lavu: add side data AV_FRAME_DATA_DETECTION_BBOXES for object detection/classification

libavutil/detection_bbox.c

@@ -0,0 +1,73 @@
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "detection_bbox.h"
+
+AVDetectionBBoxHeader *av_detection_bbox_alloc(uint32_t nb_bboxes, size_t *out_size)
+{
+    size_t size;
+    struct {
+        AVDetectionBBoxHeader header;
+        AVDetectionBBox boxes[1];
+    } *ret;
+
+    size = sizeof(*ret);
+    if (nb_bboxes - 1 > (SIZE_MAX - size) / sizeof(*ret->boxes))
+        return NULL;
+    size += sizeof(*ret->boxes) * (nb_bboxes - 1);
+
+    ret = av_mallocz(size);
+    if (!ret)
+        return NULL;
+
+    ret->header.nb_bboxes = nb_bboxes;
+    ret->header.bbox_size = sizeof(*ret->boxes);
+    ret->header.bboxes_offset = (char *)&ret->boxes - (char *)&ret->header;
+
+    if (out_size)
+        *out_size = size;
+
+    return &ret->header;
+}
+
+AVDetectionBBoxHeader *av_detection_bbox_create_side_data(AVFrame *frame, uint32_t nb_bboxes)
+{
+    AVBufferRef         *buf;
+    AVDetectionBBoxHeader *header;
+    size_t size;
+
+    header = av_detection_bbox_alloc(nb_bboxes, &size);
+    if (!header)
+        return NULL;
+    if (size > INT_MAX) {
+        av_freep(&header);
+        return NULL;
+    }
+    buf = av_buffer_create((uint8_t *)header, size, NULL, NULL, 0);
+    if (!buf) {
+        av_freep(&header);
+        return NULL;
+    }
+
+    if (!av_frame_new_side_data_from_buf(frame, AV_FRAME_DATA_DETECTION_BBOXES, buf)) {
+        av_buffer_unref(&buf);
+        return NULL;
+    }
+
+    return header;
+}