Skip to main content

ffmpeg to create a movie from images

I've switched over to ffmpeg from mencoder. ffmpeg can be obtained from here for mac.

The ffmpeg documentation on creating video slideshows is great.

An example command line for such a use is:

ffmpeg -r 1/.5 -i "0%05d.jpg" -vcodec mjpeg -r 25 drop.avi


Important: if the numbering of your images doesn't start from 1 you should use the -start_number to indicate the first image (from here):
ffmpeg -start_number 2724  -r 1/.075 -i "DSC_%04d.jpg" -vcodec mjpeg -r 25 advair.avi

If there is a break in the file name numbering (eg. you have image01.jpg ... image05.jpg then image08.jpg) ffmpeg will stop at the break and finish the movie. You can use a short bash script to generate a copy of the files numbered as you want them.
ls *.JPG| awk 'BEGIN{ a=0 }{ printf "cp %s image_%04d.jpg\n", $0, a++ }' | bash

You should add options to ls to sort the files as you wish
Here, the first rate command (-r 1/.5) indicates how long each frame should take (here 0.5 of a second) and the second rate command (-r 25) indicates the movie frame rate.

Another example command to compile images into a movie is:
ffmpeg  -i test%06d.png -vcodec libx264 -x264opts keyint=123:min-keyint=20 -an sudoku.mkv


Comments

Popular posts from this blog

A note on Python's __exit__() and errors

Python's context managers are a very neat way of handling code that needs a teardown once you are done. Python objects have do have a destructor method ( __del__ ) called right before the last instance of the object is about to be destroyed. You can do a teardown there. However there is a lot of fine print to the __del__ method. A cleaner way of doing tear-downs is through Python's context manager , manifested as the with keyword. class CrushMe: def __init__(self): self.f = open('test.txt', 'w') def foo(self, a, b): self.f.write(str(a - b)) def __enter__(self): return self def __exit__(self, exc_type, exc_val, exc_tb): self.f.close() return True with CrushMe() as c: c.foo(2, 3) One thing that is important, and that got me just now, is error handling. I made the mistake of ignoring all those 'junk' arguments ( exc_type, exc_val, exc_tb ). I just skimmed the docs and what popped out is that you need to return True or...

Remove field code from Word document

e.g. before submitting a MS, or hand manipulating some formatting because Word does things (like cross-references) so half-assed [from here ] Select all the text (CTRL-A) Press Ctrl+Shift+F9 Editing to remove anonymous comments that only contain thanks. I really appreciate the thanks, but it makes it harder to find comments that carry pertinent information. I'm also going to try and paste informative comments in the body of the post to make them easier to find.

h5py and multiprocessing

The HDF5 format has been working awesome for me, but I ran into danger when I started to mix it with multiprocessing. It was the worst kind of danger: the intermittent error. Here are the dangers/issues in order of escalation (TL;DR is use a generator to feed data from your file into the child processes as they spawn. It's the easiest way. Read on for harder ways.) An h5py file handle can't be pickled and therefore can't be passed as an argument using pool.map() If you set the handle as a global and access it from the child processes you run the risk of racing which leads to corrupted reads. My personal runin was that my code sometimes ran fine but sometimes would complain that there are NaNs or Infinity in the data. This wasted some time tracking down. Other people have had this kind of problem [ 1 ]. Same problem if you pass the filename and have the different processes open individual instances of the file separately. The hard way to solve this problem is to sw...