ii-vision/transcoder/movie.py

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"""Multiplexes video and audio inputs to encoded byte stream."""
from typing import Iterable, Iterator
import audio
import frame_grabber
import machine
import opcodes
import screen
import video
from palette import Palette
from video_mode import VideoMode
class Movie:
def __init__(
self, filename: str,
every_n_video_frames: int = 1,
audio_bitrate: int = 14700,
audio_normalization: float = None,
max_bytes_out: int = None,
video_mode: VideoMode = VideoMode.HGR,
palette: Palette = Palette.NTSC,
):
self.filename = filename # type: str
self.every_n_video_frames = every_n_video_frames # type: int
self.max_bytes_out = max_bytes_out # type: int
self.video_mode = video_mode # type: VideoMode
self.palette = palette # type: Palette
self.audio = audio.Audio(
filename, bitrate=audio_bitrate,
normalization=audio_normalization) # type: audio.Audio
self.frame_grabber = frame_grabber.FileFrameGrabber(
filename, mode=video_mode, palette=self.palette)
self.video = video.Video(
self.frame_grabber,
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ticks_per_second=self.audio.sample_rate,
mode=video_mode,
palette=self.palette
) # type: video.Video
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# Byte offset within TCP stream
self.stream_pos = 0 # type: int
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# Current audio tick opcode count within movie stream.
self.ticks = 0 # type: int
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# Tracks internal state of player virtual machine
self.state = machine.Machine()
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# Currently operating on AUX memory bank?
self.aux_memory_bank = False
def encode(self) -> Iterator[opcodes.Opcode]:
"""
:return:
"""
video_frames = self.frame_grabber.frames()
op_seq = None
yield opcodes.Header(mode=self.video_mode)
last_memory_bank = self.aux_memory_bank
for au in self.audio.audio_stream():
self.ticks += 1
new_video_frame = self.video.tick(self.ticks)
if new_video_frame:
try:
main, aux = next(video_frames)
except StopIteration:
break
should_encode_frame = (
(self.video.frame_number - 1) %
self.every_n_video_frames == 0
)
if should_encode_frame:
if self.video_mode == VideoMode.DHGR:
target_pixelmap = screen.DHGRBitmap(
main_memory=main,
aux_memory=aux,
palette=self.palette
)
else:
target_pixelmap = screen.HGRBitmap(
main_memory=main,
palette=self.palette
)
print("Starting frame %d" % self.video.frame_number)
op_seq = self.video.encode_frame(
target_pixelmap, is_aux=self.aux_memory_bank)
self.video.out_of_work = {True: False, False: False}
if self.aux_memory_bank != last_memory_bank:
# We've flipped memory banks, start new opcode sequence
last_memory_bank = self.aux_memory_bank
op_seq = self.video.encode_frame(
target_pixelmap, is_aux=self.aux_memory_bank)
# au has range -15 .. 16 (step=1)
# Tick cycles are units of 2
tick = au * 2 # -30 .. 32 (step=2)
tick += 34 # 4 .. 66 (step=2)
(page, content, offsets) = next(op_seq)
yield opcodes.TICK_OPCODES[(tick, page)](content, offsets)
def _emit_bytes(self, _op: opcodes.Opcode) -> Iterable[int]:
"""Emit compiled bytes corresponding to a player opcode.
Also tracks byte stream position.
"""
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for b in self.state.emit(_op):
yield b
self.stream_pos += 1
def emit_stream(self, ops: Iterable[opcodes.Opcode]) -> Iterator[int]:
"""Emit compiled byte stream corresponding to opcode stream.
Inserts padding opcodes at 2KB stream boundaries, to instruct player
to manage the TCP socket buffer.
:param ops:
:return:
"""
for op in ops:
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if self.max_bytes_out and self.stream_pos >= self.max_bytes_out:
yield from self.done()
return
yield from self._emit_bytes(op)
# Keep track of where we are in TCP client socket buffer
socket_pos = self.stream_pos % 2048
if socket_pos >= 2044:
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# 2 op_ack address bytes + 2 payload bytes from ACK must
# terminate 2K stream frame
if self.video_mode == VideoMode.DHGR:
# Flip-flop between MAIN and AUX banks
self.aux_memory_bank = not self.aux_memory_bank
yield from self._emit_bytes(opcodes.Ack(self.aux_memory_bank))
assert self.stream_pos % 2048 == 0, self.stream_pos % 2048
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yield from self.done()
def done(self) -> Iterator[int]:
"""Terminate byte stream by emitting terminal opcode and padding to 2KB.
:return:
"""
yield from self._emit_bytes(opcodes.Terminate())
# Player expects to fill 2K TCP buffer so pad it out
for _ in range(2048 - (self.stream_pos % 2048)):
yield 0x00