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• Using FFmpeg from .NET

  31 août 2011, par Lieven Cardoen

  I have been searching for an hour on how to use FFmpeg from .NET and it seems you need to execute the FFmpeg.exe with a Process to get things done. To get a duration of an flv file for instance, you would need to start using grep to get something back out of cmd window. It all seems complicated... + you'd have to start installing things on remote servers (@ customers)...

  Is there another way? Aren't there dll's containing the FFmpeg logic? Other solutions to get some information out of flv files in .NET?

• Anyone know of a set of C# bindings for FFMPEG ?

  31 août 2011, par MikeJ

  Does anyone know of a set of bindings for C# to drive the FFMpeg library directly ? I could shell to ffmpeg.exe directly but I found it hard to sync/control as a separate process. any help would be appreciated.

• Convert raw image using open-source library with permissive license

  30 août 2011, par Brian

  I need to convert a raw, rgb32-formatted image to a PNG with a library (written in, in order of preference, Java, C, C++) having a permissive (e.g. BSD or Apache) license.

  I'm able to convert the image using FFmpeg with this call:

  ffmpeg.exe -vframes 1 -vcodec rawvideo -f rawvideo -pix_fmt rgb32 -s 20x40 -i infile -f image2 -vcodec png out.png

  where 20x40 is the width by the height.

  But, sadly, I need to avoid FFmpeg due to its license.

  I've seen people speculate that libpng could do the job, but I'm skeptical given the documentation I've seen at the libpng site. Perhaps you'll give an example.

  I don't know what the rawvideo and rgb32 values mean to FFmpeg, so I asked this question.

  EDIT 1: edited the ffmpeg call to show width x height.

• Is there a set of working P/Invoke declarations for FFMpeg, libavutil, libavformat and libavcodec in .NET ?

  30 août 2011, par casperOne

  I'm currently looking to access libavutil, libavformat and libavcodec (all part of FFMpeg) from .NET.

  Currently, I'm getting the libraries from the automated builds of the shared FFMpeg package performed every night for Windows 32-bit.

  I am also using the code from the ffmpeg-sharp project. In that project, I have removed a number of classes that were not compiling (they are wrapper classes not the P/Invoke declarations).

  The code compiles fine, but I am running into a few issues.

  First, it appears that the build of av*.dll uses the cdecl calling convention, as I was receiving a number of PInvokeStackImbalanceException when trying to call av_open_input_file. This was easy enough to change to get it to work right. The AVFormatContext structure is populated.

  After that, I want to call av_find_stream_info to get information about the streams in the file. However, when calling that with the AVFormatContext retrieved from the call to av_open_input_file, an AccessViolationException is thrown indicating that I am trying to read or write from protected memory.

  Has anyone used P/Invoke to access the libavutil, libavformat and libavcodec dll libraries through P/Invoke and have gotten it to work?

  I should mention that working with the command-line version of FFMpeg, while a solution, is not a viable solution in this case, access needs to occur through the libraries. The reason for this is that I'd have to thrash the disk way too much to do what I need to do (I have to do a frame-by-frame analysis of some very high definition video) and I want to avoid the disk as much as possible.

• FFMPEG Convert from mov, mjpeg codec error

  30 août 2011, par vitel

  I've a problem when i try to convert a .mov to a .webm with ffmpeg... I've no problems from any others video format.

  I've enable the Quicktime formats "--enable-zlib" and with the "ffmpeg -formats" command i get .mov files as encode or decode.

  When i try to transform a video i get this :

    # ffmpeg -i /var/www/static/uploads/usersVideos/cavity0.mov -vcodec mjpeg  /var/www/static/uploads/usersVideos/cavity.webm
   ffmpeg version N-32159-gc70e852, Copyright (c) 2000-2011 the FFmpeg developers
   built on Aug 30 2011 14:16:07 with gcc 4.4.5
   configuration: --enable-gpl --enable-libmp3lame --enable-zlib --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora --enable-libvorbis --enable-libx264 --enable-libxvid --enable-nonfree --enable-postproc --enable-version3 --enable-x11grab --enable-libvpx
     libavutil    51. 14. 0 / 51. 14. 0
     libavcodec   53. 12. 0 / 53. 12. 0
     libavformat  53. 10. 0 / 53. 10. 0
     libavdevice  53.  3. 0 / 53.  3. 0
     libavfilter   2. 37. 0 /  2. 37. 0
     libswscale    2.  0. 0 /  2.  0. 0
     libpostproc  51.  2. 0 / 51.  2. 0
   [mov,mp4,m4a,3gp,3g2,mj2 @ 0x13b7320] stream 0, error opening alias:     path='/matlab_sv13/work/cavity_flow/up500.jpg', dir='cavity_flow', filename='up500.jpg', volume='NONAME', nlvl_from=1, nlvl_to=1**
   [mov,mp4,m4a,3gp,3g2,mj2 @ 0x13b7320] Could not find codec parameters (Video: mjpeg (jpeg / 0x6765706A), 434x343, 4762 kb/s)
   /var/www/static/uploads/usersVideos/cavity0.mov: could not find codec parameters
   [1]    8265 exit 1     ffmpeg -i /var/www/static/uploads/usersVideos/cavity0.mov -vcodec mjpeg
  

  Someone has an idea?