Video for a car head unit screen

An online tool that prepares video for a car screen — a factory head unit, an Android head unit, a headrest monitor or a portable player. It inspects each file and names the reason the device will not open it: a container outside the list, an H.264 profile above what the decoder understands, a frame larger than the screen, an AC-3 or DTS track instead of ordinary AAC, a size past the FAT32 limit. Then it brings the clip down to workable parameters, burns in subtitles when there are any, and writes the files to the drive one at a time in the order you set.

How to prepare video for a car head unit

Add the clips

Drop the video in, plus any .srt files if you want subtitles. The tool immediately shows the container, codec, profile, resolution and audio track of every file.

Pick the generation of the device

A headrest screen, a 2010s factory unit and an Android head unit understand different things. The choice sets the allowed H.264 profile, the resolution and the list of audio codecs.

Give the screen resolution

If you know the exact numbers for your unit, enter them: a frame that matches the screen encodes more efficiently and is shown without scaling.

Write to the drive

Pick the stick in the folder dialog. Files land one at a time in the given order; eject the drive properly so the directory table is written out.

Bring a clip down to what the car screen will actually open

Drop video here or click to browse

MP4, MKV, AVI, MOV, WMV, TS, MPG + SRT ·

You can drop .srt files in alongside the clips — they match by name and get burned into the picture. A head unit almost never reads external subtitles, so there is no other way to see them.

Clips (0)

#	Source file	On the stick	Processing

Drag rows to set the order. A FAT32 directory is not sorted — the unit reads entries straight through, so the order of writing is the order of playback.

Settings

What device do you have

The generation decides the thing that matters most: which H.264 profile the decoder understands at all. Budget screens do Constrained Baseline only, and a High-profile file will not open even though it is formally the same H.264.

Screen resolution

A frame bigger than the screen is either refused or played in jerks. The exact resolution is usually in the unit spec; if you do not know it, leave the default.

Re-encoding speed

Order

File name encoding

The unit shows the file name in its list. Latin reads everywhere; not every unit handles anything else.

Folders Put a number at the start of the name («01 — …»)

What the video preparation does

Finds the H.264 profile — the invisible cause of refusal

A phone records in High profile while a budget screen decodes Constrained Baseline only. The file still looks like an ordinary MP4 with the H.264 codec, and the owner gets «format not supported» with no hint at all. The profile is read from the header and shown in the table.

Verifies that the encoder gave the profile that was asked for

A codec string is a hint to the graphics card, not a requirement: a hardware encoder may hand back High where Baseline was requested, and no error is raised. The finished file is re-inspected, and on a mismatch the clip is redone with the software encoder and an explicit profile flag.

Leaves alone whatever already plays

A clip that clears every threshold of the chosen generation is copied to the drive as it is — no re-encoding, no quality loss, no waiting. The table says which path each file took and why.

Burns subtitles into the picture

A head unit almost never reads an external .srt, so the only way to see a translation is to print it into the frame. Subtitle files pair with clips by name; the type size is derived from the frame height, because the distance to a car screen is the same while screen resolutions differ.

Reads subtitles in any encoding

A Russian .srt is nearly always windows-1251, and burning it as-is would print gibberish into the picture permanently. The encoding is settled before burning — from the byte-order mark, from the strictness of UTF-8 and from the density of Cyrillic.

Splits a file that does not fit FAT32

A stick for a head unit is almost always FAT32, where a single file cannot exceed 4 GiB. A bigger film is cut into parts by stream copy, with no second re-encode and no further quality loss.

Why bother when you can just copy the film onto a stick

You can, and sometimes it works. The trouble is that you cannot tell in advance whether it will: a file manager shows the name, the size and the word «H.264», while what decides is the profile of that H.264, the resolution relative to the screen, the codec of the audio track and the limit of the file system. Each of those properties fails in its own way — from «format not supported» to «picture but no sound» — and none of them explains itself on the screen in the car. This tool checks them all and gives the answer before the drive, not after.

Questions about video for a car head unit

Why does the head unit say «format not supported» when this is an ordinary MP4 with H.264?

Almost always the H.264 profile. Inside one and the same codec there are several profiles of differing complexity: phones and cameras record in High, while budget screens and factory units up to the mid-2010s decode Constrained Baseline only. Neither a desktop player nor the file properties show this — everywhere it just says «H.264». This tool reads the profile out of the header and puts it in the table next to the resolution.

I do not know my head unit screen resolution. What should I pick?

Leave the default: it comes from the chosen device generation and is guaranteed not to exceed what such a screen displays. The exact numbers are usually in the model spec; the most common are 800×480 on older factory units, 1024×600 on Chinese Android head units and 1280×720 on recent ones. A frame smaller than the screen gets stretched by the device itself; a bigger one may be refused.

Why are my .srt subtitles not visible in the car?

Because a head unit almost never looks for a separate subtitle file next to the video — desktop players do that, built-in ones do not. The only reliable route is to print the text into the picture itself, which is what this tool does: drop the .srt in with the clip and it pairs by name. Burned-in subtitles cannot be undone, so you will not be able to switch them off in the car afterwards.

Why will a 5 GB file not copy onto the stick?

Because the stick is formatted FAT32, and that file system cannot hold a file larger than 4 GiB — a limit of the format itself, not of the drive size. Reformatting to exFAT or NTFS is usually not an option: the overwhelming majority of head units read FAT32 only. The tool cuts such a film into parts by plain stream copy, with no second re-encode.

Why are some clips ready instantly while others take ages?

The instant ones clear every threshold of the chosen generation and are copied untouched — there is nothing to do to them. The rest have to be re-encoded, and that is work on every single frame. Where possible the encoding runs on the graphics card and takes minutes; for containers such as Matroska and for clips with subtitles the software encoder has to be called, and then it is tens of minutes.

The picture plays but there is no sound. What is wrong?

Most often the track is AC-3, E-AC-3 or DTS — codecs that come with films downloaded from torrents, and budget devices are not licensed for them. The picture decodes fine, which is exactly why you get «video but no sound». Such a file is flagged in the table with the «audio codec» reason, and on re-encode the track is folded down to stereo AAC, which everything understands.

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Who is this tool for?

🚗 Drivers

Published 10 Sep 2026 Author: The Supreme