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La conservation du net art au musée. Les stratégies à l’œuvre
26 mai 2011
Mis à jour : Juillet 2013
Langue : français
Type : Texte
Autres articles (52)
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Use, discuss, criticize
13 avril 2011, parTalk to people directly involved in MediaSPIP’s development, or to people around you who could use MediaSPIP to share, enhance or develop their creative projects.
The bigger the community, the more MediaSPIP’s potential will be explored and the faster the software will evolve.
A discussion list is available for all exchanges between users. -
Les tâches Cron régulières de la ferme
1er décembre 2010, parLa gestion de la ferme passe par l’exécution à intervalle régulier de plusieurs tâches répétitives dites Cron.
Le super Cron (gestion_mutu_super_cron)
Cette tâche, planifiée chaque minute, a pour simple effet d’appeler le Cron de l’ensemble des instances de la mutualisation régulièrement. Couplée avec un Cron système sur le site central de la mutualisation, cela permet de simplement générer des visites régulières sur les différents sites et éviter que les tâches des sites peu visités soient trop (...) -
MediaSPIP v0.2
21 juin 2013, parMediaSPIP 0.2 is the first MediaSPIP stable release.
Its official release date is June 21, 2013 and is announced here.
The zip file provided here only contains the sources of MediaSPIP in its standalone version.
To get a working installation, you must manually install all-software dependencies on the server.
If you want to use this archive for an installation in "farm mode", you will also need to proceed to other manual (...)
Sur d’autres sites (6379)
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How to live stream from Windows 10 app to Youtube ?
12 août 2015, par BolandI’m playing around with the YouTube Live Stream API. That’s working fine so far, but the next step is to stream the web cam data to YouTube via RTMP.
In the (excellent) documentation at Google Dev, it outlines the Life of a Broadcast. However, all steps are documented in detail, except the step I’m interested in :
Step 3.2 : Start your video
Start transmitting video on your video stream.
I was able to use Open Broadcasting Software to stream to a manually created YouTube Live Event, but I have no idea how to do it from my Windows 10 App. I’ve looked at the MediaElement class, and was able to capture the web cam preview in my app. But I can only find methods to save as a file.
Also found information about FFMPEG, which should probably be able to do the job, but I cannot find a library / DLL to use FFMPEG in my App.
I just need some guidance where to look next, because now I’m just clueless what to do.
/edit : I came across MPlatform SDK, which sounds exactly what I want, but it costs $5000.... Not for a hobby :(
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Join two corrupt Mp4 Files
13 mars 2019, par skmI have a corrupted MP4 file. I want to repair the file for which I have already read some answers at SO but none of them seem to work anymore (not free anymore).
I found another trial software which can repair only the first half of the video. Using that Software, I am successfully able to get the first half of my video. Therefore, I want to join the same video two times so that I can get my video repaired.
I am using Windows and have already downloaded
ffmpeg. I tried to concatenate the videos following the answers on this SO post but concatenation did not work (probably because my .mp4 files are corrupt). -
FFmpeg:A General error in an external library occurred when using FFmpeg6.1's avcodec_send_frame
4 janvier 2024, par MMingYI have the same code that can successfully push streams (rtmp) in the environment, but in the Android environment, I fail with an error message. The error message method is avcodec_send_frame in ffmpeg6.1. By the way, I compiled the FFmpeg library on Android myself, and I downloaded the official package for Win11. I will provide the code for Android and Win11 below.


android :


static void encode(AVCodecContext *enc_ctx, AVFrame *frame, AVPacket *pkt,

 AVFormatContext *outFormatCtx) {
 int ret;

 /* send the frame to the encoder */
 if (frame)
 LOGE2("Send frame %ld\n", frame->pts);

 ret = avcodec_send_frame(enc_ctx, frame);
 if (ret < 0) {
 char errbuf[AV_ERROR_MAX_STRING_SIZE];
 av_strerror(ret, errbuf, AV_ERROR_MAX_STRING_SIZE);
 LOGE2("Error sending a frame for encoding ,%s\n", errbuf);
// exit(1);
 return;
 }

 while (ret >= 0) {
 ret = avcodec_receive_packet(enc_ctx, pkt);
 if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
 return;
 else if (ret < 0) {
 fprintf(stderr, "Error during encoding\n");
 exit(1);
 }

 printf("Write packet (size=%5d)\n", pkt->pts);
 /* ret = av_interleaved_write_frame(outFormatCtx, pkt);
 if (ret < 0) {
 LOGE2("write frame err=%s", av_err2str(ret));
 break;
 }*/
// printf("Write packet %3"PRId64" (size=%5d)\n", pkt->pts, pkt->size);
 av_write_frame(outFormatCtx, pkt); // Write the packet to the RTMP stream
 av_packet_unref(pkt);
 }
}

PUSHER_FUNC(int, testPush, jstring yuvPath, jstring outputPath) {
 const char *yvu_path = env->GetStringUTFChars(yuvPath, JNI_FALSE);
 const char *output_path = env->GetStringUTFChars(outputPath, JNI_FALSE);
 const char *rtmp_url = output_path;
 const AVCodec *codec;
 AVCodecContext *codecContext = NULL;
 AVFormatContext *outFormatCtx;
 int ret = 0;
 AVStream *outStream;
 AVFrame *frame;
 AVPacket *pkt;
 int i, x, y;
 avformat_network_init();

 codec = avcodec_find_encoder(AV_CODEC_ID_H264);
// codec = avcodec_find_encoder(AV_CODEC_ID_MPEG4);
// codec = avcodec_find_encoder(AV_CODEC_ID_H265);
 if (!codec) {
 LOGE2("JNI Error finding H.264 encoder");
 return -1;
 }
 codecContext = avcodec_alloc_context3(codec);
 if (!codecContext) {
 fprintf(stderr, "Could not allocate video codec context\n");
 return -1;
 }

 /* Allocate the output context */
 outFormatCtx = avformat_alloc_context();
 if (!outFormatCtx) {
 fprintf(stderr, "Could not allocate output context\n");
 return -1;
 }

 /* Open the RTMP output */
 const AVOutputFormat *ofmt = av_guess_format("flv", NULL, NULL);
// const AVOutputFormat *ofmt = av_guess_format("mpegts", NULL, NULL);
// const AVOutputFormat *ofmt = av_guess_format("mp4", NULL, NULL);
 if (!ofmt) {
 fprintf(stderr, "Could not find output format\n");
 return -1;
 }
 outFormatCtx->oformat = ofmt;
 outFormatCtx->url = av_strdup(rtmp_url);
 /* Add a video stream */
 outStream = avformat_new_stream(outFormatCtx, codec);
 if (!outStream) {
 fprintf(stderr, "Could not allocate stream\n");
 return -1;
 }
 outStream->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
 outStream->codecpar->codec_id = codec->id;
 outStream->codecpar->width = 352;
 outStream->codecpar->height = 288;

 /* Set the output URL */
 av_dict_set(&outFormatCtx->metadata, "url", rtmp_url, 0);

 pkt = av_packet_alloc();
 if (!pkt)
 return -1;

 /* ... (rest of the setup code) ... */
/* put sample parameters */
 codecContext->bit_rate = 400000;
 /* resolution must be a multiple of two */
 codecContext->width = 352;
 codecContext->height = 288;
 /* frames per second */
 codecContext->time_base = (AVRational) {1, 25};
 codecContext->framerate = (AVRational) {25, 1};

 /* emit one intra frame every ten frames
 * check frame pict_type before passing frame
 * to encoder, if frame->pict_type is AV_PICTURE_TYPE_I
 * then gop_size is ignored and the output of encoder
 * will always be I frame irrespective to gop_size
 */
 codecContext->gop_size = 10;
 codecContext->max_b_frames = 1;
 codecContext->pix_fmt = AV_PIX_FMT_YUV420P;

 if (codec->id == AV_CODEC_ID_H264)
 av_opt_set(codecContext->priv_data, "preset", "slow", 0);

 /* open it */
 ret = avcodec_open2(codecContext, codec, NULL);
 if (ret < 0) {
 LOGE2("JNI Error opening codec eer%s", av_err2str(ret));
 return ret;
 }

 avcodec_parameters_to_context(codecContext, outStream->codecpar);

 if (avio_open(&outFormatCtx->pb, rtmp_url, AVIO_FLAG_WRITE)) {
 fprintf(stderr, "Could not open output\n");
 return ret;
 }
 /* Write the header */
 if (avformat_write_header(outFormatCtx, NULL) != 0) {
 fprintf(stderr, "Error occurred when opening output\n");
 return ret;
 }

 frame = av_frame_alloc();
 if (!frame) {
 fprintf(stderr, "Could not allocate video frame\n");
 return -1;
 }
 frame->format = codecContext->pix_fmt;
 frame->format = AV_PIX_FMT_YUV420P;
 frame->format = 0;
 frame->width = codecContext->width;
 frame->height = codecContext->height;

 ret = av_frame_get_buffer(frame, 0);
 if (ret < 0) {
 fprintf(stderr, "Could not allocate the video frame data ,%s\n", av_err2str(ret));
 return ret;
 }

 /* FILE *yuv_file = fopen(yvu_path, "rb");
 if (yuv_file == NULL) {
 LOGE2("cannot open h264 file");
 return -1;
 }*/

 /* encode 1 second of video */
 for (i = 0; i < 25000; i++) {
// for (i = 0; i < 25; i++) {
// fflush(stdout);

 /* make sure the frame data is writable */
 ret = av_frame_make_writable(frame);
 if (ret < 0)
 exit(1);

 /* prepare a dummy image */
 /* Y */
 for (y = 0; y < codecContext->height; y++) {
 for (x = 0; x < codecContext->width; x++) {
 frame->data[0][y * frame->linesize[0] + x] = x + y + i * 3;
 }
 }

 /* Cb and Cr */
 for (y = 0; y < codecContext->height / 2; y++) {
 for (x = 0; x < codecContext->width / 2; x++) {
 frame->data[1][y * frame->linesize[1] + x] = 128 + y + i * 2;
 frame->data[2][y * frame->linesize[2] + x] = 64 + x + i * 5;
 }
 }

 frame->pts = i;

 /* encode the image */
 encode(codecContext, frame, pkt, outFormatCtx);
 }

// fclose(yuv_file);

 /* flush the encoder */
 encode(codecContext, NULL, pkt, outFormatCtx);

 /* Write the trailer */
 av_write_trailer(outFormatCtx);

 /* Close the output */
 avformat_free_context(outFormatCtx);

 avcodec_free_context(&codecContext);
 av_frame_free(&frame);
 av_packet_free(&pkt);
}


win11：


#include 
#include 
#include 

#include <libavcodec></libavcodec>avcodec.h>
#include <libavformat></libavformat>avformat.h>
#include <libavutil></libavutil>opt.h>
#include <libavutil></libavutil>imgutils.h>
#include <libavutil></libavutil>time.h>

static void encode(AVCodecContext *enc_ctx, AVFrame *frame, AVPacket *pkt,
 AVFormatContext *outFormatCtx) {
 int ret;

 /* send the frame to the encoder */
 if (frame)
 printf("Send frame %3"PRId64"\n", frame->pts);

 ret = avcodec_send_frame(enc_ctx, frame);
 if (ret < 0) {
 char errbuf[AV_ERROR_MAX_STRING_SIZE];
 av_strerror(ret, errbuf, AV_ERROR_MAX_STRING_SIZE);
 fprintf(stderr, "Error sending a frame for encoding ,%s\n", errbuf);
 exit(1);
 }

 while (ret >= 0) {
 ret = avcodec_receive_packet(enc_ctx, pkt);
 if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
 return;
 else if (ret < 0) {
 fprintf(stderr, "Error during encoding\n");
 exit(1);
 }

 printf("Write packet %3"PRId64" (size=%5d)\n", pkt->pts, pkt->size);
 av_write_frame(outFormatCtx, pkt); // Write the packet to the RTMP stream
 av_packet_unref(pkt);
 }
}

int main(int argc, char **argv) {
 av_log_set_level(AV_LOG_DEBUG);
 const char *rtmp_url, *codec_name;
 const AVCodec *codec;
 AVCodecContext *codecContext = NULL;
 int i, ret, x, y;
 AVFormatContext *outFormatCtx;
 AVStream *st;
 AVFrame *frame;
 AVPacket *pkt;
 uint8_t endcode[] = {0, 0, 1, 0xb7};

 if (argc <= 3) {
 fprintf(stderr, "Usage: %s <rtmp url="url"> <codec>\n", argv[0]);
 exit(0);
 }
 rtmp_url = argv[1];
 codec_name = argv[2];
 avformat_network_init();
 /* find the mpeg1video encoder */
// codec = avcodec_find_encoder_by_name(codec_name);
// codec = avcodec_find_encoder(AV_CODEC_ID_MPEG4);
// codec = avcodec_find_encoder(AV_CODEC_ID_VP9);
// codec = avcodec_find_encoder(AV_CODEC_ID_MPEG2VIDEO);
// codec = avcodec_find_encoder(AV_CODEC_ID_H264);
 codec = avcodec_find_encoder(AV_CODEC_ID_H264);
// codec = avcodec_find_encoder(AV_CODEC_ID_AV1);
// codec = avcodec_find_encoder(AV_CODEC_ID_H265);
 if (!codec) {
 fprintf(stderr, "Codec '%s' not found\n", codec_name);
 exit(1);
 }
 codecContext = avcodec_alloc_context3(codec);
 if (!codecContext) {
 fprintf(stderr, "Could not allocate video codec context\n");
 exit(1);
 }

 /* Allocate the output context */
 outFormatCtx = avformat_alloc_context();
 if (!outFormatCtx) {
 fprintf(stderr, "Could not allocate output context\n");
 exit(1);
 }

 /* Open the RTMP output */
 const AVOutputFormat *ofmt = av_guess_format("flv", NULL, NULL);
// const AVOutputFormat *ofmt = av_guess_format("MKV", NULL, NULL);
// const AVOutputFormat *ofmt = av_guess_format("rtmp", NULL, NULL);
// const AVOutputFormat *ofmt = av_guess_format("mpegts", NULL, NULL);
// const AVOutputFormat *ofmt = av_guess_format("mp4", NULL, NULL);
 if (!ofmt) {
 fprintf(stderr, "Could not find output format\n");
 exit(1);
 }
 outFormatCtx->oformat = ofmt;
 outFormatCtx->url = av_strdup(rtmp_url);
 /* Add a video stream */
 st = avformat_new_stream(outFormatCtx, codec);
 if (!st) {
 fprintf(stderr, "Could not allocate stream\n");
 exit(1);
 }
 st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
 st->codecpar->codec_id = codec->id;
 st->codecpar->width = 352;
 st->codecpar->height = 288;
// st->codecpar = c;
// st->codecpar->format = AV_PIX_FMT_YUV420P;
 // Set video stream parameters
// st->codecpar->framerate = (AVRational){25, 1};

 /* Set the output URL */
 av_dict_set(&outFormatCtx->metadata, "url", rtmp_url, 0);


 pkt = av_packet_alloc();
 if (!pkt)
 exit(1);

 /* ... (rest of the setup code) ... */
/* put sample parameters */
 codecContext->bit_rate = 400000;
 /* resolution must be a multiple of two */
 codecContext->width = 352;
 codecContext->height = 288;
 /* frames per second */
 codecContext->time_base = (AVRational) {1, 25};
 codecContext->framerate = (AVRational) {25, 1};

 /* emit one intra frame every ten frames
 * check frame pict_type before passing frame
 * to encoder, if frame->pict_type is AV_PICTURE_TYPE_I
 * then gop_size is ignored and the output of encoder
 * will always be I frame irrespective to gop_size
 */
 codecContext->gop_size = 10;
 codecContext->max_b_frames = 1;
 codecContext->pix_fmt = AV_PIX_FMT_YUV420P;

 if (codec->id == AV_CODEC_ID_H264)
 av_opt_set(codecContext->priv_data, "preset", "slow", 0);

 /* open it */
 ret = avcodec_open2(codecContext, codec, NULL);
 if (ret < 0) {
 fprintf(stderr, "Could not open codec: %s\n", av_err2str(ret));
 exit(1);
 }

 avcodec_parameters_to_context(codecContext, st->codecpar);

 if (avio_open(&outFormatCtx->pb, rtmp_url, AVIO_FLAG_WRITE)) {
 fprintf(stderr, "Could not open output\n");
 exit(1);
 }
 /* Write the header */
 if (avformat_write_header(outFormatCtx, NULL) != 0) {
 fprintf(stderr, "Error occurred when opening output\n");
 exit(1);
 }

 frame = av_frame_alloc();
 if (!frame) {
 fprintf(stderr, "Could not allocate video frame\n");
 exit(1);
 }
// frame->format = c->pix_fmt;
// frame->format = AV_PIX_FMT_YUV420P;
 frame->format = 0;
 frame->width = codecContext->width;
 frame->height = codecContext->height;

 ret = av_frame_get_buffer(frame, 0);
 if (ret < 0) {
 fprintf(stderr, "Could not allocate the video frame data ,%s\n", av_err2str(ret));
 exit(1);
 }

 /* encode 1 second of video */
 for (i = 0; i < 2500; i++) {
 /* ... (rest of the encoding loop) ... */
 fflush(stdout);

 /* make sure the frame data is writable */
 ret = av_frame_make_writable(frame);
 if (ret < 0)
 exit(1);

 /* prepare a dummy image */
 /* Y */
 for (y = 0; y < codecContext->height; y++) {
 for (x = 0; x < codecContext->width; x++) {
 frame->data[0][y * frame->linesize[0] + x] = x + y + i * 3;
 }
 }

 /* Cb and Cr */
 for (y = 0; y < codecContext->height / 2; y++) {
 for (x = 0; x < codecContext->width / 2; x++) {
 frame->data[1][y * frame->linesize[1] + x] = 128 + y + i * 2;
 frame->data[2][y * frame->linesize[2] + x] = 64 + x + i * 5;
 }
 }

 frame->pts = i;

 /* encode the image */
 encode(codecContext, frame, pkt, outFormatCtx);
 }

 /* flush the encoder */
 encode(codecContext, NULL, pkt, outFormatCtx);

 /* Write the trailer */
 av_write_trailer(outFormatCtx);

 /* Close the output */
 avformat_free_context(outFormatCtx);

 avcodec_free_context(&codecContext);
 av_frame_free(&frame);
 av_packet_free(&pkt);

 return 0;
}
</codec></rtmp>

I suspect it's an issue with the ffmpeg library I compiled, so I searched for a step to compile ffmpeg on GitHub, but the package it compiled still has the same problem. I don't know what to do now.


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