From: Niklas Haas <g...@haasn.dev>
See the design document introduced in the previous commit for an
in-depth introduction to the new approach.
This commit merely introduces the common dispatch code, the SwsOpList
boilerplate, and the high-level optimizer. The subsequent commits will
add the underlying implementations.
---
libswscale/Makefile | 2 +
libswscale/ops.c | 843 +++++++++++++++++++++++++++++++++++++
libswscale/ops.h | 265 ++++++++++++
libswscale/ops_internal.h | 103 +++++
libswscale/ops_optimizer.c | 810 +++++++++++++++++++++++++++++++++++
5 files changed, 2023 insertions(+)
create mode 100644 libswscale/ops.c
create mode 100644 libswscale/ops.h
create mode 100644 libswscale/ops_internal.h
create mode 100644 libswscale/ops_optimizer.c
diff --git a/libswscale/Makefile b/libswscale/Makefile
index d5e10d17dc..810c9dee78 100644
--- a/libswscale/Makefile
+++ b/libswscale/Makefile
@@ -15,6 +15,8 @@ OBJS = alphablend.o \
graph.o \
input.o \
lut3d.o \
+ ops.o \
+ ops_optimizer.o \
options.o \
output.o \
rgb2rgb.o \
diff --git a/libswscale/ops.c b/libswscale/ops.c
new file mode 100644
index 0000000000..6d9a844e06
--- /dev/null
+++ b/libswscale/ops.c
@@ -0,0 +1,843 @@
+/**
+ * Copyright (C) 2025 Niklas Haas
+ *
+ * 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 "libavutil/avassert.h"
+#include "libavutil/bswap.h"
+#include "libavutil/mem.h"
+#include "libavutil/rational.h"
+#include "libavutil/refstruct.h"
+
+#include "ops.h"
+#include "ops_internal.h"
+
+const SwsOpBackend * const ff_sws_op_backends[] = {
+ NULL
+};
+
+const int ff_sws_num_op_backends = FF_ARRAY_ELEMS(ff_sws_op_backends) - 1;
+
+#define Q(N) ((AVRational) { N, 1 })
+
+#define RET(x)
\
+ do {
\
+ if ((ret = (x)) < 0)
\
+ return ret;
\
+ } while (0)
+
+const char *ff_sws_pixel_type_name(SwsPixelType type)
+{
+ switch (type) {
+ case SWS_PIXEL_U8: return "u8";
+ case SWS_PIXEL_U16: return "u16";
+ case SWS_PIXEL_U32: return "u32";
+ case SWS_PIXEL_F32: return "f32";
+ case SWS_PIXEL_NONE: return "none";
+ case SWS_PIXEL_TYPE_NB: break;
+ }
+
+ av_assert0(!"Invalid pixel type!");
+ return "ERR";
+}
+
+int ff_sws_pixel_type_size(SwsPixelType type)
+{
+ switch (type) {
+ case SWS_PIXEL_U8: return sizeof(uint8_t);
+ case SWS_PIXEL_U16: return sizeof(uint16_t);
+ case SWS_PIXEL_U32: return sizeof(uint32_t);
+ case SWS_PIXEL_F32: return sizeof(float);
+ case SWS_PIXEL_NONE: break;
+ case SWS_PIXEL_TYPE_NB: break;
+ }
+
+ av_assert0(!"Invalid pixel type!");
+ return 0;
+}
+
+bool ff_sws_pixel_type_is_int(SwsPixelType type)
+{
+ switch (type) {
+ case SWS_PIXEL_U8:
+ case SWS_PIXEL_U16:
+ case SWS_PIXEL_U32:
+ return true;
+ case SWS_PIXEL_F32:
+ return false;
+ case SWS_PIXEL_NONE:
+ case SWS_PIXEL_TYPE_NB: break;
+ }
+
+ av_assert0(!"Invalid pixel type!");
+ return false;
+}
+
+SwsPixelType ff_sws_pixel_type_to_uint(SwsPixelType type)
+{
+ if (!type)
+ return type;
+
+ switch (ff_sws_pixel_type_size(type)) {
+ case 8: return SWS_PIXEL_U8;
+ case 16: return SWS_PIXEL_U16;
+ case 32: return SWS_PIXEL_U32;
+ }
+
+ av_assert0(!"Invalid pixel type!");
+ return SWS_PIXEL_NONE;
+}
+
+/* biased towards `a` */
+static AVRational av_min_q(AVRational a, AVRational b)
+{
+ return av_cmp_q(a, b) == 1 ? b : a;
+}
+
+static AVRational av_max_q(AVRational a, AVRational b)
+{
+ return av_cmp_q(a, b) == -1 ? b : a;
+}
+
+static AVRational expand_factor(SwsPixelType from, SwsPixelType to)
+{
+ const int src = ff_sws_pixel_type_size(from);
+ const int dst = ff_sws_pixel_type_size(to);
+ int scale = 0;
+ for (int i = 0; i < dst / src; i++)
+ scale = scale << src * 8 | 1;
+ return Q(scale);
+}
+
+void ff_sws_apply_op_q(const SwsOp *op, AVRational x[4])
+{
+ switch (op->op) {
+ case SWS_OP_READ:
+ case SWS_OP_WRITE:
+ return;
+ case SWS_OP_UNPACK: {
+ unsigned val = x[0].num;
+ int shift = ff_sws_pixel_type_size(op->type) * 8;
+ for (int i = 0; i < 4; i++) {
+ const unsigned mask = (1 << op->pack.pattern[i]) - 1;
+ shift -= op->pack.pattern[i];
+ x[i] = Q((val >> shift) & mask);
+ }
+ return;
+ }
+ case SWS_OP_PACK: {
+ unsigned val = 0;
+ int shift = ff_sws_pixel_type_size(op->type) * 8;
+ for (int i = 0; i < 4; i++) {
+ const unsigned mask = (1 << op->pack.pattern[i]) - 1;
+ shift -= op->pack.pattern[i];
+ val |= (x[i].num & mask) << shift;
+ }
+ x[0] = Q(val);
+ return;
+ }
+ case SWS_OP_SWAP_BYTES:
+ switch (ff_sws_pixel_type_size(op->type)) {
+ case 2:
+ for (int i = 0; i < 4; i++)
+ x[i].num = av_bswap16(x[i].num);
+ break;
+ case 4:
+ for (int i = 0; i < 4; i++)
+ x[i].num = av_bswap32(x[i].num);
+ break;
+ }
+ return;
+ case SWS_OP_CLEAR:
+ for (int i = 0; i < 4; i++) {
+ if (op->c.q4[i].den)
+ x[i] = op->c.q4[i];
+ }
+ return;
+ case SWS_OP_LSHIFT: {
+ AVRational mult = Q(1 << op->c.u);
+ for (int i = 0; i < 4; i++)
+ x[i] = x[i].den ? av_mul_q(x[i], mult) : x[i];
+ return;
+ }
+ case SWS_OP_RSHIFT: {
+ AVRational mult = Q(1 << op->c.u);
+ for (int i = 0; i < 4; i++)
+ x[i] = x[i].den ? av_div_q(x[i], mult) : x[i];
+ return;
+ }
+ case SWS_OP_SWIZZLE: {
+ const AVRational orig[4] = { x[0], x[1], x[2], x[3] };
+ for (int i = 0; i < 4; i++)
+ x[i] = orig[op->swizzle.in[i]];
+ return;
+ }
+ case SWS_OP_CONVERT:
+ if (ff_sws_pixel_type_is_int(op->convert.to)) {
+ const AVRational scale = expand_factor(op->type, op->convert.to);
+ for (int i = 0; i < 4; i++) {
+ x[i] = x[i].den ? Q(x[i].num / x[i].den) : x[i];
+ if (op->convert.expand)
+ x[i] = av_mul_q(x[i], scale);
+ }
+ }
+ return;
+ case SWS_OP_DITHER:
+ for (int i = 0; i < 4; i++)
+ x[i] = x[i].den ? av_add_q(x[i], av_make_q(1, 2)) : x[i];
+ return;
+ case SWS_OP_MIN:
+ for (int i = 0; i < 4; i++)
+ x[i] = av_min_q(x[i], op->c.q4[i]);
+ return;
+ case SWS_OP_MAX:
+ for (int i = 0; i < 4; i++)
+ x[i] = av_max_q(x[i], op->c.q4[i]);
+ return;
+ case SWS_OP_LINEAR: {
+ const AVRational orig[4] = { x[0], x[1], x[2], x[3] };
+ for (int i = 0; i < 4; i++) {
+ AVRational sum = op->lin.m[i][4];
+ for (int j = 0; j < 4; j++)
+ sum = av_add_q(sum, av_mul_q(orig[j], op->lin.m[i][j]));
+ x[i] = sum;
+ }
+ return;
+ }
+ case SWS_OP_SCALE:
+ for (int i = 0; i < 4; i++)
+ x[i] = x[i].den ? av_mul_q(x[i], op->c.q) : x[i];
+ return;
+ }
+
+ av_assert0(!"Invalid operation type!");
+}
+
+static void op_uninit(SwsOp *op)
+{
+ switch (op->op) {
+ case SWS_OP_DITHER:
+ av_refstruct_unref(&op->dither.matrix);
+ break;
+ }
+
+ *op = (SwsOp) {0};
+}
+
+SwsOpList *ff_sws_op_list_alloc(void)
+{
+ return av_mallocz(sizeof(SwsOpList));
+}
+
+void ff_sws_op_list_free(SwsOpList **p_ops)
+{
+ SwsOpList *ops = *p_ops;
+ if (!ops)
+ return;
+
+ for (int i = 0; i < ops->num_ops; i++)
+ op_uninit(&ops->ops[i]);
+
+ av_freep(&ops->ops);
+ av_free(ops);
+ *p_ops = NULL;
+}
+
+SwsOpList *ff_sws_op_list_duplicate(const SwsOpList *ops)
+{
+ SwsOpList *copy = av_malloc(sizeof(*copy));
+ if (!copy)
+ return NULL;
+
+ *copy = *ops;
+ copy->ops = av_memdup(ops->ops, ops->num_ops * sizeof(ops->ops[0]));
+ if (!copy->ops) {
+ av_free(copy);
+ return NULL;
+ }
+
+ for (int i = 0; i < ops->num_ops; i++) {
+ const SwsOp *op = &ops->ops[i];
+ switch (op->op) {
+ case SWS_OP_DITHER:
+ av_refstruct_ref(copy->ops[i].dither.matrix);
+ break;
+ }
+ }
+
+ return copy;
+}
+
+void ff_sws_op_list_remove_at(SwsOpList *ops, int index, int count)
+{
+ const int end = ops->num_ops - count;
+ av_assert2(index >= 0 && count >= 0 && index + count <= ops->num_ops);
+ for (int i = index; i < end; i++)
+ ops->ops[i] = ops->ops[i + count];
+ ops->num_ops = end;
+}
+
+int ff_sws_op_list_insert_at(SwsOpList *ops, int index, SwsOp *op)
+{
+ void *ret;
+ ret = av_dynarray2_add((void **) &ops->ops, &ops->num_ops, sizeof(*op),
+ (const void *) op);
+ if (!ret) {
+ op_uninit(op);
+ return AVERROR(ENOMEM);
+ }
+
+ for (int i = ops->num_ops - 1; i > index; i--)
+ ops->ops[i] = ops->ops[i - 1];
+ ops->ops[index] = *op;
+ *op = (SwsOp) {0};
+ return 0;
+}
+
+int ff_sws_op_list_append(SwsOpList *ops, SwsOp *op)
+{
+ return ff_sws_op_list_insert_at(ops, ops->num_ops, op);
+}
+
+int ff_sws_op_list_max_size(const SwsOpList *ops)
+{
+ int max_size = 0;
+ for (int i = 0; i < ops->num_ops; i++) {
+ const int size = ff_sws_pixel_type_size(ops->ops[i].type);
+ max_size = FFMAX(max_size, size);
+ }
+
+ return max_size;
+}
+
+uint32_t ff_sws_linear_mask(const SwsLinearOp c)
+{
+ uint32_t mask = 0;
+ for (int i = 0; i < 4; i++) {
+ for (int j = 0; j < 5; j++) {
+ if (av_cmp_q(c.m[i][j], Q(i == j)))
+ mask |= SWS_MASK(i, j);
+ }
+ }
+ return mask;
+}
+
+static const char *describe_lin_mask(uint32_t mask)
+{
+ /* Try to be fairly descriptive without assuming too much */
+ static const struct {
+ const char *name;
+ uint32_t mask;
+ } patterns[] = {
+ { "noop", 0 },
+ { "luma", SWS_MASK_LUMA },
+ { "alpha", SWS_MASK_ALPHA },
+ { "luma+alpha", SWS_MASK_LUMA | SWS_MASK_ALPHA },
+ { "dot3", 0b111 },
+ { "dot4", 0b1111 },
+ { "row0", SWS_MASK_ROW(0) },
+ { "row0+alpha", SWS_MASK_ROW(0) | SWS_MASK_ALPHA },
+ { "col0", SWS_MASK_COL(0) },
+ { "col0+off3", SWS_MASK_COL(0) | SWS_MASK_OFF3 },
+ { "off3", SWS_MASK_OFF3 },
+ { "off3+alpha", SWS_MASK_OFF3 | SWS_MASK_ALPHA },
+ { "diag3", SWS_MASK_DIAG3 },
+ { "diag4", SWS_MASK_DIAG4 },
+ { "diag3+alpha", SWS_MASK_DIAG3 | SWS_MASK_ALPHA },
+ { "diag3+off3", SWS_MASK_DIAG3 | SWS_MASK_OFF3 },
+ { "diag3+off3+alpha", SWS_MASK_DIAG3 | SWS_MASK_OFF3 |
SWS_MASK_ALPHA },
+ { "diag4+off4", SWS_MASK_DIAG4 | SWS_MASK_OFF4 },
+ { "matrix3", SWS_MASK_MAT3 },
+ { "matrix3+off3", SWS_MASK_MAT3 | SWS_MASK_OFF3 },
+ { "matrix3+off3+alpha", SWS_MASK_MAT3 | SWS_MASK_OFF3 | SWS_MASK_ALPHA
},
+ { "matrix4", SWS_MASK_MAT4 },
+ { "matrix4+off4", SWS_MASK_MAT4 | SWS_MASK_OFF4 },
+ };
+
+ for (int i = 0; i < FF_ARRAY_ELEMS(patterns); i++) {
+ if (!(mask & ~patterns[i].mask))
+ return patterns[i].name;
+ }
+
+ return "full";
+}
+
+static char describe_comp_flags(unsigned flags)
+{
+ if (flags & SWS_COMP_GARBAGE)
+ return 'X';
+ else if (flags & SWS_COMP_ZERO)
+ return '0';
+ else if (flags & SWS_COMP_EXACT)
+ return '+';
+ else
+ return '.';
+}
+
+static const char *print_q(const AVRational q, char buf[], int buf_len)
+{
+ if (!q.den) {
+ switch (q.num) {
+ case 1: return "inf";
+ case -1: return "-inf";
+ default: return "nan";
+ }
+ }
+
+ if (q.den == 1) {
+ snprintf(buf, buf_len, "%d", q.num);
+ return buf;
+ }
+
+ if (abs(q.num) > 1000 || abs(q.den) > 1000) {
+ snprintf(buf, buf_len, "%f", av_q2d(q));
+ return buf;
+ }
+
+ snprintf(buf, buf_len, "%d/%d", q.num, q.den);
+ return buf;
+}
+
+#define PRINTQ(q) print_q(q, (char[32]){0}, sizeof(char[32]) - 1)
+
+
+void ff_sws_op_list_print(void *log, int lev, const SwsOpList *ops)
+{
+ if (!ops->num_ops) {
+ av_log(log, lev, " (empty)\n");
+ return;
+ }
+
+ for (int i = 0; i < ops->num_ops; i++) {
+ const SwsOp *op = &ops->ops[i];
+ av_log(log, lev, " [%3s %c%c%c%c -> %c%c%c%c] ",
+ ff_sws_pixel_type_name(op->type),
+ op->comps.unused[0] ? 'X' : '.',
+ op->comps.unused[1] ? 'X' : '.',
+ op->comps.unused[2] ? 'X' : '.',
+ op->comps.unused[3] ? 'X' : '.',
+ describe_comp_flags(op->comps.flags[0]),
+ describe_comp_flags(op->comps.flags[1]),
+ describe_comp_flags(op->comps.flags[2]),
+ describe_comp_flags(op->comps.flags[3]));
+
+ switch (op->op) {
+ case SWS_OP_INVALID:
+ av_log(log, lev, "SWS_OP_INVALID\n");
+ break;
+ case SWS_OP_READ:
+ case SWS_OP_WRITE:
+ av_log(log, lev, "%-20s: %d elem(s) %s >> %d\n",
+ op->op == SWS_OP_READ ? "SWS_OP_READ"
+ : "SWS_OP_WRITE",
+ op->rw.elems, op->rw.packed ? "packed" : "planar",
+ op->rw.frac);
+ break;
+ case SWS_OP_SWAP_BYTES:
+ av_log(log, lev, "SWS_OP_SWAP_BYTES\n");
+ break;
+ case SWS_OP_LSHIFT:
+ av_log(log, lev, "%-20s: << %u\n", "SWS_OP_LSHIFT", op->c.u);
+ break;
+ case SWS_OP_RSHIFT:
+ av_log(log, lev, "%-20s: >> %u\n", "SWS_OP_RSHIFT", op->c.u);
+ break;
+ case SWS_OP_PACK:
+ case SWS_OP_UNPACK:
+ av_log(log, lev, "%-20s: {%d %d %d %d}\n",
+ op->op == SWS_OP_PACK ? "SWS_OP_PACK"
+ : "SWS_OP_UNPACK",
+ op->pack.pattern[0], op->pack.pattern[1],
+ op->pack.pattern[2], op->pack.pattern[3]);
+ break;
+ case SWS_OP_CLEAR:
+ av_log(log, lev, "%-20s: {%s %s %s %s}\n", "SWS_OP_CLEAR",
+ op->c.q4[0].den ? PRINTQ(op->c.q4[0]) : "_",
+ op->c.q4[1].den ? PRINTQ(op->c.q4[1]) : "_",
+ op->c.q4[2].den ? PRINTQ(op->c.q4[2]) : "_",
+ op->c.q4[3].den ? PRINTQ(op->c.q4[3]) : "_");
+ break;
+ case SWS_OP_SWIZZLE:
+ av_log(log, lev, "%-20s: %d%d%d%d\n", "SWS_OP_SWIZZLE",
+ op->swizzle.x, op->swizzle.y, op->swizzle.z, op->swizzle.w);
+ break;
+ case SWS_OP_CONVERT:
+ av_log(log, lev, "%-20s: %s -> %s%s\n", "SWS_OP_CONVERT",
+ ff_sws_pixel_type_name(op->type),
+ ff_sws_pixel_type_name(op->convert.to),
+ op->convert.expand ? " (expand)" : "");
+ break;
+ case SWS_OP_DITHER:
+ av_log(log, lev, "%-20s: %dx%d matrix\n", "SWS_OP_DITHER",
+ 1 << op->dither.size_log2, 1 << op->dither.size_log2);
+ break;
+ case SWS_OP_MIN:
+ av_log(log, lev, "%-20s: x <= {%s %s %s %s}\n", "SWS_OP_MIN",
+ op->c.q4[0].den ? PRINTQ(op->c.q4[0]) : "_",
+ op->c.q4[1].den ? PRINTQ(op->c.q4[1]) : "_",
+ op->c.q4[2].den ? PRINTQ(op->c.q4[2]) : "_",
+ op->c.q4[3].den ? PRINTQ(op->c.q4[3]) : "_");
+ break;
+ case SWS_OP_MAX:
+ av_log(log, lev, "%-20s: {%s %s %s %s} <= x\n", "SWS_OP_MAX",
+ op->c.q4[0].den ? PRINTQ(op->c.q4[0]) : "_",
+ op->c.q4[1].den ? PRINTQ(op->c.q4[1]) : "_",
+ op->c.q4[2].den ? PRINTQ(op->c.q4[2]) : "_",
+ op->c.q4[3].den ? PRINTQ(op->c.q4[3]) : "_");
+ break;
+ case SWS_OP_LINEAR:
+ av_log(log, lev, "%-20s: %s [[%s %s %s %s %s] "
+ "[%s %s %s %s %s] "
+ "[%s %s %s %s %s] "
+ "[%s %s %s %s %s]]\n",
+ "SWS_OP_LINEAR", describe_lin_mask(op->lin.mask),
+ PRINTQ(op->lin.m[0][0]), PRINTQ(op->lin.m[0][1]),
PRINTQ(op->lin.m[0][2]), PRINTQ(op->lin.m[0][3]), PRINTQ(op->lin.m[0][4]),
+ PRINTQ(op->lin.m[1][0]), PRINTQ(op->lin.m[1][1]),
PRINTQ(op->lin.m[1][2]), PRINTQ(op->lin.m[1][3]), PRINTQ(op->lin.m[1][4]),
+ PRINTQ(op->lin.m[2][0]), PRINTQ(op->lin.m[2][1]),
PRINTQ(op->lin.m[2][2]), PRINTQ(op->lin.m[2][3]), PRINTQ(op->lin.m[2][4]),
+ PRINTQ(op->lin.m[3][0]), PRINTQ(op->lin.m[3][1]),
PRINTQ(op->lin.m[3][2]), PRINTQ(op->lin.m[3][3]), PRINTQ(op->lin.m[3][4]));
+ break;
+ case SWS_OP_SCALE:
+ av_log(log, lev, "%-20s: * %s\n", "SWS_OP_SCALE",
+ PRINTQ(op->c.q));
+ break;
+ case SWS_OP_TYPE_NB:
+ break;
+ }
+
+ if (op->comps.min[0].den || op->comps.min[1].den ||
+ op->comps.min[2].den || op->comps.min[3].den ||
+ op->comps.max[0].den || op->comps.max[1].den ||
+ op->comps.max[2].den || op->comps.max[3].den)
+ {
+ av_log(log, AV_LOG_TRACE, " min: {%s, %s, %s, %s}, max: {%s,
%s, %s, %s}\n",
+ PRINTQ(op->comps.min[0]), PRINTQ(op->comps.min[1]),
+ PRINTQ(op->comps.min[2]), PRINTQ(op->comps.min[3]),
+ PRINTQ(op->comps.max[0]), PRINTQ(op->comps.max[1]),
+ PRINTQ(op->comps.max[2]), PRINTQ(op->comps.max[3]));
+ }
+
+ }
+
+ av_log(log, lev, " (X = unused, + = exact, 0 = zero)\n");
+}
+
+typedef struct SwsOpPass {
+ SwsCompiledOp comp;
+ SwsOpExec exec_base;
+ int num_blocks;
+ int tail_off_in;
+ int tail_off_out;
+ int tail_size_in;
+ int tail_size_out;
+ bool memcpy_in;
+ bool memcpy_out;
+} SwsOpPass;
+
+static void op_pass_free(void *ptr)
+{
+ SwsOpPass *p = ptr;
+ if (!p)
+ return;
+
+ if (p->comp.free)
+ p->comp.free(p->comp.priv);
+
+ av_free(p);
+}
+
+static void op_pass_setup(const SwsImg *out, const SwsImg *in, const SwsPass
*pass)
+{
+ const AVPixFmtDescriptor *indesc = av_pix_fmt_desc_get(in->fmt);
+ const AVPixFmtDescriptor *outdesc = av_pix_fmt_desc_get(out->fmt);
+
+ SwsOpPass *p = pass->priv;
+ SwsOpExec *exec = &p->exec_base;
+ const SwsCompiledOp *comp = &p->comp;
+ const int block_size = comp->block_size;
+ p->num_blocks = (pass->width + block_size - 1) / block_size;
+
+ /* Set up main loop parameters */
+ const int aligned_w = p->num_blocks * block_size;
+ const int safe_width = (p->num_blocks - 1) * block_size;
+ const int tail_size = pass->width - safe_width;
+ p->tail_off_in = safe_width * exec->pixel_bits_in >> 3;
+ p->tail_off_out = safe_width * exec->pixel_bits_out >> 3;
+ p->tail_size_in = tail_size * exec->pixel_bits_in >> 3;
+ p->tail_size_out = tail_size * exec->pixel_bits_out >> 3;
+ p->memcpy_in = false;
+ p->memcpy_out = false;
+
+ for (int i = 0; i < 4 && in->data[i]; i++) {
+ const int sub_x = (i == 1 || i == 2) ? indesc->log2_chroma_w : 0;
+ const int plane_w = (aligned_w + sub_x) >> sub_x;
+ const int plane_pad = (comp->over_read + sub_x) >> sub_x;
+ const int plane_size = plane_w * exec->pixel_bits_in >> 3;
+ p->memcpy_in |= plane_size + plane_pad > in->linesize[i];
+ exec->in_stride[i] = in->linesize[i];
+ }
+
+ for (int i = 0; i < 4 && out->data[i]; i++) {
+ const int sub_x = (i == 1 || i == 2) ? outdesc->log2_chroma_w : 0;
+ const int plane_w = (aligned_w + sub_x) >> sub_x;
+ const int plane_pad = (comp->over_write + sub_x) >> sub_x;
+ const int plane_size = plane_w * exec->pixel_bits_out >> 3;
+ p->memcpy_out |= plane_size + plane_pad > out->linesize[i];
+ exec->out_stride[i] = out->linesize[i];
+ }
+}
+
+/* Dispatch kernel over the last column of the image using memcpy */
+static av_always_inline void
+handle_tail(const SwsOpPass *p, SwsOpExec *exec,
+ const SwsImg *out_base, const bool copy_out,
+ const SwsImg *in_base, const bool copy_in,
+ const int y, const int y_end)
+{
+ DECLARE_ALIGNED_64(uint8_t, tmp)[2][4][sizeof(uint32_t[128])];
+
+ const SwsCompiledOp *comp = &p->comp;
+ const int block_size = comp->block_size;
+ const int tail_size_in = p->tail_size_in;
+ const int tail_size_out = p->tail_size_out;
+
+ SwsImg in = ff_sws_img_shift(*in_base, y);
+ SwsImg out = ff_sws_img_shift(*out_base, y);
+ for (int i = 0; i < 4 && in.data[i]; i++) {
+ in.data[i] += p->tail_off_in;
+ if (copy_in) {
+ exec->in[i] = (void *) tmp[0][i];
+ exec->in_stride[i] = sizeof(tmp[0][i]);
+ } else {
+ exec->in[i] = in.data[i];
+ }
+ }
+
+ for (int i = 0; i < 4 && out.data[i]; i++) {
+ out.data[i] += p->tail_off_out;
+ if (copy_out) {
+ exec->out[i] = (void *) tmp[1][i];
+ exec->out_stride[i] = sizeof(tmp[1][i]);
+ } else {
+ exec->out[i] = out.data[i];
+ }
+ }
+
+ exec->x = (p->num_blocks - 1) * block_size;
+ for (exec->y = y; exec->y < y_end; exec->y++) {
+ if (copy_in) {
+ for (int i = 0; i < 4 && in.data[i]; i++) {
+ av_assert2(tmp[0][i] + tail_size_in < (uint8_t *) tmp[1]);
+ memcpy(tmp[0][i], in.data[i], tail_size_in);
+ in.data[i] += in.linesize[i];
+ }
+ }
+
+ comp->func(exec, comp->priv, 1);
+
+ if (copy_out) {
+ for (int i = 0; i < 4 && out.data[i]; i++) {
+ av_assert2(tmp[1][i] + tail_size_out < (uint8_t *) tmp[2]);
+ memcpy(out.data[i], tmp[1][i], tail_size_out);
+ out.data[i] += out.linesize[i];
+ }
+ }
+
+ for (int i = 0; i < 4; i++) {
+ if (!copy_in)
+ exec->in[i] += in.linesize[i];
+ if (!copy_out)
+ exec->out[i] += out.linesize[i];
+ }
+ }
+}
+
+static av_always_inline void
+op_pass_run(const SwsImg *out_base, const SwsImg *in_base,
+ const int y, const int h, const SwsPass *pass)
+{
+ const SwsOpPass *p = pass->priv;
+ const SwsCompiledOp *comp = &p->comp;
+
+ /* Fill exec metadata for this slice */
+ const SwsImg in = ff_sws_img_shift(*in_base, y);
+ const SwsImg out = ff_sws_img_shift(*out_base, y);
+ SwsOpExec exec = p->exec_base;
+ exec.slice_y = y;
+ exec.slice_h = h;
+ for (int i = 0; i < 4; i++) {
+ exec.in[i] = in.data[i];
+ exec.out[i] = out.data[i];
+ }
+
+ /**
+ * To ensure safety, we need to consider the following:
+ *
+ * 1. We can overread the input, unless this is the last line of an
+ * unpadded buffer. All operation chains must be able to handle
+ * arbitrary pixel input, so arbitrary overread is fine.
+ *
+ * 2. We can overwrite the output, as long as we don't write more than the
+ * amount of pixels that fit into one linesize. So we always need to
+ * memcpy the last column on the output side if unpadded.
+ *
+ * 3. For the last row, we also need to memcpy the remainder of the input,
+ * to avoid reading past the end of the buffer. Note that since we know
+ * the run() function is called on stripes of the same buffer, we don't
+ * need to worry about this for the end of a slice.
+ */
+
+ const int last_slice = y + h == pass->height;
+ const bool memcpy_in = last_slice && p->memcpy_in;
+ const bool memcpy_out = p->memcpy_out;
+ const int num_blocks = p->num_blocks;
+ const int blocks_main = num_blocks - memcpy_out;
+ const int y_end = y + h - memcpy_in;
+
+ /* Handle main section */
+ for (exec.y = y; exec.y < y_end; exec.y++) {
+ comp->func(&exec, comp->priv, blocks_main);
+ for (int i = 0; i < 4; i++) {
+ exec.in[i] += in.linesize[i];
+ exec.out[i] += out.linesize[i];
+ }
+ }
+
+ if (memcpy_in)
+ comp->func(&exec, comp->priv, num_blocks - 1); /* safe part of last
row */
+
+ /* Handle last column via memcpy, takes over `exec` so call these last */
+ if (memcpy_out)
+ handle_tail(p, &exec, out_base, true, in_base, false, y, y_end);
+ if (memcpy_in)
+ handle_tail(p, &exec, out_base, memcpy_out, in_base, true, y_end, y +
h);
+}
+
+static int rw_pixel_bits(const SwsOp *op)
+{
+ const int elems = op->rw.packed ? op->rw.elems : 1;
+ const int size = ff_sws_pixel_type_size(op->type);
+ const int bits = 8 >> op->rw.frac;
+ av_assert1(bits >= 1);
+ return elems * size * bits;
+}
+
+int ff_sws_ops_compile_backend(SwsContext *ctx, const SwsOpBackend *backend,
+ const SwsOpList *ops, SwsCompiledOp *out)
+{
+ SwsOpList *copy, rest;
+ int ret = 0;
+
+ copy = ff_sws_op_list_duplicate(ops);
+ if (!copy)
+ return AVERROR(ENOMEM);
+
+ /* Ensure these are always set during compilation */
+ ff_sws_op_list_update_comps(copy);
+
+ /* Make an on-stack copy of `ops` to ensure we can still properly clean up
+ * the copy afterwards */
+ rest = *copy;
+
+ ret = backend->compile(ctx, &rest, out);
+ if (ret == AVERROR(ENOTSUP)) {
+ av_log(ctx, AV_LOG_DEBUG, "Backend '%s' does not support
operations:\n", backend->name);
+ ff_sws_op_list_print(ctx, AV_LOG_DEBUG, &rest);
+ } else if (ret < 0) {
+ av_log(ctx, AV_LOG_ERROR, "Failed to compile operations: %s\n",
av_err2str(ret));
+ ff_sws_op_list_print(ctx, AV_LOG_ERROR, &rest);
+ }
+
+ ff_sws_op_list_free(©);
+ return ret;
+}
+
+int ff_sws_ops_compile(SwsContext *ctx, const SwsOpList *ops, SwsCompiledOp
*out)
+{
+ for (int n = 0; ff_sws_op_backends[n]; n++) {
+ const SwsOpBackend *backend = ff_sws_op_backends[n];
+ if (ff_sws_ops_compile_backend(ctx, backend, ops, out) < 0)
+ continue;
+
+ av_log(ctx, AV_LOG_VERBOSE, "Compiled using backend '%s': "
+ "block size = %d, over-read = %d, over-write = %d\n",
+ backend->name, out->block_size, out->over_read,
out->over_write);
+ return 0;
+ }
+
+ av_log(ctx, AV_LOG_WARNING, "No backend found for operations:\n");
+ ff_sws_op_list_print(ctx, AV_LOG_WARNING, ops);
+ return AVERROR(ENOTSUP);
+}
+
+int ff_sws_compile_pass(SwsGraph *graph, SwsOpList *ops, int flags, SwsFormat
dst,
+ SwsPass *input, SwsPass **output)
+{
+ SwsContext *ctx = graph->ctx;
+ SwsOpPass *p = NULL;
+ const SwsOp *read = &ops->ops[0];
+ const SwsOp *write = &ops->ops[ops->num_ops - 1];
+ SwsPass *pass;
+ int ret;
+
+ if (ops->num_ops < 2) {
+ av_log(ctx, AV_LOG_ERROR, "Need at least two operations.\n");
+ return AVERROR(EINVAL);
+ }
+
+ if (read->op != SWS_OP_READ || write->op != SWS_OP_WRITE) {
+ av_log(ctx, AV_LOG_ERROR, "First and last operations must be a read "
+ "and write, respectively.\n");
+ return AVERROR(EINVAL);
+ }
+
+ if (flags & SWS_OP_FLAG_OPTIMIZE)
+ RET(ff_sws_op_list_optimize(ops));
+ else
+ ff_sws_op_list_update_comps(ops);
+
+ p = av_mallocz(sizeof(*p));
+ if (!p)
+ return AVERROR(ENOMEM);
+
+ p->exec_base = (SwsOpExec) {
+ .width = dst.width,
+ .height = dst.height,
+ .pixel_bits_in = rw_pixel_bits(read),
+ .pixel_bits_out = rw_pixel_bits(write),
+ };
+
+ ret = ff_sws_ops_compile(ctx, ops, &p->comp);
+ if (ret < 0)
+ goto fail;
+
+ pass = ff_sws_graph_add_pass(graph, dst.format, dst.width, dst.height,
input,
+ 1, p, op_pass_run);
+ if (!pass) {
+ ret = AVERROR(ENOMEM);
+ goto fail;
+ }
+ pass->setup = op_pass_setup;
+ pass->free = op_pass_free;
+
+ *output = pass;
+ return 0;
+
+fail:
+ op_pass_free(p);
+ return ret;
+}
diff --git a/libswscale/ops.h b/libswscale/ops.h
new file mode 100644
index 0000000000..c9c5706cbf
--- /dev/null
+++ b/libswscale/ops.h
@@ -0,0 +1,265 @@
+/**
+ * Copyright (C) 2025 Niklas Haas
+ *
+ * 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 SWSCALE_OPS_H
+#define SWSCALE_OPS_H
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stdalign.h>
+
+#include "graph.h"
+
+typedef enum SwsPixelType {
+ SWS_PIXEL_NONE = 0,
+ SWS_PIXEL_U8,
+ SWS_PIXEL_U16,
+ SWS_PIXEL_U32,
+ SWS_PIXEL_F32,
+ SWS_PIXEL_TYPE_NB
+} SwsPixelType;
+
+const char *ff_sws_pixel_type_name(SwsPixelType type);
+int ff_sws_pixel_type_size(SwsPixelType type) av_const;
+bool ff_sws_pixel_type_is_int(SwsPixelType type) av_const;
+SwsPixelType ff_sws_pixel_type_to_uint(SwsPixelType type) av_const;
+
+typedef enum SwsOpType {
+ SWS_OP_INVALID = 0,
+
+ /* Input/output handling */
+ SWS_OP_READ, /* gather raw pixels from planes */
+ SWS_OP_WRITE, /* write raw pixels to planes */
+ SWS_OP_SWAP_BYTES, /* swap byte order (for differing endianness) */
+ SWS_OP_UNPACK, /* split tightly packed data into components */
+ SWS_OP_PACK, /* compress components into tightly packed data */
+
+ /* Pixel manipulation */
+ SWS_OP_CLEAR, /* clear pixel values */
+ SWS_OP_LSHIFT, /* logical left shift of raw pixel values by (u8)
*/
+ SWS_OP_RSHIFT, /* right shift of raw pixel values by (u8) */
+ SWS_OP_SWIZZLE, /* rearrange channel order, or duplicate channels
*/
+ SWS_OP_CONVERT, /* convert (cast) between formats */
+ SWS_OP_DITHER, /* add dithering noise */
+
+ /* Arithmetic operations */
+ SWS_OP_LINEAR, /* generalized linear affine transform */
+ SWS_OP_SCALE, /* multiplication by scalar (q) */
+ SWS_OP_MIN, /* numeric minimum (q4) */
+ SWS_OP_MAX, /* numeric maximum (q4) */
+
+ SWS_OP_TYPE_NB,
+} SwsOpType;
+
+enum SwsCompFlags {
+ SWS_COMP_GARBAGE = 1 << 0, /* contents are undefined / garbage data */
+ SWS_COMP_EXACT = 1 << 1, /* value is an in-range, exact, integer */
+ SWS_COMP_ZERO = 1 << 2, /* known to be a constant zero */
+};
+
+typedef union SwsConst {
+ /* Generic constant value */
+ AVRational q;
+ AVRational q4[4];
+ unsigned u;
+} SwsConst;
+
+typedef struct SwsComps {
+ unsigned flags[4]; /* knowledge about (output) component contents */
+ bool unused[4]; /* which input components are definitely unused */
+
+ /* Keeps track of the known possible value range, or {0, 0} for undefined
+ * or (unknown range) floating point inputs */
+ AVRational min[4], max[4];
+} SwsComps;
+
+typedef struct SwsReadWriteOp {
+ /* Note: Unread pixel data is explicitly cleared to {0} for sanity */
+
+ int elems; /* number of elements (of type `op.type`) to read/write */
+ bool packed; /* read multiple elements from a single plane */
+ int frac; /* fractional pixel step factor (log2) */
+
+ /** Examples:
+ * rgba = 4x u8 packed
+ * yuv444p = 3x u8
+ * rgb565 = 1x u16 <- use SWS_OP_UNPACK to unpack
+ * monow = 1x u8 (frac 3)
+ * rgb4 = 1x u8 (frac 1)
+ */
+} SwsReadWriteOp;
+
+typedef struct SwsPackOp {
+ int pattern[4]; /* bit depth pattern, from MSB to LSB */
+} SwsPackOp;
+
+typedef struct SwsSwizzleOp {
+ /**
+ * Input component for each output component:
+ * Out[x] := In[swizzle.in[x]]
+ */
+ union {
+ uint32_t mask;
+ uint8_t in[4];
+ struct { uint8_t x, y, z, w; };
+ };
+} SwsSwizzleOp;
+
+#define SWS_SWIZZLE(X,Y,Z,W) ((SwsSwizzleOp) { .in = {X, Y, Z, W} })
+
+typedef struct SwsConvertOp {
+ SwsPixelType to; /* type of pixel to convert to */
+ bool expand; /* if true, integers are expanded to the full range */
+} SwsConvertOp;
+
+typedef struct SwsDitherOp {
+ AVRational *matrix; /* tightly packed dither matrix (refstruct) */
+ int size_log2; /* size (in bits) of the dither matrix */
+} SwsDitherOp;
+
+typedef struct SwsLinearOp {
+ /**
+ * Generalized 5x5 affine transformation:
+ * [ Out.x ] = [ A B C D E ]
+ * [ Out.y ] = [ F G H I J ] * [ x y z w 1 ]
+ * [ Out.z ] = [ K L M N O ]
+ * [ Out.w ] = [ P Q R S T ]
+ *
+ * The mask keeps track of which components differ from an identity matrix.
+ * There may be more efficient implementations of particular subsets, for
+ * example the common subset of {A, E, G, J, M, O} can be implemented with
+ * just three fused multiply-add operations.
+ */
+ AVRational m[4][5];
+ uint32_t mask; /* m[i][j] <-> 1 << (5 * i + j) */
+} SwsLinearOp;
+
+#define SWS_MASK(I, J) (1 << (5 * (I) + (J)))
+#define SWS_MASK_OFF(I) SWS_MASK(I, 4)
+#define SWS_MASK_ROW(I) (0b11111 << (5 * (I)))
+#define SWS_MASK_COL(J) (0b1000010000100001 << J)
+
+enum {
+ SWS_MASK_ALL = (1 << 20) - 1,
+ SWS_MASK_LUMA = SWS_MASK(0, 0) | SWS_MASK_OFF(0),
+ SWS_MASK_ALPHA = SWS_MASK(3, 3) | SWS_MASK_OFF(3),
+
+ SWS_MASK_DIAG3 = SWS_MASK(0, 0) | SWS_MASK(1, 1) | SWS_MASK(2, 2),
+ SWS_MASK_OFF3 = SWS_MASK_OFF(0) | SWS_MASK_OFF(1) | SWS_MASK_OFF(2),
+ SWS_MASK_MAT3 = SWS_MASK(0, 0) | SWS_MASK(0, 1) | SWS_MASK(0, 2) |
+ SWS_MASK(1, 0) | SWS_MASK(1, 1) | SWS_MASK(1, 2) |
+ SWS_MASK(2, 0) | SWS_MASK(2, 1) | SWS_MASK(2, 2),
+
+ SWS_MASK_DIAG4 = SWS_MASK_DIAG3 | SWS_MASK(3, 3),
+ SWS_MASK_OFF4 = SWS_MASK_OFF3 | SWS_MASK_OFF(3),
+ SWS_MASK_MAT4 = SWS_MASK_ALL & ~SWS_MASK_OFF4,
+};
+
+/* Helper function to compute the correct mask */
+uint32_t ff_sws_linear_mask(SwsLinearOp);
+
+typedef struct SwsOp {
+ SwsOpType op; /* operation to perform */
+ SwsPixelType type; /* pixel type to operate on */
+ union {
+ SwsReadWriteOp rw;
+ SwsPackOp pack;
+ SwsSwizzleOp swizzle;
+ SwsConvertOp convert;
+ SwsDitherOp dither;
+ SwsLinearOp lin;
+ SwsConst c;
+ };
+
+ /* For use internal use inside ff_sws_*() functions */
+ SwsComps comps;
+} SwsOp;
+
+/**
+ * Frees any allocations associated with an SwsOp and sets it to {0}.
+ */
+void ff_sws_op_uninit(SwsOp *op);
+
+/**
+ * Apply an operation to an AVRational. No-op for read/write operations.
+ */
+void ff_sws_apply_op_q(const SwsOp *op, AVRational x[4]);
+
+/**
+ * Helper struct for representing a list of operations.
+ */
+typedef struct SwsOpList {
+ SwsOp *ops;
+ int num_ops;
+} SwsOpList;
+
+SwsOpList *ff_sws_op_list_alloc(void);
+void ff_sws_op_list_free(SwsOpList **ops);
+
+/**
+ * Returns a duplicate of `ops`, or NULL on OOM.
+ */
+SwsOpList *ff_sws_op_list_duplicate(const SwsOpList *ops);
+
+/**
+ * Returns the size of the largest pixel type used in `ops`.
+ */
+int ff_sws_op_list_max_size(const SwsOpList *ops);
+
+/**
+ * These will take over ownership of `op` and set it to {0}, even on failure.
+ */
+int ff_sws_op_list_append(SwsOpList *ops, SwsOp *op);
+int ff_sws_op_list_insert_at(SwsOpList *ops, int index, SwsOp *op);
+
+void ff_sws_op_list_remove_at(SwsOpList *ops, int index, int count);
+
+/**
+ * Print out the contents of an operation list.
+ */
+void ff_sws_op_list_print(void *log_ctx, int log_level, const SwsOpList *ops);
+
+/**
+ * Infer + propagate known information about components. Called automatically
+ * when needed by the optimizer and compiler.
+ */
+void ff_sws_op_list_update_comps(SwsOpList *ops);
+
+/**
+ * Fuse compatible and eliminate redundant operations, as well as replacing
+ * some operations with more efficient alternatives.
+ */
+int ff_sws_op_list_optimize(SwsOpList *ops);
+
+enum SwsOpCompileFlags {
+ /* Automatically optimize the operations when compiling */
+ SWS_OP_FLAG_OPTIMIZE = 1 << 0,
+};
+
+/**
+ * Resolves an operation list to a graph pass. The first and last operations
+ * must be a read/write respectively. `flags` is a list of SwsOpCompileFlags.
+ *
+ * Note: `ops` may be modified by this function.
+ */
+int ff_sws_compile_pass(SwsGraph *graph, SwsOpList *ops, int flags, SwsFormat
dst,
+ SwsPass *input, SwsPass **output);
+
+#endif
diff --git a/libswscale/ops_internal.h b/libswscale/ops_internal.h
new file mode 100644
index 0000000000..ac0319321e
--- /dev/null
+++ b/libswscale/ops_internal.h
@@ -0,0 +1,103 @@
+/**
+ * Copyright (C) 2025 Niklas Haas
+ *
+ * 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 SWSCALE_OPS_INTERNAL_H
+#define SWSCALE_OPS_INTERNAL_H
+
+#include "libavutil/mem_internal.h"
+
+#include "ops.h"
+
+/**
+ * Global execution context for all compiled functions.
+ *
+ * Note: This struct is hard-coded in assembly, so do not change the layout
+ * without updating the corresponding assembly definitions.
+ */
+typedef struct SwsOpExec {
+ /* The data pointers point to the first pixel to process */
+ const uint8_t *in[4];
+ uint8_t *out[4];
+
+ /* Separation between lines in bytes */
+ ptrdiff_t in_stride[4];
+ ptrdiff_t out_stride[4];
+
+ /* Extra metadata, may or may not be useful */
+ int32_t x, y; /* Starting pixel coordinates */
+ int32_t width, height; /* Overall image dimensions */
+ int32_t slice_y, slice_h; /* Start and height of current slice */
+ int32_t pixel_bits_in; /* Bits per input pixel */
+ int32_t pixel_bits_out; /* Bits per output pixel */
+} SwsOpExec;
+
+static_assert(sizeof(SwsOpExec) == 16 * sizeof(void *) + 8 * sizeof(int32_t),
+ "SwsOpExec layout mismatch");
+
+/* Process a given number of pixel blocks */
+typedef void (*SwsOpFunc)(const SwsOpExec *exec, const void *priv, int blocks);
+
+#define SWS_DECL_FUNC(NAME) \
+ void NAME(const SwsOpExec *, const void *, int)
+
+typedef struct SwsCompiledOp {
+ SwsOpFunc func;
+
+ int block_size; /* number of pixels processed per iteration */
+ int over_read; /* implementation over-reads input by this many bytes */
+ int over_write; /* implementation over-writes output by this many bytes */
+
+ /* Arbitrary private data */
+ void *priv;
+ void (*free)(void *priv);
+} SwsCompiledOp;
+
+typedef struct SwsOpBackend {
+ const char *name; /* Descriptive name for this backend */
+
+ /**
+ * Compile an operation list to an implementation chain. May modify `ops`
+ * freely; the original list will be freed automatically by the caller.
+ *
+ * Returns 0 or a negative error code.
+ */
+ int (*compile)(SwsContext *ctx, SwsOpList *ops, SwsCompiledOp *out);
+} SwsOpBackend;
+
+/* List of all backends, terminated by NULL */
+extern const SwsOpBackend *const ff_sws_op_backends[];
+extern const int ff_sws_num_op_backends; /* excludes terminating NULL */
+
+/**
+ * Attempt to compile a list of operations using a specific backend.
+ *
+ * Returns 0 on success, or a negative error code on failure.
+ */
+int ff_sws_ops_compile_backend(SwsContext *ctx, const SwsOpBackend *backend,
+ const SwsOpList *ops, SwsCompiledOp *out);
+
+/**
+ * Compile a list of operations using the best available backend.
+ *
+ * Returns 0 on success, or a negative error code on failure.
+ */
+int ff_sws_ops_compile(SwsContext *ctx, const SwsOpList *ops, SwsCompiledOp
*out);
+
+#endif
diff --git a/libswscale/ops_optimizer.c b/libswscale/ops_optimizer.c
new file mode 100644
index 0000000000..9f509085ba
--- /dev/null
+++ b/libswscale/ops_optimizer.c
@@ -0,0 +1,810 @@
+/**
+ * Copyright (C) 2025 Niklas Haas
+ *
+ * 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 "libavutil/avassert.h"
+#include "libavutil/mem.h"
+#include "libavutil/rational.h"
+
+#include "ops.h"
+#include "ops_internal.h"
+
+#define Q(N) ((AVRational) { N, 1 })
+
+#define RET(x)
\
+ do {
\
+ if ((ret = (x)) < 0)
\
+ return ret;
\
+ } while (0)
+
+/* Returns true for operations that are independent per channel. These can
+ * usually be commuted freely other such operations. */
+static bool op_type_is_independent(SwsOpType op)
+{
+ switch (op) {
+ case SWS_OP_SWAP_BYTES:
+ case SWS_OP_LSHIFT:
+ case SWS_OP_RSHIFT:
+ case SWS_OP_CONVERT:
+ case SWS_OP_DITHER:
+ case SWS_OP_MIN:
+ case SWS_OP_MAX:
+ case SWS_OP_SCALE:
+ return true;
+ case SWS_OP_INVALID:
+ case SWS_OP_READ:
+ case SWS_OP_WRITE:
+ case SWS_OP_SWIZZLE:
+ case SWS_OP_CLEAR:
+ case SWS_OP_LINEAR:
+ case SWS_OP_PACK:
+ case SWS_OP_UNPACK:
+ return false;
+ case SWS_OP_TYPE_NB:
+ break;
+ }
+
+ av_assert0(!"Invalid operation type!");
+ return false;
+}
+
+static AVRational expand_factor(SwsPixelType from, SwsPixelType to)
+{
+ const int src = ff_sws_pixel_type_size(from);
+ const int dst = ff_sws_pixel_type_size(to);
+ int scale = 0;
+ for (int i = 0; i < dst / src; i++)
+ scale = scale << src * 8 | 1;
+ return Q(scale);
+}
+
+/* merge_comp_flags() forms a monoid with flags_identity as the null element */
+static const unsigned flags_identity = SWS_COMP_ZERO | SWS_COMP_EXACT;
+static unsigned merge_comp_flags(unsigned a, unsigned b)
+{
+ const unsigned flags_or = SWS_COMP_GARBAGE;
+ const unsigned flags_and = SWS_COMP_ZERO | SWS_COMP_EXACT;
+ return ((a & b) & flags_and) | ((a | b) & flags_or);
+}
+
+/* Infer + propagate known information about components */
+void ff_sws_op_list_update_comps(SwsOpList *ops)
+{
+ SwsComps next = { .unused = {true, true, true, true} };
+ SwsComps prev = { .flags = {
+ SWS_COMP_GARBAGE, SWS_COMP_GARBAGE, SWS_COMP_GARBAGE, SWS_COMP_GARBAGE,
+ }};
+
+ /* Forwards pass, propagates knowledge about the incoming pixel values */
+ for (int n = 0; n < ops->num_ops; n++) {
+ SwsOp *op = &ops->ops[n];
+
+ /* Prefill min/max values automatically; may have to be fixed in
+ * special cases */
+ memcpy(op->comps.min, prev.min, sizeof(prev.min));
+ memcpy(op->comps.max, prev.max, sizeof(prev.max));
+ ff_sws_apply_op_q(op, op->comps.min);
+ ff_sws_apply_op_q(op, op->comps.max);
+
+ switch (op->op) {
+ case SWS_OP_READ:
+ for (int i = 0; i < op->rw.elems; i++) {
+ if (ff_sws_pixel_type_is_int(op->type)) {
+ const int size = ff_sws_pixel_type_size(op->type);
+ const uint64_t max_val = (1 << 8 * size) - 1;
+ op->comps.flags[i] |= SWS_COMP_EXACT;
+ op->comps.min[i] = Q(0);
+ op->comps.max[i] = Q(max_val);
+ }
+ }
+ for (int i = op->rw.elems; i < 4; i++)
+ op->comps.flags[i] |= prev.flags[i];
+ break;
+ case SWS_OP_WRITE:
+ for (int i = 0; i < op->rw.elems; i++)
+ av_assert1(!(prev.flags[i] & SWS_COMP_GARBAGE));
+ /* fall through */
+ case SWS_OP_SWAP_BYTES:
+ case SWS_OP_LSHIFT:
+ case SWS_OP_RSHIFT:
+ case SWS_OP_MIN:
+ case SWS_OP_MAX:
+ /* Linearly propagate flags per component */
+ for (int i = 0; i < 4; i++)
+ op->comps.flags[i] |= prev.flags[i];
+ break;
+ case SWS_OP_DITHER:
+ /* Strip zero flag because of the nonzero dithering offset */
+ for (int i = 0; i < 4; i++)
+ op->comps.flags[i] |= prev.flags[i] & ~SWS_COMP_ZERO;
+ break;
+ case SWS_OP_UNPACK:
+ for (int i = 0; i < 4; i++) {
+ if (op->pack.pattern[i])
+ op->comps.flags[i] |= prev.flags[0];
+ else
+ op->comps.flags[i] = SWS_COMP_GARBAGE;
+ }
+ break;
+ case SWS_OP_PACK: {
+ unsigned flags = flags_identity;
+ for (int i = 0; i < 4; i++) {
+ if (op->pack.pattern[i])
+ flags = merge_comp_flags(flags, prev.flags[i]);
+ if (i > 0) /* clear remaining comps for sanity */
+ op->comps.flags[i] = SWS_COMP_GARBAGE;
+ }
+ op->comps.flags[0] |= flags;
+ break;
+ }
+ case SWS_OP_CLEAR:
+ for (int i = 0; i < 4; i++) {
+ if (op->c.q4[i].den) {
+ if (op->c.q4[i].num == 0)
+ op->comps.flags[i] |= SWS_COMP_ZERO | SWS_COMP_EXACT;
+ if (op->c.q4[i].den == 1)
+ op->comps.flags[i] |= SWS_COMP_EXACT;
+ }
+ else
+ op->comps.flags[i] |= prev.flags[i];
+ }
+ break;
+ case SWS_OP_SWIZZLE:
+ for (int i = 0; i < 4; i++)
+ op->comps.flags[i] |= prev.flags[op->swizzle.in[i]];
+ break;
+ case SWS_OP_CONVERT:
+ for (int i = 0; i < 4; i++) {
+ op->comps.flags[i] |= prev.flags[i];
+ if (ff_sws_pixel_type_is_int(op->convert.to))
+ op->comps.flags[i] |= SWS_COMP_EXACT;
+ }
+ break;
+ case SWS_OP_LINEAR:
+ for (int i = 0; i < 4; i++) {
+ unsigned flags = flags_identity;
+ AVRational min = Q(0), max = Q(0);
+ for (int j = 0; j < 4; j++) {
+ const AVRational k = op->lin.m[i][j];
+ AVRational mink = av_mul_q(prev.min[j], k);
+ AVRational maxk = av_mul_q(prev.max[j], k);
+ if (k.num) {
+ flags = merge_comp_flags(flags, prev.flags[j]);
+ if (k.den != 1) /* fractional coefficient */
+ flags &= ~SWS_COMP_EXACT;
+ if (k.num < 0)
+ FFSWAP(AVRational, mink, maxk);
+ min = av_add_q(min, mink);
+ max = av_add_q(max, maxk);
+ }
+ }
+ if (op->lin.m[i][4].num) { /* nonzero offset */
+ flags &= ~SWS_COMP_ZERO;
+ if (op->lin.m[i][4].den != 1) /* fractional offset */
+ flags &= ~SWS_COMP_EXACT;
+ min = av_add_q(min, op->lin.m[i][4]);
+ max = av_add_q(max, op->lin.m[i][4]);
+ }
+ op->comps.flags[i] |= flags;
+ op->comps.min[i] = min;
+ op->comps.max[i] = max;
+ }
+ break;
+ case SWS_OP_SCALE:
+ for (int i = 0; i < 4; i++) {
+ op->comps.flags[i] |= prev.flags[i];
+ if (op->c.q.den != 1) /* fractional scale */
+ op->comps.flags[i] &= ~SWS_COMP_EXACT;
+ if (op->c.q.num < 0)
+ FFSWAP(AVRational, op->comps.min[i], op->comps.max[i]);
+ }
+ break;
+
+ case SWS_OP_INVALID:
+ case SWS_OP_TYPE_NB:
+ av_assert0(!"Invalid operation type!");
+ }
+
+ prev = op->comps;
+ }
+
+ /* Backwards pass, solves for component dependencies */
+ for (int n = ops->num_ops - 1; n >= 0; n--) {
+ SwsOp *op = &ops->ops[n];
+
+ switch (op->op) {
+ case SWS_OP_READ:
+ case SWS_OP_WRITE:
+ for (int i = 0; i < op->rw.elems; i++)
+ op->comps.unused[i] = op->op == SWS_OP_READ;
+ for (int i = op->rw.elems; i < 4; i++)
+ op->comps.unused[i] |= next.unused[i];
+ break;
+ case SWS_OP_SWAP_BYTES:
+ case SWS_OP_LSHIFT:
+ case SWS_OP_RSHIFT:
+ case SWS_OP_CONVERT:
+ case SWS_OP_DITHER:
+ case SWS_OP_MIN:
+ case SWS_OP_MAX:
+ case SWS_OP_SCALE:
+ for (int i = 0; i < 4; i++)
+ op->comps.unused[i] |= next.unused[i];
+ break;
+ case SWS_OP_UNPACK: {
+ bool unused = true;
+ for (int i = 0; i < 4; i++) {
+ if (op->pack.pattern[i])
+ unused &= next.unused[i];
+ op->comps.unused[i] |= i > 0;
+ }
+ op->comps.unused[0] = unused;
+ break;
+ }
+ case SWS_OP_PACK:
+ for (int i = 0; i < 4; i++) {
+ if (op->pack.pattern[i])
+ op->comps.unused[i] |= next.unused[0];
+ else
+ op->comps.unused[i] = true;
+ }
+ break;
+ case SWS_OP_CLEAR:
+ for (int i = 0; i < 4; i++) {
+ if (op->c.q4[i].den)
+ op->comps.unused[i] = true;
+ else
+ op->comps.unused[i] |= next.unused[i];
+ }
+ break;
+ case SWS_OP_SWIZZLE: {
+ bool unused[4] = { true, true, true, true };
+ for (int i = 0; i < 4; i++)
+ unused[op->swizzle.in[i]] &= next.unused[i];
+ for (int i = 0; i < 4; i++)
+ op->comps.unused[i] = unused[i];
+ break;
+ }
+ case SWS_OP_LINEAR:
+ for (int j = 0; j < 4; j++) {
+ bool unused = true;
+ for (int i = 0; i < 4; i++) {
+ if (op->lin.m[i][j].num)
+ unused &= next.unused[i];
+ }
+ op->comps.unused[j] = unused;
+ }
+ break;
+ }
+
+ next = op->comps;
+ }
+}
+
+/* returns log2(x) only if x is a power of two, or 0 otherwise */
+static int exact_log2(const int x)
+{
+ int p;
+ if (x <= 0)
+ return 0;
+ p = av_log2(x);
+ return (1 << p) == x ? p : 0;
+}
+
+static int exact_log2_q(const AVRational x)
+{
+ if (x.den == 1)
+ return exact_log2(x.num);
+ else if (x.num == 1)
+ return -exact_log2(x.den);
+ else
+ return 0;
+}
+
+/**
+ * If a linear operation can be reduced to a scalar multiplication, returns
+ * the corresponding scaling factor, or 0 otherwise.
+ */
+static bool extract_scalar(const SwsLinearOp *c, SwsComps prev, SwsComps next,
+ SwsConst *out_scale)
+{
+ SwsConst scale = {0};
+
+ /* There are components not on the main diagonal */
+ if (c->mask & ~SWS_MASK_DIAG4)
+ return false;
+
+ for (int i = 0; i < 4; i++) {
+ const AVRational s = c->m[i][i];
+ if ((prev.flags[i] & SWS_COMP_ZERO) || next.unused[i])
+ continue;
+ if (scale.q.den && av_cmp_q(s, scale.q))
+ return false;
+ scale.q = s;
+ }
+
+ if (scale.q.den)
+ *out_scale = scale;
+ return scale.q.den;
+}
+
+/* Extracts an integer clear operation (subset) from the given linear op. */
+static bool extract_constant_rows(SwsLinearOp *c, SwsComps prev,
+ SwsConst *out_clear)
+{
+ SwsConst clear = {0};
+ bool ret = false;
+
+ for (int i = 0; i < 4; i++) {
+ bool const_row = c->m[i][4].den == 1; /* offset is integer */
+ for (int j = 0; j < 4; j++) {
+ const_row &= c->m[i][j].num == 0 || /* scalar is zero */
+ (prev.flags[j] & SWS_COMP_ZERO); /* input is zero */
+ }
+ if (const_row && (c->mask & SWS_MASK_ROW(i))) {
+ clear.q4[i] = c->m[i][4];
+ for (int j = 0; j < 5; j++)
+ c->m[i][j] = Q(i == j);
+ c->mask &= ~SWS_MASK_ROW(i);
+ ret = true;
+ }
+ }
+
+ if (ret)
+ *out_clear = clear;
+ return ret;
+}
+
+/* Unswizzle a linear operation by aligning single-input rows with
+ * their corresponding diagonal */
+static bool extract_swizzle(SwsLinearOp *op, SwsComps prev, SwsSwizzleOp
*out_swiz)
+{
+ SwsSwizzleOp swiz = SWS_SWIZZLE(0, 1, 2, 3);
+ SwsLinearOp c = *op;
+
+ for (int i = 0; i < 4; i++) {
+ int idx = -1;
+ for (int j = 0; j < 4; j++) {
+ if (!c.m[i][j].num || (prev.flags[j] & SWS_COMP_ZERO))
+ continue;
+ if (idx >= 0)
+ return false; /* multiple inputs */
+ idx = j;
+ }
+
+ if (idx >= 0 && idx != i) {
+ /* Move coefficient to the diagonal */
+ c.m[i][i] = c.m[i][idx];
+ c.m[i][idx] = Q(0);
+ swiz.in[i] = idx;
+ }
+ }
+
+ if (swiz.mask == SWS_SWIZZLE(0, 1, 2, 3).mask)
+ return false; /* no swizzle was identified */
+
+ c.mask = ff_sws_linear_mask(c);
+ *out_swiz = swiz;
+ *op = c;
+ return true;
+}
+
+static void op_copy_flags(SwsOp *op, const SwsOp *op2)
+{
+ for (int i = 0; i < 4; i++)
+ op->comps.flags[i] = op2->comps.flags[i];
+}
+
+/* Should only be used on ops that commute with each other, and only after
+ * applying the necessary adjustments
+ */
+static void swap_ops(SwsOp *op, SwsOp *next)
+{
+ /* Clear all inferred flags */
+ op->comps = next->comps = (SwsComps) {0};
+ FFSWAP(SwsOp, *op, *next);
+}
+
+int ff_sws_op_list_optimize(SwsOpList *ops)
+{
+ int prev_num_ops, ret;
+ bool progress;
+
+ do {
+ prev_num_ops = ops->num_ops;
+ progress = false;
+
+ ff_sws_op_list_update_comps(ops);
+
+ for (int n = 0; n < ops->num_ops;) {
+ SwsOp dummy = {0};
+ SwsOp *op = &ops->ops[n];
+ SwsOp *prev = n ? &ops->ops[n - 1] : &dummy;
+ SwsOp *next = n + 1 < ops->num_ops ? &ops->ops[n + 1] : &dummy;
+
+ /* common helper variables */
+ bool changed = false;
+ bool noop = true;
+
+ switch (op->op) {
+ case SWS_OP_READ:
+ /* Optimized further into refcopy / memcpy */
+ if (next->op == SWS_OP_WRITE &&
+ next->rw.elems == op->rw.elems &&
+ next->rw.packed == op->rw.packed &&
+ next->rw.frac == op->rw.frac)
+ {
+ ff_sws_op_list_remove_at(ops, n, 2);
+ av_assert1(ops->num_ops == 0);
+ return 0;
+ }
+
+ /* Skip reading extra unneeded components */
+ if (!op->rw.packed) {
+ int needed = op->rw.elems;
+ while (needed > 0 && next->comps.unused[needed - 1])
+ needed--;
+ if (op->rw.elems != needed) {
+ op->rw.elems = needed;
+ op->rw.packed &= op->rw.elems > 1;
+ progress = true;
+ continue;
+ }
+ }
+ break;
+
+ case SWS_OP_SWAP_BYTES:
+ /* Redundant (double) swap */
+ if (next->op == SWS_OP_SWAP_BYTES) {
+ ff_sws_op_list_remove_at(ops, n, 2);
+ continue;
+ }
+ break;
+
+ case SWS_OP_UNPACK:
+ /* Redundant unpack+pack */
+ if (next->op == SWS_OP_PACK && next->type == op->type &&
+ next->pack.pattern[0] == op->pack.pattern[0] &&
+ next->pack.pattern[1] == op->pack.pattern[1] &&
+ next->pack.pattern[2] == op->pack.pattern[2] &&
+ next->pack.pattern[3] == op->pack.pattern[3])
+ {
+ ff_sws_op_list_remove_at(ops, n, 2);
+ continue;
+ }
+
+ /* Skip unpacking components that are not used */
+ for (int i = 3; i > 0 && next->comps.unused[i]; i--)
+ op->pack.pattern[i] = 0;
+ break;
+
+ case SWS_OP_PACK:
+ /* Skip packing known-to-be-zero components */
+ for (int i = 3; i > 0; i--) {
+ if (!(prev->comps.flags[i] & SWS_COMP_ZERO))
+ break;
+ op->pack.pattern[i] = 0;
+ }
+ break;
+
+ case SWS_OP_LSHIFT:
+ case SWS_OP_RSHIFT:
+ /* Two shifts in the same direction */
+ if (next->op == op->op) {
+ op->c.u += next->c.u;
+ ff_sws_op_list_remove_at(ops, n + 1, 1);
+ continue;
+ }
+
+ /* No-op shift */
+ if (!op->c.u) {
+ ff_sws_op_list_remove_at(ops, n, 1);
+ continue;
+ }
+ break;
+
+ case SWS_OP_CLEAR:
+ for (int i = 0; i < 4; i++) {
+ if (!op->c.q4[i].den)
+ continue;
+
+ if ((prev->comps.flags[i] & SWS_COMP_ZERO) &&
+ !(prev->comps.flags[i] & SWS_COMP_GARBAGE) &&
+ op->c.q4[i].num == 0)
+ {
+ /* Redundant clear-to-zero of zero component */
+ op->c.q4[i].den = 0;
+ } else if (next->comps.unused[i]) {
+ /* Unnecessary clear of unused component */
+ op->c.q4[i] = (AVRational) {0, 0};
+ } else if (op->c.q4[i].den) {
+ noop = false;
+ }
+ }
+
+ if (noop) {
+ ff_sws_op_list_remove_at(ops, n, 1);
+ continue;
+ }
+
+ /* Transitive clear */
+ if (next->op == SWS_OP_CLEAR) {
+ for (int i = 0; i < 4; i++) {
+ if (next->c.q4[i].den)
+ op->c.q4[i] = next->c.q4[i];
+ }
+ ff_sws_op_list_remove_at(ops, n + 1, 1);
+ continue;
+ }
+
+ /* Prefer to clear as late as possible, to avoid doing
+ * redundant work */
+ if ((op_type_is_independent(next->op) && next->op !=
SWS_OP_SWAP_BYTES) ||
+ next->op == SWS_OP_SWIZZLE)
+ {
+ if (next->op == SWS_OP_CONVERT)
+ op->type = next->convert.to;
+ ff_sws_apply_op_q(next, op->c.q4);
+ swap_ops(op, next);
+ progress = true;
+ continue;
+ }
+ break;
+
+ case SWS_OP_SWIZZLE: {
+ bool seen[4] = {0};
+ bool has_duplicates = false;
+ for (int i = 0; i < 4; i++) {
+ if (next->comps.unused[i])
+ continue;
+ if (op->swizzle.in[i] != i)
+ noop = false;
+ has_duplicates |= seen[op->swizzle.in[i]];
+ seen[op->swizzle.in[i]] = true;
+ }
+
+ /* Identity swizzle */
+ if (noop) {
+ ff_sws_op_list_remove_at(ops, n, 1);
+ continue;
+ }
+
+ /* Transitive swizzle */
+ if (next->op == SWS_OP_SWIZZLE) {
+ const SwsSwizzleOp orig = op->swizzle;
+ for (int i = 0; i < 4; i++)
+ op->swizzle.in[i] = orig.in[next->swizzle.in[i]];
+ op_copy_flags(op, next);
+ ff_sws_op_list_remove_at(ops, n + 1, 1);
+ continue;
+ }
+
+ /* Try to push swizzles with duplicates towards the output */
+ if (has_duplicates && op_type_is_independent(next->op)) {
+ if (next->op == SWS_OP_CONVERT)
+ op->type = next->convert.to;
+ if (next->op == SWS_OP_MIN || next->op == SWS_OP_MAX) {
+ /* Un-swizzle the next operation */
+ const SwsConst c = next->c;
+ for (int i = 0; i < 4; i++) {
+ if (!next->comps.unused[i])
+ next->c.q4[op->swizzle.in[i]] = c.q4[i];
+ }
+ }
+ swap_ops(op, next);
+ progress = true;
+ continue;
+ }
+ break;
+ }
+
+ case SWS_OP_CONVERT:
+ /* No-op conversion */
+ if (op->type == op->convert.to) {
+ ff_sws_op_list_remove_at(ops, n, 1);
+ continue;
+ }
+
+ /* Transitive conversion */
+ if (next->op == SWS_OP_CONVERT &&
+ op->convert.expand == next->convert.expand)
+ {
+ av_assert1(op->convert.to == next->type);
+ op->convert.to = next->convert.to;
+ op_copy_flags(op, next);
+ ff_sws_op_list_remove_at(ops, n + 1, 1);
+ continue;
+ }
+
+ /* Conversion followed by integer expansion */
+ if (next->op == SWS_OP_SCALE &&
+ !av_cmp_q(next->c.q, expand_factor(op->type,
op->convert.to)))
+ {
+ op->convert.expand = true;
+ ff_sws_op_list_remove_at(ops, n + 1, 1);
+ continue;
+ }
+ break;
+
+ case SWS_OP_MIN:
+ for (int i = 0; i < 4; i++) {
+ if (next->comps.unused[i] || !op->c.q4[i].den)
+ continue;
+ if (av_cmp_q(op->c.q4[i], prev->comps.max[i]) < 0)
+ noop = false;
+ }
+
+ if (noop) {
+ ff_sws_op_list_remove_at(ops, n, 1);
+ continue;
+ }
+ break;
+
+ case SWS_OP_MAX:
+ for (int i = 0; i < 4; i++) {
+ if (next->comps.unused[i] || !op->c.q4[i].den)
+ continue;
+ if (av_cmp_q(prev->comps.min[i], op->c.q4[i]) < 0)
+ noop = false;
+ }
+
+ if (noop) {
+ ff_sws_op_list_remove_at(ops, n, 1);
+ continue;
+ }
+ break;
+
+ case SWS_OP_DITHER:
+ for (int i = 0; i < 4; i++) {
+ noop &= (prev->comps.flags[i] & SWS_COMP_EXACT) ||
+ next->comps.unused[i];
+ }
+
+ if (noop) {
+ ff_sws_op_list_remove_at(ops, n, 1);
+ continue;
+ }
+ break;
+
+ case SWS_OP_LINEAR: {
+ SwsSwizzleOp swizzle;
+ SwsConst c;
+
+ /* No-op (identity) linear operation */
+ if (!op->lin.mask) {
+ ff_sws_op_list_remove_at(ops, n, 1);
+ continue;
+ }
+
+ if (next->op == SWS_OP_LINEAR) {
+ /* 5x5 matrix multiplication after appending [ 0 0 0 0 1 ]
*/
+ const SwsLinearOp m1 = op->lin;
+ const SwsLinearOp m2 = next->lin;
+ for (int i = 0; i < 4; i++) {
+ for (int j = 0; j < 5; j++) {
+ AVRational sum = Q(0);
+ for (int k = 0; k < 4; k++)
+ sum = av_add_q(sum, av_mul_q(m2.m[i][k],
m1.m[k][j]));
+ if (j == 4) /* m1.m[4][j] == 1 */
+ sum = av_add_q(sum, m2.m[i][4]);
+ op->lin.m[i][j] = sum;
+ }
+ }
+ op_copy_flags(op, next);
+ op->lin.mask = ff_sws_linear_mask(op->lin);
+ ff_sws_op_list_remove_at(ops, n + 1, 1);
+ continue;
+ }
+
+ /* Optimize away zero columns */
+ for (int j = 0; j < 4; j++) {
+ const uint32_t col = SWS_MASK_COL(j);
+ if (!(prev->comps.flags[j] & SWS_COMP_ZERO) ||
!(op->lin.mask & col))
+ continue;
+ for (int i = 0; i < 4; i++)
+ op->lin.m[i][j] = Q(i == j);
+ op->lin.mask &= ~col;
+ changed = true;
+ }
+
+ /* Optimize away unused rows */
+ for (int i = 0; i < 4; i++) {
+ const uint32_t row = SWS_MASK_ROW(i);
+ if (!next->comps.unused[i] || !(op->lin.mask & row))
+ continue;
+ for (int j = 0; j < 5; j++)
+ op->lin.m[i][j] = Q(i == j);
+ op->lin.mask &= ~row;
+ changed = true;
+ }
+
+ if (changed) {
+ progress = true;
+ continue;
+ }
+
+ /* Convert constant rows to explicit clear instruction */
+ if (extract_constant_rows(&op->lin, prev->comps, &c)) {
+ RET(ff_sws_op_list_insert_at(ops, n + 1, &(SwsOp) {
+ .op = SWS_OP_CLEAR,
+ .type = op->type,
+ .comps = op->comps,
+ .c = c,
+ }));
+ continue;
+ }
+
+ /* Multiplication by scalar constant */
+ if (extract_scalar(&op->lin, prev->comps, next->comps, &c)) {
+ op->op = SWS_OP_SCALE;
+ op->c = c;
+ progress = true;
+ continue;
+ }
+
+ /* Swizzle by fixed pattern */
+ if (extract_swizzle(&op->lin, prev->comps, &swizzle)) {
+ RET(ff_sws_op_list_insert_at(ops, n, &(SwsOp) {
+ .op = SWS_OP_SWIZZLE,
+ .type = op->type,
+ .swizzle = swizzle,
+ }));
+ continue;
+ }
+ break;
+ }
+
+ case SWS_OP_SCALE: {
+ const int factor2 = exact_log2_q(op->c.q);
+
+ /* No-op scaling */
+ if (op->c.q.num == 1 && op->c.q.den == 1) {
+ ff_sws_op_list_remove_at(ops, n, 1);
+ continue;
+ }
+
+ /* Scaling by integer before conversion to int */
+ if (op->c.q.den == 1 &&
+ next->op == SWS_OP_CONVERT &&
+ ff_sws_pixel_type_is_int(next->convert.to))
+ {
+ op->type = next->convert.to;
+ swap_ops(op, next);
+ progress = true;
+ continue;
+ }
+
+ /* Scaling by exact power of two */
+ if (factor2 && ff_sws_pixel_type_is_int(op->type)) {
+ op->op = factor2 > 0 ? SWS_OP_LSHIFT : SWS_OP_RSHIFT;
+ op->c.u = FFABS(factor2);
+ progress = true;
+ continue;
+ }
+ break;
+ }
+ }
+
+ /* No optimization triggered, move on to next operation */
+ n++;
+ }
+ } while (prev_num_ops != ops->num_ops || progress);
+
+ return 0;
+}
--
2.49.0
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