Optimizing Video: 2021 Honda Odyssey RES

On April 7, 2024 at about 3am I physically beat the poop out of a deer on Interstate 90 crossing into Ohio from Pennsylvania (41.925716, -80.54277). The front bumper being damaged and excrement all along the drivers side of the vehicle does qualify for the “beat the crap”-stamp to be applied to the drivers side door.

Insurance did what insurance does and says that the 2012 is not cost effective to repair so they scrapped the vehicle and wrote a check. With that check the family was able to go place a down payment on a 2021 Honda Odyssey Touring.

One of the biggest improvements from 2012 to the 2021 is that the rear passengers have access to an Entertainment System. I decided one day to figure out what we could do with the USB input.

Honda’s website details the following about the Rear Entertainment System:

The Feature:
Buyers today have a heightened appreciation and desire for entertainment features in their vehicles.

• A state-of-the-art, factory-integrated Blu-ray™ Rear Entertainment System is standard on the Odyssey Touring and Elite models.
• Two sets of wireless headphones are supplied with this system.
• A 10.2-inch high-resolution WSVGA screen comes on all models.
• The DVD player conveniently resides near the bottom of the center stack.
• The system features High-Definition Multimedia Interface (HDMI)21 technology for attaching high-definition players, cameras or other hardware.
• The 110-volt power outlet eliminates the need for a personally supplied inverter.
• The system can accommodate audio- and video-streaming media via a smartphone- or mobile-hotspot hookup with the DA’s Wi-Fi®30 feature, or through the HondaLink® Telematics unit.
• The system can be operated by a remote control.
• A fun, kid-friendly “How Much Farther?®” app can use plotted-destination data from the onboard navigation system to help youngsters visualize their trip’s progress; four lighthearted themes can be selected.

https://www.hondainfocenter.com/2021/Odyssey/Feature-Guide/Interior-Features/Advanced-Rear-Entertainment-System-RES/

Not initially familiar with WSVGA I had to give it a peek of research and it appears the resolution would be 1024×576, or a 16:9 display aspect ratio.

I did some preliminary tests with random videos of known resolutions and observed the following with the RES:

• The videos do not stretch to fill the display
• They automatically letterbox/pillarbox
• They proportionally reduce their resolution to fill the display

I decided to fill a USB stick with “custom” honda-specific videos for the RES. To help with all this I wrote a script to leverage ffprobe/ffmpeg and bash arithmetic.

The script does a basic aspect detection, and if it’s 16:9 then we just tell ffmpeg to resize the video to the destination resolution. If it’s not then we use a filter to add letterboxing around.

#!/bin/bash
FFPROBE="/usr/bin/ffprobe";
FFMPEG="/usr/bin/ffmpeg";
if [ ! -e "$FFPROBE" -o ! -e "$FFMPEG" ]; then echo "ffprobe or ffmpeg not present"; exit; fi

if [ "$1" == "" ]; then echo "need a filename as a parameter"; exit; fi
if [ ! -e "$1" ]; then echo "$1 doesn't exist"; exit; fi

WIDTH=`$FFPROBE -v 0 -show_format -show_streams -print_format ini "$1" | grep -P '^width=' | cut -d'=' -f2-`;
HEIGHT=`$FFPROBE -v 0 -show_format -show_streams -print_format ini "$1" | grep -P '^height=' | cut -d'=' -f2-`;
echo "Input Resolution: $WIDTH x $HEIGHT";

# Honda display is 1024x576, or 16x9. See if the current works
RESIZE="-s 1024x576";
if [ ! "$(($WIDTH/16))" == "$(($HEIGHT/9))" ]; then
  RESIZE="-vf scale=1024:576:force_original_aspect_ratio=decrease,pad=1024:576:-1:-1:color=black";
fi

# CRF default is 23, sane range 18-28, lower=better
$FFMPEG -i "$1" -c:v libx264 -crf 28 -c:a aac -sn $RESIZE "$1-honda.mp4"

I ran this script across 5 videos, reducing their resolution, add letterboxing when necessary, keeping the original audio quality and suppressing subtitles:

Video	Original Size	Original Res	Final Size	% reduced
Frozen	1,755,005,744	1920×856	459,400,158	26.17%
Inside Out	1,546,943,392	1920×1080	503,091,183	32.52%
Moana	2,900,037,817	1920×808	931,981,950	32.13%
UglyDolls	774,008,323	1280×688	431,901,266	55.8%
Wreck-It Ralph	682,595,922	1280×544	491,145,187	71.95%
Total	7,658,591,198	–	2,817,519,744	36.79%

Tl;DR (ironically at the end) Pre-compression of all the movies that I intend to store on a USB drive and keep in the Honda I can get an average of 3x the quantity of movies without sacrificing quality.