Stream specifier '' in filtergraph description

Hi. I am running this section of code just to test out ffmpeg a little bit and am getting this error. Both of these files exist and are in the proper dictionary, and ffmpeg has worked in the command line on these files the same way.

def cutout(input_file,output_file,start,duration):
    (
        ffmpeg
            .input(input_file)
            .trim(start=start,duration=duration)
            .output(output_file)
            .run()
    )

I am then getting this error:

Stream specifier '' in filtergraph description [0]trim=duration=15:start=0[s0] matches no streams.

What should I look for to debug? I do not understand where this blank comes into play.

[ghost]

I also have this problem when trying to concatenate streams. Here’s an example of calling .compile():

['ffmpeg', '-i', "/some/path/a.m4a", '-i', '/some/path/b.m4a', '-filter_complex', '[0][1]concat=n=2[s0]', '-map', '[s0]', 'out.m4a']

In my case, I was able to manually make it work by changing [0][1]concat=n=2[s0] to [0][1]concat=n=2:v=0:a=1[s0]

Or just by saying a=1, v=0 in kwargs

[Azleal]

@Azleal nice!

Fun fact, if you add noaccurate_seek=None to your input() call, it will make the command way faster for big files.

wow, 👍 x 100, I’ll try it out. thanks~