Convert video for Uconnect USB playback

Uconnect head units in Chrysler, Jeep, Dodge and Ram vehicles play MP4 files from a USB stick, but only 8-bit H.264 at 720p or smaller with AAC stereo sound. carify checks each stream against that line, re-encodes only what's over it, and copies the result onto a stick labelled MOVIES.

curl -fsSL https://raw.githubusercontent.com/Real-Fruit-Snacks/carify/main/install.sh | sh

irm https://raw.githubusercontent.com/Real-Fruit-Snacks/carify/main/install.ps1 | iex

Needs ffmpeg on your PATH: winget install Gyan.FFmpeg, sudo apt install ffmpeg, sudo dnf install ffmpeg or brew install ffmpeg. Then carify movie.mkv.

Frame height

720from 1080Fitsh264 8-bit

carify 1.1.2Recorded run · Ubuntu 24.04 · ffmpeg 6.1.1

$ carify road-trip.mkvprobe  video hevc/yuv420p10le/Main 10 1920x1080  audio ac3 6chvideo  re-encode to H.264 High 8-bit, fits 1280x720 (slow)audio  re-encode to AAC stereo 160kframe=  720 fps=106 q=-1.0 Lsize=    8706kB time=00:00:29.99 bitrate=2377.8kbits/s speed=4.43xwrote  ./road-trip-car.mp4 (8 MB)usb    copying to /media/runner/MOVIESusb    done; safe to remove the stick

USB waitingcopyingsafe to remove

Audio channels

2from 6Fitsaac stereo

Replays of real runs, at the speed they ran: carify 1.1.2 on 30-second test clips, recorded on GitHub's Ubuntu 24.04 runner with ffmpeg 6.1.1 (how). The redlines are carify's limits: 720 pixels high, or --max-height, and 2 audio channels.

Anything outside that format shows up on the head unit as an unsupported file, or plays with no sound. I wrote carify so I could stop re-learning the ffmpeg flags for it: one command per file, and the stick is ready.

A file that already fits is copied, not re-encoded, so it takes about as long as reading it: dashcam.mp4 above took 0.4 s. A re-encode runs as fast as libx264 manages on your machine. road-trip.mkv, 30 s of 1080p HEVC, took 7.5 s on GitHub's runner.

Where the line is

ffprobe reads the first video stream (cover art is skipped) and the first audio stream. A stream is copied when it's inside every line in its rows, and re-encoded when it isn't.

These limits are the common denominator that has worked across Uconnect generations, not a published spec.

Stream	Copied if it's	Otherwise carify
Video	H.264	Re-encodes it with `libx264 -preset veryfast -crf 20`, High profile, level 4.1
	8-bit 4:2:0 (`yuv420p`)
	Baseline, Main or High, level 4.1 or lower
	Inside 1280×720. `--max-height` moves the line; the width limit is height × 16/9.	Re-encodes it, scaled down to fit with the aspect ratio kept. Nothing is scaled up.
Audio	AAC, two channels or fewer	Re-encodes it to AAC stereo at 160 kbps
Audio	A file with no audio track is converted silent, with a warning.
The rest	Subtitles, attachments and extra audio tracks are dropped.
File	An MP4 written with `+faststart` to a hidden `.part` file and renamed when ffmpeg finishes, so a cancelled run leaves nothing half-written.
Stick	If a stick labelled MOVIES is mounted, the file is copied onto it. Rename your stick once and you never drag files again.

The four test runs

The clips are 30 seconds of ffmpeg's testsrc2 picture with a sine tone, made to fail in the four ways that matter. CI records these runs again on every push and fails if carify's output changes.

Clip	Came in as	carify	Took	Went out as
`road-trip.mkv`	hevc Main 10, 1920×1080, ac3 5.1	Video re-encoded, audio re-encoded	7.5 s (4.43x)	h264 High 4.1, 1280×720, aac stereo, 8 MB
`cartoons.mkv`	h264 High, 1280×720, ac3 5.1	Video copied, audio re-encoded	1 s (41.7x)	h264 High 3.1, 1280×720, aac stereo, 9 MB
`phone-video.mp4`	h264 High, 1080×1920, aac stereo	Video re-encoded, audio copied	3.8 s (8.79x)	h264 High 4.1, 406×720, aac stereo, 2 MB
`dashcam.mp4`	h264 Main, 1280×720, aac stereo	Video copied, audio copied	0.4 s (957x)	h264 Main 3.1, 1280×720, aac stereo, 10 MB

Usage

bash 3.2 or later: Linux, macOS, WSL

carify movie.mkv                  # writes movie-car.mp4 next to it
carify movie.mkv ~/out.mp4        # explicit output path
carify --force movie.mkv          # overwrite an existing output
carify --max-height 1080 movie.mkv
carify --no-usb movie.mkv         # don't copy to the stick
for f in *.mkv; do carify "$f"; done

Windows PowerShell 5.1 and PowerShell 7

carify.ps1 movie.mkv
carify.ps1 movie.mkv D:\out.mp4 -Force
carify.ps1 movie.mkv -MaxHeight 1080
carify.ps1 movie.mkv -NoUsb
Get-Help carify.ps1 -Full
Get-ChildItem *.mkv | ForEach-Object { carify.ps1 $_.FullName }

Settings

One file per run. The installers also read CARIFY_BIN (the install folder) and CARIFY_REF (a tag such as v1.1.2 instead of main).

Setting	Default	Does
`--max-height` `-MaxHeight`	`720`	Largest frame height; the width limit is height × 16/9. Try `1080` if your unit plays it.
`CARIFY_USB_DIR`	unset	Copy to this folder instead of looking for a MOVIES stick
`CARIFY_THEME`	`nightshift`	`dayshift` for light terminal backgrounds
`NO_COLOR`	unset	Any value turns colour off

Tested on

Ubuntu 24.04, bash 5.2, ffmpeg 6.1.1: all 40 checks in tests/run.sh.
CI on every push: Ubuntu (bash, PowerShell 7), macOS (bash 5 and the system /bin/bash 3.2), Windows (PowerShell 7 and Windows PowerShell 5.1).
Not tested: a list of head units by model year. If a file played or failed on your car, an issue saying which model year and head unit is the data this project is short of.

Known issues

HDR sources (HDR10, HLG) are not tone-mapped. carify warns, and the result looks washed out.
Only the first audio track is kept. If that's commentary or the wrong language, pick the track with ffmpeg yourself.
Subtitles are dropped, not burned in.
FAT32 sticks can't hold files over 4 GB. carify says so when the copy fails; format the stick as exFAT or use a lower --max-height.