[FFmpeg-devel] [PATCH v3] libavcodec/qsvenc: Enable fixed QP configure in qsv CQP runtime

[Xiang, Haihao]

On Thu, 2022-06-23 at 13:32 +0800, Wenbin Chen wrote:
> From: Yue Heng <yue.heng at 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 at intel.com>
> Signed-off-by: Wenbin Chen <wenbin.chen at intel.com>
> ---
>  doc/encoders.texi   | 10 +++++
>  libavcodec/qsvenc.c | 89 +++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 99 insertions(+)
> 
> diff --git a/doc/encoders.texi b/doc/encoders.texi
> index 1850c99fe9..02a91ffe96 100644
> --- a/doc/encoders.texi
> +++ b/doc/encoders.texi
> @@ -3333,6 +3333,16 @@ Forcing I frames as IDR frames.
>  For encoders set this flag to ON to reduce power consumption and GPU usage.
>  @end table
>  
> + at subsection Runtime Options
> +Following options can be used durning qsv encoding.
> +
> + at table @option
> + at item @var{qsv_config_qp}
> +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.
> + at end table
> +
>  @subsection H264 options
>  These options are used by h264_qsv
>  
> diff --git a/libavcodec/qsvenc.c b/libavcodec/qsvenc.c
> index 902bada55b..2382c2f5f7 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;
> @@ -1613,6 +1621,83 @@ static int set_roi_encode_ctrl(AVCodecContext *avctx,
> const AVFrame *frame,
>      return 0;
>  }
>  
> +static int update_qp(AVCodecContext *avctx, QSVEncContext *q,
> +                     const AVFrame *frame)
> +{
> +    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);
> +        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)
> +        return 0;
> +
> +    if (avctx->hwaccel_context) {
> +        AVQSVContext *qsv = avctx->hwaccel_context;
> +        int i, j;
> +        q->param.ExtParam = q->extparam;
> +        for (i = 0; i < qsv->nb_ext_buffers; i++)
> +            q->param.ExtParam[i] = qsv->ext_buffers[i];
> +        q->param.NumExtParam = qsv->nb_ext_buffers;
> +
> +        for (i = 0; i < q->nb_extparam_internal; i++) {
> +            for (j = 0; j < qsv->nb_ext_buffers; j++) {
> +                if (qsv->ext_buffers[j]->BufferId == q->extparam_internal[i]-
> >BufferId)
> +                    break;
> +            }
> +            if (j < qsv->nb_ext_buffers)
> +                continue;
> +            q->param.ExtParam[q->param.NumExtParam++] = q-
> >extparam_internal[i];
> +        }
> +    } else {
> +        q->param.ExtParam    = q->extparam_internal;
> +        q->param.NumExtParam = q->nb_extparam_internal;
> +    }
> +    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)
>  {
> @@ -1731,6 +1816,10 @@ 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;

LGTM, will apply.

-Haihao