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ffmpeg / libavfilter / vf_blackframe.c @ 2912e87a

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/*
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 * Copyright (c) 2010 Stefano Sabatini
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 * Copyright (c) 2006 Ivo van Poorten
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 * Copyright (c) 2006 Julian Hall
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 * Copyright (c) 2002-2003 Brian J. Murrell
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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 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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 * 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
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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 Libav; 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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 * Search for black frames to detect scene transitions.
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 * Ported from MPlayer libmpcodecs/vf_blackframe.c.
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 */
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#include "avfilter.h"
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typedef struct {
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    unsigned int bamount; ///< black amount
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    unsigned int bthresh; ///< black threshold
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    unsigned int frame;   ///< frame number
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    unsigned int nblack;  ///< number of black pixels counted so far
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} BlackFrameContext;
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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_YUV410P, PIX_FMT_YUV420P, PIX_FMT_GRAY8, PIX_FMT_NV12,
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        PIX_FMT_NV21, PIX_FMT_YUV444P, PIX_FMT_YUV422P, PIX_FMT_YUV411P,
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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 av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
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{
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    BlackFrameContext *blackframe = ctx->priv;
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    blackframe->bamount = 98;
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    blackframe->bthresh = 32;
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    blackframe->nblack = 0;
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    blackframe->frame = 0;
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    if (args)
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        sscanf(args, "%u:%u", &blackframe->bamount, &blackframe->bthresh);
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    av_log(ctx, AV_LOG_INFO, "bamount:%u bthresh:%u\n",
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           blackframe->bamount, blackframe->bthresh);
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    if (blackframe->bamount > 100 || blackframe->bthresh > 255) {
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        av_log(ctx, AV_LOG_ERROR, "Too big value for bamount (max is 100) or bthresh (max is 255)\n");
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        return AVERROR(EINVAL);
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    }
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    return 0;
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}
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static void draw_slice(AVFilterLink *inlink, int y, int h, int slice_dir)
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{
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    AVFilterContext *ctx = inlink->dst;
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    BlackFrameContext *blackframe = ctx->priv;
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    AVFilterBufferRef *picref = inlink->cur_buf;
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    int x, i;
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    uint8_t *p = picref->data[0] + y * picref->linesize[0];
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    for (i = 0; i < h; i++) {
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        for (x = 0; x < inlink->w; x++)
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            blackframe->nblack += p[x] < blackframe->bthresh;
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        p += picref->linesize[0];
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    }
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    avfilter_draw_slice(ctx->outputs[0], y, h, slice_dir);
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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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    BlackFrameContext *blackframe = ctx->priv;
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    AVFilterBufferRef *picref = inlink->cur_buf;
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    int pblack = 0;
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    pblack = blackframe->nblack * 100 / (inlink->w * inlink->h);
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    if (pblack >= blackframe->bamount)
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        av_log(ctx, AV_LOG_INFO, "frame:%u pblack:%u pos:%"PRId64" pts:%"PRId64" t:%f\n",
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               blackframe->frame, pblack, 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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    blackframe->frame++;
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    blackframe->nblack = 0;
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    avfilter_end_frame(inlink->dst->outputs[0]);
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}
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AVFilter avfilter_vf_blackframe = {
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    .name        = "blackframe",
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    .description = NULL_IF_CONFIG_SMALL("Detect frames that are (almost) black."),
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    .priv_size = sizeof(BlackFrameContext),
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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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                                    .draw_slice       = draw_slice,
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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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};