How can I efficiently cut out part of a video?

Question

I want to remove the first few seconds from a video that's about 25 minutes long. I found the moviepy package, and tried writing this code:

from moviepy.editor import *
clip = VideoFileClip("video1.mp4").cutout(0, 7)
clip.write_videofile("test.mp4")

However, it's very slow even for a single video. Is there a faster way to do this in Python?

Writing the video probably means that the library has to re-encode it, resulting in a loss of quality and poor performance. It *is* possible to cut away from a MP4 video stream without re-encoding, but it's not as simple as you seem to think it is, and you can't cut at arbitrary points (only right before keyframes). I also don't know if moviepy can do this. — Colin Emonds, May 19 '16 at 08:51
I agree with @cemper93. MoviePy always decode your frames (to Numpy arrays) and reencode them at write time, which takes time. The simplest way to cut without reencoding is to use FFMPEG to extract the right segment from the mp4. You can do it directly at the command line, or from Python, using the subprocess library to call ffmpeg. — Zulko, May 19 '16 at 11:17
@Zulko: Can you write that as an answer and add a bit more explanation? I have no idea about FFMPEG and the subprocess library you are talking about. :/ — Pranav Arora, May 19 '16 at 11:45

score 128 · Accepted Answer · edited Oct 31 '18 at 23:44

128

Try this and tell us if it is faster (if it can, it will extract the video directly using ffmpeg, without decoding and reencoding):

from moviepy.video.io.ffmpeg_tools import ffmpeg_extract_subclip
ffmpeg_extract_subclip("video1.mp4", start_time, end_time, targetname="test.mp4")

If that doesn't help, have a look at the code

edited Oct 31 '18 at 23:44

Zain Rizvi

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answered May 19 '16 at 12:41

Zulko

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How is the smallest unit of time that t1,t2 can be ? – mobcdi Jun 26 '16 at 17:19
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What happens if I dont wanna cut on non key frames? Can I cut anywhere with this code? – ScipioAfricanus Mar 04 '19 at 02:52
would this work with other video formats like mkv? or would there be adverse effects? I did it on an mkv and it works but when the file launches in vlc it glitches for half a second – ScipioAfricanus Jul 19 '19 at 23:24
is there a way to run with re encode flag? I think the glitch might be due to where the video has inserted key frames? – ScipioAfricanus Aug 04 '19 at 01:29
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from moviepy.editor import * // video = VideoFileClip("myHolidays.mp4").subclip(50,60) // this line is from their page https://pypi.org/project/moviepy/ and is up to date. – Zeynab Rostami Aug 23 '20 at 07:58
units of start_time and end_time are in millisecond. – BEWARB Oct 08 '20 at 13:26
is there a moviepy function i can use where i can add timestamps instead of seconds? – Ulf Gjerdingen Dec 18 '20 at 00:21
small note - in the version you get with pip, the keywords are "t1" and "t2" instead of "start_time" and "end_time" – Nik Nov 30 '22 at 08:13

Samuel Dauzon · Answer 2 · 2020-09-02T23:12:52.380

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If you are new to moviepy you should follow these steps.

Installation :

pip install --trusted-host pypi.python.org moviepy
pip install imageio-ffmpeg

Installation (in your virtualenv) version for old systems :

pip install --trusted-host pypi.python.org moviepy
python
import imageio
imageio.plugins.ffmpeg.download()

After these commands, you have the minimal software requirements.

Usage

from moviepy.video.io.ffmpeg_tools import ffmpeg_extract_subclip
# ffmpeg_extract_subclip("full.mp4", start_seconds, end_seconds, targetname="cut.mp4")
ffmpeg_extract_subclip("full.mp4", 60, 300, targetname="cut.mp4")

edited Sep 02 '20 at 23:12

answered Jan 22 '19 at 23:27

Samuel Dauzon

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Btw, if you are looking to disable the output of `ffmpeg_extract_subclip` that not possible with the current version. You should install moviepy from the [git](https://github.com/Zulko/moviepy) repo because they actually recently added that option. – Bendemann Apr 19 '21 at 05:18

score 5 · Answer 3 · answered Apr 06 '18 at 16:14

from moviepy.video.io.ffmpeg_tools import ffmpeg_extract_subclip
ffmpeg_extract_subclip("video1.mp4", t1, t2, targetname="test.mp4")

t1 and t2 in this code represent the start time and end time for trimming. Video before t1 and after t2 will be omitted.

score 4 · Answer 4 · answered Dec 11 '21 at 19:37

4

The ffmpeg_extract_subclip did not produce correct results for me for some videos. The following code from this link worked though.

# Import everything needed to edit video clips
from moviepy.editor import *

# loading video gfg
clip = VideoFileClip("geeks.mp4")
# getting only first 5 seconds
clip = clip.subclip(0, 5)
# showing clip
clip.ipython_display(width = 360)

Then you can save the clip as follows:

clip.write_videofile("clip.mp4")

answered Dec 11 '21 at 19:37

MRM

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It worked almost fine. Somehow the sound wasn't exported. Any idea? – Mario.Cadiz Dec 31 '22 at 02:09

How can I efficiently cut out part of a video?

4 Answers4

Installation :

Installation (in your virtualenv) version for old systems :

Usage

Linked