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Autres articles (47)
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La file d’attente de SPIPmotion
28 novembre 2010, parUne file d’attente stockée dans la base de donnée
Lors de son installation, SPIPmotion crée une nouvelle table dans la base de donnée intitulée spip_spipmotion_attentes.
Cette nouvelle table est constituée des champs suivants : id_spipmotion_attente, l’identifiant numérique unique de la tâche à traiter ; id_document, l’identifiant numérique du document original à encoder ; id_objet l’identifiant unique de l’objet auquel le document encodé devra être attaché automatiquement ; objet, le type d’objet auquel (...) -
Websites made with MediaSPIP
2 mai 2011, parThis page lists some websites based on MediaSPIP.
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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
Sur d’autres sites (4987)
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How to compile ffmpeg and x264 with thread support for android ?
18 mai 2017, par Sureshkumar Menoni want to compile both x264 and ffmpeg with thread support for ANDROID .FFmpeg and x264 didn’t compile with thread support even after enabling enable-pthreads and enable-threads respectively.
Both the config.h contains #define HAVE_THREAD 0 and #define HAVE_PTHREADS 0
1.How to compile with thread support.
2.Second question is that when i increase the gop size from 1 to some other value encoder returns 0 for certain subsequent frames.This causes a delay more than 3 to 5 seconds in vide playing -
OpenCV 4.5.2 takes a long time (>100ms) to retrieve a single frame from a webcam, C++ on Windows 10
9 juin 2021, par Mustard TigerI've been having a tough time getting my webcam working quickly with opencv. Frames take a very long time to read, (a recorded average of 124ms across 500 frames) I've tried on three different computers (running Windows 10) with a logitech C922 webcam. The most recent machine I tested on has a Ryzen 9 3950X, with 32gbs of ram ; no lack of power.


Here is the code :


cv::VideoCapture cap = cv::VideoCapture(m_cameraNum);

// Check if camera opened successfully
if (!cap.isOpened())
{
 m_logger->critical("Error opening video stream or file\n\r");
 return -1;
}

bool result = true;
result &= cap.set(cv::CAP_PROP_FRAME_WIDTH, 1280);
result &= cap.set(cv::CAP_PROP_FRAME_HEIGHT, 720);

bool ready = false;
std::vector<string> timeLog;
timeLog.reserve(50000);
int i = 0;

while (i < 500)
{
 auto start = std::chrono::system_clock::now();
 
 cv::Mat img;
 ready = cap.read(img);

 // If the frame is empty, break immediately
 if (!ready)
 {
 timeLog.push_back("continue");
 continue;
 }

 i++;
 auto end = std::chrono::system_clock::now();
 timeLog.push_back(std::to_string(std::chrono::duration_cast(end - start).count()));
}

for (auto& entry : timeLog)
 m_logger->info(entry);

cap.release();
return 0;
</string>

Notice that I write the elapsed time to a log file at the end of execution. The average time is 124ms for debug and release, and not one instance of "continue" after half a dozen runs.


It doesn't matter if I use USB 2 or USB 3 ports (the camera is USB2) or if I run a debug build or a release build, the log file will show anywhere from 110ms to 130ms of time for each frame. The camera works fine in other app, OBS can get a smooth 1080@30fps or 720@60fps.


Stepping through the debugger and doing a lot of Googling, I've learned the following about my system :


- 

- The backend chosen by default is DSHOW. GStreamer and FFMPEG are also available.
- DSHOW uses FFMPEG somehow (it needs the FFMPEG dll) but I cannot use FFMPEG directly through opencv. Attempting to use cv::VideoCapture(m_cameraNum, cv::CAP_FFMPEG) always fails. It seems like Opencv's interface to FFMPEG is only capable of opening video files.
- Microsoft really screwed up camera devices in Windows a few years back, not sure if this is related to my problem.








Here's a short list of the fixes I have tried, most taken from older SO posts :


- 

- result &= cap.set(cv::CAP_PROP_FRAME_COUNT, 30) ; // Returns false, does nothing
- result &= cap.set(cv::CAP_PROP_CONVERT_RGB, 0) ; // Returns true, does nothing
- result &= cap.set(cv::CAP_PROP_MODE, cv::VideoWriter::fourcc('M', 'J', 'P', 'G')) ; // Returns false, does nothing
- Set registry key from http://alax.info/blog/1693 that should disable the new Windows camera server.
- Updated from 4.5.0 to 4.5.2, no change.
- Asked device manager to find a newer driver, no newer driver found.














I'm out of ideas. Any help ?


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Why does ffmpeg return "No such file or directory"
4 juillet 2020, par JackNewmanI'm trying to split a video file into 2 second increments and then merge the video back together.


source_vid_path = r"C:\SplitAndMergeVids\Before\before.mp4"
ffcat_path = r'C:\SplitAndMergeVids\Chunk\video.ffcat'
chunks_path = r'C:\SplitAndMergeVids\Chunk\chunk-%03d.mp4'
segments_time = '2'
cmd_input = rf'ffmpeg -fflags +genpts -i {source_vid_path} -map 0 -c copy -f segment -segment_format mp4 -segment_time {segments_time} -segment_list {ffcat_path} -reset_timestamps 1 -v error {chunks_path}'
output = str(subprocess.run(cmd_input, shell=True, capture_output=True))
print(output)

output_path = r'C:\SplitAndMergeVids\Output\output.mp4'
second_input = rf'ffmpeg -y -v error -i {ffcat_path} -map 0 -c copy {output_path}'
output = str(subprocess.run(second_input, shell=True, capture_output=True))
print(output)


First subprocess runs perfectly although the second outputs returns


"Impossible to open 'chunk-000.mp4'\r\nC:\\SplitAndMergeVids\\Chunk\\video.ffcat: No such file or directory".


Full output looks like


CompletedProcess(args='ffmpeg -fflags +genpts -i C:\\SplitAndMergeVids\\Before\\before.mp4 -map 0 -c copy -f segment -segment_format mp4 -segment_time 2 -segment_list C:\\SplitAndMergeVids\\Chunk\\video.ffcat -reset_timestamps 1 -v error C:\\SplitAndMergeVids\\Chunk\\chunk-%03d.mp4', returncode=0, stdout=b'', stderr=b'')
CompletedProcess(args='ffmpeg -y -v error -i C:\\SplitAndMergeVids\\Chunk\\video.ffcat -map 0 -c copy C:\\SplitAndMergeVids\\Output\\output.mp4', returncode=1, stdout=b'', stderr=b"[concat @ 0000028691a6c6c0] Impossible to open 'chunk-000.mp4'\r\nC:\\SplitAndMergeVids\\Chunk\\video.ffcat: No such file or directory\r\n")


When I run cmd_input and second_input manually in cmd, everything functions perfectly. I don't understand how in the first command I am making a file at "ffcat_path", then in the second command I'm using the same "ffcat_path" and it returns "No such file or directory" when it certainly does exist.


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