On Audio

[jay_jay]

i want to mute audio of my video clip for the first 4 seconds,then play normally.please suggest a method?

[Didée]

You trim the start section, length = 4 sec * (frames per second), mute the audio of this section, and splice this muted start section with the rest of the clip:

last.trim(0,4*last.framerate).amplify(0.00001) + last.trim(4*last.framerate+1,0)