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 "help_mp.h"
  72 #include "cpudetect.h"
  73
  74 #include "img_format.h"
  75 #include "mp_image.h"
  76 #include "vf.h"
  77
  78 /* Uncomment if you want to print some info on the format */
  79 // #define DUMP_FORMAT_DATA
  80
  81 /* Private data */
  82 struct vf_priv_s {
  83     /* Current frame */
  84     int  frame_cur;
  85     /* Frame output step, 0 = all */
  86     int  frame_step;
  87     /* Only I-Frame (2), print on I-Frame (1) */
  88     int  dump_iframe;
  89 };
  90
  91 /* Filter handler */
  92 static int put_image(struct vf_instance *vf, mp_image_t *mpi, double pts)
  93 {
  94     mp_image_t        *dmpi;
  95     struct vf_priv_s  *priv;
  96     int               skip;
  97
  98     priv = vf->priv;
  99
 100     /* Print the 'I' if is a intra frame. The \n advance the current line so you got the
 101      * current file time (in second) and the frame number on the console ;-)
 102      */
 103     if (priv->dump_iframe) {
 104         if (mpi->pict_type == 1) {
 105             mp_msg(MSGT_VFILTER, MSGL_INFO, "I!\n");
 106         }
 107     }
 108
 109     /* decide if frame must be shown */
 110     if (priv->dump_iframe == 2) {
 111         /* Only key frame */
 112         skip = mpi->pict_type == 1 ? 0 : 1;
 113     }
 114     else {
 115         /* Only 1 every frame_step */
 116         skip = 0;
 117         if ((priv->frame_step != 0) && ((priv->frame_cur % priv->frame_step) != 0)) {
 118             skip = 1;
 119         }
 120     }
 121     /* Increment current frame */
 122     ++priv->frame_cur;
 123
 124     if (skip == 0) {
 125         /* Get image, export type (we don't modify tghe image) */
 126         dmpi=vf_get_image(vf->next, mpi->imgfmt,
 127                       MP_IMGTYPE_EXPORT, 0,
 128                       mpi->w, mpi->h);
 129         /* Copy only the pointer ( MP_IMGTYPE_EXPORT ! ) */
 130         dmpi->planes[0] = mpi->planes[0];
 131         dmpi->planes[1] = mpi->planes[1];
 132         dmpi->planes[2] = mpi->planes[2];
 133
 134         dmpi->stride[0] = mpi->stride[0];
 135         dmpi->stride[1] = mpi->stride[1];
 136         dmpi->stride[2] = mpi->stride[2];
 137
 138         dmpi->width     = mpi->width;
 139         dmpi->height    = mpi->height;
 140
 141         /* Chain to next filter / output ... */
 142         return vf_next_put_image(vf, dmpi, pts);
 143     }
 144
 145     /* Skip the frame */
 146     return 0;
 147 }
 148
 149 static void uninit(struct vf_instance *vf)
 150 {
 151     /* Free private data */
 152     free(vf->priv);
 153 }
 154
 155 /* Main entry funct for the filter */
 156 static int vf_open(vf_instance_t *vf, char *args)
 157 {
 158         struct vf_priv_s *p;
 159
 160         vf->put_image = put_image;
 161         vf->uninit = uninit;
 162         vf->default_reqs = VFCAP_ACCEPT_STRIDE;
 163         vf->priv = p = calloc(1, sizeof(struct vf_priv_s));
 164         if (p == NULL) {
 165             return 0;
 166         }
 167
 168         if (args != NULL) {
 169 #ifdef DUMP_FORMAT_DATA
 170             if (*args == 'd') {
 171                 p->dump_iframe = 3;
 172             }
 173             else
 174 #endif
 175             if (*args == 'I') {
 176                 /* Dump only KEY (ie INTRA) frame */
 177                 p->dump_iframe = 2;
 178             }
 179             else {
 180                 if (*args == 'i') {
 181                     /* Print a 'I!' when a i-frame is encounter */
 182                     p->dump_iframe = 1;
 183                     ++args;
 184                 }
 185
 186                 if (*args != '\0') {
 187                     p->frame_step = atoi(args);
 188                     if (p->frame_step <= 0) {
 189                         mp_msg(MSGT_VFILTER, MSGL_WARN, MSGTR_MPCODECS_ErrorParsingArgument);
 190                         return 0;
 191                     }
 192                 }
 193             }
 194         }
 195         return 1;
 196 }
 197
 198 const vf_info_t vf_info_framestep = {
 199     "Dump one every n / key frames",
 200     "framestep",
 201     "Daniele Forghieri",
 202     "",
 203     vf_open,
 204     NULL
 205 };