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ffmpeg / libavfilter / vf_vflip.c @ 2912e87a

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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 Libav.
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 *
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 * Libav 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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 * Libav 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 Libav; 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
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 * video vertical flip filter
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 */
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#include "libavutil/pixdesc.h"
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#include "avfilter.h"
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typedef struct {
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    int vsub;   ///< vertical chroma subsampling
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} FlipContext;
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static int config_input(AVFilterLink *link)
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{
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    FlipContext *flip = link->dst->priv;
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    flip->vsub = av_pix_fmt_descriptors[link->format].log2_chroma_h;
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    return 0;
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}
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static AVFilterBufferRef *get_video_buffer(AVFilterLink *link, int perms,
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                                        int w, int h)
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{
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    FlipContext *flip = link->dst->priv;
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    AVFilterBufferRef *picref;
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    int i;
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    if (!(perms & AV_PERM_NEG_LINESIZES))
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        return avfilter_default_get_video_buffer(link, perms, w, h);
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    picref = avfilter_get_video_buffer(link->dst->outputs[0], perms, w, h);
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    for (i = 0; i < 4; i ++) {
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        int vsub = i == 1 || i == 2 ? flip->vsub : 0;
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        if (picref->data[i]) {
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            picref->data[i] += ((h >> vsub)-1) * picref->linesize[i];
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            picref->linesize[i] = -picref->linesize[i];
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        }
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    }
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    return picref;
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}
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static void start_frame(AVFilterLink *link, AVFilterBufferRef *inpicref)
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{
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    FlipContext *flip = link->dst->priv;
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    AVFilterBufferRef *outpicref = avfilter_ref_buffer(inpicref, ~0);
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    int i;
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    for (i = 0; i < 4; i ++) {
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        int vsub = i == 1 || i == 2 ? flip->vsub : 0;
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        if (outpicref->data[i]) {
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            outpicref->data[i] += ((link->h >> vsub)-1) * outpicref->linesize[i];
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            outpicref->linesize[i] = -outpicref->linesize[i];
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        }
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    }
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    avfilter_start_frame(link->dst->outputs[0], outpicref);
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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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    AVFilterContext *ctx = link->dst;
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    avfilter_draw_slice(ctx->outputs[0], link->h - (y+h), h, -1 * slice_dir);
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}
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AVFilter avfilter_vf_vflip = {
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    .name      = "vflip",
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    .description = NULL_IF_CONFIG_SMALL("Flip the input video vertically."),
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    .priv_size = sizeof(FlipContext),
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    .inputs    = (AVFilterPad[]) {{ .name             = "default",
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                                    .type             = AVMEDIA_TYPE_VIDEO,
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                                    .get_video_buffer = get_video_buffer,
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                                    .start_frame      = start_frame,
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                                    .draw_slice       = draw_slice,
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                                    .config_props     = config_input, },
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                                  { .name = NULL}},
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    .outputs   = (AVFilterPad[]) {{ .name             = "default",
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                                    .type             = AVMEDIA_TYPE_VIDEO, },
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                                  { .name = NULL}},
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};