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屏幕录制测试

此测试通过将有界面的浏览器会话录制为 MP4 文件来验证完整的 VNC/浏览器技术栈。它证明了：

  • Xvfb 正在运行并接受 :99 上的连接
  • Chromium 可以在虚拟显示器上以有界面模式启动
  • ffmpeg 可以通过 x11grab 捕获显示内容
  • 生成的 MP4 是有效的、可播放的视频

工作原理

Section titled “工作原理”
  1. 轮询 xdpyinfo -display :99 直到 X 显示器就绪（与入口脚本相同的模式）
  2. 以 10 fps 启动 ffmpeg 录制显示内容
  3. 通过 Playwright 的 sync_api 启动有界面的 Chromium
  4. 导航到 https://example.com（暂停 3 秒），然后导航到 https://httpbin.org（暂停 3 秒）
  5. 向 ffmpeg 发送 SIGTERM 信号以完成 MP4 文件的正常写入
  6. 报告输出路径和文件大小

脚本

Section titled “脚本”

将以下内容保存为容器内的 vnc-browser-test.py，或从本仓库的 docs/tests/ 目录复制：

#!/usr/bin/env python3
"""VNC/browser stack integration test.


Proves that Xvfb, headed Chromium (via Playwright), and ffmpeg screen
recording all work together inside the devcontainer by recording a
browser navigating to two websites and producing an MP4 video.


Usage: python3 vnc-browser-test.py [output_path]
Default output: /tmp/recording.mp4
"""


import os
import signal
import subprocess
import sys
import time


DISPLAY = os.environ.get("DISPLAY", ":99")
DEFAULT_OUTPUT = "/tmp/recording.mp4"
RESOLUTION = "1280x1024"
FRAMERATE = "10"
XVFB_TIMEOUT = 50  # iterations (~5 s at 0.1 s each)
SITES = [
    ("https://example.com", 3),
    ("https://httpbin.org", 3),
]




def wait_for_xvfb():
    """Poll xdpyinfo until the X display is ready (mirrors entrypoint.sh)."""
    print(f"Waiting for Xvfb on {DISPLAY} ...")
    for i in range(XVFB_TIMEOUT):
        result = subprocess.run(
            ["xdpyinfo", "-display", DISPLAY],
            stdout=subprocess.DEVNULL,
            stderr=subprocess.DEVNULL,
        )
        if result.returncode == 0:
            print(f"  Display ready after {i * 0.1:.1f}s")
            return
        time.sleep(0.1)
    sys.exit(f"ERROR: Xvfb display {DISPLAY} not ready after {XVFB_TIMEOUT * 0.1:.1f}s")




def start_recording(output_path):
    """Start ffmpeg x11grab recording and return the process."""
    cmd = [
        "ffmpeg",
        "-y",
        "-f", "x11grab",
        "-video_size", RESOLUTION,
        "-framerate", FRAMERATE,
        "-i", f"{DISPLAY}.0",
        "-c:v", "libx264",
        "-preset", "ultrafast",
        "-pix_fmt", "yuv420p",
        output_path,
    ]
    print(f"Starting ffmpeg recording -> {output_path}")
    return subprocess.Popen(
        cmd,
        stdout=subprocess.DEVNULL,
        stderr=subprocess.PIPE,
    )




def stop_recording(proc):
    """Send SIGTERM and wait for ffmpeg to finalize the MP4."""
    print("Stopping ffmpeg ...")
    proc.send_signal(signal.SIGTERM)
    try:
        proc.wait(timeout=10)
    except subprocess.TimeoutExpired:
        proc.kill()
        proc.wait()




def browse_sites():
    """Launch headed Chromium via Playwright and visit each site."""
    from playwright.sync_api import sync_playwright  # noqa: PLC0415


    with sync_playwright() as pw:
        browser = pw.chromium.launch(
            headless=False,
            args=[
                "--no-sandbox",
                "--disable-gpu",
                f"--display={DISPLAY}",
            ],
        )
        page = browser.new_page(viewport={"width": 1280, "height": 1024})


        for url, pause in SITES:
            print(f"  Navigating to {url} ...")
            try:
                page.goto(url, timeout=15000)
            except Exception as exc:  # noqa: BLE001
                print(f"  Warning: navigation error ({exc}), continuing")
            time.sleep(pause)


        browser.close()




def main():
    output_path = sys.argv[1] if len(sys.argv) > 1 else DEFAULT_OUTPUT


    wait_for_xvfb()


    ffmpeg = start_recording(output_path)
    # Give ffmpeg a moment to initialize before browser activity
    time.sleep(1)


    try:
        browse_sites()
    finally:
        stop_recording(ffmpeg)


    if os.path.isfile(output_path):
        size = os.path.getsize(output_path)
        print(f"\nSUCCESS: {output_path} ({size:,} bytes)")
    else:
        sys.exit(f"ERROR: output file not created: {output_path}")




if __name__ == "__main__":
    main()

运行测试

Section titled “运行测试”
Terminal window
python3 vnc-browser-test.py /tmp/recording.mp4

预期输出

Section titled “预期输出”
Waiting for Xvfb on :99 ...
  Display ready after 0.3s
Starting ffmpeg recording -> /tmp/recording.mp4
  Navigating to https://example.com ...
  Navigating to https://httpbin.org ...
Stopping ffmpeg ...


SUCCESS: /tmp/recording.mp4 (1,234,567 bytes)

MP4 文件应显示 Chromium 窗口在 fluxbox 桌面上渲染两个网站的画面。使用 ffplay、vlc 播放，或从容器中下载文件进行验证。

失败的含义

Section titled “失败的含义”
症状可能的原因
Xvfb display :99 not readyXvfb 未启动——检查入口脚本是否运行了 VNC 技术栈
ffmpeg: x11grab error显示器不匹配或 ffmpeg 缺少 x11grab 支持
Playwright launch errorChromium 未安装或缺少 --no-sandbox 参数
MP4 文件为 0 字节ffmpeg 在写入前被终止——检查 SIGTERM 处理逻辑