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• C api on capturing video stream from webcam using ffmpeg

  14 July 2013, by Tanjim Hossain Sifat

  I am a new user of ffmpeg. Ffmpeg has a good documentation on using it in command-line, but i am looking for some C API code.

  I want to make a software using C, that would capture video stream from webcam and give me the video stream in raw format, that I would encode in a codec later.

  I have visited this given link, but it provided only the command-line use, not the use of libraries provided by ffmpeg:
  http://ffmpeg.org/trac/ffmpeg/wiki/How%20to%20capture%20a%20webcam%20input

  I also visited this link, which gave me good idea on using the libavcodec, but no other tutorial is available :
  ffmpeg C API documentation/tutorial

  Please someone help me finding C api on video stream capturing from webcam using ffmpeg's library. Thanks in advance.

• error = "sh: /root/bin/ffmpeg: Permission denied

  6 August 2015, by user1503606

  Ffmpeg install location.

  Hi All i am running Centos 6.6 and i installed ffmpeg using this guide following each step.

  http://trac.ffmpeg.org/wiki/CompilationGuide/Centos

  But when i try and run.

  $output = shell_exec("cd {$targetDir} && /root/bin/ffmpeg -i {$fileName} {$wav} 2>&1");

  I get

  sh: /root/bin/ffmpeg: Permission denied

  After reading through lots of post i believe i should not have installed ffmpeg in /root/bin/

  How do i install it in say /usr/local/bin ?

  I ran this.

  PKG_CONFIG_PATH="$HOME/ffmpeg_build/lib/pkgconfig" ./configure
  —prefix="$HOME/ffmpeg_build" —extra-cflags="-I$HOME/ffmpeg_build/include" —extra-ldflags="-L$HOME/ffmpeg_build/lib" —bindir="$HOME/bin" —pkg-config-flags="—static" —enable-gpl —enable-nonfree —enable-libfdk-aac —enable-libfreetype —enable-libmp3lame —enable-libopus —enable-libvorbis —enable-libvpx —enable-libx264 —enable-libx265

  Can someone let me know who i would do this thanks.

• Unrecognized options even though compiled FFmpeg on Ubuntu manually

  11 February 2016, by Kathy Lee

  I would like to convert a video from .avi to .mp4 with same quality using ffmpeg but the command I put in the terminal always report some errors saying that there are unrecognized options.

  I have compiled the ffmpeg manually following the steps in http://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu

  After compiling the ffmpeg, I used the command below the compress the video

  ffmpeg -i input.avi -c:v libx264 -crf 19 -preset slow -c:a libfaac -b:a 192k -ac 2 output.mp4

  But the error message is saying "Unrecognized option ’crf’":

  ffmpeg version 2.8.5 Copyright (c) 2000-2016 the FFmpeg developers
  
  built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04)
  
  configuration: --enable-nonfree --enable-pic --enable-shared
  
  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
  
  libswscale      3.  1.101 /  3.  1.101
  
  libswresample   1.  2.101 /  1.  2.101
  
  Unrecognized option 'crf'.
  
  Error splitting the argument list: Option not found

  Then I tried to omit flag -crf, but I got error saying

  Unrecognized option 'preset'.
  
  Error splitting the argument list: Option not found

  Then I omitted flag -preset, it says I do not have libx264....

  [mjpeg @ 0x164f2c0] Changeing bps to 8
  
  Input #0, avi, from 'backup_bush.avi':
  
    Duration: 00:01:40.70, start: 0.000000, bitrate: 12409 kb/s
  
      Stream #0:0: Video: mjpeg (MJPG / 0x47504A4D), yuvj420p(pc, bt470bg/unknown/unknown), 400x250 [SAR 1:1 DAR 8:5], 12407 kb/s, 30 fps, 30 tbr, 30 tbn, 30 tbc
  
  Unknown encoder 'libx264'

  I am very confused what is going on because I have complied ffmpeg step by step and also installed the dependencies such as libx264 as described in http://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu. The command I used to configure ffmpeg is

   ./configure   --prefix="$HOME/ffmpeg_build"   --pkg-config-flags="--static"   --extra-cflags="-I$HOME/ffmpeg_build/include"   --extra-ldflags="-L$HOME/ffmpeg_build/lib"   --bindir="$HOME/bin"   --enable-gpl   --enable-libass   --enable-libfdk-aac   --enable-libfreetype   --enable-libmp3lame   --enable-libopus   --enable-libtheora   --enable-libvorbis   --enable-libvpx   --enable-libx264   --enable-nonfree

  Why these errors happen? How can I fix them to allow me to convert the video from .avi to .mp4?

  Thank you very much!