libmpcodecs/vf_framestep.c

   1 /*
   2  * filter to ouput only 1 every n frame, or only the I (key)frame
   3  *
   4  * The parameters are:
   5  *
   6  *    [I] | [i]num
   7  *
   8  * if you call the filter with I (uppercase) as the parameter
   9  *    ... -vf framestep=I ...
  10  * then ONLY the keyframes are outputted.
  11  * For DVD it means, generally, one every 15 frames (IBBPBBPBBPBBPBB), for avi it means
  12  * every scene change or every keyint value (see -lavcopts).
  13  *
  14  * if you call the filter with the i (lowercase)
  15  *    ... -vf framestep=i ...
  16  * then a I! followed by a cr is printed when a key frame (eg Intra frame) is
  17  * found, leaving the current line of mplayer/mencoder, where you got the
  18  * time, in seconds, and frame of the key. Use this information to split the
  19  * AVI.
  20  *
  21  * After the i or alone you can put a positive number and only one frame every
  22  * x (the number you set) is passed on the filter chain, limiting the output
  23  * of the frame.
  24  *
  25  * Example
  26  *    ... -vf framestep=i20 ...
  27  * Dump one every 20 frames, printing on the console when a I-Frame is encounter.
  28  *
  29  *    ... -vf framestep=25
  30  * Dump one every 25 frames.
  31  *
  32  * If you call the filter without parameter it does nothing (except using memory
  33  * and resource of your system,. of course).
  34  *
  35  * This filter doesn' t work like the option -sstep seconds.
  36  *
  37  * The -sstep seek to the new position, without decoding all frames but,
  38  * expecially on avi file coded whith mpeg4 (lavc or xvid or divx), the
  39  * seek is not always too much precise.
  40  *
  41  * This filter simply discard the unwanted frames, so you are very precise in
  42  * counting the frame but sometime you use a lot of CPU for nothing.
  43  *
  44  * As usual it depends on what you're doing.
  45  *
  46  * copyright (c) 2003 Daniele Forghieri ( guru@digitalfantasy.it )
  47  *
  48  * This file is part of MPlayer.
  49  *
  50  * MPlayer is free software; you can redistribute it and/or modify
  51  * it under the terms of the GNU General Public License as published by
  52  * the Free Software Foundation; either version 2 of the License, or
  53  * (at your option) any later version.
  54  *
  55  * MPlayer is distributed in the hope that it will be useful,
  56  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  57  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  58  * GNU General Public License for more details.
  59  *
  60  * You should have received a copy of the GNU General Public License along
  61  * with MPlayer; if not, write to the Free Software Foundation, Inc.,
  62  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  63  */
  64
  65 #include <stdio.h>
  66 #include <stdlib.h>
  67 #include <string.h>
  68
  69 #include "config.h"
  70 #include "mp_msg.h"
  71 #include "cpudetect.h"
  72
  73 #include "img_format.h"
  74 #include "mp_image.h"
  75 #include "vf.h"
  76
  77 /* Uncomment if you want to print some info on the format */
  78 // #define DUMP_FORMAT_DATA
  79
  80 /* Private data */
  81 struct vf_priv_s {
  82     /* Current frame */
  83     int  frame_cur;
  84     /* Frame output step, 0 = all */
  85     int  frame_step;
  86     /* Only I-Frame (2), print on I-Frame (1) */
  87     int  dump_iframe;
  88 };
  89
  90 /* Filter handler */
  91 static int put_image(struct vf_instance *vf, mp_image_t *mpi, double pts)
  92 {
  93     mp_image_t        *dmpi;
  94     struct vf_priv_s  *priv;
  95     int               skip;
  96
  97     priv = vf->priv;
  98
  99     /* Print the 'I' if is a intra frame. The \n advance the current line so you got the
 100      * current file time (in second) and the frame number on the console ;-)
 101      */
 102     if (priv->dump_iframe) {
 103         if (mpi->pict_type == 1) {
 104             mp_msg(MSGT_VFILTER, MSGL_INFO, "I!\n");
 105         }
 106     }
 107
 108     /* decide if frame must be shown */
 109     if (priv->dump_iframe == 2) {
 110         /* Only key frame */
 111         skip = mpi->pict_type == 1 ? 0 : 1;
 112     }
 113     else {
 114         /* Only 1 every frame_step */
 115         skip = 0;
 116         if ((priv->frame_step != 0) && ((priv->frame_cur % priv->frame_step) != 0)) {
 117             skip = 1;
 118         }
 119     }
 120     /* Increment current frame */
 121     ++priv->frame_cur;
 122
 123     if (skip == 0) {
 124         /* Get image, export type (we don't modify tghe image) */
 125         dmpi=vf_get_image(vf->next, mpi->imgfmt,
 126                       MP_IMGTYPE_EXPORT, 0,
 127                       mpi->w, mpi->h);
 128         /* Copy only the pointer ( MP_IMGTYPE_EXPORT ! ) */
 129         dmpi->planes[0] = mpi->planes[0];
 130         dmpi->planes[1] = mpi->planes[1];
 131         dmpi->planes[2] = mpi->planes[2];
 132
 133         dmpi->stride[0] = mpi->stride[0];
 134         dmpi->stride[1] = mpi->stride[1];
 135         dmpi->stride[2] = mpi->stride[2];
 136
 137         dmpi->width     = mpi->width;
 138         dmpi->height    = mpi->height;
 139
 140         /* Chain to next filter / output ... */
 141         return vf_next_put_image(vf, dmpi, pts);
 142     }
 143
 144     /* Skip the frame */
 145     return 0;
 146 }
 147
 148 static void uninit(struct vf_instance *vf)
 149 {
 150     /* Free private data */
 151     free(vf->priv);
 152 }
 153
 154 /* Main entry funct for the filter */
 155 static int vf_open(vf_instance_t *vf, char *args)
 156 {
 157         struct vf_priv_s *p;
 158
 159         vf->put_image = put_image;
 160         vf->uninit = uninit;
 161         vf->default_reqs = VFCAP_ACCEPT_STRIDE;
 162         vf->priv = p = calloc(1, sizeof(struct vf_priv_s));
 163         if (p == NULL) {
 164             return 0;
 165         }
 166
 167         if (args != NULL) {
 168 #ifdef DUMP_FORMAT_DATA
 169             if (*args == 'd') {
 170                 p->dump_iframe = 3;
 171             }
 172             else
 173 #endif
 174             if (*args == 'I') {
 175                 /* Dump only KEY (ie INTRA) frame */
 176                 p->dump_iframe = 2;
 177             }
 178             else {
 179                 if (*args == 'i') {
 180                     /* Print a 'I!' when a i-frame is encounter */
 181                     p->dump_iframe = 1;
 182                     ++args;
 183                 }
 184
 185                 if (*args != '\0') {
 186                     p->frame_step = atoi(args);
 187                     if (p->frame_step <= 0) {
 188                         mp_tmsg(MSGT_VFILTER, MSGL_WARN, "[VF_FRAMESTEP] Error parsing argument.\n");
 189                         return 0;
 190                     }
 191                 }
 192             }
 193         }
 194         return 1;
 195 }
 196
 197 const vf_info_t vf_info_framestep = {
 198     "Dump one every n / key frames",
 199     "framestep",
 200     "Daniele Forghieri",
 201     "",
 202     vf_open,
 203     NULL
 204 };