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• Anomalie #3329 (Nouveau) : Publication des documents en 2018

  31 octobre 2014, par guytarr °

  Ca commence à craindre, les gens ne mettent pas à jour leur site tous les quatre matins
  http://zone.spip.org/trac/spip-zone/browser/_core_/plugins/medias/action/editer_document.php?rev=85597#L183

• Makefile for c++ program cannot be compiled properly

  20 mars 2017, par Wei

  I am quite new to c++ Makefile. Recently, I am trying to re-implement the dense trajectory algorithm introduced by this paper : https://lear.inrialpes.fr/people/wang/dense_trajectories

  However, I was struggling with Makefile that they provided for quite a while. The Makefile is as follows :

  # set the binaries that have to be built
  
  TARGETS := DenseTrack Video
  
  
  
  # set the build configuration set 
  
  BUILD := release
  
  #BUILD := debug
  
  
  
  # set bin and build dirs
  
  BUILDDIR := .build_$(BUILD)
  
  BINDIR := $(BUILD)
  
  
  
  # libraries 
  
  LDLIBS = $(addprefix -l, $(LIBS) $(LIBS_$(notdir $*)))
  
  LIBS := \
  
      opencv_core opencv_highgui opencv_video opencv_imgproc \
  
      avformat avdevice avutil avcodec swscale
  
  
  
  # set some flags and compiler/linker specific commands
  
  CXXFLAGS = -pipe -D __STDC_CONSTANT_MACROS -D STD=std -Wall $(CXXFLAGS_$(BUILD)) -I. -I/usr/local/include -I/home/wei/ffmpeg_build/include
  
  CXXFLAGS_debug := -ggdb
  
  CXXFLAGS_release := -O3 -DNDEBUG -ggdb
  
  LDFLAGS = -L/usr/local/lib -L/home/wei/ffmpeg_build/lib -pipe -Wall $(LDFLAGS_$(BUILD))
  
  LDFLAGS_debug := -ggdb
  
  LDFLAGS_release := -O3 -ggdb
  
  
  
  include make/generic.mk

  I can verify that my opencv2.4.2 and ffmpeg5.4.0 are successfully installed in Ubuntu 16.04, by running an example using those two libraries.

  For opencv :
  The lib path is : /usr/local/lib

  libavcodec.a                   libopencv_gpu.so.2.4   
  
      libopencv_photo.so.2.4
  
  libavdevice.a                  libopencv_gpu.so.2.4.2        libopencv_photo.so.2.4.2
  
  libavfilter.a                  libopencv_highgui.so          libopencv_stitching.so
  
  libavformat.a                  libopencv_highgui.so.2.4      libopencv_stitching.so.2.4
  
  libavutil.a                    libopencv_highgui.so.2.4.2    libopencv_stitching.so.2.4.2
  
  libopencv_calib3d.so           libopencv_imgproc.so          libopencv_ts.so
  
  libopencv_calib3d.so.2.4       libopencv_imgproc.so.2.4      libopencv_ts.so.2.4
  
  libopencv_calib3d.so.2.4.2     libopencv_imgproc.so.2.4.2    libopencv_ts.so.2.4.2
  
  libopencv_contrib.so           libopencv_legacy.so           libopencv_video.so
  
  libopencv_contrib.so.2.4       libopencv_legacy.so.2.4       libopencv_video.so.2.4
  
  libopencv_contrib.so.2.4.2     libopencv_legacy.so.2.4.2     libopencv_video.so.2.4.2
  
  libopencv_core.so              libopencv_ml.so               libopencv_videostab.so
  
  libopencv_core.so.2.4          libopencv_ml.so.2.4           libopencv_videostab.so.2.4
  
  libopencv_core.so.2.4.2        libopencv_ml.so.2.4.2         libopencv_videostab.so.2.4.2
  
  libopencv_features2d.so        libopencv_nonfree.so          libpostproc.a
  
  libopencv_features2d.so.2.4    libopencv_nonfree.so.2.4      libswresample.a
  
  libopencv_features2d.so.2.4.2  libopencv_nonfree.so.2.4.2    libswscale.a
  
  libopencv_flann.so             libopencv_objdetect.so        pkgconfig
  
  libopencv_flann.so.2.4         libopencv_objdetect.so.2.4    python2.7
  
  libopencv_flann.so.2.4.2       libopencv_objdetect.so.2.4.2  python3.5
  
  libopencv_gpu.so               libopencv_photo.so

  The include path is : usr/local/include :

  libavcodec   libavfilter  libavutil    libswresample  opencv
  
  libavdevice  libavformat  libpostproc  libswscale     opencv2

  For ffmpeg :
  The lib path is : /home/user/ffmpeg_build/lib

  libavcodec.a   libavfilter.a  libavutil.a   libfdk-aac.la  libswresample.a  libx265.a
  
  libavdevice.a  libavformat.a  libfdk-aac.a  libpostproc.a  libswscale.a     pkgconfig

  The include path is : /home/user/ffmpeg/include

  fdk-aac     libavdevice  libavformat  libpostproc    libswscale     x265.h
  
  libavcodec  libavfilter  libavutil    libswresample  x265_config.h

  So when I make it with Makefile, I did not get error but it seems linking is working properly, nor is the compiled output.

  I tried to directly compile with g++ command.

  sudo g++ -o Video -pipe -D __STDC_CONSTANT_MACROS -D STD=std -Wall -I. -I/usr/local/include -O3 -DNDEBUG -ggdb -L/usr/local/lib -lopencv_core -lopencv_highgui -lopencv_video -lopencv_imgproc -lavformat -lavdevice -lavutil -lavcodec -lswscale *.h Video.cpp

  However,it returns errors as :

  /tmp/ccjYmwI4.o: In function `main':
  
  /home/wei/Documents/dt/dense_trajectory_release_v1.2/Video.cpp:33: undefined reference to `cvCreateFileCapture'
  
  /home/wei/Documents/dt/dense_trajectory_release_v1.2/Video.cpp:48: undefined reference to `cvQueryFrame'
  
  /home/wei/Documents/dt/dense_trajectory_release_v1.2/Video.cpp:57: undefined reference to `cvCopy'
  
  /home/wei/Documents/dt/dense_trajectory_release_v1.2/Video.cpp:60: undefined reference to `cvShowImage'
  
  /home/wei/Documents/dt/dense_trajectory_release_v1.2/Video.cpp:61: undefined reference to `cvWaitKey'
  
  /home/wei/Documents/dt/dense_trajectory_release_v1.2/Video.cpp:53: undefined reference to `cvCreateImage'
  
  /home/wei/Documents/dt/dense_trajectory_release_v1.2/Video.cpp:70: undefined reference to `cvDestroyWindow'
  
  /home/wei/Documents/dt/dense_trajectory_release_v1.2/Video.cpp:41: undefined reference to `cvNamedWindow'
  
  collect2: error: ld returned 1 exit status

  I have been working on this issue for several days. Any help or suggestions would be really appreciated.

  Thanks

• How to generate video as fast as possible with subtitles and audio on node.js + ffmpeg ?

  12 septembre 2018, par DSeregin

  Intro :

  We receive from the site some pieces of text
  Pieces arrive to node.js-server

  At the output we need to get a video, merged from all the pieces of text, voiced by the machine voice, with the added subtitles and audio substrate. So that user could be share this video in the social networks. MKV format doesn`t supported by VK.com

  The options that we have tried :
  1. Get all the text at once, generate the entire speech, create a file with subtitles, burn subtitles in the video .mp4 (vk.com does not support the .mkv container). It took 12 seconds of operations for a 45-second video on the local computer.
  2. Generate audio and video files for each piece of text (with added subtitles). It took one second for one piece of text. At the final request, we merge all pieces together. The last request (merging) took 2-3 seconds, which is already bearable.

  The second variant looks acceptable in terms of speed, but if you run 50 clients at the same time, then the computer (tested on a MacBook PRO 2013, 2.4 GHz i7, 8gb 1600 Mhz DDR3, SSD 256gb) processed only 1 piece from 1 client in 60 seconds (60 times slower), then the computer hung tight.

  • Generation of audio is done through Amazon Polly
  • Generate subtitles via https://github.com/gsantiago/subtitle.js#readme
  • From node.js we call ffmpeg using https://github.com/fluent-ffmpeg/node-fluent-ffmpeg
  • Resolution for video - 1280x720

  The commands we used :

  • Burn video subtitles and trim up to conditional 6 seconds (in the code send unix timestamp)

  ffmpeg -i import / back.mov -i export_0 / tmp.srt -scodec mov_text -t 6 export_0 / output.mov

  • Merging all audio

  ffmpeg -i audio1.mp3 .... -i audio15.mp3 merged.mp3

  • Overlay audio-substrate on the text

  ffmpeg -i merged.mp3 -i back.mp3 -filter_complex amerge -ac 2-c: a libmp3lame -q: a 4 -shortest audio.mp3

  • Merging all videos

  ffmpeg -i video.txt -f concat -c copy video.mp4

  • Overlay audio on video

  ffmpeg -i audio.mp3 -i video.mp4 -i test.mp4 -i export / output.mp3 -c: v copy -c: a aac -map 0: v: 0 -map 1: a: 0 -shortest output .mp4

  Questions that torment :

  1. Is it faster ?

  2. Can I use other codecs or methods of gluing without re-encoding ?

  3. Try to call ffmpeg directly without a wrapper ? (in fact, it gives 50-100 ms of speed)

  4. Try not to save to disk, and write data to Stream and have them glue together in the end ?