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FIX: Fix for FFmpeg + GIF#17401

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tacaswell merged 2 commits intomatplotlib:masterfrom
larsoner:ffmpeg
May 15, 2020
Merged

FIX: Fix for FFmpeg + GIF#17401
tacaswell merged 2 commits intomatplotlib:masterfrom
larsoner:ffmpeg

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@larsoner larsoner commented May 13, 2020

Working on making a GIF thumbnail for sphinx-gallery/sphinx-gallery#150 I stumbled across this bug writing GIF with FFmpeg:

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


def _update_line(num):
    line.set_data(data[..., :num])
    return line,


fig, ax = plt.subplots()
data = np.random.RandomState(0).rand(2, 25)
line, = ax.plot([], [], 'r-')
ax.set(xlim=(0, 1), ylim=(0, 1))
ani = animation.FuncAnimation(fig, _update_line, 25, interval=100, blit=True)
ani.save('test.gif', 'ffmpeg')

Produces:

$ python -ui anim.py 
MovieWriter stderr:
[gif @ 0x555affbb0580] GIF muxer supports only a single video GIF stream.
Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
Error initializing output stream 0:0 -- 

Traceback (most recent call last):
...
  File "/home/larsoner/python/matplotlib/lib/matplotlib/backends/backend_agg.py", line 429, in print_raw
    fh.write(renderer.buffer_rgba())
BrokenPipeError: [Errno 32] Broken pipe

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
...
  File "/home/larsoner/python/matplotlib/lib/matplotlib/animation.py", line 397, in cleanup
    raise subprocess.CalledProcessError(
subprocess.CalledProcessError: Command '['ffmpeg', '-f', 'rawvideo', '-vcodec', 'rawvideo', '-s', '640x480', '-pix_fmt', 'rgba', '-r', '10.0', '-loglevel', 'error', '-i', 'pipe:', '-vcodec', 'h264', '-pix_fmt', 'yuv420p', '-y', 'test.gif']' returned non-zero exit status 1.
>>> exit()

Basically the problem seems to be that you shouldn't pass -vcodec when using GIF. This PR works around the problem by not adding those arguments when the outputfile ends with .gif. Not the most elegant solution, but it seems to work.

I can try to add some simple variant of this as a test if this does seem like the right fix.

@tacaswell tacaswell added this to the v3.3.0 milestone May 14, 2020
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tacaswell approved these changes May 14, 2020
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👍 in principle, but need to fix the tests (I have proposed a patch).

@larsoner @tacaswell
Update lib/matplotlib/animation.py
1982469 
Co-authored-by: Thomas A Caswell <tcaswell@gmail.com>
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tacaswell commented May 15, 2020

I'm going to merge over the failure to downolad jquery-ui on azure.

Thanks @larsoner !

@tacaswell tacaswell merged commit 60fd88f into matplotlib:master May 15, 2020
@larsoner larsoner deleted the ffmpeg branch May 15, 2020 02:41
@dopplershift dopplershift mentioned this pull request Jul 28, 2020
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@tacaswell tacaswell tacaswell approved these changes

@timhoffm timhoffm timhoffm approved these changes

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