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• How to concat videos and apply filters to one/both of them in one render ?

  29 juillet 2019, par NeeFuu

  I am merging two files but one of them needs hard subtitle applied. I can hardcode once and then concat files but because of codec conflict, it needs encoding two times which I want to avoid because of performance issues.

  I have tried to add simple subtitle in filter complex, which I found in this documentation. Then I tried to apply it on concat video filter example code found on StackOverflow.

  ffmpeg -i segment.mp4 -i video.mp4 -filter_complex "[0:v] [0:a] [1:v] ass=subtitle.ass [1:a] concat=n=2:v=1:a=1 [v] [a]" -map "[v]" -map "[a]" output.mkv

  I have tried to add subtitle only for video.mp4 but then I got :

  [Parsed_ass_0 @ 000002db090dd000] Shaper: FriBidi 1.0.4 (SIMPLE)
  
  [Parsed_ass_0 @ 000002db090dd000] Using font provider directwrite
  
  [Parsed_ass_0 @ 000002db090dd000] Added subtitle file: 'subtitle.ass' (2 styles, 3 events)
  
  [AVFilterGraph @ 000002db096e6680] Too many inputs specified for the "ass" filter.
  
  Error initializing complex filters.
  
  Invalid argument

  I am not sure If I am just adding filter wrong or it’s just wrong way to do it.

• Downloading and using ffmpeg.dll

  17 janvier 2021, par B Davidson

  I have been writing simple GUIs using ffmpeg.exe.
Now I would like to try and learn to use the ffmpeg.dll instead.
1-Does anyone know a secure site to get the dll.
2-Is there any help on how to access the libraries within the dll.

  


  Thanks in advance.

  


• Golang and ffmpeg realtime streaming input/output

  25 avril 2017, par Anderson Scouto da Silva

  I’m new to Go !

  I’m doing a simple test that is reading the output from ffmpeg and writing to a file.

  I know I can do it in a different way, simply convert, but this is the beginning of a project where I want to later manipulate the bytes read, changing them and then sending them to the output. And the input will be UDP and output will be UDP too, that is, I will get the ffmpeg output I will treat the bytes as I wish to do and then I will throw these bytes as input into another ffmpeg process which output is UDP as well.

  With this simple test the result of the file does not run in VLC, I believe I’m writing the bytes in the output file correctly, but the output file always has 1MB less than the input file.

  I would like some help to elucidate what would be the best way to write this test that I am doing, based on that I can get out of the place. I do not know if it’s exactly wrong, but I have the impression that it is.

  The input file is a video in 4K, h264, I believe the output should be the same, because in this simple test I am simply reading what goes out in the cmd writing in the file.

  Follow the code for analysis :

  package main
  
  
  
  import (
  
      "os/exec"
  
      "os"
  
  )
  
  
  
  func verificaErro(e error) {
  
      if e != nil {
  
          panic(e)
  
      }
  
  }
  
  
  
  func main() {
  
      dir, _ := os.Getwd()
  
  
  
      cmdName := "ffmpeg"
  
      args := []string{
  
          "-hide_banner",
  
          "-re",
  
          "-i",
  
          dir + "\\teste-4k.mp4",
  
          "-preset",
  
          "superfast",
  
          "-c:v",
  
          "h264",
  
          "-crf",
  
          "0",
  
          "-c",
  
          "copy",
  
          "-f", "rawvideo", "-",
  
      }
  
      cmd := exec.Command(cmdName, args...)
  
  
  
      stdout, err := cmd.StdoutPipe()
  
      verificaErro(err)
  
      err2 := cmd.Start()
  
      verificaErro(err2)
  
  
  
      fileOutput := dir + "/out.raw"
  
      var _, err3 = os.Stat(fileOutput)
  
  
  
      if os.IsNotExist(err3) {
  
          var file, err = os.Create(fileOutput)
  
          verificaErro(err)
  
          defer file.Close()
  
      }
  
  
  
      f, err4 := os.OpenFile(dir+"/out.raw", os.O_RDWR|os.O_APPEND, 0666)
  
  
  
      verificaErro(err4)
  
  
  
      bytes := make([]byte, 1024)
  
      for {
  
          _, err5 := stdout.Read(bytes)
  
          if err5 != nil {
  
              continue
  
          }
  
          if len(bytes) > 0 {
  
              _, err6 := f.Write(bytes)
  
              verificaErro(err6)
  
          } else {
  
              break
  
          }
  
      }
  
  
  
      f.Close()
  
  }