Re: [FFmpeg-devel] [PATCH] libavcodec/qsvenc: Use parameter from AVCodecContext to reset qsv codec

["Chen, Wenbin" <wenbin.chen-at-intel.com@ffmpeg.org>]

> Using parameter from AVCodecContext to reset qsv codec is more suitable
> for MFXVideoENCODE_Reset()'s usage. Per-frame metadata is more suitable
> for the usage of mfxEncodeCtrl being passed to
> MFXVideoENCODE_EncodeFrameAsync(). Now change it to use the value
> from AVCodecContext.
> 
> Signed-off-by: Wenbin Chen <wenbin.chen@intel.com>
> ---
>  doc/encoders.texi   |  5 ++---
>  libavcodec/qsvenc.c | 26 ++++++++------------------
>  2 files changed, 10 insertions(+), 21 deletions(-)
> 
> diff --git a/doc/encoders.texi b/doc/encoders.texi
> index 02a91ffe96..bf5fafd3fe 100644
> --- a/doc/encoders.texi
> +++ b/doc/encoders.texi
> @@ -3337,10 +3337,9 @@ For encoders set this flag to ON to reduce power
> consumption and GPU usage.
>  Following options can be used durning qsv encoding.
> 
>  @table @option
> -@item @var{qsv_config_qp}
> +@item @var{global_quality}
>  Supported in h264_qsv and hevc_qsv.
> -This option can be set in per-frame metadata. QP parameter can be
> dynamically
> -changed when encoding in CQP mode.
> +Change this value to reset qsv codec's qp configuration.
>  @end table
> 
>  @subsection H264 options
> diff --git a/libavcodec/qsvenc.c b/libavcodec/qsvenc.c
> index 2382c2f5f7..82cb5a4865 100644
> --- a/libavcodec/qsvenc.c
> +++ b/libavcodec/qsvenc.c
> @@ -1625,34 +1625,24 @@ static int update_qp(AVCodecContext *avctx,
> QSVEncContext *q,
>                       const AVFrame *frame)

"const AVFrame *frame" is not used. It can be removed.

>  {
>      int updated = 0, qp = 0, new_qp;
> -    char *tail;
> -    AVDictionaryEntry *entry = NULL;
> 
>      if (avctx->codec_id != AV_CODEC_ID_H264 && avctx->codec_id !=
> AV_CODEC_ID_HEVC)
>          return 0;
> 
> -    entry = av_dict_get(frame->metadata, "qsv_config_qp", NULL, 0);
> -    if (entry && q->param.mfx.RateControlMethod ==
> MFX_RATECONTROL_CQP) {
> -        qp = strtol(entry->value, &tail, 10);
> -        if (*tail) {
> -            av_log(avctx, AV_LOG_WARNING, "Invalid qsv_config_qp string.
> Ignore this metadata\n");
> -            return 0;
> -        }
> -        if (qp < 0 || qp > 51) {
> -            av_log(avctx, AV_LOG_WARNING, "Invalid qp, clip to 0 ~ 51\n");
> -            qp = av_clip(qp, 0, 51);
> -        }
> -        av_log(avctx, AV_LOG_DEBUG, "Configure qp: %d\n",qp);
> -        UPDATE_PARAM(q->param.mfx.QPP, qp);
> +    if (q->param.mfx.RateControlMethod == MFX_RATECONTROL_CQP) {
> +        qp = avctx->global_quality / FF_QP2LAMBDA;
> +        new_qp = av_clip(qp, 0, 51);
> +        UPDATE_PARAM(q->param.mfx.QPP, new_qp);
>          new_qp = av_clip(qp * fabs(avctx->i_quant_factor) +
>                              avctx->i_quant_offset, 0, 51);
>          UPDATE_PARAM(q->param.mfx.QPI, new_qp);
>          new_qp = av_clip(qp * fabs(avctx->b_quant_factor) +
>                              avctx->b_quant_offset, 0, 51);
>          UPDATE_PARAM(q->param.mfx.QPB, new_qp);

"q->param" is passed to both "in" and "out" parameters in MFXVideoENCODE_Query() call,
so the value in q->param may be changed. There is a potential issue that codec will reset on
every frame.

I will fix these in my patch v2.

> -        av_log(avctx, AV_LOG_DEBUG,
> -                "using fixed qp = %d/%d/%d for idr/p/b frames\n",
> -                q->param.mfx.QPI, q->param.mfx.QPP, q->param.mfx.QPB);
> +        if (updated)
> +            av_log(avctx, AV_LOG_DEBUG,
> +                   "using fixed qp = %d/%d/%d for idr/p/b frames\n",
> +                   q->param.mfx.QPI, q->param.mfx.QPP, q->param.mfx.QPB);
>      }
>      return updated;
>  }
> --
> 2.32.0
> 
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