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• What does the "struct AVCodec *codec" in "struct AVCodecContext" represent ?

  7 juin 2013, par Appy

  I am using FFMpeg libraries in C/C++ to develop a media player .
  This source uses the following code to find the decoder of a video stream in a file :

  pCodec=avcodec_find_decoder(pCodecCtx->codec_id); ,

  where pCodecCtx is the pointer to the Codec Context of the video stream and pCodec is a pointer to AVCodec which was initialised to NULL .

  If we have to explicitly find the decoder , then what is the struct AVCodec *codec found in struct AVCodecContext ? This is defined here . Can someone please help me understand it's use .

• How to use libraries ".lib" and ".a" files in gcc

  16 décembre 2013, par Blue Sky

  I have a simple C code that uses some functions of libavcodec in ffmpeg. I try to compile the code with gcc (in Windows using mingw) as follows :

  gcc -o mycode mycode.c 

  but I get a lot of errors like "undefined reference to av_free". I know that these functions are defined in the libraries of ffmpeg. I do access to files like avcodec.lib and libavcodec.dll.a but I don't know how to use them with gcc so that I can compile and make my file. Any idea how to solve this problem ?

• FFMPEG, "Could not open file.. " "av_interleaved_write_frame() : Input/output error"

  10 juillet 2018, par justaguytrynabuildawebsite

  Trying to run a simple ffmpeg line on my Ubuntu 16.04 vps shell,

  ffmpeg -ss 1 -i /var/www/html/lib/vid/4581989_022810100718.mp4 -r 1 -vframes 1 /var/www/html/lib/thumbnail/4581989_022810100718/20.jpg

  but am met with

  Could not open file 

  and

  av_interleaved_write_frame(): Input/output error

  I have already tried giving the ../lib/vid folder in question 777 permissions but it didnt help.

  Full print-out :

  ffmpeg version 2.8.14-0ubuntu0.16.04.1 Copyright (c) 2000-2018 the FFmpeg developers
  
   built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.9) 20160609
  
   configuration: --prefix=/usr --extra-version=0ubuntu0.16.04.1 --build-suffix=-ffmpeg --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-libx264 --enable-libopencv
  
  libavutil      54. 31.100 / 54. 31.100
  
  libavcodec     56. 60.100 / 56. 60.100
  
  libavformat    56. 40.101 / 56. 40.101
  
  libavdevice    56.  4.100 / 56.  4.100
  
  libavfilter     5. 40.101 /  5. 40.101
  
  libavresample   2.  1.  0 /  2.  1.  0
  
  libswscale      3.  1.101 /  3.  1.101
  
  libswresample   1.  2.101 /  1.  2.101
  
  libpostproc    53.  3.100 / 53.  3.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/var/www/html/lib/vid/4581989_022810100718.mp4':
  
  Metadata:
  
  major_brand     : isom
  
  minor_version   : 512
  
  compatible_brands: isomiso2avc1mp41
  
  encoder         : Lavf56.36.100
  
  Duration: 00:00:04.90, start: 0.000000, bitrate: 2595 kb/s
  
  Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1820x1024 [SAR 1:1 DAR 455:256], 2593 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc (default)
  
  Metadata:
  
    handler_name    : VideoHandler
  
  [swscaler @ 0x1652280] deprecated pixel format used, make sure you did set range correctly
  
  Output #0, image2, to '/var/www/html/lib/thumbnail/4581989_022810100718/20.jpg':
  
  Metadata:
  
  major_brand     : isom
  
  minor_version   : 512
  
  compatible_brands: isomiso2avc1mp41
  
  encoder         : Lavf56.40.101
  
  Stream #0:0(und): Video: mjpeg, yuvj420p(pc), 1820x1024 [SAR 1:1 DAR 455:256], q=2-31, 200 kb/s, 1 fps, 1 tbn, 1 tbc (default)
  
  Metadata:
  
    handler_name    : VideoHandler
  
    encoder         : Lavc56.60.100 mjpeg
  
  Stream mapping:
  
  Stream #0:0 -> #0:0 (h264 (native) -> mjpeg (native))
  
  Press [q] to stop, [?] for help
  
  [image2 @ 0x16103a0] Could not open file : /var/www/html/lib/thumbnail/4581989_022810100718/20.jpg
  
  av_interleaved_write_frame(): Input/output error
  
  frame=    1 fps=0.0 q=3.4 Lsize=N/A time=00:00:01.00 bitrate=N/A    
  
  video:48kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
  
  Conversion failed!