vf_vflip.c 3.56 KB
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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
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
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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
 * 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
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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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 * @file
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 * video vertical flip filter
 */

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#include "libavutil/internal.h"
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#include "libavutil/pixdesc.h"
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#include "avfilter.h"
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#include "internal.h"
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#include "video.h"
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typedef struct {
    int vsub;   ///< vertical chroma subsampling
} FlipContext;

static int config_input(AVFilterLink *link)
{
    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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static AVFilterBufferRef *get_video_buffer(AVFilterLink *link, int perms,
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                                        int w, int h)
{
    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 ff_default_get_video_buffer(link, perms, w, h);
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    picref = ff_get_video_buffer(link->dst->outputs[0], perms, w, h);
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    if (!picref)
        return NULL;

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    for (i = 0; i < 4; i ++) {
        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];
        }
    }

    return picref;
}

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static int start_frame(AVFilterLink *link, AVFilterBufferRef *inpicref)
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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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    if (!outpicref)
        return AVERROR(ENOMEM);

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    for (i = 0; i < 4; i ++) {
        int vsub = i == 1 || i == 2 ? flip->vsub : 0;

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        if (outpicref->data[i]) {
            outpicref->data[i] += ((link->h >> vsub)-1) * outpicref->linesize[i];
            outpicref->linesize[i] = -outpicref->linesize[i];
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        }
    }

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    return ff_start_frame(link->dst->outputs[0], outpicref);
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}

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static int draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
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{
    AVFilterContext *ctx = link->dst;

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    return ff_draw_slice(ctx->outputs[0], link->h - (y+h), h, -1 * slice_dir);
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}

AVFilter avfilter_vf_vflip = {
    .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    = (const AVFilterPad[]) {{ .name             = "default",
                                          .type             = AVMEDIA_TYPE_VIDEO,
                                          .get_video_buffer = get_video_buffer,
                                          .start_frame      = start_frame,
                                          .draw_slice       = draw_slice,
                                          .config_props     = config_input, },
                                        { .name = NULL}},
    .outputs   = (const AVFilterPad[]) {{ .name             = "default",
                                          .type             = AVMEDIA_TYPE_VIDEO, },
                                        { .name = NULL}},
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};