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• Use parameter expansions in a command run from "find | xargs" to prevent output overwriting

  20 février 2019, par Philipp

  I have this bash script that is looking for mp4 files in subfolders with certain names and saves frames of those videos as jpeg.

  #!/bin/bash
  
  find ../folder -type f -iname '*C00*.mp4' | xargs -I %% ffmpeg -i %% -vf fps=1 -q:v 3 "../frames/_${i%.*}_frame%d.jpg"

  The problem is that everytime the script finishes one video the .jepg output files of the next videos are overwriting the existing ones.

  How can I prevent that ?

• OpenCV Cmake unable to find ffmpeg lib

  29 juillet 2016, par URMISH THAKKER

  I am trying to compile OpenCV with ffmpeg support for ARM Platform on a x86 host.

  I downloaded and compiled ffmpeg for arm platform (both static - FFMPEG_ARM_LIB and dynamic libs - FFMPEG_ARM_LIB_SO)

  When I run cmake in opencv, it gives the following -

  --   Video I/O:
  
  --     DC1394 1.x:                  NO
  
  --     DC1394 2.x:                  NO
  
  --     FFMPEG:                      **NO**
  
  --       codec:                     NO
  
  --       format:                    NO
  
  --       util:                      NO
  
  --       swscale:                   NO
  
  --       gentoo-style:              YES
  
  --     GStreamer:                   NO
  
  --     OpenNI:                      NO
  
  --     OpenNI PrimeSensor Modules:  NO
  
  --     PvAPI:                       NO
  
  --     GigEVisionSDK:               NO
  
  --     UniCap:                      NO
  
  --     UniCap ucil:                 NO
  
  --     V4L/V4L2:                    NO/YES
  
  --     XIMEA:                       NO
  
  --     Xine:                        NO

  I changed the following flags to point to the lib paths of both ffmpeg static and dynamic libs-

  1. LD_LIBRARY_PATH
  2. C_INCLUDE_PATH
  3. CPLUS_INCLUDE_PATH
  4. PKG_CONFIG_PATH
  5. PKG_CONFIG_LIBDIR
  6. PATH
  7. CMAKE_LIBRARY_PATH
  8. CMAKE_INCLUDE_PATH

  However, the opencv is still not able to recognize the ffmpeg libs.

  My FFMPEG compilation command was

  ./configure --enable-shared --disable-static\
  
   --cross-prefix=arm-linux-gnueabi- --arch=armv7a\
  
   --target-os=linux --prefix=<path>
  
  </path>

  What am I doing wrong here ?
  1. Am I compiling the ffmpeg with the wrong option ?
  2. Am I missing some element in CMake which would make it point to the compiled ffmpeg lib for ARM on my system ?

• FFMPEG Android binary cannot find file in storage

  1er novembre 2014, par user2491598

  I am trying to run ffmpeg command on my Android using the ffmpeg binary library, but I keep getting an error that says :

  ffmpeg - i /storage/emulated/0/video3.mp4 /storage/emulated/0/output.mp4: No such file or directory

  The STDOUT I get back from the ProcessBuilder is

  0-31 19:43:20.576: I/FFMPEG(13838): stdErr= ffmpeg version 0.11.1 Copyright (c) 2000-2012 the FFmpeg developers
  
  10-31 19:43:20.576: I/FFMPEG(13838):   built on Nov 15 2013 00:50:10 with gcc 4.6 20120106 (prerelease)
  
  10-31 19:43:20.576: I/FFMPEG(13838):   configuration: --arch=arm --cpu=cortex-a8 --target-os=linux --enable-runtime-cpudetect --enable-small --prefix=/data/data/info.guardianproject.ffmpeg/app_opt --enable-pic --disable-shared --enable-static --cross-prefix=/home/n8fr8/dev/android/ndk//toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86_64/bin/arm-linux-androideabi- --sysroot=/home/n8fr8/dev/android/ndk//platforms/android-3/arch-arm --extra-cflags='-I../x264 -mfloat-abi=softfp -mfpu=neon' --extra-ldflags=-L../x264 --enable-version3 --enable-gpl --disable-doc --enable-yasm --enable-decoders --enable-encoders --enable-muxers --enable-demuxers --enable-parsers --enable-protocols --enable-filters --enable-avresample --enable-libfreetype --disable-indevs --enable-indev=lavfi --disable-outdevs --enable-hwaccels --enable-ffmpeg --disable-ffplay --disable-ffprobe --disable-ffserver --disable-network --enable-libx264 --enable-zlib --enable-muxer=md5
  
  10-31 19:43:20.576: I/FFMPEG(13838):   libavutil      51. 54.100 / 51. 54.100
  
  10-31 19:43:20.576: I/FFMPEG(13838):   libavcodec     54. 23.100 / 54. 23.100
  
  10-31 19:43:20.576: I/FFMPEG(13838):   libavformat    54.  6.100 / 54.  6.100
  
  10-31 19:43:20.576: I/FFMPEG(13838):   libavdevice    54.  0.100 / 54.  0.100
  
  10-31 19:43:20.576: I/FFMPEG(13838):   libavfilter     2. 77.100 /  2. 77.100
  
  10-31 19:43:20.576: I/FFMPEG(13838):   libswscale      2.  1.100 /  2.  1.100
  
  10-31 19:43:20.576: I/FFMPEG(13838):   libswresample   0. 15.100 /  0. 15.100
  
  10-31 19:43:20.576: I/FFMPEG(13838):   libpostproc    52.  0.100 / 52.  0.100
  
  10-31 19:43:20.576: I/FFMPEG(13838): ffmpeg - i /storage/emulated/0/video3.mp4 /storage/emulated/0/output.mp4: No such file or directory

  Please keep in mind that the video file do exist on my device in that exact directory and I also have read permissions in my AndroidManifest.xml

  Please help !!!!