Recherche avancée
Autres articles (63)
-
Websites made with MediaSPIP
2 mai 2011, parThis page lists some websites based on MediaSPIP.
-
Contribute to a better visual interface
13 avril 2011MediaSPIP is based on a system of themes and templates. Templates define the placement of information on the page, and can be adapted to a wide range of uses. Themes define the overall graphic appearance of the site.
Anyone can submit a new graphic theme or template and make it available to the MediaSPIP community. -
Submit enhancements and plugins
13 avril 2011If you have developed a new extension to add one or more useful features to MediaSPIP, let us know and its integration into the core MedisSPIP functionality will be considered.
You can use the development discussion list to request for help with creating a plugin. As MediaSPIP is based on SPIP - or you can use the SPIP discussion list SPIP-Zone.
Sur d’autres sites (10050)
-
avutil/hwcontext_dxva2 : Don't improperly free IDirect3DSurface9 objects
16 mai 2017, par Aaron Levinsonavutil/hwcontext_dxva2 : Don't improperly free IDirect3DSurface9 objects
Add dxva2_pool_release_dummy() and use it in call to
av_buffer_create() in dxva2_pool_alloc().Prior to this change, av_buffer_create() was called with NULL for the
third argument, which indicates that av_buffer_default_free() should
be used to free the buffer's data. Eventually, it gets to
buffer_pool_free() and calls buf->free() on a surface object (which is
av_buffer_default_free()).This can result in a crash when the debug version of the C-runtime is
used on Windows. While it doesn't appear to result in a crash when
the release version of the C-runtime is used on Windows, it likely
results in memory corruption, since av_free() is being called on
memory that was allocated using
IDirectXVideoAccelerationService::CreateSurface().Signed-off-by : Aaron Levinson <alevinsn@aracnet.com>
Reviewed-by : wm4 <nfxjfg@googlemail.com>
Reviewed-by : Steven Liu <lingjiujianke@gmail.com>
Reviewed-by : Mark Thompson <sw@jkqxz.net> -
Problem : FFmpeg and C++ extract and save frame
26 mai 2021, par Simba_cl25I am doing a project where I must do the following : extract frames (along with the associated metadata - KLV) from a video given a period (for the moment every 10 seconds).
I have followed codes found on internet but I get an error that I can find a solution to.


extern "C" {
#include <libavcodec></libavcodec>avcodec.h>
#include <libavformat></libavformat>avformat.h>
#include <libavdevice></libavdevice>avdevice.h>
#include <libswscale></libswscale>swscale.h>
#include <libavfilter></libavfilter>avfilter.h>
#include <libswresample></libswresample>swresample.h>
#include <libavutil></libavutil>avutil.h>
#include <libavutil></libavutil>imgutils.h> 
}

static void SaveFrame(AVFrame *pFrame, int width, int height, int iFrame);


int main(int argc, const char * argv[])
{
 AVFormatContext *pFormatCtx;
 int i, videoStream;
 AVCodecContext *pCodecCtx = NULL;
 const AVCodec *pCodec = NULL;
 AVFrame *pFrame;
 AVFrame *pFrameRGB;
 AVPacket *packet = av_packet_alloc();
 AVStream *pStream;
 int numBytes;
 int64_t Duration;
 uint8_t *buffer;
 bool frameFinished = false;

 // Open video file - check for errors
 pFormatCtx = 0;
 if (avformat_open_input(&pFormatCtx, "00Video\\VideoR.ts", 0, 0) != 0)
 return -1; 

 if (avformat_find_stream_info(pFormatCtx, 0) < 0)
 return -1;

 if (av_find_best_stream(pFormatCtx, AVMEDIA_TYPE_VIDEO, -1, -1, 0, 0) <0)
 return -1;

 av_dump_format(pFormatCtx, 0, "00Video\\VideoR.ts", false);


 // Find the first video stream
 videoStream = -1;
 for (i = 0; i < pFormatCtx->nb_streams; i++)
 if (pFormatCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO)
 {
 videoStream = i;
 break;
 }
 if (videoStream == -1)
 return -1; 
 


 // Find the decoder for the video stream
 pCodec = avcodec_find_decoder(pFormatCtx->streams[videoStream]->codecpar->codec_id);
 pCodecCtx = avcodec_alloc_context3(pCodec);

 if (pCodec == NULL)
 {
 fprintf(stderr, "Codec not found\n");
 return -1; 
 }


 if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0)
 {
 fprintf(stderr, "Could not open codec\n");
 return -1; 
 }

 // Hack to correct wrong frame rates that seem to be generated by some codecs
 if (pCodecCtx->time_base.num > 1000 && pCodecCtx->time_base.den == 1)
 pCodecCtx->time_base.den = 1000;




 // Allocate video frame - original frame 
 pFrame = av_frame_alloc();

 if (!pFrame) {
 fprintf(stderr, "Could not allocate video frame\n");
 return -1;
 }


 // Allocate an AVFrame structure
 pFrameRGB = av_frame_alloc();

 if (pFrameRGB == NULL)
 {
 fprintf(stderr, "Could not allocate video RGB frame\n");
 return -1;
 }

 
 Duration = av_rescale_q(vstrm->duration, vstrm->time_base, { 1,1000 });
 
 numBytes = av_image_get_buffer_size(pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, 0);
 buffer = (uint8_t*)av_malloc(numBytes * sizeof(uint8_t));


 av_image_fill_arrays(pFrameRGB->data, pFrameRGB->linesize, buffer, AV_PIX_FMT_RGB24, pCodecCtx->width, pCodecCtx->height, 1);
 
 
 
 
 i = 0;
 while (av_read_frame(pFormatCtx, packet) >= 0)
 {
 // Is this a packet from the video stream?
 if (packet->stream_index == videoStream)
 {
 int ret;
 ret = avcodec_send_packet(pCodecCtx, packet);
 if (ret < 0 || ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
 fprintf(stderr, "Error sending a packet for decoding\n");
 //break;
 }
 while (ret >= 0) {
 ret = avcodec_receive_frame(pCodecCtx, pFrame);
 if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
 return -1;
 else if (ret < 0) {
 fprintf(stderr, "Error during decoding\n");
 return -1;
 frameFinished = true;
 }


 // Did we get a video frame?
 if (frameFinished)
 {
 static struct SwsContext *img_convert_ctx;

 
 if (img_convert_ctx == NULL) {
 int w = pCodecCtx->width;
 int h = pCodecCtx->height;
 img_convert_ctx = sws_getContext(w, h,
 pCodecCtx->pix_fmt,
 w, h, AV_PIX_FMT_RGB24, SWS_FAST_BILINEAR,
 NULL, NULL, NULL);

 if (img_convert_ctx == NULL) {
 fprintf(stderr, "Cannot initialize the conversion context!\n");
 exit(1);
 }
 }

 int ret = sws_scale(img_convert_ctx, pFrame->data, pFrame->linesize, 0,
 pCodecCtx->height, pFrameRGB->data, pFrameRGB->linesize);


 // Save the frame to disk
 if (i <= Duration)
 {
 SaveFrame(pFrameRGB, pCodecCtx->width, pCodecCtx->height, i);
 i += 10*1000;
 }
 }
 }

 
 }

 // Free the packet that was allocated by av_read_frame
 av_packet_unref(packet);
 }

 

 // Free the RGB image
 free(buffer);
 av_free(pFrameRGB);

 // Free the YUV frame
 av_free(pFrame);

 // Close the codec
 avcodec_close(pCodecCtx);

 // Close the video file
 avformat_close_input(&pFormatCtx);
 return 0;
 
}




static void SaveFrame(AVFrame *pFrame, int width, int height, int iFrame)
{
 FILE *pFile;
 char szFilename[32];
 int y;


 // Open file
 sprintf(szFilename, "Im\\frame%d.png", iFrame);
 pFile = fopen(szFilename, "wb");
 if (pFile == NULL)
 return;

 // Write header
 fprintf(pFile, "P6\n%d %d\n255\n", width, height);
 // Write pixel data
 for (y = 0; y < height; y++)
 fwrite(pFrame->data[0] + y * pFrame->linesize[0], 1, width*3, pFile);

 // Close file
 fclose(pFile);
}


The error I get is :


[swscaler @ 03055A80] bad dst image pointers


I think is because


numBytes = av_image_get_buffer_size(pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, 0);


Returns a negative value ( -22) but I don't know why.


Thanks,


-
avcodec/ljpegenc : Don't free buffer known to be NULL
15 septembre 2020, par Andreas Rheinhardtavcodec/ljpegenc : Don't free buffer known to be NULL
The lossless JPEG encoder allocates one buffer in its init function
and freeing said buffer is the only thing done in its close function.
Despite this the init function called the close function if allocating
said buffer fails, although there is nothing to free in this case.
This commit stops doing this.Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Syndiquer tout le site
