed to stereo than rendered on a 5.1 for example.

Have they? As far as I can tell, there are only requests to:
- force stereo downmixing to work-around misconfigured physical layouts (this 
does not belong in VLC, as it is not an application-specific setting), and
- force mono downmixing to abuse a stereo headset as a pair of mono speakers 
(likewise more of an system-wide than application matter).

> I can have a look for reverse-stereo, this mode is only asked by the
> user will never come from the input.
> I would also like to add the Binauralizer here.

Those flags are supposed to be format properties, set by the demuxer/
packetizer/decoder. I don't really see how a somethingizer belongs there.