Newest 'ffmpeg' Questions - Stack Overflow

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• How to create video preview from sequence image

  17 février 2017, par diepnt

  I am developing a project create video and animation from sequence image. I have created a video using opencv but it takes a long time. I need to do function transition effects preview without creating video file. After choose image sequence and click button then create preview video with multiple effect. Click and will play immediately with seekbar duration controller. Who can help me to find solutions to this problem. Thanks!

  video preview

• ffmpeg crops video, but doubles size

  17 février 2017, par Michael Cole

  I rendered an mp4 from kdenlive and it looks great (1920x1080).

  I want to crop the video, and transcode to ogv for browsers.

  I tried this, but the ffmpeg makes a much larger file for the cropped version:

  ffmpeg -i untitled.mp4 -filter:v "crop=1920:760:0:0" masthead.mp4
  ffmpeg -i masthead.mp4 masthead.ogv
  

  This video is background for a web page, so I'm exporting from kdenlive with low quality video settings and no audio.

  Original is untitled.mp4:

  186907 Feb 16 19:17 untitled.mp4
  606241 Feb 16 19:18 masthead.mp4
  434127 Feb 16 19:18 masthead.ogv
  

  The output is here: http://pastebin.com/WYjHAuCC

  untitled.mp4 looks ok (great for it's purpose). masthead.mp4 looks good but it's huge, and masthead.ogv is very pixelated.

  Any suggestions?

• 'imported-lib - NOTFOUND' in building ffmpeg 3.2 for android studio 2.2

  17 février 2017, par mdang

  I am trying to build and use ffmpeg for Android. My Andoid Studio version is 2.2.2 and ffmpeg is 3.2. Following Android documentation on how to import rebuild library, I think I got the setting right but kept on getting this error

  ninja: error: 'avcodec-NOTFOUND', needed by '../../../../build/intermediates/cmake/debug/obj/armeabi-v7a/...
  

  This is the setting

  add_library( avcodec SHARED IMPORTED )
  add_library( avdevice SHARED IMPORTED )
  add_library( avfilter SHARED IMPORTED )
  add_library( avformat SHARED IMPORTED )
  add_library( avutil SHARED IMPORTED )
  add_library( swscale SHARED IMPORTED )
  
  set_target_properties( avcodec
                          PROPERTIES FFMPEG_LIB_IMPORTED_LOCATION
                          libs/ffmpeg/${ANDROID_ABI}/lib/libavcodec.so
                          )
  set_target_properties(  avdevice
                          PROPERTIES FFMPEG_LIB_IMPORTED_LOCATION
                          libs/ffmpeg/${ANDROID_ABI}/lib/libavdevice.so
                          )
  set_target_properties( avfilter
                          PROPERTIES FFMPEG_LIB_IMPORTED_LOCATION
                          libs/ffmpeg/${ANDROID_ABI}/lib/libavfilter.so
                          )
  set_target_properties( avformat
                          PROPERTIES FFMPEG_LIB_IMPORTED_LOCATION
                          libs/ffmpeg/${ANDROID_ABI}/lib/libavformat.so
                          )
  set_target_properties( avutil
                          PROPERTIES FFMPEG_LIB_IMPORTED_LOCATION
                          libs/ffmpeg/${ANDROID_ABI}/lib/libavutil.so
                          )
  set_target_properties( swscale
                          PROPERTIES FFMPEG_LIB_IMPORTED_LOCATION
                          libs/ffmpeg/${ANDROID_ABI}/lib/libswscale.so
                          )
  
  # Specifies a path to native header files.
  include_directories(
                      libs/ffmpeg/${ANDROID_ABI}/include
                      )
  
  target_link_libraries( # Specifies the target library.
                         native-lib
  
                         # Links the target library to the log library
                         # included in the NDK.
                         avcodec avdevice avfilter avformat avutil swscale
                         ${log-lib}
                          )
  

  If I specify the full library name, libavcodec.so..., the error would go away.

  target_link_libraries( # Specifies the target library.
                         native-lib
  
                         # Links the target library to the log library
                         # included in the NDK.
                         libavcodec.so libavdevice.so libavfilter.so libavformat.so libavutil.so libswscale.so
                         ${log-lib}
                          )
  

  I wonder if anyone encountered similar issue or know why the compilation behaves this way.

• How to optimize/speed up ffmpeg resizing

  16 février 2017, par ALM

  I am trying to quickly compress mp4 videos and wanted to know if there is a better way than I am currently using.

  ffmpeg -i orig.mp4 -preset ultrafast -vf scale=iw/5:-2 out.mp4
  

  This is currently being run for videos around 2-4 minutes long but I would like to get it as quick as possible. Are there other settings for ffmpeg I should use? This is running on a i7 system with external GPU.

  Thank you

• ffmpeg video encoding progress bar

  16 février 2017, par Rahul TS

  When I run the conversion in the browser it simply shows the white blank space. Only after the conversion process page will load.

  Please suggest how to implement a progress bar which shows the progress to the user when the video conversion takes place.

  I have this in my php script

  exec("ffmpeg -i filename.flv -sameq -ab 128 -s 640x480 filename.mp4");
  

  so how should I change this script to get the progress details even to a file or directly as ouput in the page. Please can anyone give me a complete script/code to explain it in detail. Because I think I cant get the complete answers and so I am confused on what to do with this