libmpcodecs/vf_framestep.c

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