Re: [FFmpeg-devel] [PATCH] lavc/qsvenc: Set default bitrate to 2M

["Xiang, Haihao" <haihao.xiang-at-intel.com@ffmpeg.org>]

On Ma, 2023-12-18 at 06:51 +0000, Xiang, Haihao wrote:
> On Do, 2023-12-07 at 17:59 +0100, Anton Khirnov wrote:
> > Quoting Timo Rothenpieler (2023-12-06 13:26:51)
> > > On 06/12/2023 07:51, Xiang, Haihao wrote:
> > > > On Di, 2023-12-05 at 12:47 +0100, Timo Rothenpieler wrote:
> > > > > On 05.12.2023 09:15, Xiang, Haihao wrote:
> > > > > > From: Haihao Xiang <haihao.xiang@intel.com>
> > > > > > 
> > > > > > 2M is suitable for more cases, e.g. 4K video.
> > > > > > 
> > > > > > Signed-off-by: Haihao Xiang <haihao.xiang@intel.com>
> > > > > > ---
> > > > > >    libavcodec/qsvenc_av1.c   | 2 +-
> > > > > >    libavcodec/qsvenc_h264.c  | 2 +-
> > > > > >    libavcodec/qsvenc_hevc.c  | 2 +-
> > > > > >    libavcodec/qsvenc_mpeg2.c | 2 +-
> > > > > >    libavcodec/qsvenc_vp9.c   | 2 +-
> > > > > >    5 files changed, 5 insertions(+), 5 deletions(-)
> > > > > > 
> > > > > > diff --git a/libavcodec/qsvenc_av1.c b/libavcodec/qsvenc_av1.c
> > > > > > index c697845d7b..78c92c1844 100644
> > > > > > --- a/libavcodec/qsvenc_av1.c
> > > > > > +++ b/libavcodec/qsvenc_av1.c
> > > > > > @@ -129,7 +129,7 @@ static const AVClass class = {
> > > > > >    };
> > > > > >    
> > > > > >    static const FFCodecDefault qsv_enc_defaults[] = {
> > > > > > -    { "b",         "1M"   },
> > > > > > +    { "b",         "2M"   },
> > > > > 
> > > > > Wouldn't it be better to use a constant quality option as default,
> > > > > rather than a fixed bitrate?
> > > > 
> > > > Did you mean change the default bitrate control mode to CQP ? I was
> > > > concerned
> > > > about the impact to current users.
> > > 
> > > Yeah, it's technically a breaking change.
> > > Though at least libx264 also at some point changed its default to a 
> > > reasonable medium quality crf mode, away from a fixed, rather low,
> > > bitrate.
> > > Not sure if that was done on a major bump, or if it was considered low 
> > > impact enough to just push out.
> > 
> > FYI we should have a major bump if the next few months (before 7.0).
> > 
> > So you could schedule the switch for then, ideally with a runtime
> > warning and perhaps a changelog entry.
> 
> Thanks for the info, we'll try to change the default mode.

See https://ffmpeg.org/pipermail/ffmpeg-devel/2024-February/321088.html

Thanks
Haihao

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