Screencasts: seis videos silenciosos 1080p30 da demonstracao
Novo pipeline de video: scripts/screencast/render.py roda uma fase em um pty,
emula o terminal com pyte, gera frames PNG e mux com ffmpeg (H.264,
yuv420p, +faststart, sem trilha de audio). Fallback de encoder: libx264 ->
libopenh264 -> VP9.
Fases (scripts/screencast/phases/, uma sessao real contra o lab por video):
1. implementacao no kernel - fontes OpenBSD + compat + build limpo do pf.ko
2. ativacao - insmod, /dev/pf, pfctl -e, pfctl -s info
3. regras basicas - tabela, anchor, keep state, block drop
4. roteamento - route-to e reply-to (provado com tcpdump nas 2 interfaces)
5. balanceamento - pool round-robin, pool source-hash, dup-to
6. QOS - filas hfsc, pfctl -s queue -v, transferencia de 2 MB pela fila
Os videos ficam versionados em out/screencast/ (.gitignore ajustado para
nao ignorar *.mp4) e o indice/texto de descricao do YouTube em
docs/{en,pt-BR}/screencast.md.
Correcoes na propria demo (encontradas gravando): a acao de uma regra no pf
e pass OU block (nunca os dois); as regras de um anchor vivem em um ruleset
proprio (pfctl -a <anchor> -f); o nc do QOS precisa rodar na VM do servidor,
nao no firewall; o rotulo 'FASE x/6' vem do numero da fase, nao da posicao
na lista de gravacao.
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#!/usr/bin/env python3
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"""
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Render a shell session into a silent, YouTube-ready MP4 screencast.
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Pipeline: pty -> raw bytes -> pyte (terminal emulation) -> PNG frames -> MP4
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Every byte on screen is the real output of the command; only the pacing and
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the framing are produced here. No audio track is written (the videos are
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silent by design).
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Usage:
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./scripts/screencast/render.py --script scripts/screencast/phases/02-ativacao.sh \
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--out out/screencast/02-ativacao.mp4 --title "Fase 2 - Ativacao" \
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--subtitle "insmod pf.ko / pfctl -e / pfctl -s info"
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"""
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import argparse
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import errno
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import fcntl
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import os
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import pty
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import select
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import shutil
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import signal
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import struct
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import subprocess
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import sys
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import termios
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import time
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import pyte
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from PIL import Image, ImageDraw, ImageFont
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# ---------------------------------------------------------------- palette ---
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BG = (14, 17, 23)
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PANEL = (20, 24, 31)
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BORDER = (48, 54, 61)
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FG = (201, 209, 217)
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HEADER_BG = (24, 29, 38)
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HEADER_FG = (240, 246, 252)
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ACCENT = (88, 166, 255)
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MUTED = (110, 118, 129)
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TITLE_BG = (17, 21, 28)
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# pyte colour names -> RGB (a calm, high-contrast terminal palette)
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NAMED = {
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"black": (48, 54, 61),
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"red": (255, 123, 114),
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"green": (63, 185, 80),
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"yellow": (210, 153, 34),
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"blue": (88, 166, 255),
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"magenta": (188, 140, 255),
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"cyan": (57, 197, 207),
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"white": (201, 209, 217),
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"brown": (168, 115, 66),
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"default": None,
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}
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def color_of(spec, default):
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if spec == "default":
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return default
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if spec in NAMED:
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return NAMED[spec] or default
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try:
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if len(spec) == 6:
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return tuple(int(spec[i:i + 2], 16) for i in (0, 2, 4))
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except ValueError:
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pass
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return default
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class Recorder:
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"""Runs a command on a pty and keeps a timestamped snapshot per output event."""
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def __init__(self, cols, rows, env=None):
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self.cols, self.rows = cols, rows
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self.screen = pyte.Screen(cols, rows)
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self.screen.set_mode(pyte.modes.LNM)
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self.stream = pyte.ByteStream(self.screen)
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self.events = [] # (timestamp, rows_of_cells)
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self.t0 = time.time()
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def snapshot(self):
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rows = []
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for y in range(self.rows):
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line = self.screen.buffer[y]
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cells = []
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for x in range(self.cols):
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ch = line[x]
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fg = color_of(ch.fg, FG)
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bold = ch.bold
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cells.append((ch.data or " ", fg, bold))
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rows.append(cells)
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return rows, (self.screen.cursor.y, self.screen.cursor.x)
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def run(self, argv, env=None):
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master, slave = pty.openpty()
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fcntl.ioctl(slave, termios.TIOCSWINSZ,
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struct.pack("HHHH", self.rows, self.cols, 0, 0))
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e = dict(os.environ)
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e.update({"TERM": "xterm-256color", "COLUMNS": str(self.cols),
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"LINES": str(self.rows), "LC_ALL": "C.UTF-8"})
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if env:
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e.update(env)
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proc = subprocess.Popen(argv, stdin=slave, stdout=slave, stderr=slave,
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env=e, start_new_session=True, close_fds=True)
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os.close(slave)
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while True:
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try:
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r, _, _ = select.select([master], [], [], 0.25)
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except InterruptedError:
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continue
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if master in r:
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try:
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data = os.read(master, 65536)
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except OSError as exc:
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if exc.errno == errno.EIO:
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break
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raise
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if not data:
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break
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self.stream.feed(data)
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rows, cur = self.snapshot()
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self.events.append((time.time() - self.t0, rows, cur))
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elif proc.poll() is not None:
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# drain whatever is left
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try:
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while True:
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data = os.read(master, 65536)
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if not data:
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break
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self.stream.feed(data)
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rows, cur = self.snapshot()
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self.events.append((time.time() - self.t0, rows, cur))
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except OSError:
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pass
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break
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proc.wait()
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os.close(master)
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if not self.events:
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rows, cur = self.snapshot()
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self.events.append((time.time() - self.t0, rows, cur))
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return proc.returncode
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# ------------------------------------------------------------- rendering ---
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def load_font(path, size):
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return ImageFont.truetype(path, size)
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def render_frame(rows, title, subtitle, phase_no, phase_total, cols, font, bold_font,
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small_font, footer, cursor=None, panel="alpine (pf0)"):
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W, H = 1920, 1080
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img = Image.new("RGB", (W, H), BG)
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d = ImageDraw.Draw(img)
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# header
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d.rectangle([0, 0, W, 74], fill=HEADER_BG)
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d.text((44, 26), "PF on Linux", font=bold_font, fill=HEADER_FG)
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tw = d.textlength("PF on Linux", font=bold_font)
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d.text((44 + tw + 26, 30), "-", font=font, fill=MUTED)
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d.text((44 + tw + 46, 30), "OpenBSD PF 8.0 engine inside the Linux kernel",
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font=font, fill=MUTED)
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if phase_total:
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label = f"FASE {phase_no}/{phase_total}"
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lw = d.textlength(label, font=small_font)
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d.text((W - 44 - lw, 32), label, font=small_font, fill=ACCENT)
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# title block
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d.text((44, 112), title, font=bold_font, fill=HEADER_FG)
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if subtitle:
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d.text((44, 162), subtitle, font=font, fill=MUTED)
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# terminal panel, sized to the content
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top = 212
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left = 44
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right = W - 44
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lh = 30
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used = 0
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for i, line in enumerate(rows):
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if any(c[0].strip() for c in line):
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used = i + 1
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bottom = min(H - 84, top + 44 + 28 + (max(used, 4) + 1) * lh)
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d.rectangle([left, top, right, bottom], fill=PANEL, outline=BORDER, width=2)
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d.rectangle([left, top, right, top + 44], fill=HEADER_BG)
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for i, c in enumerate([(255, 95, 86), (255, 189, 46), (39, 201, 63)]):
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d.ellipse([left + 24 + i * 26, top + 15, left + 38 + i * 26, top + 29], fill=c)
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d.text((left + 110, top + 13), panel, font=small_font, fill=MUTED)
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# text
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x0 = left + 28
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y0 = top + 64
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cw = d.textlength("M", font=font)
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for i, line in enumerate(rows):
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y = y0 + i * lh
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if y > bottom - 10:
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break
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for x, (ch, fg, bold) in enumerate(line):
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if ch == " ":
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continue
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d.text((x0 + x * cw, y), ch, font=bold_font if bold else font, fill=fg)
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# cursor block
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if cursor:
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cy, cx = cursor
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if 0 <= cy < len(rows) and 0 <= cx < cols:
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d.rectangle([x0 + cx * cw, y0 + cy * lh, x0 + (cx + 1) * cw - 1,
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y0 + (cy + 1) * lh - 1], fill=ACCENT)
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# footer
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d.text((44, H - 58), footer, font=small_font, fill=MUTED)
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url = "git.labexposed.com/lgcosta/pf-linux-port"
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uw = d.textlength(url, font=small_font)
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d.text((W - 44 - uw, H - 58), url, font=small_font, fill=MUTED)
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return img
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def render_title(title, subtitle, phase_no, phase_total, bold_font, font, small_font):
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W, H = 1920, 1080
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img = Image.new("RGB", (W, H), TITLE_BG)
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d = ImageDraw.Draw(img)
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d.rectangle([0, 0, W, 8], fill=ACCENT)
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d.text((120, 400), title, font=bold_font, fill=HEADER_FG)
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if subtitle:
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d.text((120, 470), subtitle, font=font, fill=MUTED)
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if phase_total:
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d.text((120, 560), f"FASE {phase_no} DE {phase_total}", font=small_font, fill=ACCENT)
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d.text((120, 620), "PF on Linux - OpenBSD PF 8.0 no kernel Linux",
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font=small_font, fill=MUTED)
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return img
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def main():
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ap = argparse.ArgumentParser()
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ap.add_argument("--script", required=True)
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ap.add_argument("--out", required=True)
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ap.add_argument("--title", required=True)
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ap.add_argument("--subtitle", default="")
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ap.add_argument("--footer", default="")
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ap.add_argument("--phase-no", type=int, default=0)
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ap.add_argument("--phase-total", type=int, default=0)
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ap.add_argument("--cols", type=int, default=120)
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ap.add_argument("--rows", type=int, default=32)
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ap.add_argument("--fps", type=int, default=30)
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ap.add_argument("--max-hold", type=float, default=2.0)
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ap.add_argument("--min-hold", type=float, default=0.25)
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ap.add_argument("--title-card", type=float, default=3.0)
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ap.add_argument("--keep-frames", action="store_true")
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ap.add_argument("--panel", default="alpine (pf0) - lab libvirt - kernel 7.3.4 + pf.ko")
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args = ap.parse_args()
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repo = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
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mono = "/usr/share/fonts/dejavu-sans-mono-fonts/DejaVuSansMono.ttf"
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mono_b = "/usr/share/fonts/dejavu-sans-mono-fonts/DejaVuSansMono-Bold.ttf"
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font = load_font(mono, 21)
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bold_font = load_font(mono_b, 21)
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small_font = load_font(mono, 19)
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rec = Recorder(args.cols, args.rows)
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rc = rec.run(["bash", args.script])
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sys.stderr.write(f"[screencast] script rc={rc}, events={len(rec.events)}\n")
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os.makedirs(os.path.dirname(os.path.abspath(args.out)) or ".", exist_ok=True)
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frames_dir = os.path.join(os.path.dirname(os.path.abspath(args.out)), "_frames")
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shutil.rmtree(frames_dir, ignore_errors=True)
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os.makedirs(frames_dir, exist_ok=True)
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def dump(img, idx):
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img.save(os.path.join(frames_dir, f"{idx:05d}.png"))
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n = 0
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# title card
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title_img = render_title(args.title, args.subtitle, args.phase_no,
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args.phase_total, bold_font, font, small_font)
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title_frames = int(args.title_card * args.fps)
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for _ in range(title_frames):
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dump(title_img, n)
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n += 1
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# session frames, paced by the real inter-event delays
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prev_t = 0.0
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for i, (ts, rows, cur) in enumerate(rec.events):
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hold = ts - prev_t
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prev_t = ts
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if i + 1 < len(rec.events):
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hold = rec.events[i + 1][0] - ts
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hold = max(args.min_hold, min(args.max_hold, hold))
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img = render_frame(rows, args.title, args.subtitle, args.phase_no,
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args.phase_total, args.cols, font, bold_font,
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small_font, args.footer, cursor=cur, panel=args.panel)
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frames = max(1, int(round(hold * args.fps)))
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for _ in range(frames):
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dump(img, n)
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n += 1
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# closing card
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end_img = render_frame(rec.events[-1][1], args.title, args.subtitle,
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args.phase_no, args.phase_total, args.cols, font,
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bold_font, small_font,
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args.footer or "fim da fase",
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cursor=rec.events[-1][2], panel=args.panel)
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for _ in range(int(1.5 * args.fps)):
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dump(end_img, n)
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n += 1
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# encoder: prefer x264, fall back to openh264 (both H.264 in MP4, which is
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# what YouTube wants), then VP9/WebM.
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have = subprocess.run(["ffmpeg", "-hide_banner", "-encoders"],
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capture_output=True, text=True).stdout
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base = ["ffmpeg", "-y", "-loglevel", "error", "-framerate", str(args.fps),
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"-i", os.path.join(frames_dir, "%05d.png"),
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"-pix_fmt", "yuv420p", "-movflags", "+faststart", "-r", str(args.fps)]
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if "libx264" in have:
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cmd = base + ["-c:v", "libx264", "-preset", "medium", "-crf", "20",
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"-profile:v", "high", "-level", "4.0", args.out]
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elif "libopenh264" in have:
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cmd = base + ["-c:v", "libopenh264", "-b:v", "6M",
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"-profile:v", "high", args.out]
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elif "libvpx-vp9" in have:
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cmd = base + ["-c:v", "libvpx-vp9", "-b:v", "0", "-crf", "30",
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"-row-mt", "1", "-cpu-used", "4", args.out]
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else:
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raise SystemExit("[screencast] no usable H.264/VP9 encoder in ffmpeg")
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subprocess.run(cmd, check=True)
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if not args.keep_frames:
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shutil.rmtree(frames_dir, ignore_errors=True)
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dur = subprocess.run(["ffprobe", "-v", "error", "-show_entries",
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"format=duration", "-of", "csv=p=0", args.out],
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capture_output=True, text=True).stdout.strip()
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size = os.path.getsize(args.out)
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sys.stderr.write(f"[screencast] wrote {args.out} frames={n} "
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f"duration={dur}s size={size/1e6:.1f}MB\n")
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if __name__ == "__main__":
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main()
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Reference in new issue
Block a user