Running FFMPEG command through Golang exec - go

Question

I need to run an ffmpeg command to create a video from images with a crossfade between images as the transition. The command is derived from this post. I need to run it through the Golang os/exec package. The command I need to run is:
ffmpeg -loop 1 -t 5 -i img-0.png -loop 1 -t 5 -i img-1.png -loop 1 -t 5 -i img-2.png -filter_complex "[1:v][0:v]blend=all_expr='A*(if(gte(T,0.5),1,T/0.5))+B*(1-(if(gte(T,0.5),1,T/0.5)))'[b1v];[2:v][1:v]blend=all_expr='A*(if(gte(T,0.5),1,T/0.5))+B*(1-(if(gte(T,0.5),1,T/0.5)))'[b2v];[0:v][b1v][1:v][b2v][2:v]concat=n=5:v=1:a=0,format=yuv420p[v]" -map '[v]' -c:v libx264 -pix_fmt yuv420p -r 30 -s 1280x720 -aspect 16:9 -crf 1 -preset ultrafast output.mp4
If you run this command directly in the terminal, it works just fine. However, it does not work through my code. This is my code that takes a string command and runs it through the os/exec package:
command := "ffmpeg -loop 1 -t 5 -i img-0.png -loop 1 -t 5 -i img-1.png -loop 1 -t 5 -i img-2.png -filter_complex "[1:v][0:v]blend=all_expr='A*(if(gte(T,0.5),1,T/0.5))+B*(1-(if(gte(T,0.5),1,T/0.5)))'[b1v];[2:v][1:v]blend=all_expr='A*(if(gte(T,0.5),1,T/0.5))+B*(1-(if(gte(T,0.5),1,T/0.5)))'[b2v];[0:v][b1v][1:v][b2v][2:v]concat=n=5:v=1:a=0,format=yuv420p[v]" -map '[v]' -c:v libx264 -pix_fmt yuv420p -r 30 -s 1280x720 -aspect 16:9 -crf 1 -preset ultrafast output.mp4"
lastQuote := rune(0)
f := func(c rune) bool {
switch {
case c == lastQuote:
lastQuote = rune(0)
return false
case lastQuote != rune(0):
return false
case unicode.In(c, unicode.Quotation_Mark):
lastQuote = c
return false
default:
return unicode.IsSpace(c)
}
}
parts := strings.FieldsFunc(command, f)
cmd := exec.Command(parts[0], parts[1:]...)
cmd.Stderr = os.Stderr
cmd.Stdout = os.Stdout
err := cmd.Run()
if err != nil {
return err
}
When I run this, I get the ffmpeg error: No such filter: '"', Error configuring filters. I know it has something to do with the quotes that HAVE to be in the video filters, but I have tried everything to get it to work and I can't figure it out.
Any help is greatly appreciated!

Answer 1

This actually does work correctly :
exec.Command("ffmpeg", "-loop", "1", "-t", "5", "-i", "img-0.png", "-loop", "1", "-t", "5", "-i", "img-1.png", "-loop", "1", "-t", "5", "-i", "img-2.png", "-filter_complex", "[1:v][0:v]blend=all_expr='A*(if(gte(T,0.5),1,T/0.5))+B*(1-(if(gte(T,0.5),1,T/0.5)))'[b1v];[2:v][1:v]blend=all_expr='A*(if(gte(T,0.5),1,T/0.5))+B*(1-(if(gte(T,0.5),1,T/0.5)))'[b2v];[0:v][b1v][1:v][b2v][2:v]concat=n=5:v=1:a=0,format=yuv420p[v]", "-map", "[v]", "-c:v", "libx264", "-pix_fmt", "yuv420p", "-r", "30", "-s", "1280x720", "-aspect", "16:9", "-crf", "1", "-preset", "ultrafast", "output.mp4")
Notice that I did remove start and end double quotes from the -filter_complex parameters and two single quotes from the -map parameters.
Did it by hand, though, not sure of a strings function that could do it automagically.