How do I cut a section out of a video with ffmpeg?
Imagine I have a 60 second mp4 A.
I want to remove all the stuff from 0:15 to 0:45.
The result should be a 30-second mp4, which is composed of the first 15 seconds of A directly followed by the last 15 seconds of A.
How can I do this without using concat?
I know how I could do it by creating two intermediary files and then using ffmpeg to concat them. I don't want to have to perform so much manual work for this (simple?) operation.
I have also seen the trim filder used for removing multiple parts from a video. All the usages I've found show that it seems to be very verbose, and I haven't found an example for a case as simple as I would like (just a single section removed).
Do I have to use trim for this operation? Or are there other less verbose solutions?
The ideal would of course be something at least simple as -ss 0:15 -to 0:45 which removes the ends of a video (-cut 0:15-0:45 for example).
I started from
https://stackoverflow.com/a/54192662/3499840 (currently the only answer to "FFmpeg remove 2 sec from middle of video and concat the parts. Single line solution").
Working from that example, the following works for me:
# In order to keep <start-15s> and <45s-end>, you need to
# keep all the frames which are "not between 15s and 45s":
ffmpeg -i input.mp4 \
-vf "select='not(between(t,15,45))', setpts=N/FRAME_RATE/TB" \
-af "aselect='not(between(t,15,45))', asetpts=N/SR/TB" \
output.mp4
This is a one-line linux command, but I've used the bash line-continuation character ('\') so that I can vertically align the equals-signs as this helps me to understand what is going on.
I had never seen ffmpeg's not and between operators before, but I found their documentation here.
Regarding the usual ffmpeg "copy vs re-encode" dichotomy, I was hoping to be able to use ffmpeg's "copy" "codec" (yeah, I know that it's not really a codec) so that ffmpeg would not re-encode my video, but if I specify "copy", then ffmpeg starts and stops at the nearest keyframes which are not sufficiently close to my desired start and stop points. (I want to remove a piece of video that is approximately 20 seconds long, but my source video only has one keyframe every 45 seconds!). Hence I am obliged to re-encode. See https://trac.ffmpeg.org/wiki/Seeking#Seekingwhiledoingacodeccopy for more info.
The setpts/asetpts filters set the timestamps on each frame to the correct values so that your media player will play each frame at the correct time.
HTH.
If you want to use the copy "codec", consider the following approach:
ffmpeg -i input.mp4 -t "$start_cut_section" -c copy part1.mp4&
ffmpeg -i input.mp4 -ss "$end_cut_section" -c copy part2.mp4&
echo "file 'part1.mp4'" > filelist;
echo "file 'part2.mp4'" >> filelist;
wait;
ffmpeg -f concat -i filelist -c copy output.mp4;
rm filelist;
This creates two files from before and after the cut, then combines them into a new trimmed final video. Obviously, this can be used to create as many cuts as you like. It may seem like a longer approach than the accepted answer, but it likely will execute much faster because of the use of the copy codec.
Related
I am reading from an RTSP (camera) stream and writing segments, using ffmpeg. My command to do so is:
ffmpeg -rtsp_transport tcp -i rtsp://$camera_creds#$camera_ip/video/1 -map 0 -c:v h264 -preset:v ultrafast -reset_timestamps 1 -f segment -segment_time 300 -strftime 1
-segment_list ${monitor_dir}/segments$camera.txt $monitor_dir/cam${camera}_out%Y%m%d_%H%M%S.mp4
It works fine to a point. My problem is that I want to do something with each segment once it has been written.
To accomplish this, I monitor the segmentsN.txt file for lines being added to it; I then read the contents, do stuff (process, upload), and then remove the lines that I've already processed (so that I don't reprocess them).
The problem with this is that periodically, ffmpeg will start writing to a new segment, but apparently won't update the segments list file. Initially I thought this was because my "remove the lines" operation was writing a brand new file and replacing it in place (which it was), while ffmpeg was probably continuing to append to the inode it started out with (which it maybe was). Having fixed that, I think I now just have a race condition.
What I'd really like is to have ffmpeg change the filename once it has completed a segment, and/or move the completed segment file into a different folder. However, this doesn't seem like an option. Is there a more robust way to accomplish what I'm doing here? I could just poll for multiple files with a given filename pattern, and process the earliest, circumventing the segments list file...but something more robust would be nice.
Thanks
At loglevel 40 / verbose or higher, you can grep ffmpeg's log for the word ended and see lines like these:
[segment # 000002d338781120] segment:'Mymon/Cam1_out20221228_093412.mp4' count:23 ended
Get the log by reading stderr or by adding -report to generate a logfile.
I have various MP3 files which I need to process.
The processing includes quite a few steps, but one important one is to remove the Info/Xing tag from the file.
I successfully do so by running lame -t .... However, there are times when I want to run ffmpeg to do a conversion which will happen after the lame -t ... conversion and I see that ffmpeg re-insert an Info/Xing tag in the MP3 file.
Is there a command line option I can use so ffmpeg does not re-insert the Info/Xing tag?
-write_xing 0
See ffmpeg -h muxer=mp3
I got pictures named as
pic_0_new.jpg
pic_10_new.jpg
pic_20_new.jpg
...
pic_1050_new.jpg
which I want to turn into a video (Ubuntu ffmpeg). I tried the following
ffmpeg -start_number 0 -i pic_%d_new.jpg -vcodec mpeg4 test.avi
but I don't know how to set the step size and the end number. How to do this?
Thanks for help :)
If your files are named with leading zeroes then you can use the built-in globbing functionality. If not (like your's), you can create a file list and supply that as the input, just like explained here.
The other thing you need to set is the input framerate that tells FFmpeg what framerate should assume for the images (note that the option is ahead of the -i input option).
So the command should look like this:
ffmpeg -framerate 25 -i pic_%04d_new.jpg <encoding_settings> test.avi
Also note that you can use the filename expansion on files with or without leading zeroes (Thanks for #Gyan to pointing it out):
match regularly numbered files: %d (this is what you're using)
img_%d.png // This will match files with any number as a postfix starting from img_0.png
match leading zeroes: %0<number_of_digits>d
img_%03d.png // This will match files ranging from img_000.png to img_999.png
In addition, mpeg4/avi is not the most convenient encoder/container to use...
What would be the simplest ffmpeg command to truncate the video to the first two minutes (or do nothing if the video is less than two minutes) ? It can do a pass-through on any of the initial video settings.
This is an adapted version of David542's post since my edit was rejected as "completely superfluous or actively harm[ing] readability".
For extractions, it is essential to add the -c copy flag,
ffmpeg -i in.mov -ss 0 -t 120 -c copy out.mov
what is shorthand for -vcodec copy -acodec copy.
Otherwise ffmpeg reencodes the selection what is about 1000 times slower on my machine here and possibly alters the outcome in quality due to default settings taken.
Edit
As ack-inc indicated, it makes a difference whether -ss is placed before (input option) or behind (output option) the -i.
In conjunction with stream copying (-c copy), ffmpeg will seek to the closest seek point before the position (e.g. the closest keyframe), if used as an input option. This is very fast but may be inaccurate depending on the codec and codec settings used.
If used as an output option, ffmpeg first decodes the complete stream up to the position. This uses more CPU resources and therefore takes longer, but the cut is now precise.
The latter takes about 16 times longer on my computer, but in the end it only takes about 1.5 seconds to search through 1.5 hours of FHD stream (conjunction with -c copy). In other words, computers are now sufficiently fast that this is the way of choice for the vast majority of end users.
Without stream copying -- when trans-coding -- the difference was a factor of about 500 (or 6 min at 100 % CPU).
$ ffmpeg -i in.mov -ss 0 -t 120 out.mov
I have series of images with sorted names, like 0000000354 ... 0000008591
I have tried using ffmpeg or MEncoder to convert theme. In ffmpeg the problem is this that it will operate while the names are like 0000000001 ... 00000000009 with %010d syntax.I don't know what syntax i should use for my images names.in mencoder it will cover all images But when i play the output video it doesn't show images,I want to show every image in 5 seconds or somthing like this, any one can help?
ffmpeg can't read in arbitrarily named images. You'll have to rename them or do something clever with symlinks to get ffmpeg to take them as input.
From the man page:
If the pattern contains "%d" or "%0Nd", the first filename of the file
list specified by the pattern must contain a number inclusively
contained between 0 and 4, all the following numbers must be
sequential. This limitation may be hopefully fixed.
Let's say you have:
img000001.jpg
....
img000140.jpg
....
img010040.jpg
....
To encode it into a movie using ffmpeg just use the filename pattern:
ffmpeg -i "img%06d.png" -vcodec libx264 -vpre ipod640 output.mp4