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  *     Daniele Forghieri ( guru@digitalfantasy.it )
  47  */
  48
  49 #include <stdio.h>
  50 #include <stdlib.h>
  51 #include <string.h>
  52
  53 #include "config.h"
  54 #include "mp_msg.h"
  55 #include "help_mp.h"
  56 #include "cpudetect.h"
  57
  58 #include "img_format.h"
  59 #include "mp_image.h"
  60 #include "vf.h"
  61
  62 /* Uncomment if you want to print some info on the format */
  63 // #define DUMP_FORMAT_DATA
  64
  65 /* Private data */
  66 struct vf_priv_s {
  67     /* Current frame */
  68     int  frame_cur;
  69     /* Frame output step, 0 = all */
  70     int  frame_step;
  71     /* Only I-Frame (2), print on I-Frame (1) */
  72     int  dump_iframe;
  73 };
  74
  75 /* Filter handler */
  76 static int put_image(struct vf_instance_s* vf, mp_image_t *mpi, double pts)
  77 {
  78     mp_image_t        *dmpi;
  79     struct vf_priv_s  *priv;
  80     int               skip;
  81
  82     priv = vf->priv;
  83
  84     /* Print the 'I' if is a intra frame. The \n advance the current line so you got the
  85      * current file time (in second) and the frame number on the console ;-)
  86      */
  87     if (priv->dump_iframe) {
  88         if (mpi->pict_type == 1) {
  89             mp_msg(MSGT_VFILTER, MSGL_INFO, "I!\n");
  90         }
  91     }
  92
  93     /* decide if frame must be shown */
  94     if (priv->dump_iframe == 2) {
  95         /* Only key frame */
  96         skip = mpi->pict_type == 1 ? 0 : 1;
  97     }
  98     else {
  99         /* Only 1 every frame_step */
 100         skip = 0;
 101         if ((priv->frame_step != 0) && ((priv->frame_cur % priv->frame_step) != 0)) {
 102             skip = 1;
 103         }
 104     }
 105     /* Increment current frame */
 106     ++priv->frame_cur;
 107
 108     if (skip == 0) {
 109         /* Get image, export type (we don't modify tghe image) */
 110         dmpi=vf_get_image(vf->next, mpi->imgfmt,
 111                       MP_IMGTYPE_EXPORT, 0,
 112                       mpi->w, mpi->h);
 113         /* Copy only the pointer ( MP_IMGTYPE_EXPORT ! ) */
 114         dmpi->planes[0] = mpi->planes[0];
 115         dmpi->planes[1] = mpi->planes[1];
 116         dmpi->planes[2] = mpi->planes[2];
 117
 118         dmpi->stride[0] = mpi->stride[0];
 119         dmpi->stride[1] = mpi->stride[1];
 120         dmpi->stride[2] = mpi->stride[2];
 121
 122         dmpi->width     = mpi->width;
 123         dmpi->height    = mpi->height;
 124
 125         /* Chain to next filter / output ... */
 126         return vf_next_put_image(vf, dmpi, pts);
 127     }
 128
 129     /* Skip the frame */
 130     return 0;
 131 }
 132
 133 static void uninit(struct vf_instance_s* vf)
 134 {
 135     /* Free private data */
 136     free(vf->priv);
 137 }
 138
 139 /* Main entry funct for the filter */
 140 static int open(vf_instance_t *vf, char* args)
 141 {
 142         struct vf_priv_s *p;
 143
 144         vf->put_image = put_image;
 145         vf->uninit = uninit;
 146         vf->default_reqs = VFCAP_ACCEPT_STRIDE;
 147         vf->priv = p = calloc(1, sizeof(struct vf_priv_s));
 148         if (p == NULL) {
 149             return 0;
 150         }
 151
 152         if (args != NULL) {
 153 #ifdef DUMP_FORMAT_DATA
 154             if (*args == 'd') {
 155                 p->dump_iframe = 3;
 156             }
 157             else
 158 #endif
 159             if (*args == 'I') {
 160                 /* Dump only KEY (ie INTRA) frame */
 161                 p->dump_iframe = 2;
 162             }
 163             else {
 164                 if (*args == 'i') {
 165                     /* Print a 'I!' when a i-frame is encounter */
 166                     p->dump_iframe = 1;
 167                     ++args;
 168                 }
 169
 170                 if (*args != '\0') {
 171                     p->frame_step = atoi(args);
 172                     if (p->frame_step <= 0) {
 173                         mp_msg(MSGT_VFILTER, MSGL_WARN, MSGTR_MPCODECS_ErrorParsingArgument);
 174                         return 0;
 175                     }
 176                 }
 177             }
 178         }
 179         return 1;
 180 }
 181
 182 const vf_info_t vf_info_framestep = {
 183     "Dump one every n / key frames",
 184     "framestep",
 185     "Daniele Forghieri",
 186     "",
 187     open,
 188     NULL
 189 };
 190
 191