animation with 'ffmpeg' backend and 'savefig.bbox = tight' garbles video #6416

chipmuenk · 2016-05-13T11:09:09Z

Using

Matplotlib 1.5.0rc3 with Python 2.7.10 and Win 7 64 Bit (WinPython 2.7.10.3) or
Matplotlib 1.5.1 with Python 3.4.4 and Win 7 64 Bit (WinPython 3.4.4.1)
ffmpeg 20160512-git-cd244fa
animation with 'ffmpeg' backend incompative with 'bounding_box=tight' #2483 seems to be back (or still there):

Setting savefig.bbox = tight either in matplotlibrc or as an rcParam garbles an mp4 video written by ffmpeg. Even starting the script with --verbose-debug gives no warning or message that something might be wrong.

I also cannot change the frame rate - neither interval nor fps has any effect, I always get 5 fps (this is consistent with the options passed to ffmpeg which always says '-r 5').

Example (slightly modded) taken from
https://jakevdp.github.io/blog/2012/08/18/matplotlib-animation-tutorial/ :

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.animation as animation

plt.rcParams['animation.ffmpeg_path'] = 'D:/Programme/ffmpeg/bin/ffmpeg.exe'
plt.rcParams['savefig.bbox'] = 'tight'     # tight garbles the video!!!

movie_file = 'D:/Daten/basic_animation.mp4'
mywriter = animation.FFMpegWriter()

fig = plt.figure()
fig.set_size_inches(4, 5, True)
ax = plt.axes(xlim=(0, 2), ylim=(-2, 2))
line, = ax.plot([], [], lw=2)

def init():
    line.set_data([], [])
    return line,

def animate(i):
    x = np.linspace(0, 2, 1000)
    y = np.sin(2 * np.pi * (x - 0.01 * i))
    line.set_data(x, y)
    return line,

anim = animation.FuncAnimation(fig, animate, init_func=init,
                               interval = 1000, frames = 20, blit=True)

anim.save(movie_file, dpi=100, fps = 30, writer=mywriter, 
          extra_args=['-vcodec', 'libx264'])

plt.show()

The text was updated successfully, but these errors were encountered:

dopplershift · 2016-05-13T15:44:38Z

I can reproduce the fps issue here locally on OSX on python 3.4, matplotlib 1.5.1. Not sure why -r 5 is getting passed.
(I'd say let's leave the 'tight' issue to #2483).

tacaswell · 2016-05-13T15:47:23Z

It might be worth using an rccontext in anim.save to force the bounding box to always be off?

This is an awfully large foot-cannon to have very lightly documented.

dopplershift · 2016-05-13T15:54:00Z

That's a really good idea--I'll go ahead and include that when I put up a PR to fix the fps issue.

dopplershift · 2016-05-13T21:07:59Z

Ok, so there are really two things that are different cases that we haven't hit before:

Using rcparams for tight bbox. We can address this using rc_context, as suggested by @tacaswell
Passing in a MovieWriter instance along with some kwargs that are used in the creation of a MovieWriter instance (when save needs to create one). The question is: Should we modify the passed in MovieWriter using the kwargs? Or should we just document that these are ignored if writer is a MovieWriter instance?

In the meanwhile, the work-around/intended use would be to do:

mywriter = animation.FFMpegWriter(fps=30, extra_args=['-vcodec', 'libx264'])

and

anim.save(movie_file, dpi=100, writer=mywriter)

Clearly, since I had to actually dig into this problem, it's not intuitive; I'm just not sure what the right answer is.

This fixes part of matplotlib#6416 by resetting the 'savefig.bbox' rcParam if it is set to 'tight'.

chipmuenk · 2016-05-14T14:36:20Z

The workaround works for me (for the fps issue) - thanx for the explanation and the quick solution!

For debugging purposes, it would be great to see messages created by the actual movie writer (ffmpeg in my case): An invalid parameter in the extra_args list e.g. just raises an IOError.

This fixes part of matplotlib#6416 by resetting the 'savefig.bbox' rcParam if it is set to 'tight'.

dopplershift · 2016-05-16T17:11:06Z

Having given this some thought, I think the right solution is to document the kwargs which will have no effect when writer is an instance of MovieWriter and to issue a warning when both are supplied (which will of course say the arguments should be supplied when creating the MovieWriter.)

Anyone else have any thoughts?

tacaswell · 2016-05-16T17:13:09Z

No one reads warnings 👿.

I lean towards raise, but would merge a PR which added the warnings.

dopplershift · 2016-05-16T17:15:37Z

raise works for me too. One point: raising the error could break code that "works". I think this is fine (since existing code can't be working as intended)...but how do we feel about that for matplotlib?

tacaswell · 2016-05-16T17:52:02Z

I tend to view that as ok, it is just telling users that code that wasn't working really isn't working.

Animation error handling (Fixes #6416)

dopplershift · 2016-05-17T21:04:12Z

Fixed by #6441 and #6421.

This fixes part of matplotlib#6416 by resetting the 'savefig.bbox' rcParam if it is set to 'tight'.

dopplershift self-assigned this May 13, 2016

dopplershift added this to the 1.5.2 (Critical bug fix release) milestone May 13, 2016

dopplershift added a commit to dopplershift/matplotlib that referenced this issue May 13, 2016

FIX: Animations should disable savefig.bbox as necessary.

a1a76f6

This fixes part of matplotlib#6416 by resetting the 'savefig.bbox' rcParam if it is set to 'tight'.

dopplershift mentioned this issue May 13, 2016

WIP: Fix some animation confusion #6421

Merged

mdboom added the status: needs review label May 13, 2016

dopplershift added a commit to dopplershift/matplotlib that referenced this issue May 15, 2016

FIX: Animations should disable savefig.bbox as necessary.

885b6fd

This fixes part of matplotlib#6416 by resetting the 'savefig.bbox' rcParam if it is set to 'tight'.

dopplershift mentioned this issue May 17, 2016

Animation error handling (Fixes #6416) #6441

Merged

dopplershift added the topic: animation label May 17, 2016

WeatherGod added a commit that referenced this issue May 17, 2016

Merge pull request #6441 from dopplershift/anim-errors

e2549cd

Animation error handling (Fixes #6416)

dopplershift closed this as completed May 17, 2016

mdboom removed the status: needs review label May 17, 2016

tacaswell pushed a commit to tacaswell/matplotlib that referenced this issue May 22, 2016

FIX: Animations should disable savefig.bbox as necessary.

58992f0

This fixes part of matplotlib#6416 by resetting the 'savefig.bbox' rcParam if it is set to 'tight'.

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

animation with 'ffmpeg' backend and 'savefig.bbox = tight' garbles video #6416

animation with 'ffmpeg' backend and 'savefig.bbox = tight' garbles video #6416

chipmuenk commented May 13, 2016 •

edited by dopplershift

Loading

dopplershift commented May 13, 2016

tacaswell commented May 13, 2016

dopplershift commented May 13, 2016

dopplershift commented May 13, 2016

chipmuenk commented May 14, 2016

dopplershift commented May 16, 2016

tacaswell commented May 16, 2016

dopplershift commented May 16, 2016

tacaswell commented May 16, 2016

dopplershift commented May 17, 2016

animation with 'ffmpeg' backend and 'savefig.bbox = tight' garbles video #6416

animation with 'ffmpeg' backend and 'savefig.bbox = tight' garbles video #6416

Comments

chipmuenk commented May 13, 2016 • edited by dopplershift Loading

dopplershift commented May 13, 2016

tacaswell commented May 13, 2016

dopplershift commented May 13, 2016

dopplershift commented May 13, 2016

chipmuenk commented May 14, 2016

dopplershift commented May 16, 2016

tacaswell commented May 16, 2016

dopplershift commented May 16, 2016

tacaswell commented May 16, 2016

dopplershift commented May 17, 2016

chipmuenk commented May 13, 2016 •

edited by dopplershift

Loading