[FFmpeg-devel] [PATCH V6 2/2] avcodec/libx264: add support for ROI-based encoding

[Michael Niedermayer]

On Tue, Jan 08, 2019 at 03:54:38AM +0800, Guo, Yejun wrote:
> This patch just enables the path from ffmpeg to libx264,
> the more encoders can be added later.
> 
> Signed-off-by: Guo, Yejun <yejun.guo at intel.com>
> ---
>  libavcodec/libx264.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 67 insertions(+)
> 
> diff --git a/libavcodec/libx264.c b/libavcodec/libx264.c
> index a68d0a7..9cfbaed 100644
> --- a/libavcodec/libx264.c
> +++ b/libavcodec/libx264.c
> @@ -40,6 +40,10 @@
>  #include <stdlib.h>
>  #include <string.h>
>  
> +// from x264.h, for quant_offsets, Macroblocks are 16x16
> +// blocks of pixels (with respect to the luma plane)
> +#define MB_SIZE 16
> +
>  typedef struct X264Context {
>      AVClass        *class;
>      x264_param_t    params;
> @@ -282,6 +286,7 @@ static int X264_frame(AVCodecContext *ctx, AVPacket *pkt, const AVFrame *frame,
>      x264_picture_t pic_out = {0};
>      int pict_type;
>      int64_t *out_opaque;
> +    AVFrameSideData *sd;
>  
>      x264_picture_init( &x4->pic );
>      x4->pic.img.i_csp   = x4->params.i_csp;
> @@ -345,6 +350,68 @@ static int X264_frame(AVCodecContext *ctx, AVPacket *pkt, const AVFrame *frame,
>                  }
>              }
>          }
> +
> +        sd = av_frame_get_side_data(frame, AV_FRAME_DATA_REGIONS_OF_INTEREST);
> +        if (sd) {

> +            static int show_aq_warning = 1;
> +            static int show_interlaced_frame_warning = 1;

non constant statics are a bad idea.
there is not neccesarily just a single x264 encoder


> +            if (x4->params.rc.i_aq_mode == X264_AQ_NONE && show_aq_warning) {
> +                show_aq_warning = 0;
> +                av_log(ctx, AV_LOG_WARNING, "Adaptive quantization must be enabled to use ROI encoding, skipping ROI.\n");
> +            } else {
> +                if (frame->interlaced_frame == 0) {
> +                    int mbx = (frame->width + MB_SIZE - 1) / MB_SIZE;
> +                    int mby = (frame->height + MB_SIZE - 1) / MB_SIZE;
> +                    int nb_rois;
> +                    AVRegionOfInterest* roi;
> +                    float* qoffsets;

> +                    qoffsets = (float*)av_mallocz_array(mbx * mby, sizeof(*qoffsets));

the cast is unneeded



> +                    if (!qoffsets)
> +                        return AVERROR(ENOMEM);
> +
> +                    nb_rois = sd->size / sizeof(AVRegionOfInterest);
> +                    roi = (AVRegionOfInterest*)sd->data;
> +                    for (int count = 0; count < nb_rois; count++) {

> +                        int starty = FFMIN(mby, roi->top / MB_SIZE);
> +                        int endy = FFMIN(mby, (roi->bottom + MB_SIZE - 1)/ MB_SIZE);
> +                        int startx = FFMIN(mbx, roi->left / MB_SIZE);
> +                        int endx = FFMIN(mbx, (roi->right + MB_SIZE - 1)/ MB_SIZE);

vertical alignment makes this more readable


> +                        float qoffset;
> +
> +                        if (roi->qoffset.den == 0) {
> +                            av_free(qoffsets);
> +                            av_log(ctx, AV_LOG_ERROR, "AVRegionOfInterest.qoffset.den should not be zero.\n");
> +                            return AVERROR(EINVAL);
> +                        }
> +                        qoffset = roi->qoffset.num * 1.0f / roi->qoffset.den;

> +                        qoffset = FFMIN(qoffset, 1.0f);
> +                        qoffset = FFMAX(qoffset, -1.0f);

av_clipf()

> +
> +                        // 25 is a number that I think it is a possible proper scale value.
> +                        qoffset = qoffset * 25;
> +
> +                        for (int y = starty; y < endy; y++) {
> +                            for (int x = startx; x < endx; x++) {
> +                                qoffsets[x + y*mbx] = qoffset;
> +                            }
> +                        }
> +
> +                        if (roi->self_size == 0) {
> +                            av_free(qoffsets);
> +                            av_log(ctx, AV_LOG_ERROR, "AVRegionOfInterest.self_size should be set to sizeof(AVRegionOfInterest).\n");
> +                            return AVERROR(EINVAL);
> +                        }
> +                        roi = (AVRegionOfInterest*)((char*)roi + roi->self_size);
> +                    }
> +
> +                    x4->pic.prop.quant_offsets = qoffsets;
> +                    x4->pic.prop.quant_offsets_free = av_free;
> +                } else if (show_interlaced_frame_warning) {
> +                    show_interlaced_frame_warning = 0;
> +                    av_log(ctx, AV_LOG_WARNING, "interlaced_frame not supported for ROI encoding yet, skipping ROI.\n");
> +                }
> +            }
> +        }
>      }
>  
>      do {
> -- 
> 2.7.4
> 
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-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Everything should be made as simple as possible, but not simpler.
-- Albert Einstein
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