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ffmpeg / libavfilter / vf_cropdetect.c @ master

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/*
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 * Copyright (c) 2002 A'rpi
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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 modify
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 * it under the terms of the GNU General Public License as published by
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 * the Free Software Foundation; either version 2 of the License, or
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 * (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
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 * GNU General Public License for more details.
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 *
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 * You should have received a copy of the GNU General Public License along
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 * with FFmpeg; if not, write to the Free Software Foundation, Inc.,
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 * 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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 * border detection filter
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 * Ported from MPlayer libmpcodecs/vf_cropdetect.c.
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 */
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#include "libavutil/imgutils.h"
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#include "avfilter.h"
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typedef struct {
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    int x1, y1, x2, y2;
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    int limit;
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    int round;
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    int reset_count;
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    int frame_nb;
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    int max_pixsteps[4];
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} CropDetectContext;
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static int query_formats(AVFilterContext *ctx)
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{
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    static const enum PixelFormat pix_fmts[] = {
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        PIX_FMT_YUV420P, PIX_FMT_YUVJ420P,
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        PIX_FMT_YUV422P, PIX_FMT_YUVJ422P,
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        PIX_FMT_YUV444P, PIX_FMT_YUVJ444P,
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        PIX_FMT_YUV411P, PIX_FMT_GRAY8,
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        PIX_FMT_NV12,    PIX_FMT_NV21,
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        PIX_FMT_NONE
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    };
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    avfilter_set_common_formats(ctx, avfilter_make_format_list(pix_fmts));
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    return 0;
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}
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static int checkline(void *ctx, const unsigned char *src, int stride, int len, int bpp)
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{
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    int total = 0;
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    int div = len;
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    switch (bpp) {
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    case 1:
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        while (--len >= 0) {
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            total += src[0];
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            src += stride;
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        }
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        break;
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    case 3:
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    case 4:
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        while (--len >= 0) {
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            total += src[0] + src[1] + src[2];
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            src += stride;
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        }
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        div *= 3;
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        break;
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    }
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    total /= div;
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    av_log(ctx, AV_LOG_DEBUG, "total:%d\n", total);
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    return total;
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}
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static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
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{
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    CropDetectContext *cd = ctx->priv;
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    cd->limit = 24;
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    cd->round = 0;
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    cd->reset_count = 0;
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    cd->frame_nb = -2;
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    if (args)
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        sscanf(args, "%d:%d:%d", &cd->limit, &cd->round, &cd->reset_count);
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    av_log(ctx, AV_LOG_INFO, "limit:%d round:%d reset_count:%d\n",
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           cd->limit, cd->round, cd->reset_count);
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    return 0;
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}
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static int config_input(AVFilterLink *inlink)
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{
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    AVFilterContext *ctx = inlink->dst;
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    CropDetectContext *cd = ctx->priv;
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    av_image_fill_max_pixsteps(cd->max_pixsteps, NULL,
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                               &av_pix_fmt_descriptors[inlink->format]);
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    cd->x1 = inlink->w - 1;
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    cd->y1 = inlink->h - 1;
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    cd->x2 = 0;
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    cd->y2 = 0;
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    return 0;
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}
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static void end_frame(AVFilterLink *inlink)
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{
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    AVFilterContext *ctx = inlink->dst;
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    CropDetectContext *cd = ctx->priv;
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    AVFilterBufferRef *picref = inlink->cur_buf;
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    int bpp = cd->max_pixsteps[0];
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    int w, h, x, y, shrink_by;
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    // ignore first 2 frames - they may be empty
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    if (++cd->frame_nb > 0) {
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        // Reset the crop area every reset_count frames, if reset_count is > 0
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        if (cd->reset_count > 0 && cd->frame_nb > cd->reset_count) {
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            cd->x1 = picref->video->w-1;
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            cd->y1 = picref->video->h-1;
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            cd->x2 = 0;
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            cd->y2 = 0;
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            cd->frame_nb = 1;
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        }
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        for (y = 0; y < cd->y1; y++) {
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            if (checkline(ctx, picref->data[0] + picref->linesize[0] * y, bpp, picref->video->w, bpp) > cd->limit) {
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                cd->y1 = y;
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                break;
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            }
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        }
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        for (y = picref->video->h-1; y > cd->y2; y--) {
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            if (checkline(ctx, picref->data[0] + picref->linesize[0] * y, bpp, picref->video->w, bpp) > cd->limit) {
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                cd->y2 = y;
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                break;
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            }
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        }
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        for (y = 0; y < cd->x1; y++) {
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            if (checkline(ctx, picref->data[0] + bpp*y, picref->linesize[0], picref->video->h, bpp) > cd->limit) {
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                cd->x1 = y;
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                break;
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            }
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        }
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        for (y = picref->video->w-1; y > cd->x2; y--) {
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            if (checkline(ctx, picref->data[0] + bpp*y, picref->linesize[0], picref->video->h, bpp) > cd->limit) {
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                cd->x2 = y;
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                break;
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            }
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        }
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        // round x and y (up), important for yuv colorspaces
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        // make sure they stay rounded!
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        x = (cd->x1+1) & ~1;
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        y = (cd->y1+1) & ~1;
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        w = cd->x2 - x + 1;
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        h = cd->y2 - y + 1;
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        // w and h must be divisible by 2 as well because of yuv
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        // colorspace problems.
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        if (cd->round <= 1)
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            cd->round = 16;
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        if (cd->round % 2)
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            cd->round *= 2;
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        shrink_by = w % cd->round;
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        w -= shrink_by;
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        x += (shrink_by/2 + 1) & ~1;
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        shrink_by = h % cd->round;
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        h -= shrink_by;
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        y += (shrink_by/2 + 1) & ~1;
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        av_log(ctx, AV_LOG_INFO,
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               "x1:%d x2:%d y1:%d y2:%d w:%d h:%d x:%d y:%d pos:%"PRId64" pts:%"PRId64" t:%f crop=%d:%d:%d:%d\n",
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               cd->x1, cd->x2, cd->y1, cd->y2, w, h, x, y, picref->pos, picref->pts,
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               picref->pts == AV_NOPTS_VALUE ? -1 : picref->pts * av_q2d(inlink->time_base),
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               w, h, x, y);
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    }
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    avfilter_end_frame(inlink->dst->outputs[0]);
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}
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AVFilter avfilter_vf_cropdetect = {
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    .name        = "cropdetect",
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    .description = NULL_IF_CONFIG_SMALL("Auto-detect crop size."),
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    .priv_size = sizeof(CropDetectContext),
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    .init      = init,
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    .query_formats = query_formats,
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    .inputs    = (AVFilterPad[]) {{ .name = "default",
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                                    .type             = AVMEDIA_TYPE_VIDEO,
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                                    .config_props     = config_input,
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                                    .get_video_buffer = avfilter_null_get_video_buffer,
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                                    .start_frame      = avfilter_null_start_frame,
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                                    .end_frame        = end_frame, },
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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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};