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The Slip - Artworks
26 septembre 2011, par
Mis à jour : Septembre 2011
Langue : English
Type : Texte
Autres articles (80)
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Gestion de la ferme
2 mars 2010, parLa ferme est gérée dans son ensemble par des "super admins".
Certains réglages peuvent être fais afin de réguler les besoins des différents canaux.
Dans un premier temps il utilise le plugin "Gestion de mutualisation" -
Demande de création d’un canal
12 mars 2010, parEn fonction de la configuration de la plateforme, l’utilisateur peu avoir à sa disposition deux méthodes différentes de demande de création de canal. La première est au moment de son inscription, la seconde, après son inscription en remplissant un formulaire de demande.
Les deux manières demandent les mêmes choses fonctionnent à peu près de la même manière, le futur utilisateur doit remplir une série de champ de formulaire permettant tout d’abord aux administrateurs d’avoir des informations quant à (...) -
Creating farms of unique websites
13 avril 2011, parMediaSPIP platforms can be installed as a farm, with a single "core" hosted on a dedicated server and used by multiple websites.
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Sur d’autres sites (14957)
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fate : Fix the sub-mcc tests on Windows in eastern time zones
11 août, par Martin Storsjöfate : Fix the sub-mcc tests on Windows in eastern time zones
Previously, these tests failed when running on Windows, if the
system is configured with a time zone east of Greenwich, i.e.
with a positive GMT offset.The muxer converts the creation_date given by the user using
av_parse_time to unix time, as a time_t. The creation_date is
interpreted as a local time, i.e. according to the current time
zone. (This time_t value is then converted back to a broken out
local time form with localtime_r.)The given reference date/time, "1970-01-01T00:00:00", is the
origin point for unix time, corresponding to time_t zero. However
when interpreted as local time, this doesn't map to exactly zero.
Time zones east of Greenwich reached this time a number of hours
before the point of zero time_t - so the corresponding time_t
value essentially is minus the GMT offset, in seconds.Windows mktime returns an error, returning (time_t)-1, when given
such a "struct tm", while e.g. glibc mktime happily returns a
negative time_t. av_parse_time doesn't check the return value of
mktime for potential errors.This is observable with the following test snippet :
struct tm tm = 0 ;
tm.tm_year = 70 ;
tm.tm_isdst = -1 ;
tm.tm_mday = 1 ;
tm.tm_hour = 0 ;
time_t t = mktime(&tm) ;
printf("%d-%02d-%02d %02d :%02d :%02d\n", tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec) ;
printf("t %d\n", (int)t) ;By varying the value of tm_hour and the system time zone, one
can observe that Windows mktime returns -1 for all time_t values
that would have been negative.This range limit is also documented by Microsoft in detail at
https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/mktime-mktime32-mktime64.To avoid the issue, pick a different, arbitrary reference time,
which should have a nonnegative time_t for all time zones. -
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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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
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