Re: [FFmpeg-devel] [PATCH] libavcodec/qsvenc: Enable fixed QP configure in qsv CQP runtime

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

> On Wed, 2022-06-15 at 15:25 +0800, Wenbin Chen wrote:
> > From: Yue Heng <yue.heng@intel.com>
> >
> > Enable dynamic QP configuration in runtime on qsv encoder. Through
> > AVFrame->metadata, we can set key "qsv_config_qp" to change QP
> > configuration when we encode video in CQP mode.
> >
> > Signed-off-by: Yue Heng <yue.heng@intel.com>
> > Signed-off-by: Wenbin Chen <wenbin.chen@intel.com>
> > ---
> >  doc/encoders.texi   |  9 +++++++
> >  libavcodec/qsvenc.c | 59
> +++++++++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 68 insertions(+)
> >
> > diff --git a/doc/encoders.texi b/doc/encoders.texi
> > index 9796a606fa..1eb75e199a 100644
> > --- a/doc/encoders.texi
> > +++ b/doc/encoders.texi
> > @@ -3333,6 +3333,15 @@ Forcing I frames as IDR frames.
> >  For encoders set this flag to ON to reduce power consumption and GPU
> usage.
> >  @end table
> >
> > +@subsection Runtime Options
> > +Following options can be used durning qsv encoding.
> > +
> > +@table @option
> > +@item @var{qsv_config_qp}
> > +This option can be set in per-frame metadata. QP parameter can be
> dynamically
> > +changed when encode in CQP mode.
> > +@end table
> > +
> >  @subsection H264 options
> >  These options are used by h264_qsv
> >
> > diff --git a/libavcodec/qsvenc.c b/libavcodec/qsvenc.c
> > index 2b3b06767d..52462950be 100644
> > --- a/libavcodec/qsvenc.c
> > +++ b/libavcodec/qsvenc.c
> > @@ -146,6 +146,14 @@ static const struct {
> >      { MFX_RATECONTROL_QVBR,    "QVBR" },
> >  };
> >
> > +#define UPDATE_PARAM(a, b)  \
> > +do {                        \
> > +    if ((a) != (b)) {       \
> > +        a = b;              \
> > +        updated = 1;        \
> > +    }                       \
> > +} while (0)                 \
> > +
> >  static const char *print_ratecontrol(mfxU16 rc_mode)
> >  {
> >      int i;
> > @@ -1520,6 +1528,53 @@ static void
> print_interlace_msg(AVCodecContext *avctx,
> > QSVEncContext *q)
> >      }
> >  }
> >
> > +static int update_qp(AVCodecContext *avctx, QSVEncContext *q,
> > +                     const AVFrame *frame)
> > +{
> > +    int updated = 0, qp = 0, new_qp;
> > +    AVDictionaryEntry *entry = av_dict_get(frame->metadata,
> "qsv_config_qp",
> > +                                           NULL, 0);
> > +    if (entry && q->param.mfx.RateControlMethod ==
> MFX_RATECONTROL_CQP) {
> > +        qp = atoi(entry->value);
> 
> I think it is better to use strtol() because atoi() doesn't detect errors. See
> `man atoi`

Will change to strtol().

> 
> 
> > +        av_log(avctx, AV_LOG_DEBUG, "Configure qp: %d\n",qp);
> > +        if (qp < 0 || qp > 51)
> > +            av_log(avctx, AV_LOG_WARNING, "Invalid qp, clip to 0 ~ 51\n");
> 
> Is this feature for H264 and H265 only ?

I will add a codec check here.

> 
> > +
> > +        qp = av_clip(qp, 0, 51);
> > +        UPDATE_PARAM(q->param.mfx.QPP, 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);
> > +        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;
> > +}
> > +
> > +static int update_parameters(AVCodecContext *avctx, QSVEncContext *q,
> > +                             const AVFrame *frame)
> > +{
> > +    int needReset = 0, ret = 0;
> > +
> > +    if (!frame)
> > +        return 0;
> > +
> > +    needReset = update_qp(avctx, q, frame);
> > +    if (needReset) {
> > +        q->param.ExtParam    = q->extparam_internal;
> > +        q->param.NumExtParam = q->nb_extparam_internal;
> 
> User might provide external parameters in avctx->hwaccel_context. Are
> these
> parameters not required in MFXVideoENCODE_Reset() ?

Miss the user provided parameters. I will add them as well.

> 
> Thanks
> Haihao

Thanks for your review. I will fix these in new patch.

Thanks
Wenbin

> 
> > +        av_log(avctx, AV_LOG_DEBUG, "Parameter change, call msdk
> reset.\n");
> > +        ret = MFXVideoENCODE_Reset(q->session, &q->param);
> > +        if (ret < 0)
> > +            return ff_qsv_print_error(avctx, ret, "Error during resetting");
> > +    }
> > +    return 0;
> > +}
> > +
> >  static int encode_frame(AVCodecContext *avctx, QSVEncContext *q,
> >                          const AVFrame *frame)
> >  {
> > @@ -1630,6 +1685,10 @@ int ff_qsv_encode(AVCodecContext *avctx,
> QSVEncContext
> > *q,
> >  {
> >      int ret;
> >
> > +    ret = update_parameters(avctx, q, frame);
> > +    if (ret < 0)
> > +        return ret;
> > +
> >      ret = encode_frame(avctx, q, frame);
> >      if (ret < 0)
> >          return ret;
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