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

  11 February 2014, by 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.

• concatenate audio files with an image

  9 June 2020, by Roman Kubiv

  I am trying to concatenate multiple audio files and a single image into one video file using one command.
I have list of mp3 files and a playlist file (.m3u) in a direcotry.

  



  I managed to do this but my solution is bad:

  



  

  1. reading the playlist file and creating a new .txt in the ffmpeg required format

  


  2. concatenating the audio files using the .txt into an .mp3

  


  3. concatenating the large audio file and the static image into a video

  


  



  This creates 2 unnecessary files that I have to delete.

  



  ---

  



  I tried a different command

  



  ffmpeg -loop 1 -framerate 1 -i myImage.jpg -i file1.mp3 -i file2.mp3 -i file3.mp3 -filter_complex '[0:0][1:0][2:0]concat=n=3:v=0:a=1' -tune stillimage -shortest output.mp4


  



  however im getting a Error initializing complex filters.
Invalid argument error

  



  Another kick in the nuts is that the system im working on has spaces in the folder names.
i tried using -i "concat:file1.mp3|file2.mp3|..." however i cannot use double quote marks to quote out the path so I get an invalid argument error.

  



  Thank you very much for your help.

  


• stream_encoder : Improve selection of residual accumulator width

  19 June 2014, by Miroslav Lichvar

  stream_encoder : Improve selection of residual accumulator width
  In the precompute_partition_info_sums_ function, instead of selecting
  
  64-bit accumulator when the signal bps is larger than 16, revert to the
  
  original approach based on partition size, but make room for few extra
  
  bits to not overflow with unusual signals where the average residual
  
  magnitude may be larger than bps.
  It slightly improves the performance with standard encoding levels and
  
  16-bit files as the 17-bit side channel can still be processed with the
  
  32-bit accumulator and correctly selects the 64-bit accumulator with
  
  very large 16-bit partitions.
  This is related to commits 6f7ec60c and 187e596e.
  Signed-off-by: Erik de Castro Lopo <erikd@mega-nerd.com>
  

  • [DH] src/libFLAC/include/private/stream_encoder.h
  • [DH] src/libFLAC/stream_encoder.c
  • [DH] src/libFLAC/stream_encoder_intrin_sse2.c
  • [DH] src/libFLAC/stream_encoder_intrin_ssse3.c