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

  11 février 2014, 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.

• 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 concat produces bad Video

  6 mars 2019, par Amorphis

  I have installed ffmpeg on a microsoft/dotnet:2.2-aspnetcore-runtime docker container using
  1.apt-get update
  2.apt-get install ffmpeg.

  seems to be installed fine, but when I try and use it as such
  ffmpeg -f concat -i /data/mylist.txt -c : copy /data/output.mp4

  the output is that the first video part is ok, but the second colors are all messy (hard to explain) and when I change the order of the videos in the list still the first in the list is ok and the second is messed up.

  p.s same settings on a different machine works (ffmpeg for ubuntu)

  bad

  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x55ccbcce90c0] Auto-inserting h264_mp4toannexb bitstream filter
  
  Input #0, concat, from '/data/mylist.txt':
  
    Duration: N/A, start: 0.000000, bitrate: 14915 kb/s
  
      Stream #0:0(und): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 14915 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc
  
      Metadata:
  
        creation_time   : 2014-10-17T04:06:30.000000Z
  
        handler_name    : GPAC ISO Video Handler
  
  Output #0, mp4, to '/data/output.mp4':
  
    Metadata:
  
      encoder         : Lavf57.56.101
  
      Stream #0:0(und): Video: h264 (Constrained Baseline) ([33][0][0][0] / 0x0021), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 14915 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 30k tbc
  
      Metadata:
  
        creation_time   : 2014-10-17T04:06:30.000000Z
  
        handler_name    : GPAC ISO Video Handler
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)

  good

  Input #0, concat, from '/data/mylist.txt':
  
    Duration: N/A, start: 0.000000, bitrate: 14915 kb/s
  
      Stream #0:0(und): Video: h264 (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 14915 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc
  
      Metadata:
  
        creation_time   : 2014-10-17T04:06:30.000000Z
  
        handler_name    : GPAC ISO Video Handler
  
  Output #0, mp4, to '/data/outGood1.mp4':
  
    Metadata:
  
      encoder         : Lavf58.20.100
  
      Stream #0:0(und): Video: h264 (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 14915 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 30k tbc
  
      Metadata:
  
        creation_time   : 2014-10-17T04:06:30.000000Z
  
        handler_name    : GPAC ISO Video Handler
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)