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Carte de Schillerkiez
13 mai 2011, par
Mis à jour : Septembre 2011
Langue : English
Type : Texte
Autres articles (31)
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Video files are encoded in MP4, Ogv and WebM (supported by HTML5) and MP4 (supported by Flash).
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Sur d’autres sites (7130)
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Trying to save frames as colored image using Ffmpeg in C++
2 septembre 2021, par TolgaI am new to FFmpeg and I am trying to save the video frames as colored images. I have achieved saving them as grayscale using Netpbm, however, I need to save the frames as colored. I have tried implementing the code in this link.


However, I get an error :


'Exception thrown at 0x00E1FC4F (swscale-5.dll) in VideoDecoding2.exe:
 0xC0000005: Access violation writing location 0xCCCCCCCC.'



Is there any way to improve this code or another way to save frames as colored ?


Here is my code below.


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src_pix_fmt
isAV_PIX_FMT_YUV420p
.dst_pix_fmt
isAV_PIX_FMT_RGB24
.






src_pix_fmt = avcc->pix_fmt;

src_width = avcc->width;
src_height = avcc->height;

dst_width = src_width;
dst_height = src_height;

numBytes = av_image_get_buffer_size(dst_pix_fmt, dst_width, dst_height, 0);

buffer = (uint8_t*)av_malloc(numBytes);

if ((ret = av_image_alloc(src_data, src_linesize, src_width, src_height, src_pix_fmt, 16)) < 0)
{
 printf("Couldn't allocate source image.\n");
 return 0;
}

av_image_fill_arrays(frameRGB->data, frameRGB->linesize, buffer, dst_pix_fmt, dst_width, dst_height, 0);

while (av_read_frame(avfc, packet) >= 0)
{
 ret = avcodec_send_packet(avcc, packet);
 if (ret < 0)
 {
 printf("Packets could not supplied to decoder.\n");
 return -1;
 }

 ret = avcodec_receive_frame(avcc, frame);
 printf("%d", ret);

 if (packet->stream_index == videoStream)
 {
 sws_ctx = sws_getContext(src_width, src_height, src_pix_fmt,
 dst_width, dst_height, dst_pix_fmt,
 SWS_BILINEAR, NULL, NULL, NULL);

 if (!sws_ctx)
 {
 printf("Cannot create scale context for conversion\n"
 "fmt:%s s:%dx%d --> fmt:%s s:%dx%d\n",
 av_get_pix_fmt_name(src_pix_fmt), src_width, src_height,
 av_get_pix_fmt_name(dst_pix_fmt), dst_width, dst_height);
 return 0;
 }

 sws_scale(sws_ctx, (const uint8_t* const*)frame->data, frame->linesize, 0, frame->height, dst_data, dst_linesize);

 FILE* f;
 char szFilename[32];
 int y;

 snprintf(szFilename, sizeof(szFilename), "frame%d.ppm", avcc->frame_number);
 fopen_s(&f, szFilename, "wb");
 
 if (f == NULL)
 {
 printf("Couldn't open file.\n");
 return 0;
 }
 
 fprintf(f, "P6\n%d %d\n255\n", dst_width, dst_height);

 for (y = 0; y < dst_height; y++)
 fwrite(frameRGB->data[0] + y * frameRGB->linesize[0], 1, dst_width * 3, f);
 
 fclose(f);
 }
}



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git show 2473a45c85dce6872617b33fce396dbbd6347e8e avconv.c | patch ffmpeg.c
21 janvier 2012, par Michael Niedermayergit show 2473a45c85dce6872617b33fce396dbbd6347e8e avconv.c | patch ffmpeg.c
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ffprobe : show sample_fmt in the stream section
12 octobre 2011, par Stefano Sabatiniffprobe : show sample_fmt in the stream section