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Review Amimon WHDI: Remote HDTV from your PC

Posted by Kathleen Maher on July 28th 2011 | Discuss
Categories: Hardware Review
Tags: graphics gaming review computers

Israeli based Amimon developed WHDI (Wireless High-definition Interface) chipsets. A fabless semiconductor company, Amimom established the WHDI concept for uncompressed wireless HD video for CE video devices. WHDI allows flat-panel televisions and multimedia projectors to wirelessly connect to HDTV video sources and obtain a quality equivalent to that achieved with wired interfaces such as component video, DVI and HDMI, or so says the company.

The company’s modules and reference designs are for the 5GHz unlicensed band of uncompressed HD video streams, and offer equivalent video data rates of up to 3 Gbps (including 1080p) using 40 MHz of bandwidth in compliance with FCC regulations. Video data rates of up to 1.5 Gbps (including 1080i and 720p) can be delivered using 20 MHz of bandwidth, conforming to worldwide 5GHz spectrum regulations. The range is beyond 100 feet, through walls, and latency is less than one milli­second.

Some of the technical statements made by the WHDI group have raised questions about the claim of 3Git/s data rates. Sceptics say such claims violate basic laws of physics. Claims of 3Gbit/s data rates over a 40MHz channel equates to 75 bits per Hz. (3Gbit/s divided by 40MHz). For those not schooled in communications theory this is a number almost ten times what physics dictates is possible (802.11n by example only goes to 8 bits using QAM-256 best case). We asked Amimon about this and they told us

WHDI is a video modem not a data modem, so the comparisons to data modems can be confusing—when comparing wireless video links one should compare the relevant metrics of video: what video rate (1080p, 720p etc.) can be delivered at what quality (robustness, PSNR) and at what latency.

WHDI delivers 1080p 60Hz (which is 3GBps of Raw Video). WHDI can also deliver deep color (which actually brings it up to 4.5GBps). WHDI delivers the video with no loss of quality (it’s equivalent to HDMI) and with practically no latency (less than one millisec). Unlike data modems that treat every bit the same way, WHDI prioritizes the transmitted information based on visual significance: more significant information gets more protection; less visually significant information gets less protection over the channel—the result is a highly robust link that results in very high quality. (WHDI technology is used in medical applications and in professional applications because it is the highest quality wireless video solution).

Given that WHDI is based on prioritizing based on visual significance, it cannot be used for delivery of random data—so this may be the part that can be confusing (delivery of 75 bit per Hz of random data is of course impossible, but delivery of raw video with that rate is made possible with the WHDI video modem techniques).

There are a couple of other wireless techniques for sending HDTV via HDMI through the ether in your home. For example there’s Intel’s WiDi also known as WirelessHD which is based on 802.11n. The first generation only supports a 720p, Wireless Gigabit Alliance (WiGig), and the IEEE 802.11ac effort to name a few.

The tests

We got a kit from Amimon and tried out the WHDI. We’ve already experimented with the WirelessHD stuff using an HP Wireless TV Connect and were pretty pleased in an earlier review, although we felt the range could be better.

With the Amimon unit we again used an HP Envy 17 3D as the source (love that machine). Unfortunately we don’t have 120 Hz HDMI monitor so we couldn’t test remote S3D. The current transmitter dongle is delivering 1080p/60 over the HDMI cable. The TV uses a Frame Rate Converter (FRC) to convert to 120Hz, 240Hz or even higher. Amimon says their next generation chip will support resolutions of up to 4Kx2K.

The installation couldn’t have been easier. Plug the transmitter dongle into the HDMI socket on the source (the HP Envy), connect the dongle to a USB port on the PC side for power (if your PC’s USB doesn’t offer enough power you can always use a USB power plug like the type used with mobile phones. Then on the monitor side, plug in an HDMI cable between the monitor and the receiver, plug in the receiver’s power supply and bam—you’re done. No drivers to load, no setup menus, just plug and play.

We used Despicable Me as the first test, and then Kung Fu Panda. CyberLink Power DVD 10 was used for the Blu-ray player (Microsoft’s Media Player in Win 7 doesn’t support Blu-ray yet).

We used an HP Dreamcolor LP2480Zx as the HDMI display. It is a 24-inch 1900 x 1200 resolution display with 10-bit primary color—the widest gamut you can get. The screen of the HP Envy 17 3D is a 17-inch 1920 x 1080 120 Hz display and it looks fantastic, and also would show up any flaws in the original content. We paused the movies at various places and closely examined the images on the Envy 17 and the HP 24-inch monitor and could detect no difference.

When we ran the movies we looked at the HP 24-inch monitor for any stutters, frame drops, tears, or distortions and saw none—nada, nix. The data flow was perfect, and looking at them side by side we could detect no latency.

We also ran a game (“Far Cry 2”) on the HP Envy 17 and used a wireless mouse and keyboard in front of the HP 24-inch monitor. Game play was excellent.

The specifications say you can be up to 30 meters away, and although we didn’t qet quite that distance, mostly due to the limitations of the mouse and keyboard, we did get 10 meters away and everything still played fine. We declare WHDI a winner.