[FFmpeg-devel] [PATCH V4 2/2] avcodec/libx264: add support for ROI-based encoding

[Guo, Yejun]

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 | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/libavcodec/libx264.c b/libavcodec/libx264.c
index a68d0a7..927156d 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;
@@ -345,6 +349,41 @@ static int X264_frame(AVCodecContext *ctx, AVPacket *pkt, const AVFrame *frame,
                 }
             }
         }
+
+        AVFrameSideData *sd = av_frame_get_side_data(frame, AV_FRAME_DATA_ROIS);
+        if (sd) {
+            if (x4->params.rc.i_aq_mode == X264_AQ_NONE) {
+                av_log(ctx, AV_LOG_WARNING, "Adaptive quantization must be enabled to use ROI encoding, skipping ROI.\n");
+            } else {
+                if (frame->interlaced_frame == 0) {
+                    size_t mbx = (frame->width + MB_SIZE - 1) / MB_SIZE;
+                    size_t mby = (frame->height + MB_SIZE - 1) / MB_SIZE;
+                    float* qoffsets;
+                    qoffsets = (float*)av_mallocz_array(mbx * mby, sizeof(*qoffsets));
+                    if (!qoffsets)
+                        return AVERROR(ENOMEM);
+
+                    size_t nb_rois = sd->size / sizeof(AVROI);
+                    AVROI* rois = (AVROI*)sd->data;
+                    for (size_t roi = 0; roi < nb_rois; roi++) {
+                        int starty = FFMIN(mby, rois[roi].top / MB_SIZE);
+                        int endy = FFMIN(mby, (rois[roi].bottom + MB_SIZE - 1)/ MB_SIZE);
+                        int startx = FFMIN(mbx, rois[roi].left / MB_SIZE);
+                        int endx = FFMIN(mbx, (rois[roi].right + MB_SIZE - 1)/ MB_SIZE);
+                        for (int y = starty; y < endy; y++) {
+                            for (int x = startx; x < endx; x++) {
+                                qoffsets[x + y*mbx] = rois[roi].qoffset;
+                            }
+                        }
+                    }
+
+                    x4->pic.prop.quant_offsets = qoffsets;
+                    x4->pic.prop.quant_offsets_free = av_free;
+                } else {
+                    av_log(ctx, AV_LOG_WARNING, "interlaced_frame not supported for ROI encoding yet, skipping ROI.\n");
+                }
+            }
+        }
     }
 
     do {
-- 
2.7.4