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...

Store numpy arrays in sqlite

Use numpy.getbuffer (or sqlite3.Binary ) in combination with numpy.frombuffer to lug numpy data in and out of the sqlite3 database: import sqlite3, numpy r1d = numpy.random.randn(10) con = sqlite3.connect(':memory:') con.execute("CREATE TABLE eye(id INTEGER PRIMARY KEY, desc TEXT, data BLOB)") con.execute("INSERT INTO eye(desc,data) VALUES(?,?)", ("1d", sqlite3.Binary(r1d))) con.execute("INSERT INTO eye(desc,data) VALUES(?,?)", ("1d", numpy.getbuffer(r1d))) res = con.execute("SELECT * FROM eye").fetchall() con.close() #res -> #[(1, u'1d', <read-write buffer ptr 0x10371b220, size 80 at 0x10371b1e0>), # (2, u'1d', <read-write buffer ptr 0x10371b190, size 80 at 0x10371b150>)] print r1d - numpy.frombuffer(res[0][2]) #->[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.] print r1d - numpy.frombuffer(res[1][2]) #->[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.] Note that for work where data ty...