[vlc-devel] [vlc-commits] trivial_mixer: try to fix dual-mono (fixes #12673)

[Thomas Guillem]

This breaks conversion: 'f32l'->'f32l' 44100 Hz->44100 Hz Mono->Stereo.

Reproduced with a AAC mono sample on android or on desktop with pulse
forced to output stereo.

On Sun, Nov 2, 2014, at 11:10, Rémi Denis-Courmont wrote:
> vlc | branch: master | Rémi Denis-Courmont <remi at remlab.net> | Sun Nov  2
> 12:08:56 2014 +0200| [d6388f26bb6efef29397ba91b02befc427b3423e] |
> committer: Rémi Denis-Courmont
> 
> trivial_mixer: try to fix dual-mono (fixes #12673)
> 
> Original channels is under-specified in my opinion. If you know where
> the design documentation is, please tell me.
> 
> > http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=d6388f26bb6efef29397ba91b02befc427b3423e
> ---
> 
>  modules/audio_filter/channel_mixer/trivial.c |   81
>  ++++++++++++++++----------
>  1 file changed, 50 insertions(+), 31 deletions(-)
> 
> diff --git a/modules/audio_filter/channel_mixer/trivial.c
> b/modules/audio_filter/channel_mixer/trivial.c
> index a8c20dd..d05155a 100644
> --- a/modules/audio_filter/channel_mixer/trivial.c
> +++ b/modules/audio_filter/channel_mixer/trivial.c
> @@ -185,45 +185,64 @@ static block_t *ReverseStereo( filter_t *p_filter,
> block_t *p_buf )
>  static int Create( vlc_object_t *p_this )
>  {
>      filter_t *p_filter = (filter_t *)p_this;
> -    block_t *(*func)(filter_t *, block_t *) = NULL;
> +    const audio_format_t *infmt = &p_filter->fmt_in.audio;
> +    const audio_format_t *outfmt = &p_filter->fmt_out.audio;
>  
> -    if( p_filter->fmt_in.audio.i_format !=
> p_filter->fmt_out.audio.i_format
> -     || p_filter->fmt_in.audio.i_rate != p_filter->fmt_out.audio.i_rate
> -     || p_filter->fmt_in.audio.i_format != VLC_CODEC_FL32 )
> +    if( infmt->i_format != outfmt->i_format
> +     || infmt->i_rate != outfmt->i_rate
> +     || infmt->i_format != VLC_CODEC_FL32 )
>          return VLC_EGENERIC;
> -    if( p_filter->fmt_in.audio.i_physical_channels
> -           == p_filter->fmt_out.audio.i_physical_channels
> -     && p_filter->fmt_in.audio.i_original_channels
> -           == p_filter->fmt_out.audio.i_original_channels )
> +    if( infmt->i_physical_channels == outfmt->i_physical_channels
> +     && infmt->i_original_channels == outfmt->i_original_channels )
>          return VLC_EGENERIC;
>  
> -    const bool b_reverse_stereo =
> p_filter->fmt_out.audio.i_original_channels & AOUT_CHAN_REVERSESTEREO;
> -    bool b_dualmono2stereo = (p_filter->fmt_in.audio.i_original_channels
> & AOUT_CHAN_DUALMONO );
> -    b_dualmono2stereo &= (p_filter->fmt_out.audio.i_physical_channels &
> ( AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT ));
> -    b_dualmono2stereo &= ((p_filter->fmt_out.audio.i_physical_channels &
> AOUT_CHAN_PHYSMASK) != (p_filter->fmt_in.audio.i_physical_channels &
> AOUT_CHAN_PHYSMASK));
> -
> -    if( likely( !b_reverse_stereo && ! b_dualmono2stereo ) )
> +    if( outfmt->i_physical_channels == AOUT_CHANS_STEREO )
>      {
> -        if( aout_FormatNbChannels( &p_filter->fmt_out.audio )
> -            > aout_FormatNbChannels( &p_filter->fmt_in.audio ) )
> -            func = Upmix;
> -        else
> -            func = Downmix;
> +        bool swap = (outfmt->i_original_channels &
> AOUT_CHAN_REVERSESTEREO)
> +                  != (infmt->i_original_channels &
> AOUT_CHAN_REVERSESTEREO);
> +
> +        if( (outfmt->i_original_channels & AOUT_CHAN_PHYSMASK)
> +                                                            ==
> AOUT_CHAN_LEFT )
> +        {
> +            p_filter->pf_audio_filter = swap ? CopyRight : CopyLeft;
> +            return VLC_SUCCESS;
> +        }
> +
> +        if( (outfmt->i_original_channels & AOUT_CHAN_PHYSMASK)
> +                                                           ==
> AOUT_CHAN_RIGHT )
> +        {
> +            p_filter->pf_audio_filter = swap ? CopyLeft : CopyRight;
> +            return VLC_SUCCESS;
> +        }
> +
> +        if( swap )
> +        {
> +            p_filter->pf_audio_filter = ReverseStereo;
> +            return VLC_SUCCESS;
> +        }
>      }
> -    /* Special case from dual mono to stereo */
> -    else if( b_dualmono2stereo )
> +
> +    if ( aout_FormatNbChannels( outfmt ) == 1 )
>      {
> -        bool right = !(p_filter->fmt_out.audio.i_original_channels &
> AOUT_CHAN_LEFT);
> -        if( p_filter->fmt_out.audio.i_physical_channels ==
> AOUT_CHAN_CENTER )
> -            /* Mono mode */
> -            func = right ? ExtractRight : ExtractLeft;
> -        else
> -            /* Fake-stereo mode */
> -            func = right ? CopyRight : CopyLeft;
> +        bool mono = !!(infmt->i_original_channels & AOUT_CHAN_DUALMONO);
> +
> +        if( mono && (infmt->i_original_channels & AOUT_CHAN_LEFT) )
> +        {
> +            p_filter->pf_audio_filter = ExtractLeft;
> +            return VLC_SUCCESS;
> +        }
> +
> +        if( mono && (infmt->i_original_channels & AOUT_CHAN_RIGHT) )
> +        {
> +            p_filter->pf_audio_filter = ExtractRight;
> +            return VLC_SUCCESS;
> +        }
>      }
> -    else /* b_reverse_stereo */
> -        func = ReverseStereo;
>  
> -    p_filter->pf_audio_filter = func;
> +    if( aout_FormatNbChannels( outfmt ) > aout_FormatNbChannels( infmt )
> )
> +        p_filter->pf_audio_filter = Upmix;
> +    else
> +        p_filter->pf_audio_filter = Downmix;
> +
>      return VLC_SUCCESS;
>  }
> 
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