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libavfilter/libmpcodecs/vf_framestep.c

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00001 /*
00002  * filter to ouput only 1 every n frame, or only the I (key)frame
00003  *
00004  * The parameters are:
00005  *
00006  *    [I] | [i]num
00007  *
00008  * if you call the filter with I (uppercase) as the parameter
00009  *    ... -vf framestep=I ...
00010  * then ONLY the keyframes are outputted.
00011  * For DVD it means, generally, one every 15 frames (IBBPBBPBBPBBPBB), for avi it means
00012  * every scene change or every keyint value (see -lavcopts).
00013  *
00014  * if you call the filter with the i (lowercase)
00015  *    ... -vf framestep=i ...
00016  * then a I! followed by a cr is printed when a key frame (eg Intra frame) is
00017  * found, leaving the current line of mplayer/mencoder, where you got the
00018  * time, in seconds, and frame of the key. Use this information to split the
00019  * AVI.
00020  *
00021  * After the i or alone you can put a positive number and only one frame every
00022  * x (the number you set) is passed on the filter chain, limiting the output
00023  * of the frame.
00024  *
00025  * Example
00026  *    ... -vf framestep=i20 ...
00027  * Dump one every 20 frames, printing on the console when a I-Frame is encounter.
00028  *
00029  *    ... -vf framestep=25
00030  * Dump one every 25 frames.
00031  *
00032  * If you call the filter without parameter it does nothing (except using memory
00033  * and resource of your system,. of course).
00034  *
00035  * This filter doesn' t work like the option -sstep seconds.
00036  *
00037  * The -sstep seek to the new position, without decoding all frames but,
00038  * expecially on avi file coded whith mpeg4 (lavc or xvid or divx), the
00039  * seek is not always too much precise.
00040  *
00041  * This filter simply discard the unwanted frames, so you are very precise in
00042  * counting the frame but sometime you use a lot of CPU for nothing.
00043  *
00044  * As usual it depends on what you're doing.
00045  *
00046  * copyright (c) 2003 Daniele Forghieri ( guru@digitalfantasy.it )
00047  *
00048  * This file is part of MPlayer.
00049  *
00050  * MPlayer is free software; you can redistribute it and/or modify
00051  * it under the terms of the GNU General Public License as published by
00052  * the Free Software Foundation; either version 2 of the License, or
00053  * (at your option) any later version.
00054  *
00055  * MPlayer is distributed in the hope that it will be useful,
00056  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00057  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00058  * GNU General Public License for more details.
00059  *
00060  * You should have received a copy of the GNU General Public License along
00061  * with MPlayer; if not, write to the Free Software Foundation, Inc.,
00062  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
00063  */
00064 
00065 #include <stdio.h>
00066 #include <stdlib.h>
00067 #include <string.h>
00068 
00069 #include "config.h"
00070 #include "mp_msg.h"
00071 #include "help_mp.h"
00072 #include "cpudetect.h"
00073 
00074 #include "img_format.h"
00075 #include "mp_image.h"
00076 #include "vf.h"
00077 
00078 /* Uncomment if you want to print some info on the format */
00079 // #define DUMP_FORMAT_DATA
00080 
00081 /* Private data */
00082 struct vf_priv_s {
00083     /* Current frame */
00084     int  frame_cur;
00085     /* Frame output step, 0 = all */
00086     int  frame_step;
00087     /* Only I-Frame (2), print on I-Frame (1) */
00088     int  dump_iframe;
00089 };
00090 
00091 /* Filter handler */
00092 static int put_image(struct vf_instance *vf, mp_image_t *mpi, double pts)
00093 {
00094     mp_image_t        *dmpi;
00095     struct vf_priv_s  *priv;
00096     int               skip;
00097 
00098     priv = vf->priv;
00099 
00100     /* Print the 'I' if is a intra frame. The \n advance the current line so you got the
00101      * current file time (in second) and the frame number on the console ;-)
00102      */
00103     if (priv->dump_iframe) {
00104         if (mpi->pict_type == 1) {
00105             mp_msg(MSGT_VFILTER, MSGL_INFO, "I!\n");
00106         }
00107     }
00108 
00109     /* decide if frame must be shown */
00110     if (priv->dump_iframe == 2) {
00111         /* Only key frame */
00112         skip = mpi->pict_type == 1 ? 0 : 1;
00113     }
00114     else {
00115         /* Only 1 every frame_step */
00116         skip = 0;
00117         if ((priv->frame_step != 0) && ((priv->frame_cur % priv->frame_step) != 0)) {
00118             skip = 1;
00119         }
00120     }
00121     /* Increment current frame */
00122     ++priv->frame_cur;
00123 
00124     if (skip == 0) {
00125         /* Get image, export type (we don't modify tghe image) */
00126         dmpi=vf_get_image(vf->next, mpi->imgfmt,
00127                       MP_IMGTYPE_EXPORT, 0,
00128                       mpi->w, mpi->h);
00129         /* Copy only the pointer ( MP_IMGTYPE_EXPORT ! ) */
00130         dmpi->planes[0] = mpi->planes[0];
00131         dmpi->planes[1] = mpi->planes[1];
00132         dmpi->planes[2] = mpi->planes[2];
00133 
00134         dmpi->stride[0] = mpi->stride[0];
00135         dmpi->stride[1] = mpi->stride[1];
00136         dmpi->stride[2] = mpi->stride[2];
00137 
00138         dmpi->width     = mpi->width;
00139         dmpi->height    = mpi->height;
00140 
00141         /* Chain to next filter / output ... */
00142         return vf_next_put_image(vf, dmpi, pts);
00143     }
00144 
00145     /* Skip the frame */
00146     return 0;
00147 }
00148 
00149 static void uninit(struct vf_instance *vf)
00150 {
00151     /* Free private data */
00152     free(vf->priv);
00153 }
00154 
00155 /* Main entry funct for the filter */
00156 static int vf_open(vf_instance_t *vf, char *args)
00157 {
00158         struct vf_priv_s *p;
00159 
00160         vf->put_image = put_image;
00161         vf->uninit = uninit;
00162         vf->default_reqs = VFCAP_ACCEPT_STRIDE;
00163         vf->priv = p = calloc(1, sizeof(struct vf_priv_s));
00164         if (p == NULL) {
00165             return 0;
00166         }
00167 
00168         if (args != NULL) {
00169 #ifdef DUMP_FORMAT_DATA
00170             if (*args == 'd') {
00171                 p->dump_iframe = 3;
00172             }
00173             else
00174 #endif
00175             if (*args == 'I') {
00176                 /* Dump only KEY (ie INTRA) frame */
00177                 p->dump_iframe = 2;
00178             }
00179             else {
00180                 if (*args == 'i') {
00181                     /* Print a 'I!' when a i-frame is encounter */
00182                     p->dump_iframe = 1;
00183                     ++args;
00184                 }
00185 
00186                 if (*args != '\0') {
00187                     p->frame_step = atoi(args);
00188                     if (p->frame_step <= 0) {
00189                         mp_msg(MSGT_VFILTER, MSGL_WARN, MSGTR_MPCODECS_ErrorParsingArgument);
00190                         return 0;
00191                     }
00192                 }
00193             }
00194         }
00195         return 1;
00196 }
00197 
00198 const vf_info_t vf_info_framestep = {
00199     "Dump one every n / key frames",
00200     "framestep",
00201     "Daniele Forghieri",
00202     "",
00203     vf_open,
00204     NULL
00205 };

Generated on Fri Feb 22 2013 07:24:30 for FFmpeg by  doxygen 1.7.1