Kindle Video Playback Hack

Prerequsite

  • The Kindle needs to be jailbroken.
  • Terimnal access on Kindle (Kterm or SSH)
    • Generate a directory to store all temporary files on Kindle, using /mnt/us/demo/ for example in this tutorial.

Slice Video Frames

i=INPUT.mp4; w=1236; h=1648;
# Adjust resolution accordingly:
# - Kindle Paperwhite (11th gen.): 1236x1648
# - Kindle Paperwhite (12th gen.): 1264×1680
# - Kindle Colorsoft: 1264×1680

mkdir -p ./frames && ffmpeg -i "$i" \
-vf "transpose=1,\
	scale=$w:$h:force_original_aspect_ratio=decrease,\
	pad=$w:$h:(ow-iw)/2:(oh-ih)/2,\
	format=gray" \
-r 5 ./frames/frames_%04d.png

Copy all PNG images (the frames folder) to Kindle, put under /mnt/us/demo/.

Transcode Audio

Export raw PCM audio (Signed 16-bit Little-Endian, 44100 Hz, Stereo):

i=INPUT.mp4;
ffmpeg -i "$i" -f s16le -acodec pcm_s16le -ar 44100 -ac 2 audio.raw

Copy the PCM file audio.raw to Kindle, put under /mnt/us/demo/.

E-Ink Refreshing Control

  1. Download FBInk source code from https://github.com/NiLuJe/FBInk/releases.

  2. Install cross-compiling tools via HomeBrew:

    brew tap messense/macos-cross-toolchains
brew install messense/macos-cross-toolchains/armv7-unknown-linux-gnueabihf

  3. Compile FBink for Kindle: change directory to the root directory of FBInk source code, and run the code snippet to start compiling.

    make clean
make KINDLE=1 \
    CROSS_COMPILE=armv7-unknown-linux-gnueabihf- \
    CC=armv7-unknown-linux-gnueabihf-gcc \
    STATIC=1 \
    STB_IMAGE=1 \
    static

  4. Copy and paste the binary file fbink of FBink under the folder ./Release/ to Kindle, put under /mnt/us/demo/.

Shell Script

Run on kindle to orchestrate the “video” playback, put under /mnt/us/demo/.

Shell Script Template:

#!/bin/sh

# 1. Pause Kindle UI
stop framework

# 2. Force refreshing e-ink (-c: clear display, -W GC16: Grayscale Clear 16-level Waveform)
/mnt/us/demo/fbink -q -c -f -W GC16

# 3. Play audio and frames
gst-launch-0.10 -q filesrc location=/mnt/us/demo/audio.raw ! \
  "audio/x-raw-int,endianness=(int)1234,signed=(boolean)true,width=(int)16,depth=(int)16,rate=(int)44100,channels=(int)2" ! \
  mixersink &
AUDIO_PID=$!

for img in /mnt/us/demo/frames/*.png; do
    /mnt/us/demo/fbink -q -f -W A2 -g file="$img"
done

kill -9 $AUDIO_PID 2>/dev/null

# 4. Restore Kindle UI
start framework

To start the “video” playback, simply connect the Kindle to a Bluetooth audio device, and run the shell script, named as play_demo for example in this tutoial.

chmod +x /mnt/us/demo/fbink /mnt/us/demo/play_demo.sh

/mnt/us/demo/play_demo.sh

Demo

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