From bf738412e849bcb8c63a330dfb814281b3d97f6b Mon Sep 17 00:00:00 2001 From: Niklas Haas Date: Thu, 10 Oct 2024 16:39:20 +0200 Subject: [PATCH] swscale/graph: add new high-level scaler dispatch mechanism 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. Additionally, a dedicated (multi-threaded) noop memcpy pass substantially improves throughput of that fast path. 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 --- libswscale/Makefile | 1 + libswscale/graph.c | 617 ++++++++++++++++++++++++++++++++++++++++++++ libswscale/graph.h | 152 +++++++++++ 3 files changed, 770 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..ee9d9847a9 --- /dev/null +++ b/libswscale/graph.c @@ -0,0 +1,617 @@ +/* + * 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/imgutils.h" +#include "libavutil/macros.h" +#include "libavutil/mem.h" +#include "libavutil/opt.h" +#include "libavutil/pixdesc.h" +#include "libavutil/slicethread.h" + +#include "libswscale/swscale.h" +#include "libswscale/utils.h" + +#include "swscale_internal.h" +#include "graph.h" + +static int pass_alloc_output(SwsPass *pass) +{ + if (!pass || pass->output.fmt != AV_PIX_FMT_NONE) + return 0; + pass->output.fmt = pass->format; + return av_image_alloc(pass->output.data, pass->output.linesize, pass->width, + pass->num_slices * pass->slice_h, pass->format, 64); +} + +/* slice_align should be a power of two, or 0 to disable slice threading */ +static SwsPass *pass_add(SwsGraph *graph, void *priv, enum AVPixelFormat fmt, + int w, int h, SwsPass *input, int slice_align, + sws_filter_run_t run) +{ + int ret; + SwsPass *pass = av_mallocz(sizeof(*pass)); + if (!pass) + return NULL; + + pass->graph = graph; + pass->run = run; + pass->priv = priv; + pass->format = fmt; + pass->width = w; + pass->height = h; + pass->input = input; + pass->output.fmt = AV_PIX_FMT_NONE; + + ret = pass_alloc_output(input); + if (ret < 0) { + av_free(pass); + return NULL; + } + + 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; +} + +/* Wrapper around pass_add that chains a pass "in-place" */ +static int pass_append(SwsGraph *graph, void *priv, enum AVPixelFormat fmt, + int w, int h, SwsPass **pass, int slice_align, + sws_filter_run_t run) +{ + SwsPass *new = pass_add(graph, priv, fmt, w, h, *pass, slice_align, run); + if (!new) + return AVERROR(ENOMEM); + *pass = new; + return 0; +} + +static int vshift(enum AVPixelFormat fmt, int plane) +{ + const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(fmt); + return (plane == 1 || plane == 2) ? desc->log2_chroma_h : 0; +} + +/* Shift an image vertically by y lines */ +static SwsImg shift_img(const SwsImg *img_base, int y) +{ + SwsImg img = *img_base; + for (int i = 0; i < 4 && img.data[i]; i++) + img.data[i] += (y >> vshift(img.fmt, i)) * img.linesize[i]; + return img; +} + +static void run_copy(const SwsImg *out_base, const SwsImg *in_base, + int y, int h, const SwsPass *pass) +{ + SwsImg in = shift_img(in_base, y); + SwsImg out = shift_img(out_base, y); + + for (int i = 0; i < FF_ARRAY_ELEMS(in.data) && in.data[i]; i++) { + const int lines = h >> vshift(in.fmt, i); + if (in.linesize[i] == out.linesize[i]) { + memcpy(out.data[i], in.data[i], lines * out.linesize[i]); + } else { + const int linesize = FFMIN(out.linesize[i], in.linesize[i]); + for (int j = 0; j < lines; j++) { + memcpy(out.data[i], in.data[i], linesize); + in.data[i] += in.linesize[i]; + out.data[i] += out.linesize[i]; + } + } + } +} + +static void run_rgb0(const SwsImg *out, const SwsImg *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 SwsImg *out, const SwsImg *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 SwsImg *out, const SwsImg *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); +} + +/*********************************************************************** + * Internal ff_swscale() wrapper. This re-uses the legacy scaling API. * + * This is considered fully deprecated, and will be replaced by a full * + * reimplementation ASAP. * + ***********************************************************************/ + +static void free_legacy_swscale(void *priv) +{ + SwsContext *sws = priv; + sws_free_context(&sws); +} + +static void setup_legacy_swscale(const SwsImg *out, const SwsImg *in, + const SwsPass *pass) +{ + SwsContext *sws = pass->priv; + SwsInternal *c = sws_internal(sws); + if (sws->flags & SWS_BITEXACT && sws->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]) * (sws->dst_w + 2)); + } + + if (usePal(sws->src_format)) + ff_update_palette(c, (const uint32_t *) in->data[1]); +} + +static inline SwsContext *slice_ctx(const SwsPass *pass, int y) +{ + SwsContext *sws = pass->priv; + SwsInternal *parent = sws_internal(sws); + if (pass->num_slices == 1) + return sws; + + av_assert1(parent->nb_slice_ctx == pass->num_slices); + sws = parent->slice_ctx[y / pass->slice_h]; + + if (usePal(sws->src_format)) { + SwsInternal *sub = sws_internal(sws); + memcpy(sub->pal_yuv, parent->pal_yuv, sizeof(sub->pal_yuv)); + memcpy(sub->pal_rgb, parent->pal_rgb, sizeof(sub->pal_rgb)); + } + + return sws; +} + +static void run_legacy_unscaled(const SwsImg *out, const SwsImg *in_base, + int y, int h, const SwsPass *pass) +{ + SwsContext *sws = slice_ctx(pass, y); + SwsInternal *c = sws_internal(sws); + const SwsImg in = shift_img(in_base, y); + + c->convert_unscaled(c, (const uint8_t *const *) in.data, in.linesize, y, h, + out->data, out->linesize); +} + +static void run_legacy_swscale(const SwsImg *out_base, const SwsImg *in, + int y, int h, const SwsPass *pass) +{ + SwsContext *sws = slice_ctx(pass, y); + SwsInternal *c = sws_internal(sws); + const SwsImg out = shift_img(out_base, y); + + ff_swscale(c, (const uint8_t *const *) in->data, in->linesize, 0, + sws->src_h, out.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 void legacy_chr_pos(SwsGraph *graph, int *chr_pos, int override, int *warned) +{ + if (override == -513 || override == *chr_pos) + return; + + if (!*warned) { + av_log(NULL, AV_LOG_WARNING, + "Setting chroma position directly is deprecated, make sure " + "the frame is tagged with the correct chroma location.\n"); + *warned = 1; + } + + *chr_pos = override; +} + +static int init_legacy_subpass(SwsGraph *graph, SwsContext *sws, int cascaded, + SwsPass *input, SwsPass **output) +{ + SwsInternal *c = sws_internal(sws); + const int src_w = sws->src_w, src_h = sws->src_h; + const int dst_w = sws->dst_w, dst_h = sws->dst_h; + const int unscaled = src_w == dst_w && src_h == dst_h; + int align = c->dst_slice_align; + SwsPass *pass = NULL; + 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]; + const int is_last = i + 1 == num_cascaded; + ret = init_legacy_subpass(graph, sub, 1, input, is_last ? output : &input); + if (ret < 0) + return ret; + } + + return 0; + } + + if (sws->dither == SWS_DITHER_ED && !c->convert_unscaled) + align = 0; /* disable slice threading */ + + if (c->src0Alpha && !c->dst0Alpha && isALPHA(sws->dst_format)) { + ret = pass_append(graph, c, AV_PIX_FMT_RGBA, src_w, src_h, &input, 1, run_rgb0); + if (ret < 0) + return ret; + } + + if (c->srcXYZ && !(c->dstXYZ && unscaled)) { + ret = pass_append(graph, c, AV_PIX_FMT_RGB48, src_w, src_h, &input, 1, run_xyz2rgb); + if (ret < 0) + return ret; + } + + pass = pass_add(graph, sws, sws->dst_format, dst_w, dst_h, input, align, + c->convert_unscaled ? run_legacy_unscaled : run_legacy_swscale); + if (!pass) + return AVERROR(ENOMEM); + pass->setup = setup_legacy_swscale; + if (!cascaded) /* parent context frees this automatically */ + pass->free = free_legacy_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->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++) { + SwsContext *slice; + SwsInternal *c2; + slice = c->slice_ctx[i] = sws_alloc_context(); + if (!slice) + return AVERROR(ENOMEM); + c->nb_slice_ctx++; + + c2 = sws_internal(slice); + c2->parent = sws; + + ret = av_opt_copy(slice, sws); + if (ret < 0) + return ret; + + ret = ff_sws_init_single_context(slice, NULL, NULL); + if (ret < 0) + return ret; + + sws_setColorspaceDetails(slice, c->srcColorspaceTable, + slice->src_range, c->dstColorspaceTable, + slice->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)) { + ret = pass_append(graph, c, AV_PIX_FMT_RGB48, dst_w, dst_h, &pass, 1, run_rgb2xyz); + if (ret < 0) + return ret; + } + + *output = pass; + return 0; +} + +static int add_legacy_sws_pass(SwsGraph *graph, SwsFormat src, SwsFormat dst, + SwsPass *input, SwsPass **output) +{ + int ret, warned = 0; + SwsContext *const ctx = graph->ctx; + SwsContext *sws = sws_alloc_context(); + if (!sws) + return AVERROR(ENOMEM); + + sws->flags = ctx->flags; + sws->dither = ctx->dither; + sws->alpha_blend = ctx->alpha_blend; + sws->gamma_flag = ctx->gamma_flag; + + 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); + + graph->incomplete |= src.range == AVCOL_RANGE_UNSPECIFIED; + graph->incomplete |= dst.range == AVCOL_RANGE_UNSPECIFIED; + + /* Allow overriding chroma position with the legacy API */ + legacy_chr_pos(graph, &sws->src_h_chr_pos, ctx->src_h_chr_pos, &warned); + legacy_chr_pos(graph, &sws->src_v_chr_pos, ctx->src_v_chr_pos, &warned); + legacy_chr_pos(graph, &sws->dst_h_chr_pos, ctx->dst_h_chr_pos, &warned); + legacy_chr_pos(graph, &sws->dst_v_chr_pos, ctx->dst_v_chr_pos, &warned); + + ret = sws_init_context(sws, NULL, NULL); + if (ret < 0) { + sws_free_context(&sws); + 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_legacy_subpass(graph, sws, 0, input, output); + if (ret < 0) { + sws_free_context(&sws); + return ret; + } + + return 0; +} + + +/*************************************** + * Main filter graph construction code * + ***************************************/ + +static int init_passes(SwsGraph *graph) +{ + const SwsFormat src = graph->src; + const SwsFormat dst = graph->dst; + SwsPass *pass = NULL; /* read from main input image */ + int ret; + + if (!ff_fmt_equal(&src, &dst)) { + ret = add_legacy_sws_pass(graph, src, dst, pass, &pass); + if (ret < 0) + return ret; + } + + if (!pass) { + /* No passes were added, so no operations were necessary */ + graph->noop = 1; + + /* Add threaded memcpy pass */ + pass = pass_add(graph, NULL, dst.format, dst.width, dst.height, pass, 1, run_copy); + if (!pass) + return AVERROR(ENOMEM); + } + + return 0; +} + +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 SwsImg *input = pass->input ? &pass->input->output : &graph->exec.input; + const SwsImg *output = pass->output.fmt != AV_PIX_FMT_NONE ? &pass->output : &graph->exec.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_copy = *ctx; + + graph->exec.input.fmt = src->format; + graph->exec.output.fmt = dst->format; + + 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->free) + pass->free(pass->priv); + if (pass->output.fmt != AV_PIX_FMT_NONE) + av_free(pass->output.data[0]); + av_free(pass); + } + av_free(graph->passes); + + av_free(graph); + *pgraph = NULL; +} + +/* Tests only options relevant to SwsGraph */ +static int opts_equal(const SwsContext *c1, const SwsContext *c2) +{ + return c1->flags == c2->flags && + c1->threads == c2->threads && + c1->dither == c2->dither && + c1->alpha_blend == c2->alpha_blend && + c1->gamma_flag == c2->gamma_flag && + c1->src_h_chr_pos == c2->src_h_chr_pos && + c1->src_v_chr_pos == c2->src_v_chr_pos && + c1->dst_h_chr_pos == c2->dst_h_chr_pos && + c1->dst_v_chr_pos == c2->dst_v_chr_pos && + !memcmp(c1->scaler_params, c2->scaler_params, sizeof(c1->scaler_params)); + +} + +int sws_graph_reinit(SwsContext *ctx, const SwsFormat *dst, const SwsFormat *src, + int field, SwsGraph **out_graph) +{ + const SwsGraph *graph = *out_graph; + if (graph && ff_fmt_equal(&graph->src, src) && + ff_fmt_equal(&graph->dst, dst) && + opts_equal(ctx, &graph->opts_copy)) + return 0; + + sws_graph_free(out_graph); + return sws_graph_create(ctx, dst, src, field, out_graph); +} + + +void sws_graph_run(SwsGraph *graph, uint8_t *const out_data[4], + const int out_linesize[4], + const uint8_t *const in_data[4], + const int in_linesize[4]) +{ + SwsImg *out = &graph->exec.output; + SwsImg *in = &graph->exec.input; + memcpy(out->data, out_data, sizeof(out->data)); + memcpy(out->linesize, out_linesize, sizeof(out->linesize)); + memcpy(in->data, in_data, sizeof(in->data)); + memcpy(in->linesize, in_linesize, sizeof(in->linesize)); + + 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..989695043d --- /dev/null +++ b/libswscale/graph.h @@ -0,0 +1,152 @@ +/* + * 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 SwsImg { + enum AVPixelFormat fmt; + uint8_t *data[4]; /* points to y=0 */ + int linesize[4]; +} SwsImg; + +typedef struct SwsPass SwsPass; +typedef struct SwsGraph SwsGraph; + +/** + * Output `h` lines of filtered data. `out` and `in` point to the + * start of the image buffer for this pass. + */ +typedef void (*sws_filter_run_t)(const SwsImg *out, const SwsImg *in, + int y, int h, const SwsPass *pass); + +/** + * Represents a single filter pass in the scaling graph. Each filter will + * read from some previous pass's output, and write to a buffer associated + * with the pass (or into the final output image). + */ +struct SwsPass { + const SwsGraph *graph; + + /** + * Filter main execution function. Called from multiple threads, with + * the granularity dictated by `slice_h`. Individual slices sent to `run` + * are always equal to (or smaller than, for the last slice) `slice_h`. + */ + sws_filter_run_t run; + enum AVPixelFormat format; /* new pixel format */ + int width, height; /* new output size */ + int slice_h; /* filter granularity */ + int num_slices; + + /** + * Filter input. This pass's output will be resolved to form this pass's. + * input. If NULL, the original input image is used. + */ + const SwsPass *input; + + /** + * Filter output buffer. Allocated on demand and freed automatically. + */ + SwsImg 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 SwsImg *out, const SwsImg *in, const SwsPass *pass); + + /** + * Optional private state and associated free() function. + */ + void (*free)(void *priv); + 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 */ + int noop; /* set during init() if the graph is a no-op */ + + /** Sorted sequence of filter passes to apply */ + SwsPass **passes; + int num_passes; + + /** + * Cached copy of the public options that were used to construct this + * SwsGraph. Used only to detect when the graph needs to be reinitialized. + */ + SwsContext opts_copy; + + /** + * Currently active format and processing parameters. + */ + SwsFormat src, dst; + int field; + + /** Temporary execution state inside sws_graph_run */ + struct { + const SwsPass *pass; /* current filter pass */ + SwsImg input; + SwsImg 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); + +/** + * Wrapper around sws_graph_create that does nothing if the format is + * unchanged. Must be called after changing any of the fields in `ctx`, or else + * they will have no effect. + */ +int sws_graph_reinit(SwsContext *ctx, const SwsFormat *dst, const SwsFormat *src, + int field, SwsGraph **graph); + +/** + * Dispatch the filter graph on a single field. Internally threaded. + */ +void sws_graph_run(SwsGraph *graph, uint8_t *const out_data[4], + const int out_linesize[4], + const uint8_t *const in_data[4], + const int in_linesize[4]); + +#endif /* SWSCALE_GRAPH_H */