lavu: add video_hint API

Add side data type to provide hint to the video encoders about unchanged portions of each frame. Signed-off-by: Anton Khirnov <anton@khirnov.net>
2023-07-10 14:34:53 +02:00
parent c0709706dd
commit 5012b4ab4c
6 changed files with 204 additions and 1 deletions
--- a/libavutil/video_hint.h
+++ b/libavutil/video_hint.h
@@ -0,0 +1,107 @@
+/**
+ * Copyright 2023 Elias Carotti <eliascrt at amazon dot it>
+ *
+ * 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
+ */
+
+#ifndef AVUTIL_VIDEO_HINT_H
+#define AVUTIL_VIDEO_HINT_H
+
+#include <stddef.h>
+#include <stdint.h>
+#include "libavutil/avassert.h"
+#include "libavutil/frame.h"
+
+typedef struct AVVideoRect {
+    uint32_t x, y;
+    uint32_t width, height;
+} AVVideoRect;
+
+typedef enum AVVideoHintType {
+    /* rectangled delimit the constant areas (unchanged), default is changed */
+    AV_VIDEO_HINT_TYPE_CONSTANT,
+
+    /* rectangled delimit the constant areas (changed), default is not changed */
+    AV_VIDEO_HINT_TYPE_CHANGED,
+} AVVideoHintType;
+
+typedef struct AVVideoHint {
+    /**
+     * Number of AVVideoRect present.
+     *
+     * May be 0, in which case no per-rectangle information is present. In this
+     * case the values of rect_offset / rect_size are unspecified and should
+     * not be accessed.
+     */
+    size_t nb_rects;
+
+    /**
+     * Offset in bytes from the beginning of this structure at which the array
+     * of AVVideoRect starts.
+     */
+    size_t rect_offset;
+
+    /**
+     * Size in bytes of AVVideoRect.
+     */
+    size_t rect_size;
+
+    AVVideoHintType type;
+} AVVideoHint;
+
+static av_always_inline AVVideoRect *
+av_video_hint_rects(const AVVideoHint *hints) {
+    return (AVVideoRect *)((uint8_t *)hints + hints->rect_offset);
+}
+
+static av_always_inline AVVideoRect *
+av_video_hint_get_rect(const AVVideoHint *hints, size_t idx) {
+    return (AVVideoRect *)((uint8_t *)hints + hints->rect_offset + idx * hints->rect_size);
+}
+
+/**
+ * Allocate memory for the AVVideoHint struct along with an nb_rects-sized
+ * arrays of AVVideoRect.
+ *
+ * The side data contains a list of rectangles for the portions of the frame
+ * which changed from the last encoded one (and the remainder are assumed to be
+ * changed), or, alternately (depending on the type parameter) the unchanged
+ * ones (and the remanining ones are those which changed).
+ * Macroblocks will thus be hinted either to be P_SKIP-ped or go through the
+ * regular encoding procedure.
+ *
+ * It's responsibility of the caller to fill the AVRects accordingly, and to set
+ * the proper AVVideoHintType field.
+ *
+ * @param out_size if non-NULL, the size in bytes of the resulting data array is
+ *                 written here
+ *
+ * @return newly allocated AVVideoHint struct (must be freed by the caller using
+ *         av_free()) on success, NULL on memory allocation failure
+ */
+AVVideoHint *av_video_hint_alloc(size_t nb_rects,
+                                 size_t *out_size);
+
+/**
+ * Same as av_video_hint_alloc(), except newly-allocated AVVideoHint is attached
+ * as side data of type AV_FRAME_DATA_VIDEO_HINT_INFO to frame.
+ */
+AVVideoHint *av_video_hint_create_side_data(AVFrame *frame,
+                                            size_t nb_rects);
+
+
+#endif /* AVUTIL_VIDEO_HINT_H */