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Bug de détection d’ogg
22 mars 2013, par
Mis à jour : Avril 2013
Langue : français
Type : Video
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Les autorisations surchargées par les plugins
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autoriser_auteur_modifier() afin que les visiteurs soient capables de modifier leurs informations sur la page d’auteurs -
Publier sur MédiaSpip
13 juin 2013Puis-je poster des contenus à partir d’une tablette Ipad ?
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10 avril 2011Un logiciel n’est malheureusement jamais parfait...
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Sur d’autres sites (10930)
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Detect frames that have a given image/logo with FFmpeg
7 juillet 2022, par sccI'm trying to split a video by detecting the presence of a marker (an image) in the frames. I've gone over the documentation and I see
removelogobut notdetectlogo.


Does anyone know how this could be achieved ? I know what the logo is and the region it will be on.



I'm thinking I can extract all frames to png's and then analyse them one by one (or n by n) but it might be a lengthy process...



Any pointers ?


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Detect frames that have a given image/logo with FFmpeg
15 juillet 2012, par sofiaI'm trying to split a video by detecting the presence of a marker (an image) in the frames. I've gone over the documentation and I see
removelogobut notdetectlogo.Does anyone know how this could be achieved ? I know what the logo is and the region it will be on.
I'm thinking I can extract all frames to png's and then analyse them one by one (or n by n) but it might be a lengthy process...
Any pointers ?
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FFMPEG libx265 encoding leaves memory unfreed after avcodec_free_context
28 août 2020, par ahugeatI am working on H265 encoding software and, in my unit tests, I have some weird memory leaks. To found them, I have modified the
encode_video.cexample from FFMPEG documentation. I have changed the resolution to correspond at a 4K video, I have adapted the bitrate and I have added a pause before context allocation and another one before the final return :

#include 
#include 
#include 
#include 

#include <libavcodec></libavcodec>avcodec.h>

#include <libavutil></libavutil>opt.h>
#include <libavutil></libavutil>imgutils.h>

static void encode(AVCodecContext *enc_ctx, AVFrame *frame, AVPacket *pkt,
 FILE *outfile)
{
 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) {
 fprintf(stderr, "Error sending a frame for encoding\n");
 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);
 fwrite(pkt->data, 1, pkt->size, outfile);
 av_packet_unref(pkt);
 }
}

int main(int argc, char **argv)
{
 const char *filename, *codec_name;
 const AVCodec *codec;
 AVCodecContext *c= NULL;
 int i, ret, x, y;
 FILE *f;
 AVFrame *frame;
 AVPacket *pkt;
 uint8_t endcode[] = { 0, 0, 1, 0xb7 };

 if (argc <= 2) {
 fprintf(stderr, "Usage: %s <output file="file"> <codec>\n", argv[0]);
 exit(0);
 }
 filename = argv[1];
 codec_name = argv[2];

 sleep(10);

 /* find the mpeg1video encoder */
 codec = avcodec_find_encoder_by_name(codec_name);
 if (!codec) {
 fprintf(stderr, "Codec '%s' not found\n", codec_name);
 exit(1);
 }

 c = avcodec_alloc_context3(codec);
 if (!c) {
 fprintf(stderr, "Could not allocate video codec context\n");
 exit(1);
 }

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

 /* put sample parameters */
 c->bit_rate = 1000000;
 /* resolution must be a multiple of two */
 c->width = 3840;
 c->height = 2160;
 /* frames per second */
 c->time_base = (AVRational){1, 25};
 c->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
 */
 c->gop_size = 10;
 c->max_b_frames = 1;
 c->pix_fmt = AV_PIX_FMT_YUV420P;

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

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

 f = fopen(filename, "wb");
 if (!f) {
 fprintf(stderr, "Could not open %s\n", filename);
 exit(1);
 }

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

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

 /* encode 1 second of video */
 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 < c->height; y++) {
 for (x = 0; x < c->width; x++) {
 frame->data[0][y * frame->linesize[0] + x] = x + y + i * 3;
 }
 }

 /* Cb and Cr */
 for (y = 0; y < c->height/2; y++) {
 for (x = 0; x < c->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(c, frame, pkt, f);
 }

 /* flush the encoder */
 encode(c, NULL, pkt, f);

 /* add sequence end code to have a real MPEG file */
 if (codec->id == AV_CODEC_ID_MPEG1VIDEO || codec->id == AV_CODEC_ID_MPEG2VIDEO)
 fwrite(endcode, 1, sizeof(endcode), f);
 fclose(f);

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

 sleep(10);

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

I was expecting that the RAM memory usage at the first pause is the same as the second pause but there is about 55 Mo of difference. If I increase the number of encoded frames, this difference up to 390 Mo. I have tested this code under Linux Mint LMDE 4 (roughly same as Debian 10).


I guess this memory "leak" it isn't a real memory leak but that it's some internal values used by libx265 to be maybe reused for another encoding. But has there a way to free this memory through FFMPEG API ?


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