
Recherche avancée
Médias (1)
-
The Great Big Beautiful Tomorrow
28 octobre 2011, par
Mis à jour : Octobre 2011
Langue : English
Type : Texte
Autres articles (43)
-
Les autorisations surchargées par les plugins
27 avril 2010, parMediaspip core
autoriser_auteur_modifier() afin que les visiteurs soient capables de modifier leurs informations sur la page d’auteurs -
Publier sur MédiaSpip
13 juin 2013Puis-je poster des contenus à partir d’une tablette Ipad ?
Oui, si votre Médiaspip installé est à la version 0.2 ou supérieure. Contacter au besoin l’administrateur de votre MédiaSpip pour le savoir -
Support audio et vidéo HTML5
10 avril 2011MediaSPIP utilise les balises HTML5 video et audio pour la lecture de documents multimedia en profitant des dernières innovations du W3C supportées par les navigateurs modernes.
Pour les navigateurs plus anciens, le lecteur flash Flowplayer est utilisé.
Le lecteur HTML5 utilisé a été spécifiquement créé pour MediaSPIP : il est complètement modifiable graphiquement pour correspondre à un thème choisi.
Ces technologies permettent de distribuer vidéo et son à la fois sur des ordinateurs conventionnels (...)
Sur d’autres sites (6240)
-
FFMPEG : extracting jpegs at 1 fps rate with "-r 1" or "vf fps=fps=1" causes first three frames to be wrong [closed]
11 avril 2013, par StefanI need to use ffmpeg to extract video stills from a video, one picture per second, starting with second 0. I created a 4min test video with a running timecode (25fps, starting with 00:00:00 running to 03:59:24) If I use either
ffmpeg -i input.mp4 -f image2 -r 1 still-%d.jpeg
or
ffmpeg -i input.mp4 -f image2 -vf fps="fps=1" still-%d.jpeg
I fail because the first three images do not display expected time codes 00:00:00, 00:01:00, 00:02:00, but 00:00:00, 00:00:01, 00:00:13, and all subsequent images show having frame 13 in their timecode (and not :00). This causes my video preview to be off by 1-2 seconds.
I had to resort to invoke ffmpeg for each frame, using -ss 0..240 and -vframes 1 to extract exactly one frame at the exact time. This works perfectly, all output files show the timecode of the first frame of that second.
This method is considerably slower, however, and I'd rather not use it.
Is there something I missed with the -r option or fps filter ? I tried specifying fps=fps=1:round=zero, but I got an error saying that the key "round" was not found.
Thank you in advance !
-
Failed to capture a avi file using opencv
30 avril 2017, par WeiI am quite new to c++ compilation. I am trying to work on a simple problem using opencv where I read a video file and display it.
My code looks like :
#include <opencv></opencv>cv.h>
#include <opencv></opencv>highgui.h>
#include "opencv2/opencv.hpp"
#include <opencv2></opencv2>core/core.hpp>
#include <opencv2></opencv2>highgui/highgui.hpp>
#include
#include
#include <algorithm>
#include
#include
#include
#include <fstream>
#include <iostream>
#include <vector>
#include <list>
#include <string>
using namespace cv;
IplImage* image = 0;
IplImage* prev_image = 0;
int show = 1;
int main( int argc, char** argv )
{
int frameNum = 0;
char* video = argv[1];
VideoCapture capture(video);
if( !capture.isOpened() ) {
printf( "Could not initialize capturing..\n" );
return -1;
}
if( show == 1 )
cvNamedWindow( "Video", 0 );
while( true ) {
IplImage* frame = 0;
int i, j, c;
// get a new frame
//frame = cvQueryFrame( capture );
Mat mat_img;
capture >> mat_img;
IplImage frame1 = mat_img.operator IplImage();
frame = &frame1;
if( !frame )
break;
if( !image ) {
image = cvCreateImage( cvSize(frame->width,frame->height), 8, 3 );
image->origin = frame->origin;
}
cvCopy( frame, image, 0 );
if( show == 1 ) {
cvShowImage( "Video", image);
c = cvWaitKey(3);
if((char)c == 27) break;
}
std::cerr << "The " << frameNum << "-th frame" << std::endl;
frameNum++;
}
if( show == 1 )
cvDestroyWindow("Video");
return 0;
}
</string></list></vector></iostream></fstream></algorithm>Then I compile it like :
g++ test.cpp -o Video -pipe -D __STDC_CONSTANT_MACROS -D STD=std -Wall -I. -I/usr/local/ -O3 -DNDEBUG -ggdb -L/usr/local/ -lopencv_core -lopencv_highgui -lopencv_video -lopencv_imgproc -lavformat -lavdevice -lavutil -lavcodec -lswscale
Compilation works fine and no errors returned.
However, when I was running it, I got :
(Video:5651): GLib-GObject-CRITICAL **: g_object_set: assertion 'G_IS_OBJECT (object)' failed
Could not initialize capturing..Some other information :
1. I test my opencv and ffmpeg by running simple examples, which work well.
2. I can stream frames from my camera and display it using opencv.Anyone has idea of what causes this ?
Any idea is appreciated.
-
FFMPEG interactive Mode help options
7 février 2018, par Pliny Ida PlisetskyWhile streaming a simple command like below
ffmpeg -i "Alien.mkv" -f webm tcp://localhost:8080/listen.webm
if I press ’ ?’ ffmpeg seems to have an interactive mode with the below options
? show this help
+ increase verbosity
- decrease verbosity
c Send command to first matching filter supporting it
C Send/Queue command to all matching filters
D cycle through available debug modes
h dump packets/hex press to cycle through the 3 states
q quit
s Show QP histogramI was curious about option ’c’
Does this mean that I can execute further commands on the running stream ? Say for instance seeking a new position in a running stream ? (I realise you wouldn’t normally do this)
I don’t really know anything about these and couldn’t find much in the ffmpeg documentation or else where. If I press ’c’ it suggests the syntax I should use is :
Enter command: <target>|all <time>|-1 <command>[ <argument>]
</argument></command></time></target>but I still don’t really understand how to execute a command. Would someone please give a few examples ? I suspect that this isn’t used much.