[FFmpeg-devel] [PATCH] avutil/channel_layout: make pre-defined channel layouts C++ friendly

[Paul B Mahol]

On Wed, Aug 16, 2023 at 6:21 PM James Almer <jamrial at gmail.com> wrote:

> On 8/16/2023 12:44 PM, Zhao Zhili wrote:
> > From: Zhao Zhili <zhilizhao at tencent.com>
> >
> > C++ doesn't support designated initializers until C++20. We have
> > a bunch of pre-defined channel layouts, the gains to make them
> > usable in C++ exceed the losses.
> >
> > Signed-off-by: Zhao Zhili <zhilizhao at tencent.com>
> > ---
> >   libavutil/channel_layout.h | 4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/libavutil/channel_layout.h b/libavutil/channel_layout.h
> > index f345415c55..817a5ad370 100644
> > --- a/libavutil/channel_layout.h
> > +++ b/libavutil/channel_layout.h
> > @@ -359,7 +359,7 @@ typedef struct AVChannelLayout {
> >   } AVChannelLayout;
> >
> >   #define AV_CHANNEL_LAYOUT_MASK(nb, m) \
> > -    { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = (nb), .u = {
> .mask = (m) }}
> > +    { AV_CHANNEL_ORDER_NATIVE, (nb), { m }, NULL }
>
> Comment out the field names instead of removing them altogether, and add
> a comment about how this is done for the sake of c++ projects including
> this header.
>
> >
> >   /**
> >    * @name Common pre-defined channel layouts
> > @@ -397,7 +397,7 @@ typedef struct AVChannelLayout {
> >   #define AV_CHANNEL_LAYOUT_STEREO_DOWNMIX    AV_CHANNEL_LAYOUT_MASK(2,
> AV_CH_LAYOUT_STEREO_DOWNMIX)
> >   #define AV_CHANNEL_LAYOUT_22POINT2          AV_CHANNEL_LAYOUT_MASK(24,
> AV_CH_LAYOUT_22POINT2)
> >   #define AV_CHANNEL_LAYOUT_AMBISONIC_FIRST_ORDER \
> > -    { .order = AV_CHANNEL_ORDER_AMBISONIC, .nb_channels = 4, .u = {
> .mask = 0 }}
> > +    { AV_CHANNEL_ORDER_AMBISONIC, 4, { 0 }, NULL }
> >   /** @} */
> >
> >   struct AVBPrint;
>
> This needs a minor bump IMO. Something said c++ projects can look for
> before using these defines.
>

OK,  I had enough, I'm leaving FFmpeg once and forever.


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