mpv/libmpcodecs/vf_framestep.c

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/*
* vf_fstep.c - filter to ouput only 1 every n frame, or only the I (key)
* frame
*
* The parameters are:
*
* [I] | [i]num
*
* if you call the filter with I (uppercase) as the parameter
* ... -vf framestep=I ...
* then ONLY the keyframes are outputted.
* For DVD it means, generally, one every 15 frames (IBBPBBPBBPBBPBB), for avi it means
* every scene change or every keyint value (see -lavcopts).
*
* if you call the filter with the i (lowercase)
* ... -vf framestep=i ...
* then a I! followed by a cr is printed when a key frame (eg Intra frame) is
* found, leaving the current line of mplayer/mencoder, where you got the
* time, in seconds, and frame of the key. Use this information to split the
* AVI.
*
* After the i or alone you can put a positive number and only one frame every
* x (the number you set) is passed on the filter chain, limiting the output
* of the frame.
*
* Example
* ... -vf framestep=i20 ...
* Dump one every 20 frames, printing on the console when a I-Frame is encounter.
*
* ... -vf framestep=25
* Dump one every 25 frames.
*
* If you call the filter without parameter it does nothing (except using memory
* and resource of your system,. of course).
*
* This filter doesn' t work like the option -sstep seconds.
*
* The -sstep seek to the new position, without decoding all frames but,
* expecially on avi file coded whith mpeg4 (lavc or xvid or divx), the
* seek is not always too much precise.
*
* This filter simply discard the unwanted frames, so you are very precise in
* counting the frame but sometime you use a lot of CPU for nothing.
*
* As usual it depends on what you're doing.
*
* Daniele Forghieri ( guru@digitalfantasy.it )
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "config.h"
#include "mp_msg.h"
#include "help_mp.h"
#include "cpudetect.h"
#include "img_format.h"
#include "mp_image.h"
#include "vf.h"
/* Uncomment if you want to print some info on the format */
// #define DUMP_FORMAT_DATA
/* Private data */
struct vf_priv_s {
/* Current frame */
int frame_cur;
/* Frame output step, 0 = all */
int frame_step;
/* Only I-Frame (2), print on I-Frame (1) */
int dump_iframe;
};
/* Filter handler */
static int put_image(struct vf_instance_s* vf, mp_image_t *mpi, double pts)
{
mp_image_t *dmpi;
struct vf_priv_s *priv;
int skip;
priv = vf->priv;
/* Print the 'I' if is a intra frame. The \n advance the current line so you got the
* current file time (in second) and the frame number on the console ;-)
*/
if (priv->dump_iframe) {
if (mpi->pict_type == 1) {
mp_msg(MSGT_VFILTER, MSGL_INFO, "I!\n");
}
}
/* decide if frame must be shown */
if (priv->dump_iframe == 2) {
/* Only key frame */
skip = mpi->pict_type == 1 ? 0 : 1;
}
else {
/* Only 1 every frame_step */
skip = 0;
if ((priv->frame_step != 0) && ((priv->frame_cur % priv->frame_step) != 0)) {
skip = 1;
}
}
/* Increment current frame */
++priv->frame_cur;
if (skip == 0) {
/* Get image, export type (we don't modify tghe image) */
dmpi=vf_get_image(vf->next, mpi->imgfmt,
MP_IMGTYPE_EXPORT, 0,
mpi->w, mpi->h);
/* Copy only the pointer ( MP_IMGTYPE_EXPORT ! ) */
dmpi->planes[0] = mpi->planes[0];
dmpi->planes[1] = mpi->planes[1];
dmpi->planes[2] = mpi->planes[2];
dmpi->stride[0] = mpi->stride[0];
dmpi->stride[1] = mpi->stride[1];
dmpi->stride[2] = mpi->stride[2];
dmpi->width = mpi->width;
dmpi->height = mpi->height;
/* Chain to next filter / output ... */
return vf_next_put_image(vf, dmpi, pts);
}
/* Skip the frame */
return 0;
}
static void uninit(struct vf_instance_s* vf)
{
/* Free private data */
free(vf->priv);
}
/* Main entry funct for the filter */
static int open(vf_instance_t *vf, char* args)
{
struct vf_priv_s *p;
vf->put_image = put_image;
vf->uninit = uninit;
vf->default_reqs = VFCAP_ACCEPT_STRIDE;
vf->priv = p = calloc(1, sizeof(struct vf_priv_s));
if (p == NULL) {
return(0);
}
if (args != NULL) {
#ifdef DUMP_FORMAT_DATA
if (*args == 'd') {
p->dump_iframe = 3;
}
else
#endif
if (*args == 'I') {
/* Dump only KEY (ie INTRA) frame */
p->dump_iframe = 2;
}
else {
if (*args == 'i') {
/* Print a 'I!' when a i-frame is encounter */
p->dump_iframe = 1;
++args;
}
if (*args != '\0') {
p->frame_step = atoi(args);
if (p->frame_step <= 0) {
mp_msg(MSGT_VFILTER, MSGL_WARN, MSGTR_MPCODECS_ErrorParsingArgument);
return(0);
}
}
}
}
return 1;
}
vf_info_t vf_info_framestep = {
"Dump one every n / key frames",
"framestep",
"Daniele Forghieri",
"",
open,
NULL
};