Display movie file with support for browsing forward and backward through frames with a slider or arrow keys.

browse_video.py

#!/usr/bin/env python3

"""
Display movie file with support for browsing forward and backward through frames
with a slider or arrow keys.
"""

import argparse
import datetime
import os

import imageio as im
import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
from matplotlib.widgets import Slider

parser = argparse.ArgumentParser(description='Browse frames in movie file')
parser.add_argument('file_name', help='input movie file')
args = parser.parse_args()
file_name = args.file_name

vid = im.get_reader(file_name, 'ffmpeg')
metadata = vid.get_meta_data()
st = os.stat(file_name)
start_time = datetime.datetime.fromtimestamp(st.st_mtime)-\
        pd.to_timedelta(metadata['nframes']/metadata['fps'], unit='s')

# Set up figure:
fig = plt.figure(figsize=(8, 6))
ax = fig.add_subplot(111)
ax.axis('off')
ax.autoscale(True)
plt.subplots_adjust(left=0.25, bottom=0.25)

# Render first frame:
frame = 0
axim = ax.imshow(vid.get_data(0))

# Create the slider:
axframe = plt.axes([0.25, 0.1, 0.65, 0.04])
sframe = Slider(axframe, 'Frame', 0, metadata['nframes'], valinit=0, valfmt='%d')

# Update rendered frame:
def update(val):
    frame = int(np.floor(sframe.val))
    axim.set_data(vid.get_data(frame))
    ax.set_title(str(start_time+pd.to_timedelta(frame/metadata['fps'], unit='s')))
    fig.canvas.draw()

# Move forward or backward in movie:
def arrow_key_image_ctrl(event):
    if event.key == 'left':
        if round(sframe.val) <= sframe.valmin:
            pass
        else:
            sframe.set_val(sframe.val-1)
            update(sframe.val)
    elif event.key == 'right':
        if round(sframe.val) >= sframe.valmax-1:
            pass
        else:
            sframe.set_val(sframe.val+1)
            update(sframe.val)
    else:
        print('unrecognized event')

fig.canvas.mpl_connect('key_release_event', arrow_key_image_ctrl)

# Connect callback to slider:
sframe.on_changed(update)

# Set title:
update(0)

# Display:
plt.show()