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• OpenCV 3.0.0 make error with FFMPEG

  24 mars 2016, par Ujjwal Aryan

  I have been using OpenCV for a while. However I have recently changed my system to a cluster where I do not have any admin permission. The problem is like this :

  In my home folder, I installed FFMPEG (latest stable version available on ffmpeg site). I installed it in $HOME, and so in $HOME/lib there are the library files installed. For more information I compiled FFMPEG with following options :

  ./configure --prefix=$HOME --enable-shared --enable-pic

  I then downloaded the latest stable version of OpenCV 3.0.0 and configured it using ccmake. When I try to make -j8, it gives me the following error.

   Scanning dependencies of target opencv_videoio
  
  [ 63%] [ 63%] [ 63%] [ 63%] [ 63%] [ 63%] Building CXX object modules/videoio/CMakeFiles/opencv_videoio.dir/src/cap.cpp.o
  
  Building CXX object modules/videoio/CMakeFiles/opencv_videoio.dir/src/cap_mjpeg_decoder.cpp.o
  
  Building CXX object modules/videoio/CMakeFiles/opencv_videoio.dir/src/cap_images.cpp.o
  
  Building CXX object modules/videoio/CMakeFiles/opencv_videoio.dir/src/cap_v4l.cpp.o
  
  Building CXX object modules/videoio/CMakeFiles/opencv_videoio.dir/src/cap_mjpeg_encoder.cpp.o
  
  Building CXX object modules/videoio/CMakeFiles/opencv_videoio.dir/src/cap_ffmpeg.cpp.o
  
  In file included from /home/uujjwal/libraries/opencv-nogpu/opencv-3.0.0/modules/videoio/src/cap_ffmpeg.cpp:45:0:
  
  /home/uujjwal/libraries/opencv-nogpu/opencv-3.0.0/modules/videoio/src/cap_ffmpeg_impl.hpp:1546:71: error: use of enum 'AVCodecID' without previous declaration
  
  /home/uujjwal/libraries/opencv-nogpu/opencv-3.0.0/modules/videoio/src/cap_ffmpeg_impl.hpp:1556:83: error: use of enum 'AVCodecID' without previous declaration
  
  make[2]: *** [modules/videoio/CMakeFiles/opencv_videoio.dir/src/cap_ffmpeg.cpp.o] Error 1
  
  make[2]: *** Waiting for unfinished jobs....

  However without ffmpeg support it works fine. However I need ffmpeg support due to the nature of my work.

  In trying to resolve the problem, I tried installing OpenCV 2.4.11 but it also gave this error. The latest GIT version does not give me this error but rather an error a part of which goes like this

  Linking CXX shared library ../../lib/libopencv_highgui.so /usr/bin/ld: /home/matheus/ffmpeg_build/lib/../lib/libavcodec.a(avpacket.o): relocation R_X86_64_32 against `.rodata.str1.1' can not be used

  I have pasted the above error from another unresolved question online and so the folder names are different but the relocation error is exactly the same.

  In trying to resolve the problem I searched and found the following link http://answers.opencv.org/question/12597/build-problems-for-opencv-241-with-ubuntu-1204-lts/

  However, one of the answers over there mentioned changing some lines in cap_ffmpeg_impl.hpp file. I tried doing that but either i am not able to do it correctly or something else is going wrong and it is not working. Exact line numbers and exact changes are not mentioned and so I am having difficulty changing things and being sure.

  I am using Fedora 19 (Schrodinger Cat) as the operating system I hope the details of my question are clear and I hope that the community would oblige me with a good response.

  Regards
  Ujjwal

• OpenCV 3.0.0 make error with FFMPEG

  14 octobre 2017, par Ujjwal Aryan

  I have been using OpenCV for a while. However I have recently changed my system to a cluster where I do not have any admin permission. The problem is like this :

  In my home folder, I installed FFMPEG (latest stable version available on ffmpeg site). I installed it in $HOME, and so in $HOME/lib there are the library files installed. For more information I compiled FFMPEG with following options :

  ./configure --prefix=$HOME --enable-shared --enable-pic

  I then downloaded the latest stable version of OpenCV 3.0.0 and configured it using ccmake. When I try to make -j8, it gives me the following error.

   Scanning dependencies of target opencv_videoio
  
  [ 63%] [ 63%] [ 63%] [ 63%] [ 63%] [ 63%] Building CXX object modules/videoio/CMakeFiles/opencv_videoio.dir/src/cap.cpp.o
  
  Building CXX object modules/videoio/CMakeFiles/opencv_videoio.dir/src/cap_mjpeg_decoder.cpp.o
  
  Building CXX object modules/videoio/CMakeFiles/opencv_videoio.dir/src/cap_images.cpp.o
  
  Building CXX object modules/videoio/CMakeFiles/opencv_videoio.dir/src/cap_v4l.cpp.o
  
  Building CXX object modules/videoio/CMakeFiles/opencv_videoio.dir/src/cap_mjpeg_encoder.cpp.o
  
  Building CXX object modules/videoio/CMakeFiles/opencv_videoio.dir/src/cap_ffmpeg.cpp.o
  
  In file included from /home/uujjwal/libraries/opencv-nogpu/opencv-3.0.0/modules/videoio/src/cap_ffmpeg.cpp:45:0:
  
  /home/uujjwal/libraries/opencv-nogpu/opencv-3.0.0/modules/videoio/src/cap_ffmpeg_impl.hpp:1546:71: error: use of enum 'AVCodecID' without previous declaration
  
  /home/uujjwal/libraries/opencv-nogpu/opencv-3.0.0/modules/videoio/src/cap_ffmpeg_impl.hpp:1556:83: error: use of enum 'AVCodecID' without previous declaration
  
  make[2]: *** [modules/videoio/CMakeFiles/opencv_videoio.dir/src/cap_ffmpeg.cpp.o] Error 1
  
  make[2]: *** Waiting for unfinished jobs....

  However without ffmpeg support it works fine. However I need ffmpeg support due to the nature of my work.

  In trying to resolve the problem, I tried installing OpenCV 2.4.11 but it also gave this error. The latest GIT version does not give me this error but rather an error a part of which goes like this

  Linking CXX shared library ../../lib/libopencv_highgui.so /usr/bin/ld: /home/matheus/ffmpeg_build/lib/../lib/libavcodec.a(avpacket.o): relocation R_X86_64_32 against `.rodata.str1.1' can not be used

  I have pasted the above error from another unresolved question online and so the folder names are different but the relocation error is exactly the same.

  In trying to resolve the problem I searched and found the following link http://answers.opencv.org/question/12597/build-problems-for-opencv-241-with-ubuntu-1204-lts/

  However, one of the answers over there mentioned changing some lines in cap_ffmpeg_impl.hpp file. I tried doing that but either i am not able to do it correctly or something else is going wrong and it is not working. Exact line numbers and exact changes are not mentioned and so I am having difficulty changing things and being sure.

  I am using Fedora 19 (Schrodinger Cat) as the operating system I hope the details of my question are clear and I hope that the community would oblige me with a good response.

  Regards
  Ujjwal

• ffmpeg dash Segment offset

  18 mars 2019, par inkubux

  I’m trying to integrate live-transcoding like "plex" or "emby" with my application.

  I am able to serve dash content over to shaka-player or dash.js but only in ’live-mode’. But I want to enable seeking through the player.

  I looked at plex and to enable this they create their own mpd file with duration so the player will have a full seekbar.

  However when seeking the player will ask for a segment number eg : 449. I need to stop ffmpeg and restart with an offset (-ss &lt;<segment>>)</segment>, but ffmpeg will just restart a transcode session from segment 0 with an initial segment.

  What I want is to tell ffmpeg to start at a seekpoint but only output from segment number and now-on.

  When playing with hls and mpegts, I can tell ffmpeg to output at a certain segment : with the option -segment_start_number but this is not available for dash. And plex use their own transcoder based of ffmpeg with the option -skip_to_segment

  I tried to ’hack’ around by keeping a manual offset on my web-server, even if I serve the "supposed" right segment after the seek point dash.js and shaka-player can’t recover the stream.. VLC on the other habd is able to (probably more tolerent) to errors in segments.

  Is the supposed right segment after a seek in dash (contains the initial segment) or only the segment.

  Is ffmpeg able to start segmenting dash as a supposed segment (for seek and resume)

  The same technique works in hls with forced key frames and a custom m3u8 (with all the "predicted" segments) but calculating the right segment length and the right bandwidth is much harder and hackish and dash is more tolerant to variation.

  I would really like to be able to seek through my live transcoding video.

  For reference here is a custom mpd file I serve to enable "seeking" :

  <mpd xmlns="urn:mpeg:dash:schema:mpd:2011" profiles="urn:mpeg:dash:profile:isoff-live:2011" type="static" suggestedpresentationdelay="PT1S" mediapresentationduration="PT49M2.920S" maxsegmentduration="PT2S" minbuffertime="PT10S">
  
      <period start="PT0S" duration="PT49M2.920S">
  
          <adaptationset segmentalignment="true">
  
              <segmenttemplate timescale="1" duration="1" initialization="$RepresentationID$/initial.mp4" media="$RepresentationID$/$Number$.m4s" startnumber="1">
  
              </segmenttemplate>
  
              <representation mimetype="video/mp4" codecs="avc1.640029" bandwidth="3766000" width="1920" height="1080">
  
              </representation>
  
          </adaptationset>
  
          <adaptationset segmentalignment="true">
  
              <segmenttemplate timescale="1" duration="1" initialization="$RepresentationID$/initial.mp4" media="$RepresentationID$/$Number$.m4s" startnumber="1">
  
              </segmenttemplate>
  
              <representation mimetype="audio/mp4" codecs="mp4a.40.2" bandwidth="188000" audiosamplingrate="48000">
  
                  <audiochannelconfiguration schemeiduri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="6"></audiochannelconfiguration>
  
              </representation>
  
          </adaptationset>
  
      </period>
  
  </mpd>

  And here is the ffmpeg command to pull it off :

  ffmpeg -ss 0 -i movie.mkv -y -acodec aac -vcodec libx264 -f dash -min_seg_duration 1000000 -individual_header_trailer 0 -pix_fmt yuv420p -vf scale=trunc(min(max(iw\,ih*dar)\,1920)/2)*2:trunc(ow/dar/2)*2 -bsf:v h264_mp4toannexb -profile:v high -level 4.1 -map_chapters -1 -map_metadata -1 -preset veryfast -movflags frag_keyframe+empty_moov -use_template 1 -use_timeline 0 -remove_at_exit 1 -crf 23 -bufsize 7532k -maxrate 3766k -start_at_zero -threads 0 -force_key_frames expr:if(isnan(prev_forced_t),eq(t,t),gte(t,prev_forced_t+1)) -init_seg_name $RepresentationID$/0_initial.mp4 -media_seg_name $RepresentationID$/0_$Number$.m4s /transcoding_temp/Z1GVWEc/index.mpd

  The media_seg_name is where I prepend the custom seek_point let’s say I want to seek to segment 1233 the template would be :

  -media_seg_name $RepresentationID$/1233_$Number$.m4s

  and the segments would be 1233_1 1233_2 1233_* So I can serve the right segment after seek. but the player does not recover and still downloading subsequent segments. I guess since a new initial segment is generated and I somehow miss headers for continuous playback after seek but I’m probably wrong.

  Thanks for your help