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ffmpeg / libavfilter / libmpcodecs / vf_blackframe.c @ e4852fb3

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/*
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 * detect frames that are (almost) black
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 * search for black frames to detect scene transitions
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 * (c) 2006 Julian Hall
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 *
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 * based on code designed for skipping commercials
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 * (c) 2002-2003 Brian J. Murrell
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 *
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 * cleanup, simplify, speedup (c) 2006 by Ivo van Poorten
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 *
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 * This file is part of MPlayer.
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 *
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 * MPlayer 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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 * MPlayer 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 MPlayer; 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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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "config.h"
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#include "mp_msg.h"
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#include "img_format.h"
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#include "mp_image.h"
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#include "vf.h"
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struct vf_priv_s {
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    unsigned int bamount, bthresh, frame, lastkeyframe;
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};
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static int config(struct vf_instance *vf, int width, int height, int d_width,
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                    int d_height, unsigned int flags, unsigned int outfmt) {
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    return vf_next_config(vf,width,height,d_width,d_height,flags,outfmt);
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}
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static int query_format(struct vf_instance *vf, unsigned fmt) {
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    switch(fmt) {
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    case IMGFMT_YVU9:
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    case IMGFMT_IF09:
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    case IMGFMT_YV12:
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    case IMGFMT_I420:
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    case IMGFMT_IYUV:
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    case IMGFMT_CLPL:
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    case IMGFMT_Y800:
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    case IMGFMT_Y8:
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    case IMGFMT_NV12:
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    case IMGFMT_NV21:
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    case IMGFMT_444P:
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    case IMGFMT_422P:
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    case IMGFMT_411P:
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    case IMGFMT_HM12:
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        return vf_next_query_format(vf, fmt);
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    }
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    return 0;
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}
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static int put_image(struct vf_instance *vf, mp_image_t *mpi, double pts){
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    mp_image_t *dmpi;
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    int x, y;
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    int nblack=0, pblack=0;
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    unsigned char *yplane = mpi->planes[0];
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    unsigned int ystride = mpi->stride[0];
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    int pict_type = mpi->pict_type;
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    int w = mpi->w, h = mpi->h;
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    int bthresh = vf->priv->bthresh;
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    int bamount = vf->priv->bamount;
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    static const char *const picttypes[4] = { "unknown", "I", "P", "B" };
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    for (y=1; y<=h; y++) {
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        for (x=0; x<w; x++)
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            nblack += yplane[x] < bthresh;
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        pblack = nblack*100/(w*y);
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        if (pblack < bamount) break;
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        yplane += ystride;
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    }
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    if (pict_type > 3 || pict_type < 0) pict_type = 0;
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    if (pict_type == 1) vf->priv->lastkeyframe = vf->priv->frame;
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    if (pblack >= bamount)
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        mp_msg(MSGT_VFILTER, MSGL_INFO,"vf_blackframe: %u, %i%%, %s (I:%u)\n",
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                                vf->priv->frame, pblack, picttypes[pict_type],
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                                vf->priv->lastkeyframe);
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    vf->priv->frame++;
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    dmpi = vf_get_image(vf->next, mpi->imgfmt, MP_IMGTYPE_EXPORT, 0,
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                                                    mpi->width, mpi->height);
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    dmpi->planes[0] = mpi->planes[0];
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    dmpi->stride[0] = mpi->stride[0];
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    dmpi->planes[1] = mpi->planes[1];
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    dmpi->stride[1] = mpi->stride[1];
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    dmpi->planes[2] = mpi->planes[2];
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    dmpi->stride[2] = mpi->stride[2];
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    vf_clone_mpi_attributes(dmpi, mpi);
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    return vf_next_put_image(vf, dmpi, pts);
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}
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static int control(struct vf_instance *vf, int request, void* data){
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    return vf_next_control(vf,request,data);
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}
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static void uninit(struct vf_instance *vf) {
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    free(vf->priv);
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}
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static int vf_open(vf_instance_t *vf, char *args){
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    vf->priv = malloc(sizeof(struct vf_priv_s));
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    if (!vf->priv) return 0;
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    vf->config = config;
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    vf->put_image = put_image;
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    vf->control = control;
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    vf->uninit = uninit;
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    vf->query_format = query_format;
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    vf->priv->bamount = 98;
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    vf->priv->bthresh = 0x20;
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    vf->priv->frame = 0;
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    vf->priv->lastkeyframe = 0;
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    if (args)
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        sscanf(args, "%u:%u", &vf->priv->bamount, &vf->priv->bthresh);
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    return 1;
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}
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const vf_info_t vf_info_blackframe = {
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    "detects black frames",
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    "blackframe",
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    "Brian J. Murrell, Julian Hall, Ivo van Poorten",
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    "Useful for detecting scene transitions",
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    vf_open,
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    NULL
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};