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ffmpeg / libavfilter / vf_scale.c @ 5f6cb6eb

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/*
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 * copyright (c) 2007 Bobby Bingham
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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/**
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 * @file libavfilter/vf_scale.c
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 * scale video filter
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 */
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#include "avfilter.h"
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#include "libswscale/swscale.h"
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typedef struct {
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    struct SwsContext *sws;     ///< software scaler context
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    /**
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     * New dimensions. Special values are:
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     *   0 = original width/height
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     *  -1 = keep original aspect
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     */
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    int w, h;
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    int hsub, vsub;             ///< chroma subsampling
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    int slice_y;                ///< top of current output slice
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    int input_is_pal;           ///< set to 1 if the input format is paletted
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} ScaleContext;
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static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
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{
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    ScaleContext *scale = ctx->priv;
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    if (args)
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        sscanf(args, "%d:%d", &scale->w, &scale->h);
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    /* sanity check params */
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    if (scale->w <  -1 || scale->h <  -1) {
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        av_log(ctx, AV_LOG_ERROR, "Size values less than -1 are not acceptable.\n");
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        return -1;
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    }
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    if (scale->w == -1 && scale->h == -1)
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        scale->w = scale->h = 0;
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    return 0;
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}
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static av_cold void uninit(AVFilterContext *ctx)
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{
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    ScaleContext *scale = ctx->priv;
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    sws_freeContext(scale->sws);
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    scale->sws = NULL;
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}
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static int query_formats(AVFilterContext *ctx)
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{
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    AVFilterFormats *formats;
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    if (ctx->inputs[0]) {
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        formats = avfilter_all_colorspaces();
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        avfilter_formats_ref(formats, &ctx->inputs[0]->out_formats);
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    }
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    if (ctx->outputs[0]) {
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        formats = avfilter_all_colorspaces();
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        avfilter_formats_ref(formats, &ctx->outputs[0]->in_formats);
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    }
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    return 0;
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}
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static int config_props(AVFilterLink *outlink)
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{
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    AVFilterContext *ctx = outlink->src;
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    AVFilterLink *inlink = outlink->src->inputs[0];
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    ScaleContext *scale = ctx->priv;
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    int64_t w, h;
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    if (!(w = scale->w))
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        w = inlink->w;
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    if (!(h = scale->h))
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        h = inlink->h;
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    if (w == -1)
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        w = av_rescale(h, inlink->w, inlink->h);
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    if (h == -1)
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        h = av_rescale(w, inlink->h, inlink->w);
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    if (w > INT_MAX || h > INT_MAX ||
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        (h * inlink->w) > INT_MAX  ||
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        (w * inlink->h) > INT_MAX)
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        av_log(ctx, AV_LOG_ERROR, "Rescaled value for width or height is too big.\n");
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    outlink->w = w;
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    outlink->h = h;
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    /* TODO: make algorithm configurable */
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    scale->sws = sws_getContext(inlink ->w, inlink ->h, inlink ->format,
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                                outlink->w, outlink->h, outlink->format,
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                                SWS_BILINEAR, NULL, NULL, NULL);
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    av_log(ctx, AV_LOG_INFO, "w:%d h:%d fmt:%s\n",
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           outlink->w, outlink->h, avcodec_get_pix_fmt_name(outlink->format));
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    scale->input_is_pal = inlink->format == PIX_FMT_PAL8      ||
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                          inlink->format == PIX_FMT_BGR4_BYTE ||
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                          inlink->format == PIX_FMT_RGB4_BYTE ||
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                          inlink->format == PIX_FMT_BGR8      ||
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                          inlink->format == PIX_FMT_RGB8;
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    return !scale->sws;
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}
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static void start_frame(AVFilterLink *link, AVFilterPicRef *picref)
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{
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    ScaleContext *scale = link->dst->priv;
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    AVFilterLink *outlink = link->dst->outputs[0];
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    AVFilterPicRef *outpicref;
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    avcodec_get_chroma_sub_sample(link->format, &scale->hsub, &scale->vsub);
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    outpicref = avfilter_get_video_buffer(outlink, AV_PERM_WRITE, outlink->w, outlink->h);
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    outpicref->pts = picref->pts;
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    outlink->outpic = outpicref;
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    av_reduce(&outpicref->pixel_aspect.num, &outpicref->pixel_aspect.den,
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              (int64_t)picref->pixel_aspect.num * outlink->h * link->w,
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              (int64_t)picref->pixel_aspect.den * outlink->w * link->h,
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              INT_MAX);
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    scale->slice_y = 0;
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    avfilter_start_frame(outlink, avfilter_ref_pic(outpicref, ~0));
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}
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static void draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
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{
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    ScaleContext *scale = link->dst->priv;
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    int out_h;
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    AVFilterPicRef *cur_pic = link->cur_pic;
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    uint8_t *data[4];
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    if (scale->slice_y == 0 && slice_dir == -1)
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        scale->slice_y = link->dst->outputs[0]->h;
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    data[0] = cur_pic->data[0] +  y               * cur_pic->linesize[0];
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    data[1] = scale->input_is_pal ?
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              cur_pic->data[1] :
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              cur_pic->data[1] + (y>>scale->vsub) * cur_pic->linesize[1];
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    data[2] = cur_pic->data[2] + (y>>scale->vsub) * cur_pic->linesize[2];
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    data[3] = cur_pic->data[3] +  y               * cur_pic->linesize[3];
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    out_h = sws_scale(scale->sws, data, cur_pic->linesize, y, h,
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                      link->dst->outputs[0]->outpic->data,
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                      link->dst->outputs[0]->outpic->linesize);
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    if (slice_dir == -1)
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        scale->slice_y -= out_h;
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    avfilter_draw_slice(link->dst->outputs[0], scale->slice_y, out_h, slice_dir);
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    if (slice_dir == 1)
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        scale->slice_y += out_h;
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}
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AVFilter avfilter_vf_scale = {
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    .name      = "scale",
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    .description = "Scale the input video to width:height size and/or convert the image format.",
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    .init      = init,
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    .uninit    = uninit,
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    .query_formats = query_formats,
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    .priv_size = sizeof(ScaleContext),
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    .inputs    = (AVFilterPad[]) {{ .name             = "default",
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                                    .type             = CODEC_TYPE_VIDEO,
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                                    .start_frame      = start_frame,
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                                    .draw_slice       = draw_slice,
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                                    .min_perms        = AV_PERM_READ, },
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                                  { .name = NULL}},
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    .outputs   = (AVFilterPad[]) {{ .name             = "default",
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                                    .type             = CODEC_TYPE_VIDEO,
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                                    .config_props     = config_props, },
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                                  { .name = NULL}},
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};