trim is not truly trimming duration, keeping stillframe before after

i took trimming example and try to make use in app i am working on. its simple gui (pyqt5) to help me work do batch processing. graph / operations happening in following order Crop > trim > pad > drawtext > watermark i tried changing order by keeping trim in start and moving crop ahead as well. same result. previously i was doing all above via batch files separately, it works but i hate it, Earlier in my tests with batch file, i had noticed same issue as well. Stack OverFlow searches taught me that, adding -strict -2 before end helps. command in batch file looked like this ffmpeg -i %dtp% -ss %s% -strict -2 -t %t% %filepath%\%filename above line worked correctly in batch file. Q. how can i make use of that here if my triming funtion looks like below

def trim_video(input,ss=0,t=100):
    trimmed_out = (
        input
        .trim(start_frame=ss, end_frame=t)
    )
    return trimmed_out

thanks again for support

[bidspells]

Solved! I observed the same issue of the ‘still frames’. As ffmpeg-python is a wrapper the root cause lies in most cases in FFmpeg itself.

In this case, two additional filters are required:

• in the video filter chain “setpts=PTS-STARTPTS”
• in the audio filter chain “asetpts=PTS-STARTPTS”

ffmpeg: “Be aware that frames are taken from each input [video] in timestamp order, so it is a good idea to pass all overlay inputs through a setpts=PTS-STARTPTS filter to have them begin in the same zero timestamp, such as …”

Translating back to ffmpeg-python, this means you have to add the following calls to you filter chains. An respective API call is available for video (but not for audio):

.setpts('PTS-STARTPTS')

A generic filter call can be used in both cases:

.filter('setpts', expr='PTS-STARTPTS'))
.filter('asetpts', expr='PTS-STARTPTS'))

–Bid

[TTransmit]

I think the problem may be keyframes. You can use ss on the input to seek to the needed frame.

ffmpeg.input('video.mp4', ss=20, t=10)

Starts video.mp4 at 20 seconds and plays ten seconds of it without including a paused frame.

See: https://trac.ffmpeg.org/wiki/Seeking#Cuttingsmallsections