HDMI converters exist because the a/v industry has spent the last 30 years inventing ways to make perfectly good old gear obsolete. For example, Yif you have a new Roku and an old TV. A laptop with HDMI and a projector with VGA. A DVD player with RCA outputs and a television that has forgotten RCA ever existed. Somewhere in the middle sits a little powered box promising to make peace between them. That box is an HDMI converter.
The important thing is knowing which kind you need, which direction it works, and when a converter is the wrong tool entirely.
What Does an HDMI Converter Actually Do?
An HDMI converter changes one audio/video signal format into another.
For example:
HDMI → RCA composite
or:
VGA → HDMI
or:
HDMI → component video
The converter isn’t merely changing the shape of the plug. HDMI is a digital signal. RCA composite and VGA are analog signals. To get from one to the other, electronics inside the converter have to process the incoming signal and create a new one the receiving device understands.
That’s why a cable with HDMI on one end and RCA plugs on the other usually isn’t a substitute for a converter. The connectors may fit, but the signals haven’t magically agreed to become compatible.
HDMI-to-RCA Converters
This is one of the most common converter jobs.
Suppose you have a streaming stick, cable box, or newer DVD/Blu-ray player with HDMI output, but your older TV has only the familiar yellow, red, and white RCA inputs.
You need an HDMI-to-RCA converter.
The hookup is:
HDMI source → converter → yellow/red/white RCA → TV
The converter takes the digital HDMI signal and produces analog composite video plus stereo audio.
There’s a significant catch: composite video is standard definition. A converter may accept a 1080p HDMI signal, but the old yellow RCA video connection isn’t suddenly becoming HD because “1080p” appeared in the product listing.
The picture will be limited by the output format.
RCA-to-HDMI Converters
Going the other direction is just as common.
Maybe you have a VCR, old DVD player, camcorder, retro game console, or another device with composite RCA outputs, but your new TV has HDMI and little else.
Then you need an RCA-to-HDMI converter:
RCA source → converter → HDMI → TV
These converters usually scale the old analog picture into a resolution the television can display over HDMI.
“Upscaling,” however, is not the same as creating additional picture detail. A fuzzy VHS recording does not become Blu-ray quality because the converter outputs 1080p. It becomes a fuzzy VHS recording neatly packaged inside a 1080p HDMI signal.
Sometimes that’s exactly what you need.
HDMI-to-VGA Converters
VGA still turns up on older projectors, computer monitors, classroom equipment, and commercial displays.
If your laptop or media player has HDMI but the display accepts only VGA, an HDMI-to-VGA converter can bridge the gap.
One wrinkle: VGA carries video only.
HDMI carries both video and audio, so if you need sound, choose a converter with a separate audio output and route that to speakers or another audio system.
This is an excellent example of why “does the plug fit?” isn’t enough of a buying strategy.
VGA-to-HDMI Is a Different Product
Direction matters.
An HDMI-to-VGA converter is not normally reversible. If your old computer outputs VGA and your new monitor accepts HDMI, you need a VGA-to-HDMI converter.
That unit has a different job: digitizing the analog VGA signal and packaging it as HDMI.
The same rule applies throughout the converter world:
Input first, output second.
“HDMI to RCA” means HDMI goes in and RCA comes out.
“RCA to HDMI” means RCA goes in and HDMI comes out.
Buying the right formats in the wrong direction is one of the easiest ways to acquire a very small, very useless plastic box.
Component Video Is Not the Same as Composite
This catches people constantly.
Composite video normally uses one yellow RCA connector for video.
Component video normally uses three RCA-style connectors—red, green, and blue—for video, with separate cables for audio.
The plugs look related because both use RCA connectors, but the signals are very different.
If your equipment has green/blue/red component video, don’t buy an HDMI-to-composite converter just because both products contain the word “RCA.” Look specifically for an HDMI-to-component or component-to-HDMI converter, depending on the direction you need.
When You Need an RF Modulator Instead
An HDMI converter is not the right tool if your goal is to connect HDMI to a television’s ANT IN or RF IN coaxial input.
That input doesn’t expect ordinary video. It expects a television channel.
So if your Roku has HDMI and your old TV has nothing but a threaded coax jack, you need an HDMI RF modulator, not an HDMI-to-RCA converter and not a passive HDMI-to-coax cable.
A modulator turns the source into a tunable channel.
A converter changes the source into another direct audio/video format.
That’s a genuinely important distinction.
What About HDMI Over Coax?
There is another category that gets mixed into this discussion: HDMI-over-coax extenders.
These products use coax simply as the transmission cable between a transmitter and receiver.
The arrangement looks like:
HDMI source → transmitter → coax → receiver → HDMI → TV
The television still receives HDMI. It doesn’t tune a TV channel.
This can be useful when coax already runs between two rooms and pulling a new HDMI or Ethernet cable would require opening walls.
Again, that’s different from RF modulation.
Check Resolution Before You Buy
Converters have limits.
A unit may support 1080p but not 4K. It may accept 60 Hz at one resolution but only 30 Hz at another. Some older converters struggle with unusual computer resolutions or specific refresh rates.
If you’re connecting ordinary 1080p consumer equipment, this usually isn’t complicated. If you’re connecting a 4K streaming device, gaming console, computer, or high-refresh-rate display, read the actual specifications instead of trusting the largest number printed on the box.
HDCP Can Complicate Things
HDMI can use HDCP, or High-bandwidth Digital Content Protection, for copy protection.
That means some sources may refuse to output protected video through equipment that doesn’t handle HDCP correctly. You can end up with sound but no picture, a black screen, or an HDCP error.
This tends to matter more with streaming devices, cable/satellite boxes, Blu-ray players, and other protected sources than with something like a camera or computer desktop.
If you’re converting protected HDMI content, make sure the converter explicitly supports the HDCP version required by your source.
Powered Converters Are Usually the Real Thing
Actual signal conversion requires electronics, and electronics require power.
Many HDMI converters use USB power. Others use a small AC adapter.
If a product claims to convert HDMI into a fundamentally different analog format with nothing more than a passive cable, approach it with suspicion. There are specialized cases where unusual cables are valid, but HDMI-to-composite-video conversion isn’t normally one of them.
Don’t Expect Conversion to Improve the Original Picture
Converters solve compatibility problems. They don’t perform miracles.
If your source is VHS, the picture is still VHS.
If you’re converting 1080p HDMI down to composite video, you’re throwing away resolution.
If you’re converting VGA to HDMI, the HDMI output can’t recover detail that wasn’t present in the VGA signal.
A good converter should preserve the source as well as the destination format allows. That’s a much more realistic goal than expecting it to upgrade the source.
The HDMI Guy’s Quick Buying Rule
Before buying anything, answer three questions:
What connection comes out of my source?
What connection goes into my TV or display?
Which direction does the converter need to work?
Then check whether you actually need conversion at all.
If both devices have HDMI, use HDMI.
If you’re changing HDMI into RCA, VGA, component, or another direct A/V format, use the appropriate converter.
If you’re trying to feed HDMI into the TV’s coax/antenna jack or make the source appear as a television channel, use an RF modulator.
And if you’re only trying to move HDMI a long distance over existing coax, look at HDMI-over-coax extenders.
The central rule is wonderfully unglamorous: buy the device that converts the signal you actually have into the signal your equipment actually accepts.
That sounds obvious right up until you’ve spent $24.99 on the same converter in the wrong direction twice.