Skip to content

Instantly share code, notes, and snippets.

@mildsunrise

mildsunrise/sona_gif.py

Last active Dec 2, 2020
Embed
What would you like to do?
GIF of chilling Sona
# 1. download video:
# youtube-dl -f 399 https://www.youtube.com/watch?v=hawThTG5No8 -o youtube_video.mkv
# 2. extract important segment:
# ffmpeg -ss 1:08 -to 1:27 -i youtube_video.mkv -c copy -map 0:0 out.mkv
# 3. run this to generate out.gif
from math import tau
import numpy as np
import cv2
import av
import logging
logging.basicConfig()
logging.getLogger('libav').setLevel(logging.DEBUG)
# rgb24 -> rgb8 quantizer with random spatial-only dither
def rgb8_random_dither(shape):
dither = (np.random.random_sample(shape[:2] + (3,)) - 0.5).astype('float32')
def quantize(x):
x = x.astype('float32') / 255
x[:,:,0] *= 0b111
x[:,:,1] *= 0b111
x[:,:,2] *= 0b11
x = np.round(x + dither).astype('int')
x = (np.clip(x[:,:,0], 0, 0b111) << 5) + (np.clip(x[:,:,1], 0, 0b111) << 2) + (np.clip(x[:,:,2], 0, 0b11))
return av.VideoFrame.from_ndarray(x.astype('uint8'), format='rgb8')
return quantize
FRAME_START = 61 # animation scene starts (but not exactly at beginning)
FRAME_END = 467 # animation seeks to beginning
#468 first frame that shows transition to black
#470 actual frame that matches FRAME_START
RATIO = 0.906335
EASE_CURVE = lambda x: np.sin(tau/4 * x*.86) * 1.0247
# grab FRAME_END (FIXME: do a seek, which is the correct & efficient thing)
with av.open('out.mkv') as vin:
for iframe in vin.decode():
if iframe.index == FRAME_END:
im_end = iframe.to_ndarray(format='rgb24')
break
with av.open('out.mkv') as vin, av.open('out.gif', 'w') as vout:
sin = vin.streams[0]
#sout = vout.add_stream('libx264', rate=sin.rate, bit_rate=1986000)
sout = vout.add_stream('gif', rate=sin.rate, pix_fmt='rgb8')
sout.width = sin.width
sout.height = sin.height
def encode_frame(frame=None, pts=None):
if frame != None: frame.pts = pts
for packet in sout.encode(frame): vout.mux(packet)
h, w = im_end.shape[:2]
im_orig = im_end.copy()
im = im_orig.copy()
bbox = np.zeros(im.shape[:2], dtype=bool)
bbox[460:900, 585:900] = True
#bbox[:, :] = True
quant = rgb8_random_dither(im.shape)
for iframe in vin.decode(sin):
idx = iframe.index
if idx < FRAME_START: continue
if idx > FRAME_END: break
print('Processing: {}'.format(idx))
frame = iframe.to_ndarray(format='rgb24')
fx = EASE_CURVE( (idx - FRAME_START) / (FRAME_END - FRAME_START) )
ratio = RATIO * (1-fx) + fx
tf = np.array([[ ratio, 0, w * (1-ratio)/2 ], [ 0, ratio, h * (1-ratio)/2 ]])
cv2.warpAffine(frame, tf, (w, h), im, cv2.INTER_AREA, cv2.BORDER_TRANSPARENT)
# (somewhat aggressive) hysteresis
diff = im_orig.astype('int16') - im.astype('int16')
diff = cv2.GaussianBlur(diff.astype('float32'), (0,0), 2)
diff_mag = (diff.astype('float32') ** 2).sum(2)
#mask = bbox & (diff_mag > 9)
mask = bbox
im_orig[mask] = im[mask]
#encode_frame(oframe := av.VideoFrame.from_ndarray(im_orig, format='rgb24'))
encode_frame(oframe := quant(im_orig))
# append 2 copies of last frame
for _ in range(2): encode_frame(oframe)
encode_frame()
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment