[FFmpeg-devel] [PATCH 15/19] swscale/graph: add new high-level scaler dispatch mechanism
Niklas Haas
ffmpeg at haasn.xyz
Fri Oct 11 01:27:02 EEST 2024
From: Niklas Haas <git at haasn.dev>
This interface has been designed from the ground up to serve as a new
framework for dispatching various scaling operations at a high level. This
will eventually replace the old ad-hoc system of using cascaded contexts,
as well as allowing us to plug in more dynamic scaling passes requiring
intermediate steps, such as colorspace conversions, etc.
The starter implementation merely piggybacks off the existing sws_init() and
sws_scale(), functions, though it does bring the immediate improvement of
splitting up cascaded functions and pre/post conversion functions into
separate filter passes, which allows them to e.g. be executed in parallel
even when the main scaler is required to be single threaded.
Follow-up commits will eventually expand this to move all of the scaling
decision logic into the graph init function, and also eliminate some of the
current special cases.
Sponsored-by: Sovereign Tech Fund
Signed-off-by: Niklas Haas <git at haasn.dev>
---
libswscale/Makefile | 1 +
libswscale/graph.c | 501 ++++++++++++++++++++++++++++++++++++++++++++
libswscale/graph.h | 123 +++++++++++
3 files changed, 625 insertions(+)
create mode 100644 libswscale/graph.c
create mode 100644 libswscale/graph.h
diff --git a/libswscale/Makefile b/libswscale/Makefile
index 757997b401..81f32f4dd7 100644
--- a/libswscale/Makefile
+++ b/libswscale/Makefile
@@ -9,6 +9,7 @@ OBJS = alphablend.o \
hscale.o \
hscale_fast_bilinear.o \
gamma.o \
+ graph.o \
half2float.o \
input.o \
options.o \
diff --git a/libswscale/graph.c b/libswscale/graph.c
new file mode 100644
index 0000000000..ac438ae2c0
--- /dev/null
+++ b/libswscale/graph.c
@@ -0,0 +1,501 @@
+/*
+ * Copyright (C) 2024 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/error.h"
+#include "libavutil/mem.h"
+#include "libavutil/opt.h"
+#include "libavutil/pixdesc.h"
+#include "libavutil/slicethread.h"
+
+#include "libswscale/swscale.h"
+
+#include "swscale_internal.h"
+#include "graph.h"
+
+/* slice_align should be a power of two, or 0 to disable slice threading */
+static SwsPass *pass_add(SwsGraph *graph, void *priv, int w, int h,
+ SwsField in, SwsField out, int slice_align)
+{
+ SwsPass *pass = av_mallocz(sizeof(*pass));
+ int ret;
+
+ pass->graph = graph;
+ pass->input = in;
+ pass->output = out;
+ pass->priv = priv;
+ pass->width = w;
+ pass->height = h;
+
+ if (!slice_align) {
+ pass->slice_h = pass->height;
+ pass->num_slices = 1;
+ } else {
+ pass->slice_h = (pass->height + graph->num_threads - 1) / graph->num_threads;
+ pass->slice_h = FFALIGN(pass->slice_h, slice_align);
+ pass->num_slices = (pass->height + pass->slice_h - 1) / pass->slice_h;
+ }
+
+ ret = av_dynarray_add_nofree(&graph->passes, &graph->num_passes, pass);
+ if (ret < 0)
+ av_freep(&pass);
+ return pass;
+}
+
+/* Set output linesize before calling this */
+static int pass_alloc_output(SwsPass *pass)
+{
+ const int aligned_h = pass->num_slices * pass->slice_h;
+ const int *linesize = pass->output.linesize;
+
+ size_t offset[4];
+ size_t total_size = 0;
+ for (int i = 0; i < 4; i++) {
+ const size_t size = FFABS(linesize[i]) * aligned_h;
+ offset[i] = total_size;
+ total_size = FFALIGN(total_size + size, 16);
+ }
+
+ av_assert0(!pass->buf);
+ pass->buf = av_malloc(total_size);
+ if (!pass->buf)
+ return AVERROR(ENOMEM);
+
+ for (int i = 0; i < 4; i++) {
+ uint8_t *base = pass->buf + offset[i];
+ if (linesize[i] < 0)
+ base -= linesize[i] * (aligned_h - 1);
+ pass->output.data[i] = linesize[i] ? base : NULL;
+ }
+
+ return 0;
+}
+
+static void setup_swscale(const SwsField *out, const SwsField *in,
+ const SwsPass *pass)
+{
+ SwsInternal *c = pass->priv;
+ if (c->opts.flags & SWS_BITEXACT && c->opts.dither == SWS_DITHER_ED && c->dither_error[0]) {
+ for (int i = 0; i < 4; i++)
+ memset(c->dither_error[i], 0, sizeof(c->dither_error[0][0]) * (c->opts.dst_w + 2));
+ }
+
+ if (usePal(c->opts.src_format))
+ ff_update_palette(c, (const uint32_t *) in->data[1]);
+}
+
+static void run_rgb0(const SwsField *out, const SwsField *in, int y, int h,
+ const SwsPass *pass)
+{
+ SwsInternal *c = pass->priv;
+ const int x0 = c->src0Alpha - 1;
+ const int w4 = 4 * pass->width;
+ const int src_stride = in->linesize[0];
+ const int dst_stride = out->linesize[0];
+ const uint8_t *src = in->data[0] + y * src_stride;
+ uint8_t *dst = out->data[0] + y * dst_stride;
+
+ for (int y = 0; y < h; y++) {
+ memcpy(dst, src, w4 * sizeof(*dst));
+ for (int x = x0; x < w4; x += 4)
+ dst[x] = 0xFF;
+
+ src += src_stride;
+ dst += dst_stride;
+ }
+}
+
+static void run_xyz2rgb(const SwsField *out, const SwsField *in, int y, int h,
+ const SwsPass *pass)
+{
+ ff_xyz12Torgb48(pass->priv, out->data[0] + y * out->linesize[0], out->linesize[0],
+ in->data[0] + y * in->linesize[0], in->linesize[0],
+ pass->width, h);
+}
+
+static void run_rgb2xyz(const SwsField *out, const SwsField *in, int y, int h,
+ const SwsPass *pass)
+{
+ ff_rgb48Toxyz12(pass->priv, out->data[0] + y * out->linesize[0], out->linesize[0],
+ in->data[0] + y * in->linesize[0], in->linesize[0],
+ pass->width, h);
+}
+
+static void run_unscaled(const SwsField *out, const SwsField *in, int y, int h,
+ const SwsPass *pass)
+{
+ SwsInternal *c = pass->priv;
+ const uint8_t *src_data[4];
+
+ for (int i = 0; i < 4; i++) {
+ const int vshift = (i == 1 || i == 2) ? c->chrSrcVSubSample : 0;
+ src_data[i] = in->data[i];
+ if (src_data[i] && (!i || !usePal(c->opts.src_format)))
+ src_data[i] += (y >> vshift) * in->linesize[i];
+ }
+
+ c->convert_unscaled(c, src_data, in->linesize, y, h, out->data, out->linesize);
+}
+
+static void run_swscale(const SwsField *out, const SwsField *in, int y, int h,
+ const SwsPass *pass)
+{
+ SwsInternal *c = pass->priv;
+ const SwsGraph *const graph = pass->graph;
+ const int src_h = graph->src.height;
+ const int sub_y = graph->dst.desc->log2_chroma_h;
+ const uint8_t *src_data[4];
+ uint8_t *dst_data[4];
+ int src_stride[4];
+
+ if (pass->num_slices > 1) {
+ SwsInternal *parent = c;
+ av_assert1(c->nb_slice_ctx == pass->num_slices);
+ c = sws_internal(c->slice_ctx[y / pass->slice_h]);
+
+ if (usePal(c->opts.src_format)) {
+ memcpy(c->pal_yuv, parent->pal_yuv, sizeof(c->pal_yuv));
+ memcpy(c->pal_rgb, parent->pal_rgb, sizeof(c->pal_rgb));
+ }
+ }
+
+ for (int i = 0; i < 4; i++) {
+ const int vshift = (i == 1 || i == 2) ? sub_y : 0;
+ src_stride[i] = in->linesize[i];
+ src_data[i] = in->data[i];
+ dst_data[i] = out->data[i];
+ if (dst_data[i] && (!i || !usePal(c->opts.dst_format)))
+ dst_data[i] += (y >> vshift) * out->linesize[i];
+ }
+
+ ff_swscale(c, src_data, src_stride, 0, src_h, dst_data, out->linesize, y, h);
+}
+
+static void get_chroma_pos(SwsGraph *graph, int *h_chr_pos, int *v_chr_pos,
+ const SwsFormat *fmt)
+{
+ enum AVChromaLocation chroma_loc = fmt->loc;
+ const int sub_x = fmt->desc->log2_chroma_w;
+ const int sub_y = fmt->desc->log2_chroma_h;
+ int x_pos, y_pos;
+
+ /* Explicitly default to center siting for compatibility with swscale */
+ if (chroma_loc == AVCHROMA_LOC_UNSPECIFIED) {
+ chroma_loc = AVCHROMA_LOC_CENTER;
+ graph->incomplete |= sub_x || sub_y;
+ }
+
+ /* av_chroma_location_enum_to_pos() always gives us values in the range from
+ * 0 to 256, but we need to adjust this to the true value range of the
+ * subsampling grid, which may be larger for h/v_sub > 1 */
+ av_chroma_location_enum_to_pos(&x_pos, &y_pos, chroma_loc);
+ x_pos *= (1 << sub_x) - 1;
+ y_pos *= (1 << sub_y) - 1;
+
+ /* Fix vertical chroma position for interlaced frames */
+ if (sub_y && fmt->interlaced) {
+ /* When vertically subsampling, chroma samples are effectively only
+ * placed next to even rows. To access them from the odd field, we need
+ * to account for this shift by offsetting the distance of one luma row.
+ *
+ * For 4x vertical subsampling (v_sub == 2), they are only placed
+ * next to every *other* even row, so we need to shift by three luma
+ * rows to get to the chroma sample. */
+ if (graph->field == FIELD_BOTTOM)
+ y_pos += (256 << sub_y) - 256;
+
+ /* Luma row distance is doubled for fields, so halve offsets */
+ y_pos >>= 1;
+ }
+
+ /* Explicitly strip chroma offsets when not subsampling, because it
+ * interferes with the operation of flags like SWS_FULL_CHR_H_INP */
+ *h_chr_pos = sub_x ? x_pos : -513;
+ *v_chr_pos = sub_y ? y_pos : -513;
+}
+
+static int init_pass(SwsGraph *graph, SwsContext *sws,
+ SwsField input, SwsField output)
+{
+ SwsInternal *c = sws_internal(sws);
+ const int src_w = c->opts.src_w, src_h = c->opts.src_h;
+ const int dst_w = c->opts.dst_w, dst_h = c->opts.dst_h;
+ const int unscaled = src_w == dst_w && src_h == dst_h;
+ int align = c->dst_slice_align;
+ SwsPass *pass;
+ int ret;
+
+ if (c->cascaded_context[0]) {
+ const int num_cascaded = c->cascaded_context[2] ? 3 : 2;
+ for (int i = 0; i < num_cascaded; i++) {
+ SwsContext *sub = c->cascaded_context[i];
+
+ if (i + 1 == num_cascaded) {
+ ret = init_pass(graph, sub, input, output);
+ } else {
+ /* Steal the intermediate buffers that were already allocated */
+ SwsField tmp;
+ av_assert1(i < FF_ARRAY_ELEMS(c->cascaded_tmp));
+ memcpy(tmp.data, c->cascaded_tmp[i], sizeof(tmp.data));
+ memcpy(tmp.linesize, c->cascaded_tmpStride[i], sizeof(tmp.linesize));
+
+ ret = init_pass(graph, sub, input, tmp);
+ input = tmp;
+ }
+
+ if (ret < 0)
+ return ret;
+ }
+
+ return 0;
+ }
+
+ if (c->opts.dither == SWS_DITHER_ED && !c->convert_unscaled)
+ align = 0; /* disable slice threading */
+
+ if (c->src0Alpha && !c->dst0Alpha && isALPHA(c->opts.dst_format)) {
+ SwsField tmp = { .linesize = { FFALIGN(src_w * sizeof(uint8_t[4]), 16) }};
+ SwsPass *sub = pass_add(graph, c, src_w, src_h, input, tmp, 1);
+ if (!sub || pass_alloc_output(sub) < 0)
+ return AVERROR(ENOMEM);
+ sub->run = run_rgb0;
+ input = sub->output;
+ }
+
+ if (c->srcXYZ && !(c->dstXYZ && unscaled)) {
+ SwsField tmp = { .linesize = { FFALIGN(src_w * sizeof(uint16_t[3]), 16) }};
+ SwsPass *sub = pass_add(graph, c, src_w, src_h, input, tmp, 1);
+ if (!sub || pass_alloc_output(sub) < 0)
+ return AVERROR(ENOMEM);
+ sub->run = run_xyz2rgb;
+ input = sub->output;
+ }
+
+ pass = pass_add(graph, c, dst_w, dst_h, input, output, align);
+ if (!pass)
+ return AVERROR(ENOMEM);
+ pass->setup = setup_swscale;
+ pass->run = c->convert_unscaled ? run_unscaled : run_swscale;
+
+ /**
+ * For slice threading, we need to create sub contexts, similar to how
+ * swscale normally handles it internally. The most important difference
+ * is that we handle cascaded contexts before threaded contexts; whereas
+ * context_init_threaded() does it the other way around.
+ */
+
+ if (pass->num_slices > 1 && !c->convert_unscaled) {
+ c->slice_ctx = av_calloc(pass->num_slices, sizeof(*c->slice_ctx));
+ if (!c->slice_ctx)
+ return AVERROR(ENOMEM);
+
+ for (int i = 0; i < pass->num_slices; i++) {
+ SwsInternal *c2;
+ c->slice_ctx[i] = sws_alloc_context();
+ if (!c->slice_ctx[i])
+ return AVERROR(ENOMEM);
+ c->nb_slice_ctx++;
+
+ c2 = sws_internal(c->slice_ctx[i]);
+ c2->parent = sws;
+ c2->opts = c->opts;
+
+ ret = sws_init_single_context(c->slice_ctx[i], NULL, NULL);
+ if (ret < 0)
+ return ret;
+
+ sws_setColorspaceDetails(c->slice_ctx[i], c->srcColorspaceTable,
+ c->opts.src_range, c->dstColorspaceTable,
+ c->opts.dst_range, c->brightness, c->contrast,
+ c->saturation);
+
+ for (int i = 0; i < FF_ARRAY_ELEMS(c->srcColorspaceTable); i++) {
+ c2->srcColorspaceTable[i] = c->srcColorspaceTable[i];
+ c2->dstColorspaceTable[i] = c->dstColorspaceTable[i];
+ }
+ }
+ }
+
+ if (c->dstXYZ && !(c->srcXYZ && unscaled)) {
+ SwsPass *sub = pass_add(graph, c, dst_w, dst_h, output, output, 1);
+ if (!sub)
+ return AVERROR(ENOMEM);
+ sub->run = run_rgb2xyz;
+ }
+
+ return 0;
+}
+
+static int init_passes(SwsGraph *graph)
+{
+ SwsContext *const ctx = graph->ctx;
+ const SwsFormat *const src = &graph->src;
+ const SwsFormat *const dst = &graph->dst;
+ const SwsDither dither = ctx->dither;
+ SwsContext *sws;
+ int ret;
+
+ graph->incomplete |= src->range == AVCOL_RANGE_UNSPECIFIED;
+ graph->incomplete |= dst->range == AVCOL_RANGE_UNSPECIFIED;
+
+ sws = graph->sws = sws_alloc_context();
+ if (!sws)
+ return AVERROR(ENOMEM);
+
+ sws->flags = ctx->flags;
+ sws->dither = dither;
+ sws->src_w = src->width;
+ sws->src_h = src->height;
+ sws->src_format = src->format;
+ sws->src_range = src->range == AVCOL_RANGE_JPEG;
+
+ sws->dst_w = dst->width;
+ sws->dst_h = dst->height;
+ sws->dst_format = dst->format;
+ sws->dst_range = dst->range == AVCOL_RANGE_JPEG;
+ get_chroma_pos(graph, &sws->src_h_chr_pos, &sws->src_v_chr_pos, src);
+ get_chroma_pos(graph, &sws->dst_h_chr_pos, &sws->dst_v_chr_pos, dst);
+
+ ret = sws_init_context(sws, NULL, NULL);
+ if (ret < 0)
+ return ret;
+
+ /* Set correct color matrices */
+ {
+ int in_full, out_full, brightness, contrast, saturation;
+ const int *inv_table, *table;
+ sws_getColorspaceDetails(sws, (int **)&inv_table, &in_full,
+ (int **)&table, &out_full,
+ &brightness, &contrast, &saturation);
+
+ inv_table = sws_getCoefficients(src->csp);
+ table = sws_getCoefficients(dst->csp);
+
+ graph->incomplete |= src->csp != dst->csp &&
+ src->csp == AVCOL_SPC_UNSPECIFIED ||
+ dst->csp == AVCOL_SPC_UNSPECIFIED;
+
+ sws_setColorspaceDetails(sws, inv_table, in_full, table, out_full,
+ brightness, contrast, saturation);
+ }
+
+ ret = init_pass(graph, sws, SWS_INPUT, SWS_OUTPUT);
+ if (ret < 0)
+ return ret;
+
+ return 0;
+}
+
+const uint8_t sws_input_sentinel, sws_output_sentinel;
+
+static const SwsField *resolve_field(SwsGraph *graph, const SwsField *field)
+{
+ if (field->data[0] == &sws_input_sentinel)
+ return &graph->exec.input;
+ else if (field->data[0] == &sws_output_sentinel)
+ return &graph->exec.output;
+ else
+ return field;
+}
+
+static void sws_graph_worker(void *priv, int jobnr, int threadnr, int nb_jobs,
+ int nb_threads)
+{
+ SwsGraph *graph = priv;
+ const SwsPass *pass = graph->exec.pass;
+ const SwsField *input = resolve_field(graph, &pass->input);
+ const SwsField *output = resolve_field(graph, &pass->output);
+ const int slice_y = jobnr * pass->slice_h;
+ const int slice_h = FFMIN(pass->slice_h, pass->height - slice_y);
+
+ pass->run(output, input, slice_y, slice_h, pass);
+}
+
+int sws_graph_create(SwsContext *ctx, const SwsFormat *dst, const SwsFormat *src,
+ int field, SwsGraph **out_graph)
+{
+ int ret;
+ SwsGraph *graph = av_mallocz(sizeof(*graph));
+ if (!graph)
+ return AVERROR(ENOMEM);
+
+ graph->ctx = ctx;
+ graph->src = *src;
+ graph->dst = *dst;
+ graph->field = field;
+ graph->opts = *ctx;
+ graph->opts.internal = NULL; /* sanity */
+
+ ret = avpriv_slicethread_create(&graph->slicethread, (void *) graph,
+ sws_graph_worker, NULL, ctx->threads);
+ if (ret == AVERROR(ENOSYS))
+ graph->num_threads = 1;
+ else if (ret < 0)
+ goto error;
+ else
+ graph->num_threads = ret;
+
+ ret = init_passes(graph);
+ if (ret < 0)
+ goto error;
+
+ *out_graph = graph;
+ return 0;
+
+error:
+ sws_graph_free(&graph);
+ return ret;
+}
+
+void sws_graph_free(SwsGraph **pgraph)
+{
+ SwsGraph *graph = *pgraph;
+ if (!graph)
+ return;
+
+ avpriv_slicethread_free(&graph->slicethread);
+
+ for (int i = 0; i < graph->num_passes; i++) {
+ SwsPass *pass = graph->passes[i];
+ if (pass->uninit)
+ pass->uninit(pass);
+ av_free(pass->buf);
+ av_free(pass);
+ }
+ av_free(graph->passes);
+
+ sws_freeContext(graph->sws);
+ av_free(graph);
+ *pgraph = NULL;
+}
+
+void sws_graph_run(SwsGraph *graph, const SwsField *out, const SwsField *in)
+{
+ graph->exec.input = *in;
+ graph->exec.output = *out;
+
+ for (int i = 0; i < graph->num_passes; i++) {
+ const SwsPass *pass = graph->passes[i];
+ graph->exec.pass = pass;
+ if (pass->setup)
+ pass->setup(out, in, pass);
+ avpriv_slicethread_execute(graph->slicethread, pass->num_slices, 0);
+ }
+}
diff --git a/libswscale/graph.h b/libswscale/graph.h
new file mode 100644
index 0000000000..afa2c134d7
--- /dev/null
+++ b/libswscale/graph.h
@@ -0,0 +1,123 @@
+/*
+ * Copyright (C) 2024 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_GRAPH_H
+#define SWSCALE_GRAPH_H
+
+#include "libavutil/slicethread.h"
+#include "swscale.h"
+#include "utils.h"
+
+/* Represents a view into a single field of frame data */
+typedef struct SwsField {
+ uint8_t *data[4]; /* points to y=0 */
+ int linesize[4];
+} SwsField;
+
+enum {
+ FIELD_TOP, /* top/even rows, or progressive */
+ FIELD_BOTTOM, /* bottom/odd rows */
+};
+
+/**
+ * Sentinel values to refer to the overall image input / output during
+ * filter graph construction, as the true values are not known.
+ */
+extern const uint8_t sws_input_sentinel, sws_output_sentinel;
+#define SWS_INPUT ((SwsField) {{ (uint8_t *) &sws_input_sentinel }})
+#define SWS_OUTPUT ((SwsField) {{ (uint8_t *) &sws_output_sentinel }})
+
+typedef struct SwsPass SwsPass;
+typedef struct SwsGraph SwsGraph;
+
+struct SwsPass {
+ const SwsGraph *graph;
+ uint8_t *buf; /* temporary buffer for this pass, freed automatically */
+
+ int width, height; /* new output size */
+ int pixel_bytes; /* bytes per pixel */
+ int slice_h; /* filter granularity */
+ int num_slices;
+
+ /* Filter input/output. */
+ SwsField input;
+ SwsField output;
+
+ /**
+ * Called once from the main thread before running the filter. Optional.
+ * `out` and `in` always point to the main image input/output, regardless
+ * of `input` and `output` fields.
+ */
+ void (*setup)(const SwsField *out, const SwsField *in,
+ const SwsPass *pass);
+
+ /**
+ * Output `slice_h` lines of filtered data. `src` and `dst` point to the
+ * start of the image buffer for this pass.
+ */
+ void (*run)(const SwsField *out, const SwsField *in, int y, int h,
+ const SwsPass *pass);
+
+ void (*uninit)(const SwsPass *pass); /* optional */
+ void *priv;
+};
+
+/* Filter graph, which represents a 'baked' pixel format conversion */
+typedef struct SwsGraph {
+ SwsContext *ctx;
+ AVSliceThread *slicethread;
+ int num_threads; /* resolved at init() time */
+ int incomplete; /* set during init() if formats had to be inferred */
+ SwsContext *sws; /* wrapped legacy context */
+
+ /* Sorted sequence of filter passes to apply */
+ SwsPass **passes;
+ int num_passes;
+
+ /* Overall image parameters and flags */
+ SwsContext opts;
+ SwsFormat src, dst;
+ int field;
+
+ /* Temporary execution state inside sws_graph_run */
+ struct {
+ const SwsPass *pass; /* current filter pass */
+ SwsField input;
+ SwsField output;
+ } exec;
+} SwsGraph;
+
+/**
+ * Allocate and initialize the filter graph. Returns 0 or a negative error.
+ */
+int sws_graph_create(SwsContext *ctx, const SwsFormat *dst, const SwsFormat *src,
+ int field, SwsGraph **out_graph);
+
+/**
+ * Uninitialize any state associate with this filter graph and free it.
+ */
+void sws_graph_free(SwsGraph **graph);
+
+/**
+ * Dispatch the filter graph on a single field. Internally threaded.
+ */
+void sws_graph_run(SwsGraph *graph, const SwsField *out, const SwsField *in);
+
+#endif /* SWSCALE_GRAPH_H */
--
2.46.1
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