How to use python variable inside ffmpeg command

Question

I've python variable like this

diff #var


print(diff)
output: 0:01:36.992727

print(type(diff))
output: <class 'datetime.timedelta'>

I want to use this dif var inside ffmpeg command

os.system(' ffmpeg -i Thermal.mkv -ss 00:00:01 -t $diff -async 1 -c copy cut.mp4 ')

error I'm getting

Invalid duration specification for t: diff

I also tried

os.system(' ffmpeg -i Thermal.mkv -ss 00:00:01 -t "$diff" -async 1 -c copy cut.mp4 ')

also

os.system(' ffmpeg -i Thermal.mkv -ss 00:00:01 -t "${diff}" -async 1 -c copy cut.mp4 ')

when I given directly it works...

os.system(' ffmpeg -i Thermal.mkv -ss 00:00:01 -t  0:01:36.992727 -async 1 -c copy cut.mp4 ')

Am i missing anything here?...It's not the right way to do it?. If you guys know any reference pls share with me

K.Mat · Accepted Answer · 2022-07-28 09:32:58Z

2

You try to use bash-styled variable injection to string, however you need to inject variable to string on python level, and then run os.system() on this string.

Use f-strings literal interpolation like this:

cmd = f'ffmpeg -i Thermal.mkv -ss 00:00:01 -t {diff} -async 1 -c copy cut.mp4'

Another part is preparing your diff variable. I assume ffmpeg expects duration in seconds, so you have to convert your datetime.timedelta to seconds

diff # some var
print(diff) # 0:01:36.992727
print(type(diff)) # <class 'datetime.timedelta'>
diff = int(diff.total_seconds())
cmd = f'ffmpeg -i Thermal.mkv -ss 00:00:01 -t {diff} -async 1 -c copy cut.mp4'
os.system(cmd)

answered Jul 28, 2022 at 9:32

K.Mat

1,78915 silver badges22 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

user17993062 Over a year ago

Sorry for accepting late. Forget to accept a valid answer.

Collectives™ on Stack Overflow

How to use python variable inside ffmpeg command

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related