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• Running batch file from C# causes file not found error [on hold]

  29 juillet 2018, par user10152616

  I am streaming an IP camera using the program FFMPEG. I made a C# windows sform app to restart the FFMPEG process if it stops running. The C# app kills the process and starts a batch file which runs the FFMPEG command. It works great. However, I wanted to change the FFMPEG command so that it loads a .acv color file to correct some haze in the image. The problem is FFMPEG says file not found when it tries to load the .acv file. FFMPEG and the .acv file are in the same directory so I don’t see how this is possible. The batch file works fine if I double click on it. It’s only when run from the C# program that FFMPEG can’t find the .acv file.

  Any help greatly appreciated,

  Thanks

• Use ffmpeg libraries to convert stream formats

  17 septembre 2021, par Syrinx

  I'm attempting to write a small program and link it to a minimal set of ffmpeg libraries, like libavformat and whatever other libraries I need.

  


  I am looking for documentation to get me started, or maybe a quick fix to the example program I am using.

  


  I know ffmpeg (the project) provides example programs to help developers get started. I'm using the transcoding example, as it's close to my end goal, but it exits during init with an error about an audio issue.

  


  Here I am using the transcoding example program that come with ffmpeg v4.4, on Ubuntu 18.04. My input source has one video channel (h264) and one audio channel (pcm_mulaw).

  


  $ LD_LIBRARY_PATH=../../dist/lib ./transcoding rtsp://ip-camera/stream out.flv
...
  Stream #0:0: Video: h264, yuv420p, 1280x720, q=2-31, 20 tbn
  Stream #0:1: Audio: pcm_mulaw, 8000 Hz, 0 channels, s16
auto_resampler_0 @ 0x55da787fa140] [SWR @ 0x55da787fa5c0] Rematrix is needed between mono and 0 channels but there is not enough information to do it
[auto_resampler_0 @ 0x55da787fa140] Failed to configure output pad on auto_resampler_0


  


  In libswresample/swresample.c :

  


  320      if ((!s->out_ch_layout || !s->in_ch_layout) && s->used_ch_count != s->out.ch_count && !s->rematrix_custom) {
321          av_log(s, AV_LOG_ERROR, "Rematrix is needed between %s and %s "
322                 "but there is not enough information to do it\n", l1, l2);
323          ret = AVERROR(EINVAL);
324          goto fail;
325      }


  


  I'd really like it if I could make the transcoding example program work (fix it, or maybe use it appropriately if I am misunderstanding something). But short of that, where should I look for documentation about using the ffmpeg libraries ?

  


  I don't even care about the audio. If I can just disable the audio, I would be happy with that solution. I tried tracking the "-an" option to ffmpeg (the program) to see how it does that in source code, but the options handling is a mess and I can't distinguish the parts of the code that I need from all the noise.

  


  ffmpeg has web pages like this that aren't useful at all. There is documentation in the source code that looks like it should be viewed as HTML, but I don't see it exported anywhere. "make doc" generates a very small set of man pages that are insufficient to get me started.

  


• Overlaying a green screen intro over video using FFMPEG

  29 novembre 2020, par BitBit

  Can someone please help me with a program that overlays a green screen intro in the start of the video.
  
Basically I need help with a FFMPEG program that overlays a green screen video which is the intro of the video, so the first few seconds are with the green screen overlay and then the normal video continues.