[FFmpeg-devel] [PATCH 1/3] lavc/avcodec: Add caps for the support of variable dimension encoding

[Fu, Linjie]

> From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of Fu,
> Linjie
> Sent: Tuesday, June 9, 2020 17:02
> To: FFmpeg development discussions and patches <ffmpeg-
> devel at ffmpeg.org>
> Subject: Re: [FFmpeg-devel] [PATCH 1/3] lavc/avcodec: Add caps for the
> support of variable dimension encoding
> 
> > From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
> > Linjie Fu
> > Sent: Monday, June 8, 2020 23:11
> > To: FFmpeg development discussions and patches <ffmpeg-
> > devel at ffmpeg.org>
> > Subject: Re: [FFmpeg-devel] [PATCH 1/3] lavc/avcodec: Add caps for the
> > support of variable dimension encoding
> >
> > > From: "Anton Khirnov" <anton at khirnov.net>
> > > Sent Time: 2020-06-08 18:50:43 (Monday)
> > > To: "FFmpeg development discussions and patches" <ffmpeg-
> > devel at ffmpeg.org>
> > > Cc:
> > > Subject: Re: [FFmpeg-devel] [PATCH 1/3] lavc/avcodec: Add caps for the
> > support	of variable dimension encoding
> > >
> > > Quoting Linjie Fu (2020-06-08 10:58:03)
> > > > And declare AV_CODEC_CAP_VARIABLE_DIMENSIONS for rawvideo
> and
> > > > wrapped_avframe.
> > > >
> > > > Signed-off-by: Linjie Fu <linjie.fu at intel.com>
> > > > ---
> > > >  doc/APIchanges               | 3 +++
> > > >  fftools/cmdutils.c           | 2 ++
> > > >  libavcodec/avcodec.h         | 4 +++-
> > > >  libavcodec/codec.h           | 5 +++++
> > > >  libavcodec/rawenc.c          | 1 +
> > > >  libavcodec/version.h         | 2 +-
> > > >  libavcodec/wrapped_avframe.c | 1 +
> > > >  7 files changed, 16 insertions(+), 2 deletions(-)
> > >
> > > During the last iteration, I asked how is this preferable to just making
> > > a new encoder instance. Don't think I got a sufficient reply.
> >
> > Thanks Anton for the remind, indeed making a new encoder instance
> would
> > be
> > more general and suitable for all encoders, with resolution changing in key
> > frames.
> >
> > In this patch set, I prefer to restrict the implementation/support to
> > rawvideo and wrapped_avframe encoders, since they don't need to be
> > recreated
> > when resolution/dimension changes and are required. at this moment.
> >
> > Also as we've discussed about whether it's worthwhile:
> >
> > >> Do we get sufficient benefits from having parameter change capability
> > inside
> > >> encoders over just creating a new encoder instance when needed? Do
> > people
> > >> really need to change resolution mid-GOP?
> >
> > This implementation didn't touch the logic of encoders which supports
> > variable
> > resolution encoding on inter frames(vp9, av1), since such
> > enhancement/requirement
> > seems to be rare for now.
> 
> Sent the encoder instance recreate patch set for review as a follow-up step,
> please
> help to review:
> https://patchwork.ffmpeg.org/project/ffmpeg/list/?series=1450

Will apply this patch set (1-3) as discussed in:
https://lists.ffmpeg.org/pipermail/ffmpeg-devel/2020-June/264649.html

Thx.

- Linjie