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Keeping control of your media in your hands
13 avril 2011, parThe vocabulary used on this site and around MediaSPIP in general, aims to avoid reference to Web 2.0 and the companies that profit from media-sharing.
While using MediaSPIP, you are invited to avoid using words like "Brand", "Cloud" and "Market".
MediaSPIP is designed to facilitate the sharing of creative media online, while allowing authors to retain complete control of their work.
MediaSPIP aims to be accessible to as many people as possible and development is based on expanding the (...) -
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 -
Les formats acceptés
28 janvier 2010, parLes commandes suivantes permettent d’avoir des informations sur les formats et codecs gérés par l’installation local de ffmpeg :
ffmpeg -codecs ffmpeg -formats
Les format videos acceptés en entrée
Cette liste est non exhaustive, elle met en exergue les principaux formats utilisés : h264 : H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 m4v : raw MPEG-4 video format flv : Flash Video (FLV) / Sorenson Spark / Sorenson H.263 Theora wmv :
Les formats vidéos de sortie possibles
Dans un premier temps on (...)
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AVCodecContex returns zero for width and height in android
17 février 2023, par WhoamiNot sure what was my mistake in the below code. I m trying with ffmpeg 0.11 and SDL2.0 in android.



QUESTION :
Why Width and Height of the CodecContext gives me always zero ?..



int main(int argc, char *argv[])
{

 int flags;
 flags = SDL_INIT_VIDEO | SDL_INIT_TIMER;

 if (SDL_Init (flags)) {
 LOGD ("Could not intialize Video for SDL: %s \n", SDL_GetError());
 }
 else 
 LOGD (" SUCCESS: SDL_Init ");

 // ffmpeg Register all services..
 ffmpeg_register_all (); 


 pFrame = avcodec_alloc_frame ();
 context = avformat_alloc_context();

 err = avformat_open_input (&context, "rtsp:ip:port", NULL, NULL);
 if ( err < 0) {
 __android_log_print(ANDROID_LOG_DEBUG, "ffmpegguard", "Unable to open rtsp... ");

 return -1;
 }

 for (i = 0; i < context->nb_streams; i++)
 { 
 // Find the Decoder.
 codec = avcodec_find_decoder(context->streams[i]->codec->codec_id);
 if (codec->type == AVMEDIA_TYPE_VIDEO ) {
 __android_log_print(ANDROID_LOG_DEBUG, "ffmpegguard", "Found Video Streaming.. ");
 videoStreamIndex = i;

 }
 }

 // Play RTSP
 av_read_play(context);

 // Get Codec Context.
 pCodecCtx = context->streams[videoStreamIndex]->codec;
 if ( pCodecCtx == NULL )
 __android_log_print(ANDROID_LOG_DEBUG, "ffmpegguard", "CodecCtx is NULL>>> ");
 else
 __android_log_print(ANDROID_LOG_DEBUG, "ffmpegguard", "CodecCtx is <<<ok>>> ");


 //Find the Decoder.
 pCodec = avcodec_find_decoder (pCodecCtx->codec_id);
 avcodec_open2 (pCodecCtx, pCodec, NULL);


 int w = pCodecCtx->width; // Why me getting 0 ? 
 int h = pCodecCtx->height;

 window = SDL_CreateWindow ("Test ffmpeg",SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, w, h, SDL_WINDOW_SHOWN|SDL_WINDOW_ALLOW_HIGHDPI);
 // What this HIGHDPI Means ??

 if ( window != NULL ) 
 {
 LOGD (" WINDOW CREATED.. , create Renderer ..");
 renderer = SDL_CreateRenderer (window, -1, 0); 
 }
 else
 {
 LOGD (" Invalid SDL Window "); 
 }
__android_log_print(ANDROID_LOG_DEBUG, "ffmpegguard", "Width and Height of PCodeccCtx.. %d .. %d " , w, h); 
 return 0;
}
</ok>

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AVCodecContex returns zero for width and height in android
7 mars 2014, par WhoamiNot sure what was my mistake in the below code. I m trying with ffmpeg 0.11 and SDL2.0 in android.
QUESTION :
Why Width and Height of the CodecContext gives me always zero ?..int main(int argc, char *argv[])
{
int flags;
flags = SDL_INIT_VIDEO | SDL_INIT_TIMER;
if (SDL_Init (flags)) {
LOGD ("Could not intialize Video for SDL: %s \n", SDL_GetError());
}
else
LOGD (" SUCCESS: SDL_Init ");
// ffmpeg Register all services..
ffmpeg_register_all ();
pFrame = avcodec_alloc_frame ();
context = avformat_alloc_context();
err = avformat_open_input (&context, "rtsp:ip:port", NULL, NULL);
if ( err < 0) {
__android_log_print(ANDROID_LOG_DEBUG, "ffmpegguard", "Unable to open rtsp... ");
return -1;
}
for (i = 0; i < context->nb_streams; i++)
{
// Find the Decoder.
codec = avcodec_find_decoder(context->streams[i]->codec->codec_id);
if (codec->type == AVMEDIA_TYPE_VIDEO ) {
__android_log_print(ANDROID_LOG_DEBUG, "ffmpegguard", "Found Video Streaming.. ");
videoStreamIndex = i;
}
}
// Play RTSP
av_read_play(context);
// Get Codec Context.
pCodecCtx = context->streams[videoStreamIndex]->codec;
if ( pCodecCtx == NULL )
__android_log_print(ANDROID_LOG_DEBUG, "ffmpegguard", "CodecCtx is NULL>>> ");
else
__android_log_print(ANDROID_LOG_DEBUG, "ffmpegguard", "CodecCtx is <<<ok>>> ");
//Find the Decoder.
pCodec = avcodec_find_decoder (pCodecCtx->codec_id);
avcodec_open2 (pCodecCtx, pCodec, NULL);
int w = pCodecCtx->width; // Why me getting 0 ?
int h = pCodecCtx->height;
window = SDL_CreateWindow ("Test ffmpeg",SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, w, h, SDL_WINDOW_SHOWN|SDL_WINDOW_ALLOW_HIGHDPI);
// What this HIGHDPI Means ??
if ( window != NULL )
{
LOGD (" WINDOW CREATED.. , create Renderer ..");
renderer = SDL_CreateRenderer (window, -1, 0);
}
else
{
LOGD (" Invalid SDL Window ");
}
__android_log_print(ANDROID_LOG_DEBUG, "ffmpegguard", "Width and Height of PCodeccCtx.. %d .. %d " , w, h);
return 0;
}
</ok> -
OpenCV returns an Array of All Zeros on video.read
19 janvier 2020, par Ikechukwu AnudeBelow is the relevant code
import cv2 as cv
import numpy as np
video = cv.VideoCapture(0) #tells obj to use built in camera\
#create a face cascade object
face_cascade =
cv.CascadeClassifier(r"C:\Users\xxxxxxx\AppData\Roaming\Python\Python36\site-
packages\cv2\data\haarcascade_frontalcatface.xml")
a = 1
#create loop to display a video
while True:
a = a + 1
check, frame = video.read()
print(frame)
#converts to a gray scale img
gray = cv.cvtColor(frame, cv.COLOR_BGR2GRAY)
#create the faces
faces = face_cascade.detectMultiScale(gray, scaleFactor=1.5, minNeighbors=5)
for(x, y, w, h) in faces:
print(x, y, w, h)
#show the image
cv.imshow('capturing', gray)
key = cv.waitKey(1) #gen a new frame every 1ms
if key == ord('q'): #once you enter 'q' the loop will be exited
break
print(a) #this will print the number of frames
#captures the first frame
video.release() #end the web cam
#destroys the windows when you are not defined
cv.destroyAllWindows()The code displays a video captured from my webcam camera. Despite that, OpevCV doesn’t seem to be processing any frames as all the frames look like this
[[0 0 0]
[0 0 0]
[0 0 0]
...
[0 0 0]
[0 0 0]
[0 0 0]]]which I assume means that they are empty.
This I believe is preventing the algorithm from being able to detect my face in the frame. I have a feeling that the issue lies in the ffmpeg codec, but I’m not entirely sure how to proceed even if that is the case.
OS : Windows 10
Language : PythonEDIT : The Frame is not empty but all the values in the array seem to be ’0’
Why is the frame empty and how can I get OpenCV to detect my face in the frame ?
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