[FFmpeg-devel] [PATCH, v2] lavc/qsvenc: expose low_power option in H264 QSV

[Li, Zhong]

> From: ffmpeg-devel [mailto:ffmpeg-devel-bounces at ffmpeg.org] On Behalf
> Of Linjie Fu
> Sent: Tuesday, March 26, 2019 1:51 PM
> To: ffmpeg-devel at ffmpeg.org
> Cc: Fu, Linjie <linjie.fu at intel.com>
> Subject: [FFmpeg-devel] [PATCH, v2] lavc/qsvenc: expose low_power option
> in H264 QSV
> 
> Always exposes low_power option for h264 qsv, and reports a warning if
> VDENC is not supported with current version of MSDK.
> 
> Signed-off-by: Linjie Fu <linjie.fu at intel.com>
> ---
> [v2]: repalce "VDENC" with "low_power" to be more understandable.
> 
>  libavcodec/qsvenc.c      | 11 ++++++++++-
>  libavcodec/qsvenc_h264.c |  2 --
>  2 files changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/libavcodec/qsvenc.c b/libavcodec/qsvenc.c index
> 5aa020d47b..8264d0a413 100644
> --- a/libavcodec/qsvenc.c
> +++ b/libavcodec/qsvenc.c
> @@ -495,9 +495,18 @@ static int init_video_param(AVCodecContext *avctx,
> QSVEncContext *q)
>          }
>      }
> 
> +    if (q->low_power) {
>  #if QSV_HAVE_VDENC
> -    q->param.mfx.LowPower           = q->low_power ?
> MFX_CODINGOPTION_ON : MFX_CODINGOPTION_OFF;
> +        q->param.mfx.LowPower = MFX_CODINGOPTION_ON; #else
> +        av_log(avctx, AV_LOG_WARNING, "The low_power option is "
> +                            "not supported with this MSDK
> version.\n");
> +        q->low_power = 0;
> +        q->param.mfx.LowPower = MFX_CODINGOPTION_OFF;
>  #endif
> +    } else
> +        q->param.mfx.LowPower = MFX_CODINGOPTION_OFF;
> +
>      q->param.mfx.CodecProfile       = q->profile;
>      q->param.mfx.TargetUsage        = avctx->compression_level;
>      q->param.mfx.GopPicSize         = FFMAX(0, avctx->gop_size);
> diff --git a/libavcodec/qsvenc_h264.c b/libavcodec/qsvenc_h264.c index
> f458137848..93044a58c9 100644
> --- a/libavcodec/qsvenc_h264.c
> +++ b/libavcodec/qsvenc_h264.c
> @@ -154,9 +154,7 @@ static const AVOption options[] = {
>      { "auto"   , NULL, 0, AV_OPT_TYPE_CONST, { .i64 =
> MFX_MF_AUTO     }, INT_MIN, INT_MAX,     VE, "mfmode" },
>  #endif
> 
> -#if QSV_HAVE_VDENC
>      { "low_power", "enable low power mode(experimental: many
> limitations by mfx version, BRC modes, etc.)", OFFSET(qsv.low_power),
> AV_OPT_TYPE_BOOL, { .i64 =  0 }, 0, 1, VE}, -#endif
> 
>      { "repeat_pps", "repeat pps for every frame", OFFSET(qsv.repeat_pps),
> AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, VE },

How about move this h264 private option to qsvenc.h to make it a common option for all codecs?
Though it is not supported for all codecs, but IMHO this not a big problem since we will check it at runtime: https://github.com/FFmpeg/FFmpeg/blob/master/libavcodec/qsvenc.c#L389 

It will be aligned with ffmpeg-vaapi, and avoid extra effort if other codecs add low_power support.