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Médias (91)
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Valkaama DVD Cover Outside
4 octobre 2011, par
Mis à jour : Octobre 2011
Langue : English
Type : Image
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Valkaama DVD Label
4 octobre 2011, par
Mis à jour : Février 2013
Langue : English
Type : Image
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Valkaama DVD Cover Inside
4 octobre 2011, par
Mis à jour : Octobre 2011
Langue : English
Type : Image
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1,000,000
27 septembre 2011, par
Mis à jour : Septembre 2011
Langue : English
Type : Audio
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Demon Seed
26 septembre 2011, par
Mis à jour : Septembre 2011
Langue : English
Type : Audio
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The Four of Us are Dying
26 septembre 2011, par
Mis à jour : Septembre 2011
Langue : English
Type : Audio
Autres articles (86)
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Personnaliser en ajoutant son logo, sa bannière ou son image de fond
5 septembre 2013, parCertains thèmes prennent en compte trois éléments de personnalisation : l’ajout d’un logo ; l’ajout d’une bannière l’ajout d’une image de fond ;
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Ecrire une actualité
21 juin 2013, parPrésentez les changements dans votre MédiaSPIP ou les actualités de vos projets sur votre MédiaSPIP grâce à la rubrique actualités.
Dans le thème par défaut spipeo de MédiaSPIP, les actualités sont affichées en bas de la page principale sous les éditoriaux.
Vous pouvez personnaliser le formulaire de création d’une actualité.
Formulaire de création d’une actualité Dans le cas d’un document de type actualité, les champs proposés par défaut sont : Date de publication ( personnaliser la date de publication ) (...) -
Gestion des droits de création et d’édition des objets
8 février 2011, parPar défaut, beaucoup de fonctionnalités sont limitées aux administrateurs mais restent configurables indépendamment pour modifier leur statut minimal d’utilisation notamment : la rédaction de contenus sur le site modifiables dans la gestion des templates de formulaires ; l’ajout de notes aux articles ; l’ajout de légendes et d’annotations sur les images ;
Sur d’autres sites (12016)
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avformat : add AV1 RTP depacketizer and packetizer
26 août 2024, par Chris Hodgesavformat : add AV1 RTP depacketizer and packetizer
Add RTP packetizer and depacketizer according to (most)
of the official AV1 RTP specification. This enables
streaming via RTSP between ffmpeg and ffmpeg and has
also been tested to work with AV1 RTSP streams via
GStreamer.It also adds the required SDP attributes for AV1.
AV1 RTP encoding is marked as experimental due to
draft specification status, debug amount reduced
and other changes suggested by Tristan.Added optional code for searching the sequence
header to determine the first packet for broken
AV1 encoders / parsers.Stops depacketizing on corruption until next keyframe,
no longer prematurely issues packet on decoding if
temporal unit was not complete yet.Change-Id : I90f5c5b9d577908a0d713606706b5654fde5f910
Signed-off-by : Chris Hodges <chrishod@axis.com>
Signed-off-by : Ronald S. Bultje <rsbultje@gmail.com> -
Introducing the Matomo Connector for Looker Studio (Formerly Google Data Studio)
26 janvier 2024, par Erin — Community -
why is ffmpeg so fast
8 juillet 2017, par jx.xuI have written a ffmpeg-based C++ program about converting yuv to rgb using libswscale, similar to the official example.
Just simple copy and modify the official example before build in my visual studio 2017 on windows 10. However, the time performance is much slower than the ffmpeg.exe executable file, as 36 seconds vs 12 seconds.
I already know that ffmpeg uses some optimization techniques like SIMD instructions. While in my performance profiling, the bottleneck is disk I/O writing which takes at least 2/3 time.
Then I develop a concurrent version where a dedicated thread will handle all I/O task while the situation doesn’t seem to improve. It’s worth noting that I use Boost C++ library to utilize multi-thread and asynchronous events.So, I just wanna know how can I modify program using the libraries of ffmpeg or the time performance gap towards ffmpeg.exe just can’ be catched up.
As requested by friendly answers, I post my codes. Compiler is msvc in vs2017 and I turn on the full optimization /Ox .
Supplement my main question, I make another plain disk I/O test merely copying the file of the same size. It’s surprising to find that plain sequential disk I/O costs 28 seconds while the front codes cost 36 seconds in total... Any one knows how can ffmpeg finishes the same job in only 12 seconds ? That must use some optimization techniques, like random disk I/O or memory buffer reusing ?
#include "stdafx.h"
#define __STDC_CONSTANT_MACROS
extern "C" {
#include <libavutil></libavutil>imgutils.h>
#include <libavutil></libavutil>parseutils.h>
#include <libswscale></libswscale>swscale.h>
}
#ifdef _WIN64
#pragma comment(lib, "avformat.lib")
#pragma comment(lib, "avcodec.lib")
#pragma comment(lib, "avutil.lib")
#pragma comment(lib, "swscale.lib")
#endif
#include <common></common>cite.hpp> // just include headers of c++ STL/Boost
int main(int argc, char **argv)
{
chrono::duration<double> period;
auto pIn = fopen("G:/Panorama/UHD/originalVideos/DrivingInCountry_3840x1920_30fps_8bit_420_erp.yuv", "rb");
auto time_mark = chrono::steady_clock::now();
int src_w = 3840, src_h = 1920, dst_w, dst_h;
enum AVPixelFormat src_pix_fmt = AV_PIX_FMT_YUV420P, dst_pix_fmt = AV_PIX_FMT_RGB24;
const char *dst_filename = "G:/Panorama/UHD/originalVideos/out.rgb";
const char *dst_size = "3840x1920";
FILE *dst_file;
int dst_bufsize;
struct SwsContext *sws_ctx;
int i, ret;
if (av_parse_video_size(&dst_w, &dst_h, dst_size) < 0) {
fprintf(stderr,
"Invalid size '%s', must be in the form WxH or a valid size abbreviation\n",
dst_size);
exit(1);
}
dst_file = fopen(dst_filename, "wb");
if (!dst_file) {
fprintf(stderr, "Could not open destination file %s\n", dst_filename);
exit(1);
}
/* create scaling context */
sws_ctx = sws_getContext(src_w, src_h, src_pix_fmt,
dst_w, dst_h, dst_pix_fmt,
SWS_BILINEAR, NULL, NULL, NULL);
if (!sws_ctx) {
fprintf(stderr,
"Impossible to create scale context for the conversion "
"fmt:%s s:%dx%d -> fmt:%s s:%dx%d\n",
av_get_pix_fmt_name(src_pix_fmt), src_w, src_h,
av_get_pix_fmt_name(dst_pix_fmt), dst_w, dst_h);
ret = AVERROR(EINVAL);
exit(1);
}
io_service srv; // Boost.Asio class
auto work = make_shared(srv);
thread t{ bind(&io_service::run,&srv) }; // I/O worker thread
vector> result;
/* utilize function class so that lambda can capture itself */
function)> recursion;
recursion = [&](int left, unique_future<bool> writable)
{
if (left <= 0)
{
writable.wait();
return;
}
uint8_t *src_data[4], *dst_data[4];
int src_linesize[4], dst_linesize[4];
/* promise-future pair used for thread synchronizing so that the file part is written in the correct sequence */
promise<bool> sync;
/* allocate source and destination image buffers */
if ((ret = av_image_alloc(src_data, src_linesize,
src_w, src_h, src_pix_fmt, 16)) < 0) {
fprintf(stderr, "Could not allocate source image\n");
}
/* buffer is going to be written to rawvideo file, no alignment */
if ((ret = av_image_alloc(dst_data, dst_linesize,
dst_w, dst_h, dst_pix_fmt, 1)) < 0) {
fprintf(stderr, "Could not allocate destination image\n");
}
dst_bufsize = ret;
fread(src_data[0], src_h*src_w, 1, pIn);
fread(src_data[1], src_h*src_w / 4, 1, pIn);
fread(src_data[2], src_h*src_w / 4, 1, pIn);
result.push_back(async([&] {
/* convert to destination format */
sws_scale(sws_ctx, (const uint8_t * const*)src_data,
src_linesize, 0, src_h, dst_data, dst_linesize);
if (left>0)
{
assert(writable.get() == true);
srv.post([=]
{
/* write scaled image to file */
fwrite(dst_data[0], 1, dst_bufsize, dst_file);
av_freep((void*)&dst_data[0]);
});
}
sync.set_value(true);
av_freep(&src_data[0]);
}));
recursion(left - 1, sync.get_future());
};
promise<bool> root;
root.set_value(true);
recursion(300, root.get_future()); // .yuv file only has 300 frames
wait_for_all(result.begin(), result.end()); // wait for all unique_future to callback
work.reset(); // io_service::work releses
srv.stop(); // io_service stops
t.join(); // I/O thread joins
period = steady_clock::now() - time_mark; // calculate valid time
fprintf(stderr, "Scaling succeeded. Play the output file with the command:\n"
"ffplay -f rawvideo -pix_fmt %s -video_size %dx%d %s\n",
av_get_pix_fmt_name(dst_pix_fmt), dst_w, dst_h, dst_filename);
cout << "period" << et << period << en;
end:
fclose(dst_file);
// av_freep(&src_data[0]);
// av_freep(&dst_data[0]);
sws_freeContext(sws_ctx);
return ret < 0;
}
</bool></bool></bool></double>