[FFmpeg-devel] [PATCH] lavc/vaapi_encode_h265: add support for low-power encoding

[Xiang, Haihao]

> On 06/02/18 08:17, Haihao Xiang wrote:
> > Although VAEntrypointEncSliceLP was added in old version of VAAPI, we
> > never implemented it for VAAPI H265 encoder before. so it is reasonable
> > to require VAAPI 1.0
> > 
> > Signed-off-by: Haihao Xiang <haihao.xiang at intel.com>
> > ---
> >  libavcodec/vaapi_encode_h265.c | 18 +++++++++++++++++-
> >  1 file changed, 17 insertions(+), 1 deletion(-)
> > 
> > diff --git a/libavcodec/vaapi_encode_h265.c b/libavcodec/vaapi_encode_h265.c
> > index f3b4f6c7e26..efe1148127f 100644
> > --- a/libavcodec/vaapi_encode_h265.c
> > +++ b/libavcodec/vaapi_encode_h265.c
> > @@ -65,6 +65,7 @@ typedef struct VAAPIEncodeH265Options {
> >      int aud;
> >      int profile;
> >      int level;
> > +    int low_power;
> >  } VAAPIEncodeH265Options;
> >  
> >  
> > @@ -914,7 +915,18 @@ static av_cold int
> > vaapi_encode_h265_init(AVCodecContext *avctx)
> >                 avctx->profile);
> >          return AVERROR(EINVAL);
> >      }
> > -    ctx->va_entrypoint = VAEntrypointEncSlice;
> > +
> > +    if (opt->low_power) {
> > +#if VA_CHECK_VERSION(1, 0, 0)
> > +        ctx->va_entrypoint = VAEntrypointEncSliceLP;
> > +#else
> > +        av_log(avctx, AV_LOG_ERROR, "Low-power encoding is not "
> > +               "supported with this VAAPI version.\n");
> > +        return AVERROR(EINVAL);
> > +#endif
> > +    } else {
> > +        ctx->va_entrypoint = VAEntrypointEncSlice;
> > +    }
> >  
> >      if (avctx->bit_rate > 0) {
> >          if (avctx->rc_max_rate == avctx->bit_rate)
> > @@ -986,6 +998,10 @@ static const AVOption vaapi_encode_h265_options[] = {
> >      { LEVEL("6.2", 186) },
> >  #undef LEVEL
> >  
> > +    { "low_power", "Use low-power encoding mode (experimental: only
> > supported "
> 
> Do you want to copy this comment?
> 

Actually I want to delete the comments in (), but the limitation for HEVC low
power encoding still exist. It would be better to add some VAAPI attributes to
query the capability/limitation etc.


> > +      "on some platforms, does not support all features)",
> > +      OFFSET(low_power), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, FLAGS },
> > +
> >      { NULL },
> >  };
> >  
> > 
> 
> How can I test this (and the following patch)?  It doesn't appear to exist on
> any current platform/driver.
> 

Cannon Lake support HEVC low power encoding, do you have this platform?  https:/
/github.com/intel/media-driver/ should support this feature but it isn't ready
in https://github.com/intel/intel-vaapi-driver. 

> I don't like how this code is being copied around, but I guess it would work
> for now.  I'll look into doing something more sensible here.
> 

I also dislike duplicated code. I wanted to add some common options for VAAPI
encoder in FFmpeg, such as QP. However low power encoding is not available for
some codecs, such as VP8, so I copied&pasted the code here. 

Another thing is a driver may not support both VAEntrypointEncSliceLP and
VAEntrypointEncSlice, so I want to change the value range of low_power to -1, 0,
1. -1 means auto mode, FFmpeg-vaapi will select the first applicable entrypoint,
what is your comment for this proposal?

Thanks
Haihao


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