Oppo HM-31
HDMI Switcher

Oppo Digital HM-31 Advanced 3x1 HDMI Switch

HDMI video switches are a necessary part of the modern Home Theater experience, especially if you have more than one computer in the same room together or a HDTV and a computer in the same room or other combination of devices in the same room that use similar interfaces like D-Sub or DVI connections.

OPPO is known in the Audio Video community for building high-quality components for inexpensive prices. They make HDMI cables, the HM-31 HDMI switch being reviewed here, and Universal DVD players with HDMI connections. The HM-31 is the first device from OPPO that I've received on the review bench.


  • asy and convenient selection from up to three HDMI sources
  • HDMI 1.3 specification with DDC and HPD switching
  • Fully supports 1080p, Deep Color , and all HDTV resolutions
  • EIA/CEA-861D, DVI 1.0, HDCP 1.1 compliant
  • Long cable support with built-in equalizer
  • Maintains highest video and audio quality
  • Remote control
  • Custom installation options - external IR input and RS-232C port

So what is HDMI anyway? HDMI stands for the High Definition Multimedia Interface. It is a audio/video connection to connect to computers, HDTVs, video game consoles like the Xbox360 and DVD players. On the computer side, HDMI has started being installed in new LCD monitors replacing the DVI standard that has been around for years.

HDMI has several standards in the marketplace today: 1.0, 1.1, 1.2, 1.2a, 1.3, 1.3a, 1.3b and 1.3b1. The first implementation had support for 1080p and 8-channel/192 Khz/24-bit audio. Version 1.1 added support for DVD Audio. HDMI 1.2 added support for HDMI Type A connectors for PC and One BIT audio. Version 1.3 increased the bandwidth of HDMI to 10.2Gbits/Second and supports Dolby TrueHD and DTS-HD master Audio CODECs.

High Definition Television (HDTV) has taken over the marketplace over the analog TVs of earlier years and HDMI is the main interface for HDTV in use today. The modern HDTV has support for 1080p resolution which is 1920x1080 progressive scan resolutions. The HM-31 supports version 1.3 HDMI which allows for a maximum resolution of 2560x1600@75hz which is the highest resolution available on the standard computer monitor and video card combination on the market today.

Blu-Ray has won the format war between it and HD-DVD as the next standard in optical media. After July 1st 2008 Blu-Ray Discs will be the primary optical drive standard for movies released in the HD arena. The HM-31 supports connecting either a Blu-Ray Drive or HD-DVD to it and playback at all resolutions of those formats on a HDTV.

The Xbox 360 and Playstation 3 support High Definition gaming. The Xbox 360 supports HDMI version 1.2 and upscales the resolution up to 1080p. The PS3 supports HDMI 1.3a and has native 1080p resolution support. The HM-31 can connect to either the PS3 or the Xbox 360 or both at the same time and use the switch to switch between the consoles.


  • OPPO HM-31 Advanced 3x1 HDMI Switch
  • Remote Control
  • AC Adapter
  • User Manual

The OPPO HM-31 comes with everything needed to run a multiple device HDMI system except the HDMI cables which are available online from OPPO for an additional $9.99 or come with your HDMI device that's being connected to the HM-31. OPPO includes a carrying case made out of faux leather which is a nice touch but as a user who intends to use the HM-31 unnecessary.

The HM-31 itself is sized similarly to an old-style VHS tape. The review unit came in an all-black metal case which looks great sitting next to my black HDTV. You can mount it on a wall or on top of your TV or other HDMI device. The front of the unit has three LEDs to show which device is active 1, 2 or 3, the IR Remote Sensor, a Power light and the Select switch which allows you to choose which device to use.

The rear of the device contains the DC-In jack to where the AC Adapter is plugged into, a RS-232C connection, the External IR Remote Sensor Input connection, the HDMI Output port and three HDMI Input ports. The Manual discusses usage and mounting scenarios and gives a description of the various components of the HM-31 switch.

HM-31 includes a Infra Red (IR) remote control unit to control it. There are a total of four buttons on the IR Remote, including the next channel and specific buttons for each channel on the Switch. The remote uses a Lithium battery (one is included with the package), so when it runs out just order another from OPPO. The switch button on the HM-31 device also works well as pushing the button changes the channel.

Setup and Usage

Setup of the HM-31 is easy. Plug the AC Adapter into the wall and then plug the DC plug into the DC In port. Plug the Primary HDMI Outport into the monitor or HDTV and plug the HDMI cables from the other devices into the HDMI In ports. A typical installation might consist of attaching the HDMI cable to the HDTV in the living room then using HDMI cables to PS3, Xbox 360 and Blu-Ray Drive.

In the test system I set up using a 52" HDTV from Samsung, a PS3 and a Blu-Ray Drive from Sony. The PS3 outputted the same as connecting it directly to the HDTV. The Blu-Ray Drive played 1080p Blu-Ray Discs with no loss of quality on the switch that I could see. Switching to the Cable TV was a simple matter of pushing the channel switch on the remote and it worked as well.

The HM-31 has an Automatic Input Selection ability which automatically switches to the next priority input on the 1, 2, or 3 lists. When an active input is turned off (i.e. turning off the PS3), the next port in line is made the active port. This works extremely well and is intuitive. The priority of the switches is 1, 2 then 3. If you have an active HDMI output when turned off as in some cable boxes plug the input into input 3 so it has the least priority.

You can mount the HM-31 on a wall, with pre-drilled holes set to allow you to mount it on the wall. Note that if you want to put the unit on top of the HDTV this switcher is small enough not to be obtrusive anywhere as it is smaller than a VHS tape. Mounting it on a wall requires drilling 3 holes in the wall and mounting the unit aligning with the holes. Another option is to hide the HDMI switch, but that requires an external IR Sensor to be plugged into the IR In port and line of sight with the switch to work.


The idea of a switch box to switch between video signals has been around for many years on the PC. We've used D-sub switch boxes for years until the current DVI switch box we use today was installed. The HM-31 is an excellent switch box well worth the $99 price tag, especially if you're hurting for places to plug in another HDMI or DVI device as the modern HTPC owner might have with PS3, X360, BRD, HDTV, and a HDMI equipped video card can quickly lead to having too many connections. OPPO offers a 1 year warranty on their HM-31 device and for the cost of a few dollars you get a very functional product.