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Le profil des utilisateurs
12 avril 2011, parChaque utilisateur dispose d’une page de profil lui permettant de modifier ses informations personnelle. Dans le menu de haut de page par défaut, un élément de menu est automatiquement créé à l’initialisation de MediaSPIP, visible uniquement si le visiteur est identifié sur le site.
L’utilisateur a accès à la modification de profil depuis sa page auteur, un lien dans la navigation "Modifier votre profil" est (...) -
Configurer la prise en compte des langues
15 novembre 2010, parAccéder à la configuration et ajouter des langues prises en compte
Afin de configurer la prise en compte de nouvelles langues, il est nécessaire de se rendre dans la partie "Administrer" du site.
De là, dans le menu de navigation, vous pouvez accéder à une partie "Gestion des langues" permettant d’activer la prise en compte de nouvelles langues.
Chaque nouvelle langue ajoutée reste désactivable tant qu’aucun objet n’est créé dans cette langue. Dans ce cas, elle devient grisée dans la configuration et (...) -
XMP PHP
13 mai 2011, parDixit Wikipedia, XMP signifie :
Extensible Metadata Platform ou XMP est un format de métadonnées basé sur XML utilisé dans les applications PDF, de photographie et de graphisme. Il a été lancé par Adobe Systems en avril 2001 en étant intégré à la version 5.0 d’Adobe Acrobat.
Étant basé sur XML, il gère un ensemble de tags dynamiques pour l’utilisation dans le cadre du Web sémantique.
XMP permet d’enregistrer sous forme d’un document XML des informations relatives à un fichier : titre, auteur, historique (...)
Sur d’autres sites (10293)
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avformat/mov : fix seeking with HEVC open GOP files
18 février 2022, par Clément Bœschavformat/mov : fix seeking with HEVC open GOP files
This was tested with medias recorded from an iPhone XR and an iPhone 13.
Here is how a typical stream looks like in coding order :
┌────────┬─────┬─────┬──────────┐
│ sample | PTS | DTS | keyframe |
├────────┼─────┼─────┼──────────┤
┊ ┊ ┊ ┊ ┊
│ 53 │ 560 │ 510 │ No │
│ 54 │ 540 │ 520 │ No │
│ 55 │ 530 │ 530 │ No │
│ 56 │ 550 │ 540 │ No │
│ 57 │ 600 │ 550 │ Yes │
│ * 58 │ 580 │ 560 │ No │
│ * 59 │ 570 │ 570 │ No │
│ * 60 │ 590 │ 580 │ No │
│ 61 │ 640 │ 590 │ No │
│ 62 │ 620 │ 600 │ No │
┊ ┊ ┊ ┊ ┊In composition/display order :
┌────────┬─────┬─────┬──────────┐
│ sample | PTS | DTS | keyframe |
├────────┼─────┼─────┼──────────┤
┊ ┊ ┊ ┊ ┊
│ 55 │ 530 │ 530 │ No │
│ 54 │ 540 │ 520 │ No │
│ 56 │ 550 │ 540 │ No │
│ 53 │ 560 │ 510 │ No │
│ * 59 │ 570 │ 570 │ No │
│ * 58 │ 580 │ 560 │ No │
│ * 60 │ 590 │ 580 │ No │
│ 57 │ 600 │ 550 │ Yes │
│ 63 │ 610 │ 610 │ No │
│ 62 │ 620 │ 600 │ No │
┊ ┊ ┊ ┊ ┊Sample/frame 58, 59 and 60 are B-frames which actually depends on the
key frame (57). Here the key frame is not an IDR but a "CRA" (Clean
Random Access).Initially, I thought I could rely on the sdtp box (independent and
disposable samples), but unfortunately :sdtp[54] is_leading:0 sample_depends_on:1 sample_is_depended_on:0 sample_has_redundancy:0
sdtp[55] is_leading:0 sample_depends_on:1 sample_is_depended_on:2 sample_has_redundancy:0
sdtp[56] is_leading:0 sample_depends_on:1 sample_is_depended_on:2 sample_has_redundancy:0
sdtp[57] is_leading:0 sample_depends_on:2 sample_is_depended_on:0 sample_has_redundancy:0
sdtp[58] is_leading:0 sample_depends_on:1 sample_is_depended_on:0 sample_has_redundancy:0
sdtp[59] is_leading:0 sample_depends_on:1 sample_is_depended_on:2 sample_has_redundancy:0
sdtp[60] is_leading:0 sample_depends_on:1 sample_is_depended_on:2 sample_has_redundancy:0
sdtp[61] is_leading:0 sample_depends_on:1 sample_is_depended_on:0 sample_has_redundancy:0
sdtp[62] is_leading:0 sample_depends_on:1 sample_is_depended_on:0 sample_has_redundancy:0The information that might have been useful here would have been
is_leading, but all the samples are set to 0 so this was unusable.Instead, we need to rely on sgpd/sbgp tables. In my case the video track
contained 3 sgpd tables with the following grouping types : tscl, sync
and tsas. In the sync table we have the following 2 entries (only) :sgpd.sync[1] : sync nal_unit_type:0x14
sgpd.sync[2] : sync nal_unit_type:0x15(The count starts at 1 because 0 carries the undefined semantic, we'll
see that later in the reference table).The NAL unit types presented here correspond to :
libavcodec/hevc.h : HEVC_NAL_IDR_N_LP = 20,
libavcodec/hevc.h : HEVC_NAL_CRA_NUT = 21,In parallel, the sbgp sync table contains the following :
┌────┬───────┬─────┐
│ id │ count │ gdi │
├────┼───────┼─────┤
│ 0 │ 1 │ 1 │
│ 1 │ 56 │ 0 │
│ 2 │ 1 │ 2 │
│ 3 │ 59 │ 0 │
│ 4 │ 1 │ 2 │
│ 5 │ 59 │ 0 │
│ 6 │ 1 │ 2 │
│ 7 │ 59 │ 0 │
│ 8 │ 1 │ 2 │
│ 9 │ 59 │ 0 │
│ 10 │ 1 │ 2 │
│ 11 │ 11 │ 0 │
└────┴───────┴─────┘The gdi column (group description index) directly refers to the index in
the sgpd.sync table. This means the first frame is an IDR, then we have
batches of undefined frames interlaced with CRA frames. No IDR ever
appears again (tried on a 30+ seconds sample).With that information, we can build an heuristic using the presentation
order.A few things needed to be introduced in this commit :
1. min_sample_duration is extracted from the stts : we need the minimal
step between sample in order to PTS-step backward to a valid point
2. In order to avoid a loop over the ctts table systematically during a
seek, we build an expanded list of sample offsets which will be used
to translate from DTS to PTS
3. An open_key_samples index to keep track of all the non-IDR key
frames ; for now it only supports HEVC CRA frames. We should probably
add BLA frames as well, but I don't have any sample so I prefered to
leave that for laterIt is entirely possible I missed something obvious in my approach, but I
couldn't come up with a better solution. Also, as mentioned in the diff,
we could optimize is_open_key_sample(), but the linear scaling overhead
should be fine for now since it only happens in seek events.Fixing this issue prevents sending broken packets to the decoder. With
FFmpeg hevc decoder the frames are skipped, with VideoToolbox the frames
are glitching. -
fileapi::WriteFile() doesn't send an input, if processthreadsapi::STARTUPINFO::hStdError is set (ffmpeg)
23 avril 2021, par LidekysI'm trying to capture my screen using
ffmpegin a different thread (which I create usingprocessthreadsapi::CreateProcess())so I'd be able to do something else in the main thread, and redirectffmpegoutput, so it wouldn't pop up in the console for the user to see. To stop filming, I send a 'q' input usingWriteFile(), and after that I want to saveffmpegaccumulated output usingReadFile().

However, if I set
STARTUPINFO::hStdError(note, thatffmpegoutput goes tostderr) to a pipe, from which I could read the accumulated data, the inputs I send usingWriteFile()are no longer registered and ffmpeg.exe keeps running.

I've tried redirecting
ffmpegoutput in a simple command line, but I can still stop the process by pressing the q button.

Also, if I record for less than 8 seconds, the input is registered and
ffmpeg.execloses.

Is there something wrong with my code, or is it processthreadsapi issue, any hints will be kindly appreciared !


Here's a minimal code of how I am trying to do it :



#include <iostream>

#include 
#include 

using namespace std;

HANDLE g_hChildStd_IN_Rd = NULL;
HANDLE g_hChildStd_IN_Wr = NULL;
HANDLE g_hChildStd_OUT_Rd = NULL;
HANDLE g_hChildStd_OUT_Wr = NULL;

int main()
{
 //Create IN and OUT pipes
 SECURITY_ATTRIBUTES saAttr;
 saAttr.nLength = sizeof(SECURITY_ATTRIBUTES);
 saAttr.lpSecurityDescriptor = NULL;


 if (! CreatePipe(&g_hChildStd_OUT_Rd, &g_hChildStd_OUT_Wr, &saAttr, 0) )
 cout<<"StdoutRd CreatePipe error"</Start recording
 if(!CreateProcess(NULL,
 "ffmpeg -y -f gdigrab -framerate 2 -i desktop record.avi", // command line
 NULL, // process security attributes
 NULL, // primary thread security attributes
 TRUE, // handles are inherited
 0, // creation flags
 NULL, // use parent's environment
 NULL, // use parent's current directory
 &siStartInfo, // STARTUPINFO pointer
 &piProcInfo)) // receives PROCESS_INFORMATION
 {
 cout<<"Error create process"</Record for a while
 while(getch() != 'k'){
 cout<<"While press k"</Stop recording by emulating a Q button push
 DWORD dwWritten;
 CHAR chBufW[1] = {'q'};

 if ( ! WriteFile(g_hChildStd_IN_Wr, chBufW, 1, &dwWritten, NULL) )
 cout<<"Error write file"</Save stdError (ffmpeg) data
 DWORD dwRead;
 char stdErrorData[4096];
 bool bSuccess;

 bSuccess = ReadFile( g_hChildStd_OUT_Wr, stdErrorData, 4096, &dwRead, NULL);

 if(!bSuccess || dwRead == 0)
 cout<<"Read failed"<code></iostream>

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Streaming H.264 over UDP using FFmpeg, and "dimensions not set" error
3 septembre 2015, par Baris DemirayI’m trying to stream H.264 over UDP with no luck so far. Here is a minimal code that you can reproduce the problem.
To compile,
g++ -o test -lavcodec -lavformat -lavutil test.cppExtra information, I start
ffplayas follows. Currently it’s of no use.ffplay -i udp://127.0.0.1:8554/live.sdpOutput of my code (see
avio_open()call),[libx264 @ 0x6a26c0] using mv_range_thread = 24
[libx264 @ 0x6a26c0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.1 Cache64
[libx264 @ 0x6a26c0] profile High, level 3.1
Output #0, h264, to 'udp://127.0.0.1:8554/live.sdp':
Stream #0:0, 0, 0/0: Video: h264 (libx264), -1 reference frame, none, q=-1--1
[h264 @ 0x6a2020] dimensions not set
Cannot write header to stream: SuccessAnd the code,
extern "C" {
#include <libavcodec></libavcodec>avcodec.h>
#include <libavformat></libavformat>avformat.h>
#include <libavutil></libavutil>avutil.h>
}
#include <iostream>
using namespace std;
int main() {
AVCodecContext* m_codecContext;
AVCodec* m_codec;
AVFormatContext* m_formatContext;
AVStream* m_stream;
unsigned m_outWidth = 768;
unsigned m_outHeight = 608;
av_register_all();
avcodec_register_all();
avformat_network_init();
int errorStatus = 0;
char errorLog[128] = { 0 };
av_log_set_level(AV_LOG_TRACE);
string m_output("udp://127.0.0.1:8554/live.sdp");
if (avformat_alloc_output_context2(&m_formatContext, NULL, "h264", m_output.c_str()) < 0) {
cerr << "Cannot allocate output context: "
<< av_make_error_string(errorLog, 128, errorStatus) << endl;
return -1;
}
AVOutputFormat *m_outputFormat = m_formatContext->oformat;
m_codec = avcodec_find_encoder(AV_CODEC_ID_H264);
if (!m_codec) {
cerr << "Cannot find an encoder: "
<< av_make_error_string(errorLog, 128, errorStatus) << endl;
return -1;
}
m_codecContext = avcodec_alloc_context3(m_codec);
if (!m_codecContext) {
cerr << "Cannot allocate a codec context: "
<< av_make_error_string(errorLog, 128, errorStatus) << endl;
return -1;
}
m_codecContext->pix_fmt = AV_PIX_FMT_YUV420P;
m_codecContext->width = m_outWidth;
m_codecContext->height = m_outHeight;
if (avcodec_open2(m_codecContext, m_codec, NULL) < 0) {
cerr << "Cannot open codec: "
<< av_make_error_string(errorLog, 128, errorStatus) << endl;
return -1;
}
m_stream = avformat_new_stream(m_formatContext, m_codec);
if (!m_stream) {
cerr << "Cannot create a new stream: "
<< av_make_error_string(errorLog, 128, errorStatus) << endl;
return -1;
}
av_dump_format(m_formatContext, 0, m_output.c_str(), 1);
if ((errorStatus = avio_open(&m_formatContext->pb, m_output.c_str(), AVIO_FLAG_WRITE)) < 0) {
cerr << "Cannot open output: "
<< av_make_error_string(errorLog, 128, errorStatus) << endl;
return -1;
}
if (avformat_write_header(m_formatContext, NULL) < 0) {
cerr << "Cannot write header to stream: "
<< av_make_error_string(errorLog, 128, errorStatus) << endl;
return -1;
}
cout << "All done." << endl;
return 0;
}
</iostream>For those who has even more time to spare on my problem, when I change
m_outputtortsp://127.0.0.1:8554/live.sdp, andffplaycommand toffplay -rtsp_flags listen -i rtsp://127.0.0.1:8554/live.sdpI get the error,[libx264 @ 0x1e056c0] using mv_range_thread = 24
[libx264 @ 0x1e056c0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.1 Cache64
[libx264 @ 0x1e056c0] profile High, level 3.1
Output #0, h264, to 'rtsp://127.0.0.1:8554/live.sdp':
Stream #0:0, 0, 0/0: Video: h264 (libx264), -1 reference frame, none, q=-1--1
Cannot open output: Protocol not foundAm I naive to expect that streaming protocol will be changed like this ?
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