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ED-ME-5 1-DVD
11 octobre 2011, par
Mis à jour : Octobre 2011
Langue : English
Type : Audio
Autres articles (101)
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Changer le statut par défaut des nouveaux inscrits
26 décembre 2015, parPar défaut, lors de leur inscription, les nouveaux utilisateurs ont le statut de visiteur. Ils disposent de certains droits mais ne peuvent pas forcément publier leurs contenus eux-même etc...
Il est possible de changer ce statut par défaut. en "rédacteur".
Pour ce faire, un administrateur webmestre du site doit aller dans l’espace privé de SPIP en ajoutant ecrire/ à l’url de son site.
Une fois dans l’espace privé, il lui faut suivre les menus configuration > Interactivité et activer (...) -
Changer son thème graphique
22 février 2011, parLe thème graphique ne touche pas à la disposition à proprement dite des éléments dans la page. Il ne fait que modifier l’apparence des éléments.
Le placement peut être modifié effectivement, mais cette modification n’est que visuelle et non pas au niveau de la représentation sémantique de la page.
Modifier le thème graphique utilisé
Pour modifier le thème graphique utilisé, il est nécessaire que le plugin zen-garden soit activé sur le site.
Il suffit ensuite de se rendre dans l’espace de configuration du (...) -
Encodage et transformation en formats lisibles sur Internet
10 avril 2011MediaSPIP transforme et ré-encode les documents mis en ligne afin de les rendre lisibles sur Internet et automatiquement utilisables sans intervention du créateur de contenu.
Les vidéos sont automatiquement encodées dans les formats supportés par HTML5 : MP4, Ogv et WebM. La version "MP4" est également utilisée pour le lecteur flash de secours nécessaire aux anciens navigateurs.
Les documents audios sont également ré-encodés dans les deux formats utilisables par HTML5 :MP3 et Ogg. La version "MP3" (...)
Sur d’autres sites (7014)
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Decode audio and video and process both flows — ffmpeg, sdl, opencv
24 février 2012, par EricMy goal is to proceed on audio and video of mpeg-2 file independently, and to keep synchronicity on both flows. Duration of video is about 1 or 2 minutes maximum.
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First, following this post "opencv for reading videos (and do the process),ffmpeg for audio , and SDL used to play both" sounds perfect. I have done some modification on the code considering recent ffmpeg naming changes. Compilation with cmake on 64-bits machine is fine. I get an error "Unsupported codec [3]" when opening codec.
The code is following. -
Second, I looking for code dealing with synchronicity on both flows.
#include "opencv/highgui.h"
#include "opencv/cv.h"
#ifndef INT64_C
#define INT64_C(c) (c ## LL)
#define UINT64_C(c) (c ## ULL)
#endif
extern "C"{
#include <sdl></sdl>SDL.h>
#include <sdl></sdl>SDL_thread.h>
#include <libavcodec></libavcodec>avcodec.h>
#include <libavformat></libavformat>avformat.h>
}
#include <iostream>
#include
#include
using namespace cv;
#define SDL_AUDIO_BUFFER_SIZE 1024
typedef struct PacketQueue
{
AVPacketList *first_pkt, *last_pkt;
int nb_packets;
int size;
SDL_mutex *mutex;
SDL_cond *cond;
} PacketQueue;
PacketQueue audioq;
int audioStream = -1;
int videoStream = -1;
int quit = 0;
SDL_Surface* screen = NULL;
SDL_Surface* surface = NULL;
AVFormatContext* pFormatCtx = NULL;
AVCodecContext* aCodecCtx = NULL;
AVCodecContext* pCodecCtx = NULL;
void show_frame(IplImage* img){
if (!screen){
screen = SDL_SetVideoMode(img->width, img->height, 0, 0);
if (!screen){
fprintf(stderr, "SDL: could not set video mode - exiting\n");
exit(1);
}
}
// Assuming IplImage packed as BGR 24bits
SDL_Surface* surface = SDL_CreateRGBSurfaceFrom((void*)img->imageData,
img->width,
img->height,
img->depth * img->nChannels,
img->widthStep,
0xff0000, 0x00ff00, 0x0000ff, 0
);
SDL_BlitSurface(surface, 0, screen, 0);
SDL_Flip(screen);
}
void packet_queue_init(PacketQueue *q){
memset(q, 0, sizeof(PacketQueue));
q->mutex = SDL_CreateMutex();
q->cond = SDL_CreateCond();
}
int packet_queue_put(PacketQueue *q, AVPacket *pkt){
AVPacketList *pkt1;
if (av_dup_packet(pkt) < 0){
return -1;
}
pkt1 = (AVPacketList*) av_malloc(sizeof(AVPacketList));
//pkt1 = (AVPacketList*) malloc(sizeof(AVPacketList));
if (!pkt1) return -1;
pkt1->pkt = *pkt;
pkt1->next = NULL;
SDL_LockMutex(q->mutex);
if (!q->last_pkt)
q->first_pkt = pkt1;
else
q->last_pkt->next = pkt1;
q->last_pkt = pkt1;
q->nb_packets++;
q->size += pkt1->pkt.size;
SDL_CondSignal(q->cond);
SDL_UnlockMutex(q->mutex);
return 0;
}
static int packet_queue_get(PacketQueue *q, AVPacket *pkt, int block){
AVPacketList *pkt1;
int ret;
SDL_LockMutex(q->mutex);
for (;;){
if( quit){
ret = -1;
break;
}
pkt1 = q->first_pkt;
if (pkt1){
q->first_pkt = pkt1->next;
if (!q->first_pkt)
q->last_pkt = NULL;
q->nb_packets--;
q->size -= pkt1->pkt.size;
*pkt = pkt1->pkt;
av_free(pkt1);
//free(pkt1);
ret = 1;
break;
}
else if (!block){
ret = 0;
break;
}
else{
SDL_CondWait(q->cond, q->mutex);
}
}
SDL_UnlockMutex(q->mutex);
return ret;
}
int audio_decode_frame(AVCodecContext *aCodecCtx, uint8_t *audio_buf, int buf_size){
static AVPacket pkt;
static uint8_t *audio_pkt_data = NULL;
static int audio_pkt_size = 0;
int len1, data_size;
for (;;){
while (audio_pkt_size > 0){
data_size = buf_size;
len1 = avcodec_decode_audio3(aCodecCtx, (int16_t*)audio_buf, &data_size, &pkt);
if (len1 < 0){
// if error, skip frame
audio_pkt_size = 0;
break;
}
audio_pkt_data += len1;
audio_pkt_size -= len1;
if (data_size <= 0){
// No data yet, get more frames
continue;
}
// We have data, return it and come back for more later
return data_size;
}
if (pkt.data)
av_free_packet(&pkt);
if (quit) return -1;
if (packet_queue_get(&audioq, &pkt, 1) < 0) return -1;
audio_pkt_data = pkt.data;
audio_pkt_size = pkt.size;
}
}
void audio_callback(void *userdata, Uint8 *stream, int len){
AVCodecContext *aCodecCtx = (AVCodecContext *)userdata;
int len1, audio_size;
static uint8_t audio_buf[(AVCODEC_MAX_AUDIO_FRAME_SIZE * 3) / 2];
static unsigned int audio_buf_size = 0;
static unsigned int audio_buf_index = 0;
while (len > 0){
if (audio_buf_index >= audio_buf_size){
// We have already sent all our data; get more
audio_size = audio_decode_frame(aCodecCtx, audio_buf, sizeof(audio_buf));
if(audio_size < 0){
// If error, output silence
audio_buf_size = 1024; // arbitrary?
memset(audio_buf, 0, audio_buf_size);
}
else{
audio_buf_size = audio_size;
}
audio_buf_index = 0;
}
len1 = audio_buf_size - audio_buf_index;
if (len1 > len)
len1 = len;
memcpy(stream, (uint8_t *)audio_buf + audio_buf_index, len1);
len -= len1;
stream += len1;
audio_buf_index += len1;
}
}
void setup_ffmpeg(char* filename)
{
if (avformat_open_input(&pFormatCtx, filename, NULL, NULL) != 0){
fprintf(stderr, "FFmpeg failed to open file %s!\n", filename);
exit(-1);
}
if (av_find_stream_info(pFormatCtx) < 0){
fprintf(stderr, "FFmpeg failed to retrieve stream info!\n");
exit(-1);
}
// Dump information about file onto standard error
av_dump_format(pFormatCtx, 0, filename, 0);
// Find the first video stream
int i = 0;
for (i; i < pFormatCtx->nb_streams; i++){
if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO && videoStream < 0){
videoStream = i;
}
if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO && audioStream < 0){
audioStream = i;
}
}
if (videoStream == -1){
fprintf(stderr, "No video stream found in %s!\n", filename);
exit(-1);
}
if (audioStream == -1){
fprintf(stderr, "No audio stream found in %s!\n", filename);
exit(-1);
}
// Get a pointer to the codec context for the audio stream
aCodecCtx = pFormatCtx->streams[audioStream]->codec;
// Set audio settings from codec info
SDL_AudioSpec wanted_spec;
wanted_spec.freq = aCodecCtx->sample_rate;
wanted_spec.format = AUDIO_S16SYS;
wanted_spec.channels = aCodecCtx->channels;
wanted_spec.silence = 0;
wanted_spec.samples = SDL_AUDIO_BUFFER_SIZE;
wanted_spec.callback = audio_callback;
wanted_spec.userdata = aCodecCtx;
SDL_AudioSpec spec;
if (SDL_OpenAudio(&wanted_spec, &spec) < 0){
fprintf(stderr, "SDL_OpenAudio: %s\n", SDL_GetError());
exit(-1);
}
AVCodec* aCodec = avcodec_find_decoder(aCodecCtx->codec_id);
if (!aCodec){
fprintf(stderr, "Unsupported codec [1]!\n");
exit(-1);
}
avcodec_open(aCodecCtx, aCodec);
// audio_st = pFormatCtx->streams[index]
packet_queue_init(&audioq);
SDL_PauseAudio(0);
// Get a pointer to the codec context for the video stream
pCodecCtx = pFormatCtx->streams[videoStream]->codec;
// Find the decoder for the video stream
AVCodec* pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
if (pCodec == NULL){
fprintf(stderr, "Unsupported codec [2]!\n");
exit(-1); // Codec not found
}
// Open codec
if (avcodec_open(pCodecCtx, pCodec) < 0){
fprintf(stderr, "Unsupported codec [3]!\n");
exit(-1); // Could not open codec
}
}
int main(int argc, char* argv[])
{
if (argc < 2){
std::cout << "Usage: " << argv[0] << " <video>" << std::endl;
return -1;
}
av_register_all();
// Init SDL
if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER))
{
fprintf(stderr, "Could not initialize SDL - %s\n", SDL_GetError());
return -1;
}
// Init ffmpeg and setup some SDL stuff related to Audio
setup_ffmpeg(argv[1]);
VideoCapture cap(argv[1]);
if (!cap.isOpened()){
std::cout << "Failed to load file!" << std::endl;
return -1;
}
AVPacket packet;
while (av_read_frame(pFormatCtx, &packet) >= 0)
{
if (packet.stream_index == videoStream)
{
// Actually this is were SYNC between audio/video would happen.
// Right now I assume that every VIDEO packet contains an entire video frame, and that's not true. A video frame can be made by multiple packets!
// But for the time being, assume 1 video frame == 1 video packet,
// so instead of reading the frame through ffmpeg, I read it through OpenCV.
Mat frame;
cap >> frame; // get a new frame from camera
// do some processing on the frame, either as a Mat or as IplImage.
// For educational purposes, applying a lame grayscale conversion
IplImage ipl_frame = frame;
for (int i = 0; i < ipl_frame.width * ipl_frame.height * ipl_frame.nChannels; i += ipl_frame.nChannels)
{
ipl_frame.imageData[i] = (ipl_frame.imageData[i] + ipl_frame.imageData[i+1] + ipl_frame.imageData[i+2])/3; //B
ipl_frame.imageData[i+1] = (ipl_frame.imageData[i] + ipl_frame.imageData[i+1] + ipl_frame.imageData[i+2])/3; //G
ipl_frame.imageData[i+2] = (ipl_frame.imageData[i] + ipl_frame.imageData[i+1] + ipl_frame.imageData[i+2])/3; //R
}
// Display it on SDL window
show_frame(&ipl_frame);
av_free_packet(&packet);
}
else if (packet.stream_index == audioStream)
{
packet_queue_put(&audioq, &packet);
}
else
{
av_free_packet(&packet);
}
SDL_Event event;
SDL_PollEvent(&event);
switch (event.type)
{
case SDL_QUIT:
SDL_FreeSurface(surface);
SDL_Quit();
break;
default:
break;
}
}
// the camera will be deinitialized automatically in VideoCapture destructor
// Close the codec
avcodec_close(pCodecCtx);
// Close the video file
av_close_input_file(pFormatCtx);
return 0;
}
</video></iostream> -
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fatal error : 'Carbon/Carbon.h' file not found when trying to compile with glfw module macos monterey
21 avril 2022, par Nowfal Salahudeen


i have searched about carbon in glfw. some answers says that it was removed. Any alternative solution for this ?


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I got a message "using Plots" in Julia and I do no how to resolve it
7 septembre 2020, par EhsanI am a new in Julia and after adding the Plots package I tried to use Plots and I got this Error message :


julia> using Plots
[ Info: Precompiling Plots [91a5bcdd-55d7-5caf-9e0b-520d859cae80]
ERROR: LoadError: InitError: could not load library "C:\Users\niri.julia\artifacts\7350a6401f1c0d38cc3518193083bc4f83adfe99\bin\avcodec-58.dll"
The specified module could not be found.
Stacktrace:

ERROR: LoadError: Failed to precompile FFMPEG [c87230d0-a227-11e9-1b43-d7ebe4e7570a] to C:\Users\niri.julia\compiled\v1.5\FFMPEG\TGvga_Ik59J.ji.

ERROR: Failed to precompile Plots [91a5bcdd-55d7-5caf-9e0b-520d859cae80] to 


can someone help me to resolve the problem


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