越狱我的 Kindle 以将其用作电子墨水显示器

越狱我的 Kindle 以将其用作电子墨水显示器
Jailbroke my Kindle to use it as an e-ink monitor

原始链接: https://gist.github.com/adtac/eb639d3c707b55a28f0ee9a420aa7e0c

总而言之，用户描述了他们通过按照网上找到的说明越狱来破解 Kindle Paperwhite 3 的过程。他们使用 Go 编程语言创建了一个侦听器服务器，该服务器接收文件并调用 eips（用于在屏幕上显示图像的内置实用程序）。用户还开发了 Screenshot Capture 和 ImageMagick 工具，可以在 Mac OS 上截取屏幕截图，并将其转换为 Kindle 可接受的格式，并通过 USB 网络传输这些图像。尽管在性能和可用性方面还有改进的空间，但他们承认，鉴于目前可用的压缩功能，为每个帧发送完整的 JPEG 文件可能会造成浪费，因此可能允许使用现有工具进行快速改进。提供了其他资源的链接，例如 GitHub 存储库、论坛讨论和博客文章。

用户讨论电子纸 (E-Ink) 与液晶显示器 (LCD) 相比的特性。他们指出，电子墨水的对比度较低，根据年份约为 12:1 或 15:1，而 LCD 通常提供卓越的对比度。然而，电子墨水在明亮的照明条件下表现更好，例如直射阳光，与传统印刷材料相比更容易阅读。用户指出，添加额外的层（例如触摸屏或背光）会降低电子墨水的对比度。他们提到，较新的型号可能会提高对比度，但具体细节尚不清楚。他们还将电子墨水与透射式液晶平板电脑进行了比较，表明它们可能具有相似的对比度水平，尽管这仍然不确定。用户发现电子墨水适合作为辅助设备，尽管由于高延迟而导致打字体验较差。有用的应用程序包括非打字任务，例如查看静态信息或聊天窗口。刷新率因显示模式而异，范围从高质量模式的 2-4Hz 到更快更新模式的 16-60Hz。通常有四种可用模式，每种模式提供不同程度的视觉清晰度和速度。最后，该用户提到了受媒体描述影响的公众认知的主观性，并引用了埃隆·马斯克和唐纳德·特朗普等人物。他们强调媒体支持或批评的变化如何显着影响公众舆论，从而导致强烈的情绪反应。尽管存在潜在的分歧，但用户主张在围绕有争议的个人的讨论中进行深思熟虑和客观性。

原文

3.5 fps, Paperwhite 3
@adtac_

step 1: jailbreak your Kindle

mobileread.com is your best resource here, follow the instructions from the LanguageBreak thread

I didn't really follow the LanguageBreak instructions because I didn't care about most of the features + I was curious to do it myself, but the LanguageBreak github repo was invaluable for debugging

it doesn't matter how you jailbreak your device as long as you get to a root shell somehow

step 2: listener server on the Kindle

I wrote a Go program to receive files on port 8000 and then invoke eips, which is Kindle's built-in utility to draw images on the screen

for example, if the Go program received a JPG file and saved it under /tmp/img.jpg, the following command would draw the image with a partial update (full update looks awful):

eips -g /tmp/img.jpg -w gc16 -x 128 -y 0

read the eips wiki for details on what the flags mean

you may want to clear the screen with a eips -c before the first frame

unfortunately I lost the Go source code, but it was pretty simple, like under 30 lines

step 3: screencapture + imagemagick

I wrote a script to use screencapture on macOS to repeatedly capture the screen into a png file, which is then converted into a shape, size and color the Kindle likes using imagemagick, and then transferred over usbnet using netcat

/usr/sbin/screencapture -C -x /tmp/orig.png
convert /tmp/orig.png -rotate 270 -resize '810x1448!' -type GrayScale -depth 8 -colors 256 /tmp/gray.jpg
cat /tmp/gray.jpg | nc -w 0 192.168.15.244 8000

change the resolution to match your device and port to match the listener server

I hacked this together last night for fun and obviously there's a lot of room for improvement here, both in terms of performance and usability

it's super wasteful to send a full jpeg file for each frame when the delta between consecutive frames is mostly going to be empty and very compressible (like when you're using a text editor)

without reinventing codecs like h.264 and protocols like vnc, it should be possible to quickly improve this with just the tools we already have

have fun!

https://www.sixfoisneuf.fr/posts/kindle-hacking-deeper-dive-internals/

https://github.com/NiLuJe/KindleTool

https://www.mobileread.com/forums/showthread.php?t=356766 - the vulnerability that makes LanguageBreak possible