ii-vision/video.py
2019-03-14 23:05:15 +00:00

240 lines
7.3 KiB
Python

import heapq
import random
import os
import threading
import queue
import subprocess
from typing import List, Iterator, Tuple
from PIL import Image
import numpy as np
import skvideo.io
import edit_distance
import opcodes
import screen
class Video:
"""Apple II screen memory map encoding a bitmapped frame."""
CLOCK_SPEED = 1024 * 1024 # type: int
def __init__(self, filename: str):
self.filename = filename # type: str
self._reader = skvideo.io.FFmpegReader(filename)
# Compute frame rate from input video
# TODO: possible to compute time offset for each frame instead?
data = skvideo.io.ffprobe(self.filename)['video']
rate_data = data['@r_frame_rate'].split("/") # e.g. 12000/1001
self._input_frame_rate = float(
rate_data[0]) / float(rate_data[1]) # type: float
self.cycles_per_frame = (
1024. * 1024 / self._input_frame_rate) # type: float
self.frame_number = 0 # type: int
# Initialize empty screen
self.memory_map = screen.MemoryMap(
screen_page=1) # type: screen.MemoryMap
# Accumulates pending edit weights across frames
self.update_priority = np.zeros((32, 256), dtype=np.int64)
def tick(self, cycles: int) -> bool:
if cycles > (self.cycles_per_frame * self.frame_number):
self.frame_number += 1
return True
return False
def _frame_grabber(self) -> Iterator[Image]:
for frame_array in self._reader.nextFrame():
yield Image.fromarray(frame_array)
def frames(self) -> Iterator[screen.MemoryMap]:
"""Encode frame to HGR using bmp2dhr.
We do the encoding in a background thread to parallelize.
"""
frame_dir = self.filename.split(".")[0]
try:
os.mkdir(frame_dir)
except FileExistsError:
pass
q = queue.Queue(maxsize=10)
def worker():
"""Invoke bmp2dhr to encode input image frames and push to queue."""
for _idx, _frame in enumerate(self._frame_grabber()):
outfile = "%s/%08dC.BIN" % (frame_dir, _idx)
bmpfile = "%s/%08d.bmp" % (frame_dir, _idx)
try:
os.stat(outfile)
except FileNotFoundError:
_frame = _frame.resize((280, 192))
_frame.save(bmpfile)
subprocess.call(
["/usr/local/bin/bmp2dhr", bmpfile, "hgr", "D9"])
os.remove(bmpfile)
_frame = np.fromfile(outfile, dtype=np.uint8)
q.put(_frame)
q.put(None)
t = threading.Thread(target=worker, daemon=True)
t.start()
while True:
frame = q.get()
if frame is None:
break
yield screen.FlatMemoryMap(
screen_page=1, data=frame).to_memory_map()
q.task_done()
t.join()
def encode_frame(
self, target: screen.MemoryMap
) -> Iterator[opcodes.Opcode]:
"""Update to match content of frame within provided budget."""
print("Similarity %f" % (self.update_priority.mean()))
yield from self._index_changes(self.memory_map, target)
def _index_changes(
self,
source: screen.MemoryMap,
target: screen.MemoryMap
) -> Iterator[Tuple[int, int, List[int]]]:
"""Transform encoded screen to sequence of change tuples."""
diff_weights = self._diff_weights(source, target)
# Clear any update priority entries that have resolved themselves
# with new frame
self.update_priority[diff_weights == 0] = 0
# Halve existing weights to increase bias to new diffs.
# In particular this means that existing updates with diff 1 will
# become diff 0, i.e. will only be prioritized if they are still
# diffs in the new frame.
# self.update_priority >>= 1
self.update_priority += diff_weights
priorities = self._heapify_priorities()
content_deltas = {}
while priorities:
_, _, page, offset = heapq.heappop(priorities)
# Check whether we've already cleared this diff while processing
# an earlier opcode
if self.update_priority[page, offset] == 0:
continue
offsets = [offset]
content = target.page_offset[page, offset]
# Clear priority for the offset we're emitting
self.update_priority[page, offset] = 0
self.memory_map.page_offset[page, offset] = content
# Need to find 3 more offsets to fill this opcode
for o in self._compute_error(
page,
content,
target,
diff_weights,
content_deltas
):
offsets.append(o)
# Clear priority for the offset we're emitting
self.update_priority[page, o] = 0
self.memory_map.page_offset[page, o] = content
# Pad to 4 if we didn't find enough
for _ in range(len(offsets), 4):
offsets.append(offsets[0])
yield (page + 32, content, offsets)
# If we run out of things to do, pad forever
content = target.page_offset[(0, 0)]
while True:
yield (32, content, [0, 0, 0, 0])
@staticmethod
def _diff_weights(
source: screen.MemoryMap,
target: screen.MemoryMap
):
return edit_distance.array_edit_weight(
source.page_offset, target.page_offset)
def _heapify_priorities(self) -> List:
priorities = []
it = np.nditer(self.update_priority, flags=['multi_index'])
while not it.finished:
priority = it[0]
if not priority:
it.iternext()
continue
page, offset = it.multi_index
# Don't use deterministic order for page, offset
nonce = random.random()
priorities.append((-priority, nonce, page, offset))
it.iternext()
heapq.heapify(priorities)
return priorities
@staticmethod
def _compute_delta(content, target, old):
"""
This function is the critical path for the video encoding.
"""
return edit_distance.content_edit_weight(content, target) - old
_OFFSETS = np.arange(256)
def _compute_error(self, page, content, target, old_error, content_deltas):
offsets = []
delta_screen = content_deltas.get(content)
if delta_screen is None:
delta_screen = self._compute_delta(
content, target.page_offset, old_error)
content_deltas[content] = delta_screen
delta_page = delta_screen[page]
cond = delta_page < 0
candidate_offsets = self._OFFSETS[cond]
priorities = self.update_priority[page][cond]
l = [
(-priorities[i], random.random(), candidate_offsets[i])
for i in range(len(candidate_offsets))
]
heapq.heapify(l)
while l:
_, _, o = heapq.heappop(l)
offsets.append(o)
if len(offsets) == 3:
break
return offsets