sws_ops.c

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/*
 * 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/avstring.h"
#include "libavutil/mem.h"
#include "libavutil/pixdesc.h"
#include "libavutil/tree.h"
#include "libswscale/ops.h"
#include "libswscale/ops_dispatch.h"
#include "libswscale/format.h"
 
#ifdef _WIN32
#include <io.h>
#include <fcntl.h>
#endif
 
static int pass_idx;
 
static int print_ops(SwsContext *ctx, SwsOpList *ops, SwsCompiledOp *out)
{
    if (pass_idx > 0)
        av_log(NULL, AV_LOG_INFO, " Sub-pass #%d:\n", pass_idx);
 
    ff_sws_op_list_print(NULL, AV_LOG_INFO, AV_LOG_INFO, ops);
    *out = (SwsCompiledOp) {0}; /* dummy value, will be immediately freed */
 
    bool has_filters = false;
    for (int i = 0; i < ops->num_ops; i++) {
        const SwsOp *op = &ops->ops[i];
        if (op->op == SWS_OP_FILTER_H || op->op == SWS_OP_FILTER_V) {
            has_filters = true;
            break;
        }
    }
 
    if (has_filters) {
        av_log(NULL, AV_LOG_INFO, " Retrying with split passes:\n");
        return AVERROR(ENOTSUP);
    }
 
    pass_idx++;
    return 0;
}
 
/* Dummy backend that just prints all seen op lists */
static const SwsOpBackend backend_print = {
    .name    = "print_ops",
    .compile = print_ops,
};
 
static int print_passes(SwsContext *ctx, void *graph, SwsOpList *ops)
{
    av_log(NULL, AV_LOG_INFO, "%s %dx%d -> %s %dx%d:\n",
           av_get_pix_fmt_name(ops->src.format),
           ops->src.width, ops->src.height,
           av_get_pix_fmt_name(ops->dst.format),
           ops->dst.width, ops->dst.height);
 
    if (ff_sws_op_list_is_noop(ops)) {
        av_log(NULL, AV_LOG_INFO, "  (no-op)\n");
        return 0;
    }
 
    /* ff_sws_compile_pass() takes over ownership of `ops` */
    SwsOpList *copy = ff_sws_op_list_duplicate(ops);
    if (!copy)
        return AVERROR(ENOMEM);
 
    pass_idx = 0;
    return ff_sws_compile_pass(graph, &backend_print, &copy, 0, NULL, NULL);
}
 
static int cmp_str(const void *a, const void *b)
{
    return strcmp(a, b);
}
 
static int register_op(SwsContext *ctx, void *opaque, SwsOp *op)
{
    struct AVTreeNode **root = opaque;
    AVBPrint bp;
    char *desc;
 
    /* Strip irrelevant constant data from some operations */
    switch (op->op) {
    case SWS_OP_LINEAR:
        for (int i = 0; i < 4; i++) {
            for (int j = 0; j < 5; j++)
                op->lin.m[i][j] = (AVRational) { 0, 1 };
        }
        break;
    case SWS_OP_SCALE:
        op->scale.factor = (AVRational) { 0, 1 };
        break;
    case SWS_OP_MIN:
    case SWS_OP_MAX:
        for (int i = 0; i < 4; i++)
            op->clamp.limit[i] = (AVRational) { 0, 1 };
        break;
    case SWS_OP_CLEAR:
        for (int i = 0; i < 4; i++)
            op->clear.value[i] = (AVRational) { 0, SWS_COMP_TEST(op->clear.mask, i) };
        break;
    case SWS_OP_DITHER:
        /* Strip arbitrary offset */
        for (int i = 0; i < 4; i++)
            op->dither.y_offset[i] = op->dither.y_offset[i] >= 0 ? 0 : -1;
        break;
    }
 
    av_bprint_init(&bp, 0, AV_BPRINT_SIZE_AUTOMATIC);
    ff_sws_op_desc(&bp, op);
    int ret = av_bprint_finalize(&bp, &desc);
    if (ret < 0)
        return ret;
 
    struct AVTreeNode *node = av_tree_node_alloc();
    if (!node) {
        av_free(desc);
        return AVERROR(ENOMEM);
    }
 
    av_tree_insert(root, desc, cmp_str, &node);
    if (node) {
        av_free(node);
        av_free(desc);
    }
    return ret;
}
 
static int print_and_free_summary(void *opaque, void *key)
{
    char *desc = key;
    av_log(opaque, AV_LOG_INFO, "%s\n", desc);
    av_free(desc);
    return 0;
}
 
static void log_stdout(void *avcl, int level, const char *fmt, va_list vl)
{
    if (level != AV_LOG_INFO) {
        av_log_default_callback(avcl, level, fmt, vl);
    } else if (av_log_get_level() >= AV_LOG_INFO) {
        vfprintf(stdout, fmt, vl);
    }
}
 
int main(int argc, char **argv)
{
    enum AVPixelFormat src_fmt = AV_PIX_FMT_NONE;
    enum AVPixelFormat dst_fmt = AV_PIX_FMT_NONE;
    bool summarize = false;
    int ret = 1;
 
#ifdef _WIN32
    _setmode(_fileno(stdout), _O_BINARY);
#endif
 
    for (int i = 1; i < argc; i++) {
        if (!strcmp(argv[i], "-help") || !strcmp(argv[i], "--help")) {
            fprintf(stderr,
                    "sws_ops [options...]\n"
                    "   -help\n"
                    "       This text\n"
                    "   -dst <pixfmt>\n"
                    "       Only test the specified destination pixel format\n"
                    "   -src <pixfmt>\n"
                    "       Only test the specified source pixel format\n"
                    "   -v <level>\n"
                    "       Enable log verbosity at given level\n"
                    "   -summarize\n"
                    "       Summarize operation types, instead of printing op lists\n"
            );
            return 0;
        }
        if (!strcmp(argv[i], "-src")) {
            if (i + 1 >= argc)
                goto bad_option;
            src_fmt = av_get_pix_fmt(argv[i + 1]);
            if (src_fmt == AV_PIX_FMT_NONE) {
                fprintf(stderr, "invalid pixel format %s\n", argv[i + 1]);
                goto error;
            }
            i++;
        } else if (!strcmp(argv[i], "-dst")) {
            if (i + 1 >= argc)
                goto bad_option;
            dst_fmt = av_get_pix_fmt(argv[i + 1]);
            if (dst_fmt == AV_PIX_FMT_NONE) {
                fprintf(stderr, "invalid pixel format %s\n", argv[i + 1]);
                goto error;
            }
            i++;
        } else if (!strcmp(argv[i], "-v")) {
            if (i + 1 >= argc)
                goto bad_option;
            av_log_set_level(atoi(argv[i + 1]));
            i++;
        } else if (!strcmp(argv[i], "-summarize")) {
            summarize = true;
        } else {
bad_option:
            fprintf(stderr, "bad option or argument missing (%s) see -help\n", argv[i]);
            goto error;
        }
    }
 
    SwsContext *ctx = sws_alloc_context();
    if (!ctx)
        goto fail;
    ctx->scaler = SWS_SCALE_BILINEAR; /* reduce filter generation overhead */
 
    av_log_set_callback(log_stdout);
 
    if (summarize) {
        struct AVTreeNode *root = NULL;
        ret = ff_sws_enum_ops(ctx, &root, src_fmt, dst_fmt, register_op);
        if (ret < 0)
            goto fail;
        av_tree_enumerate(root, NULL, NULL, print_and_free_summary);
        av_tree_destroy(root);
    } else {
        /* Allocate dummy graph and context for ff_sws_compile_pass() */
        SwsGraph *graph = ff_sws_graph_alloc();
        if (!graph) {
            ret = AVERROR(ENOMEM);
            goto fail;
        }
        graph->ctx = ctx;
 
        ret = ff_sws_enum_op_lists(ctx, graph, src_fmt, dst_fmt, print_passes);
        ff_sws_graph_free(&graph);
        if (ret < 0)
            goto fail;
    }
 
    ret = 0;
fail:
    sws_free_context(&ctx);
    return ret;
 
error:
    return AVERROR(EINVAL);
}