Adding upstream version 0.37.0.upstream/0.37.0

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1035 insertions, 0 deletions

diff --git a/sub/draw_bmp.c b/sub/draw_bmp.c
new file mode 100644
index 0000000..58db162
--- /dev/null
+++ b/sub/draw_bmp.c
@@ -0,0 +1,1035 @@
+/*
+ * This file is part of mpv.
+ *
+ * mpv 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.
+ *
+ * mpv 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 mpv.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stddef.h>
+#include <stdbool.h>
+#include <assert.h>
+#include <math.h>
+#include <inttypes.h>
+
+#include "common/common.h"
+#include "draw_bmp.h"
+#include "img_convert.h"
+#include "video/mp_image.h"
+#include "video/repack.h"
+#include "video/sws_utils.h"
+#include "video/img_format.h"
+#include "video/csputils.h"
+
+const bool mp_draw_sub_formats[SUBBITMAP_COUNT] = {
+    [SUBBITMAP_LIBASS] = true,
+    [SUBBITMAP_BGRA] = true,
+};
+
+struct part {
+    int change_id;
+    // Sub-bitmaps scaled to final sizes.
+    int num_imgs;
+    struct mp_image **imgs;
+};
+
+// Must be a power of 2. Height is 1, but mark_rect() effectively operates on
+// multiples of chroma sized macro-pixels. (E.g. 4:2:0 -> every second line is
+// the same as the previous one, and x0%2==x1%2==0.)
+#define SLICE_W 256u
+
+// Whether to scale in tiles. Faster, but can't use correct chroma position.
+// Should be a runtime option. SLICE_W is used as tile width. The tile size
+// should probably be small; too small or too big will cause overhead when
+// scaling.
+#define SCALE_IN_TILES 1
+#define TILE_H 4u
+
+struct slice {
+    uint16_t x0, x1;
+};
+
+struct mp_draw_sub_cache
+{
+    struct mpv_global *global;
+
+    // Possibly cached parts. Also implies what's in the video_overlay.
+    struct part parts[MAX_OSD_PARTS];
+    int64_t change_id;
+
+    struct mp_image_params params;  // target image params
+
+    int w, h;                       // like params.w/h, but rounded up to chroma
+    unsigned align_x, align_y;      // alignment for all video pixels
+
+    struct mp_image *rgba_overlay;  // all OSD in RGBA
+    struct mp_image *video_overlay; // rgba_overlay converted to video colorspace
+    struct mp_image *alpha_overlay; // alpha plane ref. to video_overlay
+    struct mp_image *calpha_overlay; // alpha_overlay scaled to chroma plane size
+
+    unsigned s_w;                   // number of slices per line
+    struct slice *slices;           // slices[y * s_w + x / SLICE_W]
+    bool any_osd;
+
+    struct mp_sws_context *rgba_to_overlay; // scaler for rgba -> video csp.
+    struct mp_sws_context *alpha_to_calpha; // scaler for overlay -> calpha
+    bool scale_in_tiles;
+
+    struct mp_sws_context *sub_scale; // scaler for SUBBITMAP_BGRA
+
+    struct mp_repack *overlay_to_f32; // convert video_overlay to float
+    struct mp_image *overlay_tmp;   // slice in float32
+
+    struct mp_repack *calpha_to_f32; // convert video_overlay to float
+    struct mp_image *calpha_tmp;    // slice in float32
+
+    struct mp_repack *video_to_f32; // convert video to float
+    struct mp_repack *video_from_f32; // convert float back to video
+    struct mp_image *video_tmp;     // slice in float32
+
+    struct mp_sws_context *premul;  // video -> premultiplied video
+    struct mp_sws_context *unpremul; // reverse
+    struct mp_image *premul_tmp;
+
+    // Function that works on the _f32 data.
+    void (*blend_line)(void *dst, void *src, void *src_a, int w);
+
+    struct mp_image res_overlay;    // returned by mp_draw_sub_overlay()
+};
+
+static void blend_line_f32(void *dst, void *src, void *src_a, int w)
+{
+    float *dst_f = dst;
+    float *src_f = src;
+    float *src_a_f = src_a;
+
+    for (int x = 0; x < w; x++)
+        dst_f[x] = src_f[x] + dst_f[x] * (1.0f - src_a_f[x]);
+}
+
+static void blend_line_u8(void *dst, void *src, void *src_a, int w)
+{
+    uint8_t *dst_i = dst;
+    uint8_t *src_i = src;
+    uint8_t *src_a_i = src_a;
+
+    for (int x = 0; x < w; x++)
+        dst_i[x] = src_i[x] + dst_i[x] * (255u - src_a_i[x]) / 255u;
+}
+
+static void blend_slice(struct mp_draw_sub_cache *p)
+{
+    struct mp_image *ov = p->overlay_tmp;
+    struct mp_image *ca = p->calpha_tmp;
+    struct mp_image *vid = p->video_tmp;
+
+    for (int plane = 0; plane < vid->num_planes; plane++) {
+        int xs = vid->fmt.xs[plane];
+        int ys = vid->fmt.ys[plane];
+        int h = (1 << vid->fmt.chroma_ys) - (1 << ys) + 1;
+        int cw = mp_chroma_div_up(vid->w, xs);
+        for (int y = 0; y < h; y++) {
+            p->blend_line(mp_image_pixel_ptr_ny(vid, plane, 0, y),
+                          mp_image_pixel_ptr_ny(ov, plane, 0, y),
+                          xs || ys ? mp_image_pixel_ptr_ny(ca, 0, 0, y)
+                            : mp_image_pixel_ptr_ny(ov, ov->num_planes - 1, 0, y),
+                          cw);
+        }
+    }
+}
+
+static bool blend_overlay_with_video(struct mp_draw_sub_cache *p,
+                                     struct mp_image *dst)
+{
+    if (!repack_config_buffers(p->video_to_f32, 0, p->video_tmp, 0, dst, NULL))
+        return false;
+    if (!repack_config_buffers(p->video_from_f32, 0, dst, 0, p->video_tmp, NULL))
+        return false;
+
+    int xs = dst->fmt.chroma_xs;
+    int ys = dst->fmt.chroma_ys;
+
+    for (int y = 0; y < dst->h; y += p->align_y) {
+        struct slice *line = &p->slices[y * p->s_w];
+
+        for (int sx = 0; sx < p->s_w; sx++) {
+            struct slice *s = &line[sx];
+
+            int w = s->x1 - s->x0;
+            if (w <= 0)
+                continue;
+            int x = sx * SLICE_W + s->x0;
+
+            assert(MP_IS_ALIGNED(x, p->align_x));
+            assert(MP_IS_ALIGNED(w, p->align_x));
+            assert(x + w <= p->w);
+
+            repack_line(p->overlay_to_f32, 0, 0, x, y, w);
+            repack_line(p->video_to_f32, 0, 0, x, y, w);
+            if (p->calpha_to_f32)
+                repack_line(p->calpha_to_f32, 0, 0, x >> xs, y >> ys, w >> xs);
+
+            blend_slice(p);
+
+            repack_line(p->video_from_f32, x, y, 0, 0, w);
+        }
+    }
+
+    return true;
+}
+
+static bool convert_overlay_part(struct mp_draw_sub_cache *p,
+                                 int x0, int y0, int w, int h)
+{
+    struct mp_image src = *p->rgba_overlay;
+    struct mp_image dst = *p->video_overlay;
+
+    mp_image_crop(&src, x0, y0, x0 + w, y0 + h);
+    mp_image_crop(&dst, x0, y0, x0 + w, y0 + h);
+
+    if (mp_sws_scale(p->rgba_to_overlay, &dst, &src) < 0)
+        return false;
+
+    if (p->calpha_overlay) {
+        src = *p->alpha_overlay;
+        dst = *p->calpha_overlay;
+
+        int xs = p->video_overlay->fmt.chroma_xs;
+        int ys = p->video_overlay->fmt.chroma_ys;
+        mp_image_crop(&src, x0, y0, x0 + w, y0 + h);
+        mp_image_crop(&dst, x0 >> xs, y0 >> ys, (x0 + w) >> xs, (y0 + h) >> ys);
+
+        if (mp_sws_scale(p->alpha_to_calpha, &dst, &src) < 0)
+            return false;
+    }
+
+    return true;
+}
+
+static bool convert_to_video_overlay(struct mp_draw_sub_cache *p)
+{
+    if (!p->video_overlay)
+        return true;
+
+    if (p->scale_in_tiles) {
+        int t_h = p->rgba_overlay->h / TILE_H;
+        for (int ty = 0; ty < t_h; ty++) {
+            for (int sx = 0; sx < p->s_w; sx++) {
+                struct slice *s = &p->slices[ty * TILE_H * p->s_w + sx];
+                bool pixels_set = false;
+                for (int y = 0; y < TILE_H; y++) {
+                    if (s[0].x0 < s[0].x1) {
+                        pixels_set = true;
+                        break;
+                    }
+                    s += p->s_w;
+                }
+                if (!pixels_set)
+                    continue;
+                if (!convert_overlay_part(p, sx * SLICE_W, ty * TILE_H,
+                                          SLICE_W, TILE_H))
+                    return false;
+            }
+        }
+    } else {
+        if (!convert_overlay_part(p, 0, 0, p->rgba_overlay->w, p->rgba_overlay->h))
+            return false;
+    }
+
+    return true;
+}
+
+// Mark the given rectangle of pixels as possibly non-transparent.
+// The rectangle must have been pre-clipped.
+static void mark_rect(struct mp_draw_sub_cache *p, int x0, int y0, int x1, int y1)
+{
+    x0 = MP_ALIGN_DOWN(x0, p->align_x);
+    y0 = MP_ALIGN_DOWN(y0, p->align_y);
+    x1 = MP_ALIGN_UP(x1, p->align_x);
+    y1 = MP_ALIGN_UP(y1, p->align_y);
+
+    assert(x0 >= 0 && x0 <= x1 && x1 <= p->w);
+    assert(y0 >= 0 && y0 <= y1 && y1 <= p->h);
+
+    const int sx0 = x0 / SLICE_W;
+    const int sx1 = MPMIN(x1 / SLICE_W, p->s_w - 1);
+
+    for (int y = y0; y < y1; y++) {
+        struct slice *line = &p->slices[y * p->s_w];
+
+        struct slice *s0 = &line[sx0];
+        struct slice *s1 = &line[sx1];
+
+        s0->x0 = MPMIN(s0->x0, x0 % SLICE_W);
+        s1->x1 = MPMAX(s1->x1, ((x1 - 1) % SLICE_W) + 1);
+
+        if (s0 != s1) {
+            s0->x1 = SLICE_W;
+            s1->x0 = 0;
+
+            for (int x = sx0 + 1; x < sx1; x++) {
+                struct slice *s = &line[x];
+                s->x0 = 0;
+                s->x1 = SLICE_W;
+            }
+        }
+
+        // Ensure the very last slice does not extend
+        // beyond the total width.
+        struct slice *last_s = &line[p->s_w - 1];
+        last_s->x1 = MPMIN(p->w - ((p->s_w - 1) * SLICE_W), last_s->x1);
+
+        p->any_osd = true;
+    }
+}
+
+static void draw_ass_rgba(uint8_t *dst, ptrdiff_t dst_stride,
+                          uint8_t *src, ptrdiff_t src_stride,
+                          int w, int h, uint32_t color)
+{
+    const unsigned int r = (color >> 24) & 0xff;
+    const unsigned int g = (color >> 16) & 0xff;
+    const unsigned int b = (color >>  8) & 0xff;
+    const unsigned int a = 0xff - (color & 0xff);
+
+    for (int y = 0; y < h; y++) {
+        uint32_t *dstrow = (uint32_t *) dst;
+        for (int x = 0; x < w; x++) {
+            const unsigned int v = src[x];
+            unsigned int aa = a * v;
+            uint32_t dstpix = dstrow[x];
+            unsigned int dstb =  dstpix        & 0xFF;
+            unsigned int dstg = (dstpix >>  8) & 0xFF;
+            unsigned int dstr = (dstpix >> 16) & 0xFF;
+            unsigned int dsta = (dstpix >> 24) & 0xFF;
+            dstb = (v * b * a   + dstb * (255 * 255 - aa)) / (255 * 255);
+            dstg = (v * g * a   + dstg * (255 * 255 - aa)) / (255 * 255);
+            dstr = (v * r * a   + dstr * (255 * 255 - aa)) / (255 * 255);
+            dsta = (aa * 255    + dsta * (255 * 255 - aa)) / (255 * 255);
+            dstrow[x] = dstb | (dstg << 8) | (dstr << 16) | (dsta << 24);
+        }
+        dst += dst_stride;
+        src += src_stride;
+    }
+}
+
+static void render_ass(struct mp_draw_sub_cache *p, struct sub_bitmaps *sb)
+{
+    assert(sb->format == SUBBITMAP_LIBASS);
+
+    for (int i = 0; i < sb->num_parts; i++) {
+        struct sub_bitmap *s = &sb->parts[i];
+
+        draw_ass_rgba(mp_image_pixel_ptr(p->rgba_overlay, 0, s->x, s->y),
+                      p->rgba_overlay->stride[0], s->bitmap, s->stride,
+                      s->w, s->h, s->libass.color);
+
+        mark_rect(p, s->x, s->y, s->x + s->w, s->y + s->h);
+    }
+}
+
+static void draw_rgba(uint8_t *dst, ptrdiff_t dst_stride,
+                      uint8_t *src, ptrdiff_t src_stride, int w, int h)
+{
+    for (int y = 0; y < h; y++) {
+        uint32_t *srcrow = (uint32_t *)src;
+        uint32_t *dstrow = (uint32_t *)dst;
+        for (int x = 0; x < w; x++) {
+            uint32_t srcpix = srcrow[x];
+            uint32_t dstpix = dstrow[x];
+            unsigned int srcb =  srcpix        & 0xFF;
+            unsigned int srcg = (srcpix >>  8) & 0xFF;
+            unsigned int srcr = (srcpix >> 16) & 0xFF;
+            unsigned int srca = (srcpix >> 24) & 0xFF;
+            unsigned int dstb =  dstpix        & 0xFF;
+            unsigned int dstg = (dstpix >>  8) & 0xFF;
+            unsigned int dstr = (dstpix >> 16) & 0xFF;
+            unsigned int dsta = (dstpix >> 24) & 0xFF;
+            dstb = srcb + dstb * (255 * 255 - srca) / (255 * 255);
+            dstg = srcg + dstg * (255 * 255 - srca) / (255 * 255);
+            dstr = srcr + dstr * (255 * 255 - srca) / (255 * 255);
+            dsta = srca + dsta * (255 * 255 - srca) / (255 * 255);
+            dstrow[x] = dstb | (dstg << 8) | (dstr << 16) | (dsta << 24);
+        }
+        dst += dst_stride;
+        src += src_stride;
+    }
+}
+
+static bool render_rgba(struct mp_draw_sub_cache *p, struct part *part,
+                        struct sub_bitmaps *sb)
+{
+    assert(sb->format == SUBBITMAP_BGRA);
+
+    if (part->change_id != sb->change_id) {
+        for (int n = 0; n < part->num_imgs; n++)
+            talloc_free(part->imgs[n]);
+        part->num_imgs = sb->num_parts;
+        MP_TARRAY_GROW(p, part->imgs, part->num_imgs);
+        for (int n = 0; n < part->num_imgs; n++)
+            part->imgs[n] = NULL;
+
+        part->change_id = sb->change_id;
+    }
+
+    for (int i = 0; i < sb->num_parts; i++) {
+        struct sub_bitmap *s = &sb->parts[i];
+
+        // Clipping is rare but necessary.
+        int sx0 = s->x;
+        int sy0 = s->y;
+        int sx1 = s->x + s->dw;
+        int sy1 = s->y + s->dh;
+
+        int x0 = MPCLAMP(sx0, 0, p->w);
+        int y0 = MPCLAMP(sy0, 0, p->h);
+        int x1 = MPCLAMP(sx1, 0, p->w);
+        int y1 = MPCLAMP(sy1, 0, p->h);
+
+        int dw = x1 - x0;
+        int dh = y1 - y0;
+        if (dw <= 0 || dh <= 0)
+            continue;
+
+        // We clip the source instead of the scaled image, because that might
+        // avoid excessive memory usage when applying a ridiculous scale factor,
+        // even if that stretches it to up to 1 pixel due to integer rounding.
+        int sx = 0;
+        int sy = 0;
+        int sw = s->w;
+        int sh = s->h;
+        if (x0 != sx0 || y0 != sy0 || x1 != sx1 || y1 != sy1) {
+            double fx = s->dw / (double)s->w;
+            double fy = s->dh / (double)s->h;
+            sx = MPCLAMP((x0 - sx0) / fx, 0, s->w);
+            sy = MPCLAMP((y0 - sy0) / fy, 0, s->h);
+            sw = MPCLAMP(dw / fx, 1, s->w);
+            sh = MPCLAMP(dh / fy, 1, s->h);
+        }
+
+        assert(sx >= 0 && sw > 0 && sx + sw <= s->w);
+        assert(sy >= 0 && sh > 0 && sy + sh <= s->h);
+
+        ptrdiff_t s_stride = s->stride;
+        void *s_ptr = (char *)s->bitmap + s_stride * sy + sx * 4;
+
+        if (dw != sw || dh != sh) {
+            struct mp_image *scaled = part->imgs[i];
+
+            if (!scaled) {
+                struct mp_image src_img = {0};
+                mp_image_setfmt(&src_img, IMGFMT_BGRA);
+                mp_image_set_size(&src_img, sw, sh);
+                src_img.planes[0] = s_ptr;
+                src_img.stride[0] = s_stride;
+                src_img.params.alpha = MP_ALPHA_PREMUL;
+
+                scaled = mp_image_alloc(IMGFMT_BGRA, dw, dh);
+                if (!scaled)
+                    return false;
+                part->imgs[i] = talloc_steal(p, scaled);
+                mp_image_copy_attributes(scaled, &src_img);
+
+                if (mp_sws_scale(p->sub_scale, scaled, &src_img) < 0)
+                    return false;
+            }
+
+            assert(scaled->w == dw);
+            assert(scaled->h == dh);
+
+            s_stride = scaled->stride[0];
+            s_ptr = scaled->planes[0];
+        }
+
+        draw_rgba(mp_image_pixel_ptr(p->rgba_overlay, 0, x0, y0),
+                  p->rgba_overlay->stride[0], s_ptr, s_stride, dw, dh);
+
+        mark_rect(p, x0, y0, x1, y1);
+    }
+
+    return true;
+}
+
+static bool render_sb(struct mp_draw_sub_cache *p, struct sub_bitmaps *sb)
+{
+    struct part *part = &p->parts[sb->render_index];
+
+    switch (sb->format) {
+    case SUBBITMAP_LIBASS:
+        render_ass(p, sb);
+        return true;
+    case SUBBITMAP_BGRA:
+        return render_rgba(p, part, sb);
+    }
+
+    return false;
+}
+
+static void clear_rgba_overlay(struct mp_draw_sub_cache *p)
+{
+    assert(p->rgba_overlay->imgfmt == IMGFMT_BGRA);
+
+    for (int y = 0; y < p->rgba_overlay->h; y++) {
+        uint32_t *px = mp_image_pixel_ptr(p->rgba_overlay, 0, 0, y);
+        struct slice *line = &p->slices[y * p->s_w];
+
+        for (int sx = 0; sx < p->s_w; sx++) {
+            struct slice *s = &line[sx];
+
+            // Ensure this final slice doesn't extend beyond the width of p->s_w
+            if (s->x1 == SLICE_W && sx == p->s_w - 1 && y == p->rgba_overlay->h - 1)
+                s->x1 = MPMIN(p->w - ((p->s_w - 1) * SLICE_W), s->x1);
+
+            if (s->x0 <= s->x1) {
+                memset(px + s->x0, 0, (s->x1 - s->x0) * 4);
+                *s = (struct slice){SLICE_W, 0};
+            }
+
+            px += SLICE_W;
+        }
+    }
+
+    p->any_osd = false;
+}
+
+static struct mp_sws_context *alloc_scaler(struct mp_draw_sub_cache *p)
+{
+    struct mp_sws_context *s = mp_sws_alloc(p);
+    mp_sws_enable_cmdline_opts(s, p->global);
+    return s;
+}
+
+static void init_general(struct mp_draw_sub_cache *p)
+{
+    p->sub_scale = alloc_scaler(p);
+
+    p->s_w = MP_ALIGN_UP(p->rgba_overlay->w, SLICE_W) / SLICE_W;
+
+    p->slices = talloc_zero_array(p, struct slice, p->s_w * p->rgba_overlay->h);
+
+    mp_image_clear(p->rgba_overlay, 0, 0, p->w, p->h);
+    clear_rgba_overlay(p);
+}
+
+static bool reinit_to_video(struct mp_draw_sub_cache *p)
+{
+    struct mp_image_params *params = &p->params;
+    mp_image_params_guess_csp(params);
+
+    bool need_premul = params->alpha != MP_ALPHA_PREMUL &&
+        (mp_imgfmt_get_desc(params->imgfmt).flags & MP_IMGFLAG_ALPHA);
+
+    // Intermediate format for video_overlay. Requirements:
+    //  - same subsampling as video
+    //  - uses video colorspace
+    //  - has alpha
+    //  - repacker support (to the format used in p->blend_line)
+    //  - probably 8 bit per component rather than something wasteful or strange
+    struct mp_regular_imgfmt vfdesc = {0};
+
+    int rflags = REPACK_CREATE_EXPAND_8BIT;
+    bool use_shortcut = false;
+
+    p->video_to_f32 = mp_repack_create_planar(params->imgfmt, false, rflags);
+    talloc_steal(p, p->video_to_f32);
+    if (!p->video_to_f32)
+        return false;
+    mp_get_regular_imgfmt(&vfdesc, mp_repack_get_format_dst(p->video_to_f32));
+    assert(vfdesc.num_planes); // must have succeeded
+
+    if (params->color.space == MP_CSP_RGB && vfdesc.num_planes >= 3) {
+        use_shortcut = true;
+
+        if (vfdesc.component_type == MP_COMPONENT_TYPE_UINT &&
+            vfdesc.component_size == 1 && vfdesc.component_pad == 0)
+            p->blend_line = blend_line_u8;
+    }
+
+    // If no special blender is available, blend in float.
+    if (!p->blend_line) {
+        TA_FREEP(&p->video_to_f32);
+
+        rflags |= REPACK_CREATE_PLANAR_F32;
+
+        p->video_to_f32 = mp_repack_create_planar(params->imgfmt, false, rflags);
+        talloc_steal(p, p->video_to_f32);
+        if (!p->video_to_f32)
+            return false;
+
+        mp_get_regular_imgfmt(&vfdesc, mp_repack_get_format_dst(p->video_to_f32));
+        assert(vfdesc.component_type == MP_COMPONENT_TYPE_FLOAT);
+
+        p->blend_line = blend_line_f32;
+    }
+
+    p->scale_in_tiles = SCALE_IN_TILES;
+
+    int vid_f32_fmt = mp_repack_get_format_dst(p->video_to_f32);
+
+    p->video_from_f32 = mp_repack_create_planar(params->imgfmt, true, rflags);
+    talloc_steal(p, p->video_from_f32);
+    if (!p->video_from_f32)
+        return false;
+
+    assert(mp_repack_get_format_dst(p->video_to_f32) ==
+           mp_repack_get_format_src(p->video_from_f32));
+
+    int overlay_fmt = 0;
+    if (use_shortcut) {
+        // No point in doing anything fancy.
+        overlay_fmt = IMGFMT_BGRA;
+        p->scale_in_tiles = false;
+    } else {
+        struct mp_regular_imgfmt odesc = vfdesc;
+        // Just use 8 bit as well (should be fine, may use less memory).
+        odesc.component_type = MP_COMPONENT_TYPE_UINT;
+        odesc.component_size = 1;
+        odesc.component_pad = 0;
+
+        // Ensure there's alpha.
+        if (odesc.planes[odesc.num_planes - 1].components[0] != 4) {
+            if (odesc.num_planes >= 4)
+                return false; // wat
+            odesc.planes[odesc.num_planes++] =
+                (struct mp_regular_imgfmt_plane){1, {4}};
+        }
+
+        overlay_fmt = mp_find_regular_imgfmt(&odesc);
+        p->scale_in_tiles = odesc.chroma_xs || odesc.chroma_ys;
+    }
+    if (!overlay_fmt)
+        return false;
+
+    p->overlay_to_f32 = mp_repack_create_planar(overlay_fmt, false, rflags);
+    talloc_steal(p, p->overlay_to_f32);
+    if (!p->overlay_to_f32)
+        return false;
+
+    int render_fmt = mp_repack_get_format_dst(p->overlay_to_f32);
+
+    struct mp_regular_imgfmt ofdesc = {0};
+    mp_get_regular_imgfmt(&ofdesc, render_fmt);
+
+    if (ofdesc.planes[ofdesc.num_planes - 1].components[0] != 4)
+        return false;
+
+    // The formats must be the same, minus possible lack of alpha in vfdesc.
+    if (ofdesc.num_planes != vfdesc.num_planes &&
+        ofdesc.num_planes - 1 != vfdesc.num_planes)
+        return false;
+    for (int n = 0; n < vfdesc.num_planes; n++) {
+        if (vfdesc.planes[n].components[0] != ofdesc.planes[n].components[0])
+            return false;
+    }
+
+    p->align_x = mp_repack_get_align_x(p->video_to_f32);
+    p->align_y = mp_repack_get_align_y(p->video_to_f32);
+
+    assert(p->align_x >= mp_repack_get_align_x(p->overlay_to_f32));
+    assert(p->align_y >= mp_repack_get_align_y(p->overlay_to_f32));
+
+    if (p->align_x > SLICE_W || p->align_y > TILE_H)
+        return false;
+
+    p->w = MP_ALIGN_UP(params->w, p->align_x);
+    int slice_h = p->align_y;
+    p->h = MP_ALIGN_UP(params->h, slice_h);
+
+    // Size of the overlay. If scaling in tiles, round up to tiles, so we don't
+    // need to reinit the scale for right/bottom tiles.
+    int w = p->w;
+    int h = p->h;
+    if (p->scale_in_tiles) {
+        w = MP_ALIGN_UP(w, SLICE_W);
+        h = MP_ALIGN_UP(h, TILE_H);
+    }
+
+    p->rgba_overlay = talloc_steal(p, mp_image_alloc(IMGFMT_BGRA, w, h));
+    p->overlay_tmp = talloc_steal(p, mp_image_alloc(render_fmt, SLICE_W, slice_h));
+    p->video_tmp = talloc_steal(p, mp_image_alloc(vid_f32_fmt, SLICE_W, slice_h));
+    if (!p->rgba_overlay || !p->overlay_tmp || !p->video_tmp)
+        return false;
+
+    mp_image_params_guess_csp(&p->rgba_overlay->params);
+    p->rgba_overlay->params.alpha = MP_ALPHA_PREMUL;
+
+    p->overlay_tmp->params.color = params->color;
+    p->video_tmp->params.color = params->color;
+
+    if (p->rgba_overlay->imgfmt == overlay_fmt) {
+        if (!repack_config_buffers(p->overlay_to_f32, 0, p->overlay_tmp,
+                                   0, p->rgba_overlay, NULL))
+            return false;
+    } else {
+        // Generally non-RGB.
+        p->video_overlay = talloc_steal(p, mp_image_alloc(overlay_fmt, w, h));
+        if (!p->video_overlay)
+            return false;
+
+        p->video_overlay->params.color = params->color;
+        p->video_overlay->params.chroma_location = params->chroma_location;
+        p->video_overlay->params.alpha = MP_ALPHA_PREMUL;
+
+        if (p->scale_in_tiles)
+            p->video_overlay->params.chroma_location = MP_CHROMA_CENTER;
+
+        p->rgba_to_overlay = alloc_scaler(p);
+        p->rgba_to_overlay->allow_zimg = true;
+        if (!mp_sws_supports_formats(p->rgba_to_overlay,
+                            p->video_overlay->imgfmt, p->rgba_overlay->imgfmt))
+            return false;
+
+        if (!repack_config_buffers(p->overlay_to_f32, 0, p->overlay_tmp,
+                                   0, p->video_overlay, NULL))
+            return false;
+
+        // Setup a scaled alpha plane if chroma-subsampling is present.
+        int xs = p->video_overlay->fmt.chroma_xs;
+        int ys = p->video_overlay->fmt.chroma_ys;
+        if (xs || ys) {
+            // Require float so format selection becomes simpler (maybe).
+            assert(rflags & REPACK_CREATE_PLANAR_F32);
+
+            // For extracting the alpha plane, construct a gray format that is
+            // compatible with the alpha one.
+            struct mp_regular_imgfmt odesc = {0};
+            mp_get_regular_imgfmt(&odesc, overlay_fmt);
+            assert(odesc.component_size);
+            int aplane = odesc.num_planes - 1;
+            assert(odesc.planes[aplane].num_components == 1);
+            assert(odesc.planes[aplane].components[0] == 4);
+            struct mp_regular_imgfmt cadesc = odesc;
+            cadesc.num_planes = 1;
+            cadesc.planes[0] = (struct mp_regular_imgfmt_plane){1, {1}};
+            cadesc.chroma_xs = cadesc.chroma_ys = 0;
+
+            int calpha_fmt = mp_find_regular_imgfmt(&cadesc);
+            if (!calpha_fmt)
+                return false;
+
+            // Unscaled alpha plane from p->video_overlay.
+            p->alpha_overlay = talloc_zero(p, struct mp_image);
+            mp_image_setfmt(p->alpha_overlay, calpha_fmt);
+            mp_image_set_size(p->alpha_overlay, w, h);
+            p->alpha_overlay->planes[0] = p->video_overlay->planes[aplane];
+            p->alpha_overlay->stride[0] = p->video_overlay->stride[aplane];
+
+            // Full range gray always has the same range as alpha.
+            p->alpha_overlay->params.color.levels = MP_CSP_LEVELS_PC;
+            mp_image_params_guess_csp(&p->alpha_overlay->params);
+
+            p->calpha_overlay =
+                talloc_steal(p, mp_image_alloc(calpha_fmt, w >> xs, h >> ys));
+            if (!p->calpha_overlay)
+                return false;
+            p->calpha_overlay->params.color = p->alpha_overlay->params.color;
+
+            p->calpha_to_f32 = mp_repack_create_planar(calpha_fmt, false, rflags);
+            talloc_steal(p, p->calpha_to_f32);
+            if (!p->calpha_to_f32)
+                return false;
+
+            int af32_fmt = mp_repack_get_format_dst(p->calpha_to_f32);
+            p->calpha_tmp = talloc_steal(p, mp_image_alloc(af32_fmt, SLICE_W, 1));
+            if (!p->calpha_tmp)
+                return false;
+
+            if (!repack_config_buffers(p->calpha_to_f32, 0, p->calpha_tmp,
+                                       0, p->calpha_overlay, NULL))
+                return false;
+
+            p->alpha_to_calpha = alloc_scaler(p);
+            if (!mp_sws_supports_formats(p->alpha_to_calpha,
+                                         calpha_fmt, calpha_fmt))
+                return false;
+        }
+    }
+
+    if (need_premul) {
+        p->premul = alloc_scaler(p);
+        p->unpremul = alloc_scaler(p);
+        p->premul_tmp = mp_image_alloc(params->imgfmt, params->w, params->h);
+        talloc_steal(p, p->premul_tmp);
+        if (!p->premul_tmp)
+            return false;
+        mp_image_set_params(p->premul_tmp, params);
+        p->premul_tmp->params.alpha = MP_ALPHA_PREMUL;
+
+        // Only zimg supports this.
+        p->premul->force_scaler = MP_SWS_ZIMG;
+        p->unpremul->force_scaler = MP_SWS_ZIMG;
+    }
+
+    init_general(p);
+
+    return true;
+}
+
+static bool reinit_to_overlay(struct mp_draw_sub_cache *p)
+{
+    p->align_x = 1;
+    p->align_y = 1;
+
+    p->w = p->params.w;
+    p->h = p->params.h;
+
+    p->rgba_overlay = talloc_steal(p, mp_image_alloc(IMGFMT_BGRA, p->w, p->h));
+    if (!p->rgba_overlay)
+        return false;
+
+    mp_image_params_guess_csp(&p->rgba_overlay->params);
+    p->rgba_overlay->params.alpha = MP_ALPHA_PREMUL;
+
+    // Some non-sense with the intention to somewhat isolate the returned image.
+    mp_image_setfmt(&p->res_overlay, p->rgba_overlay->imgfmt);
+    mp_image_set_size(&p->res_overlay, p->rgba_overlay->w, p->rgba_overlay->h);
+    mp_image_copy_attributes(&p->res_overlay, p->rgba_overlay);
+    p->res_overlay.planes[0] = p->rgba_overlay->planes[0];
+    p->res_overlay.stride[0] = p->rgba_overlay->stride[0];
+
+    init_general(p);
+
+    // Mark all dirty (for full reinit of user state).
+    for (int y = 0; y < p->rgba_overlay->h; y++) {
+        for (int sx = 0; sx < p->s_w; sx++)
+            p->slices[y * p->s_w + sx] = (struct slice){0, SLICE_W};
+    }
+
+    return true;
+}
+
+static bool check_reinit(struct mp_draw_sub_cache *p,
+                         struct mp_image_params *params, bool to_video)
+{
+    if (!mp_image_params_equal(&p->params, params) || !p->rgba_overlay) {
+        talloc_free_children(p);
+        *p = (struct mp_draw_sub_cache){.global = p->global, .params = *params};
+        if (!(to_video ? reinit_to_video(p) : reinit_to_overlay(p))) {
+            talloc_free_children(p);
+            *p = (struct mp_draw_sub_cache){.global = p->global};
+            return false;
+        }
+    }
+    return true;
+}
+
+char *mp_draw_sub_get_dbg_info(struct mp_draw_sub_cache *p)
+{
+    assert(p);
+
+    return talloc_asprintf(NULL,
+        "align=%d:%d ov=%-7s, ov_f=%s, v_f=%s, a=%s, ca=%s, ca_f=%s",
+        p->align_x, p->align_y,
+        mp_imgfmt_to_name(p->video_overlay ? p->video_overlay->imgfmt : 0),
+        mp_imgfmt_to_name(p->overlay_tmp->imgfmt),
+        mp_imgfmt_to_name(p->video_tmp->imgfmt),
+        mp_imgfmt_to_name(p->alpha_overlay ? p->alpha_overlay->imgfmt : 0),
+        mp_imgfmt_to_name(p->calpha_overlay ? p->calpha_overlay->imgfmt : 0),
+        mp_imgfmt_to_name(p->calpha_tmp ? p->calpha_tmp->imgfmt : 0));
+}
+
+struct mp_draw_sub_cache *mp_draw_sub_alloc(void *ta_parent, struct mpv_global *g)
+{
+    struct mp_draw_sub_cache *c = talloc_zero(ta_parent, struct mp_draw_sub_cache);
+    c->global = g;
+    return c;
+}
+
+// For tests.
+struct mp_draw_sub_cache *mp_draw_sub_alloc_test(struct mp_image *dst)
+{
+    struct mp_draw_sub_cache *c = talloc_zero(NULL, struct mp_draw_sub_cache);
+    reinit_to_video(c);
+    return c;
+}
+
+bool mp_draw_sub_bitmaps(struct mp_draw_sub_cache *p, struct mp_image *dst,
+                         struct sub_bitmap_list *sbs_list)
+{
+    bool ok = false;
+
+    // dst must at least be as large as the bounding box, or you may get memory
+    // corruption.
+    assert(dst->w >= sbs_list->w);
+    assert(dst->h >= sbs_list->h);
+
+    if (!check_reinit(p, &dst->params, true))
+        return false;
+
+    if (p->change_id != sbs_list->change_id) {
+        p->change_id = sbs_list->change_id;
+
+        clear_rgba_overlay(p);
+
+        for (int n = 0; n < sbs_list->num_items; n++) {
+            if (!render_sb(p, sbs_list->items[n]))
+                goto done;
+        }
+
+        if (!convert_to_video_overlay(p))
+            goto done;
+    }
+
+    if (p->any_osd) {
+        struct mp_image *target = dst;
+        if (p->premul_tmp) {
+            if (mp_sws_scale(p->premul, p->premul_tmp, dst) < 0)
+                goto done;
+            target = p->premul_tmp;
+        }
+
+        if (!blend_overlay_with_video(p, target))
+            goto done;
+
+        if (target != dst) {
+            if (mp_sws_scale(p->unpremul, dst, p->premul_tmp) < 0)
+                goto done;
+        }
+    }
+
+    ok = true;
+
+done:
+    return ok;
+}
+
+// Bounding boxes for mp_draw_sub_overlay() API. For simplicity, each rectangle
+// covers a fixed tile on the screen, starts out empty, but is not extended
+// beyond the tile. In the simplest case, there's only 1 rect/tile for everything.
+struct rc_grid {
+    unsigned w, h;                  // size in grid tiles
+    unsigned r_w, r_h;              // size of a grid tile in pixels
+    struct mp_rect *rcs;            // rcs[x * w + y]
+};
+
+static void init_rc_grid(struct rc_grid *gr, struct mp_draw_sub_cache *p,
+                         struct mp_rect *rcs, int max_rcs)
+{
+    *gr = (struct rc_grid){ .w = max_rcs ? 1 : 0, .h = max_rcs ? 1 : 0,
+                            .rcs = rcs, .r_w = p->s_w * SLICE_W, .r_h = p->h, };
+
+    // Dumb iteration to figure out max. size because I'm stupid.
+    bool more = true;
+    while (more) {
+        more = false;
+        if (gr->r_h >= 128) {
+            if (gr->w * gr->h * 2 > max_rcs)
+                break;
+            gr->h *= 2;
+            gr->r_h = (p->h + gr->h - 1) / gr->h;
+            more = true;
+        }
+        if (gr->r_w >= SLICE_W * 2) {
+            if (gr->w * gr->h * 2 > max_rcs)
+                break;
+            gr->w *= 2;
+            gr->r_w = (p->s_w + gr->w - 1) / gr->w * SLICE_W;
+            more = true;
+        }
+    }
+
+    assert(gr->r_h * gr->h >= p->h);
+    assert(!(gr->r_w & (SLICE_W - 1)));
+    assert(gr->r_w * gr->w >= p->w);
+
+    // Init with empty (degenerate) rectangles.
+    for (int y = 0; y < gr->h; y++) {
+        for (int x = 0; x < gr->w; x++) {
+            struct mp_rect *rc = &gr->rcs[y * gr->w + x];
+            rc->x1 = x * gr->r_w;
+            rc->y1 = y * gr->r_h;
+            rc->x0 = rc->x1 + gr->r_w;
+            rc->y0 = rc->y1 + gr->r_h;
+        }
+    }
+}
+
+// Extend given grid with contents of p->slices.
+static void mark_rcs(struct mp_draw_sub_cache *p, struct rc_grid *gr)
+{
+    for (int y = 0; y < p->h; y++) {
+        struct slice *line = &p->slices[y * p->s_w];
+        struct mp_rect *rcs = &gr->rcs[y / gr->r_h * gr->w];
+
+        for (int sx = 0; sx < p->s_w; sx++) {
+            struct slice *s = &line[sx];
+            if (s->x0 < s->x1) {
+                unsigned xpos = sx * SLICE_W;
+                struct mp_rect *rc = &rcs[xpos / gr->r_w];
+                rc->y0 = MPMIN(rc->y0, y);
+                rc->y1 = MPMAX(rc->y1, y + 1);
+                rc->x0 = MPMIN(rc->x0, xpos + s->x0);
+                // Ensure this does not extend beyond the total width
+                rc->x1 = MPCLAMP(xpos + s->x1, rc->x1, p->w);
+            }
+        }
+    }
+}
+
+// Remove empty RCs, and return rc count.
+static int return_rcs(struct rc_grid *gr)
+{
+    int num = 0, cnt = gr->w * gr->h;
+    for (int n = 0; n < cnt; n++) {
+        struct mp_rect *rc = &gr->rcs[n];
+        if (rc->x0 < rc->x1 && rc->y0 < rc->y1)
+            gr->rcs[num++] = *rc;
+    }
+    return num;
+}
+
+struct mp_image *mp_draw_sub_overlay(struct mp_draw_sub_cache *p,
+                                     struct sub_bitmap_list *sbs_list,
+                                     struct mp_rect *act_rcs,
+                                     int max_act_rcs,
+                                     int *num_act_rcs,
+                                     struct mp_rect *mod_rcs,
+                                     int max_mod_rcs,
+                                     int *num_mod_rcs)
+{
+    *num_act_rcs = 0;
+    *num_mod_rcs = 0;
+
+    struct mp_image_params params = {.w = sbs_list->w, .h = sbs_list->h};
+    if (!check_reinit(p, &params, false))
+        return NULL;
+
+    struct rc_grid gr_act, gr_mod;
+    init_rc_grid(&gr_act, p, act_rcs, max_act_rcs);
+    init_rc_grid(&gr_mod, p, mod_rcs, max_mod_rcs);
+
+    if (p->change_id != sbs_list->change_id) {
+        p->change_id = sbs_list->change_id;
+
+        mark_rcs(p, &gr_mod);
+
+        clear_rgba_overlay(p);
+
+        for (int n = 0; n < sbs_list->num_items; n++) {
+            if (!render_sb(p, sbs_list->items[n])) {
+                p->change_id = 0;
+                return NULL;
+            }
+        }
+
+        mark_rcs(p, &gr_mod);
+    }
+
+    mark_rcs(p, &gr_act);
+
+    *num_act_rcs = return_rcs(&gr_act);
+    *num_mod_rcs = return_rcs(&gr_mod);
+
+    return &p->res_overlay;
+}
+
+// vim: ts=4 sw=4 et tw=80