FFmpeg
Usage[edit]
Merging mp4 and m4a[edit]
Using ffmpeg
you can combine the two together:
# ffmpeg -i video.mp4 -i audio.m4a -acodec copy -vcodec copy output.mp4
Extracting a video section[edit]
To extract a video section:
# ffmpeg -i input.mp4 -ss 00:00:15 -t 00:00:10 -async 1 output.mp4
Where:
-ss | The start time in HH:MM:SS |
---|---|
-t | The length of the video in HH:MM:SS |
Slideshow to Video[edit]
See: https://trac.ffmpeg.org/wiki/Slideshow
Example usage:
## Remove any empty image files (explained below)
# find ./images -size 0 -print0 | xargs -0 rm --
## Process images to 25fps with 8 CPU cores
# ffmpeg -pattern_type glob \
-i ./images/\*.jpg \
-c:v libx264 \
-vf "fps=25,format=yuv420p" \
-threads 8 \
output.mp4
The *
needs to be escaped or contained in single quotes because ffmpeg
will do the globbing, not the shell.
Empty files will cause ffmpeg
to stop processing additional files. Run find ./slideshow -size 0 -print0
to delete zero-sized files to prevent this from happening.
Issues[edit]
Copying DASH video (via -vcodec copy
) using versions older than 0.10 will result in an empty file because it is unable to read the video contents.