NEW YORK –When it comes to the HDTV interface, industry watchers agree that HDMI, originally developed by Silicon Image, is the hands-down winner.

But in the mobile world, no such consensus applies. The mobile industry hasn’t indicated its interface preference for streaming HD video from a smartphone or a tablet to an external large-screen TV.

Analogix Semiconductor, Inc. (Santa Clara), focused on DisplayPort-based interconnect technologies, is hoping to tip this uncertain balance, by joining STMicroelectronics’ effort to push MYDP (Mobility DisplayPort).

MYDP is a mobile digital interface designed to reduce the number of communication signal pins for the mobile market. Earlier this year, ST, billing it as a companion to the DisplayPort standard, submitted an MYDP proposal to the Video Electronics Standards Association (VESA).

ST and ST-Ericsson are now both behind MYDP.

Carlo Bozotti, ST’s CEO, expressed in May ST’s commitment to extend the adoption of DisplayPort beyond monitors to mobile devices. Bozotti then said: “DisplayPort can contribute a lot to our top-line evolution.”

Although VESA’s comment period hasn’t started for MYDP, Analogix is jumping the gun and announcing Wednesday (Sept. 7th) that the company’s own SlimPort family of transmitter and receiver chips – which use the same underlying technology as DisplayPort – is compatible with the ST-promoted MYDP digital interface.
   
Consider this move an opening salvo in the MYDP vs. Mobile High-Definition Link (MHL) battle.

As Jon Peddie, president of Jon Peddie Research, explained, the MYDP interface doesn’t specify the connector type. “That makes it up to the device makers to decide whatever connector they want to use.” MYDP features a MUX that allows the DisplayPort signal to share signaling with USB, allowing the standard Micro USB port to be used for both DisplayPort and USB connectivity, he added.

Both Analogix and ST, armed with SlimPort and MYDP, intend to go head-to-head against Silicon Image and MHL.

More than three years ago, Silicon Image and a consortium of companies developed MHL, a new mobile audio/video interface standard for connecting mobile phones and other portable devices to high-definition televisions (HDTVs) and displays.

MYDP is ‘a rogue’ interface

Industry observers and analysts are hedging their bets on MYDP – for now – over concerns that it’s just a re-invention of the MHL wheel.

Randy Lawson, IHS iSuppli, principal analyst for display electronics and consumer market research, noted, “I do believe that MHL has much promise, despite a slow start (MHL was announced in 2008; but the first official standard was not released until last year and first products only coming out now from Samsung).” He described HDMI “the de-facto standard for HD display interface,” because its ubiquitous status in HDTVs, and on-going growth of HDMI transmission ports into the mobile space (like laptops). “That would seem to bolster a view that MHL has ample opportunity for future design-ins,” he added.

Peddie agreed. “MHL has some consortium backing and therefore has more brain power and maybe political power behind it. So if I had to pick a winner it would be MHL.”  

Peddie, however, also acknowledged the strong adoption rate DisplayPort has achieved in the PC, notebook, tablet and monitor spaces. As acceptance of DisplayPort grows, “it would be a natural progression of DisplayPort to support HD display connectivity from mobile devices.”

The two analysts agree on this: MYDP and MHL are trying to accomplish the same thing. Lawson said, “I am not aware of any significant trend to support DisplayPort in mobile devices [at this point]. And I would say that the capability added would seem redundant anyway.” Calling MYDP “a rogue,” Peddie said that it threatens to take the industry “back to the future of a different connector on every system trying to do the same thing.”

‘MHL to HDMI is not a done deal’

Meanwhile, STMicroelectronics and Analogix are on a mission to let the whole world know that MHL to HDMI is far from a done deal in the mobile world. They insist that MYDP and SlimPort still have a plenty of time and opportunity to achieve broader acceptance.  

Andre Bouwer, vice president of marketing for Analogix, believes MYDP will win support in mobile application processors, operating systems and mobile handsets.  Bouwer, while declining to name names, hinted that his company has stirred interest in its forthcoming Slimport products from handset OEMs and apps processor companies.

What exactly would make MYDP more attractive than MHL, then?

Being royalty-free is the first and foremost advantage. SlimPort and MYDP are both based on DisplayPort, a standard owned by VESA and conceived to be a free, open standard.

Second, SlimPort and MYDP can connect to HDMI, VGA and DisplayPort displays. This is an important distinction from MHL, in the view of Analogix’s Bouwer, because with SlimPort (or MYDP), professionals can deliver presentations by connecting a smart phone to a projector. “There is no way to connect a phone with MHL to VGA or DisplayPort display devices like projectors,” he added.

Third, it’s important to note that MHL, SlimPort and MYDP were all created to make the USB connector – already present to power the phone – also transfer video. The key difference between SlimPort/MYDP and MHL, lies in power consumption when streaming video.

Take an example of Samsung’s Galaxy S II smartphone, the first MHL-enabled handset. The Galaxy S II’s standard Micro USB port can be used with an MHL connector for HDMI connection to an external display such as an HDTV set. MHL lets the handset send uncompressed 1080P video and audio to the TV. MHL’s advantage is that it allows the smartphone’s battery to charge while playing back multimedia content.  


‘MHL and HDMI are not the same thing’

What may be less openly publicized, though, is that the MHL-enabled mobile device can only draw power from MHL-enabled external displays. “MHL and HDMI are not the same thing,” stressed Bouwer. To date, Toshiba is the only company openly committed with a plan to launching MHL-enabled digital TVs.

In the absence of MHL-enabled HDTV today [HDTV sets on the market today do not support MHL], a smartphone like Galaxy SII featuring MHL could end up eating its own mobile device’s battery when streaming HD video to external displays. Alternatively, MHL-enabled mobile devices can connect to legacy HDMI TVs by using a MHL-to-HDMI dongle. However, because of power consumption issues, “a separate power cable is required,” noted Bouwer.

In contrast, SlimPort can be implemented immediately, driving legacy TVs without modifications and without the need for inconvenient power cables, he added.  

Bouwer offered the example of displays with DisplayPort input, like the Dell Ultrasharp U2711.  SlimPort devices can charge batteries while playing video on the display.

But not every HDTV today has a DisplayPort.  No problem, says Bouwer. “DisplayPort inputs will naturally be added to TVs to replace VGA inputs as VGA declines in the coming years. This input can provide power to the mobile device -- 1.5 watts (W) according to the DisplayPort specifications.”

OK, so what happens if you connect SlimPort to a legacy HDMI-equipped HDTV? In this scenario, SlimPort consumes around 100 milliwatts (mW) in the SlimPort transmitter and around zero milliwatts (mW) in the dongle, according to Bouwer. “This is due in part to the nature of DisplayPort as well as Analogix power recovery technology. The power consumption is less than the internal display of the mobile device, so you can play video longer on the big screen than you can on the internal display. Therefore, no power cables are required.”

To be absolutely fair to Silicon Image, though, MHL-enabled DTVs have been in development, and the company is waiting for its OEMs to announce them, according to a Silicon Image spokesperson. Asked what it would take for OEMs who designed in Silicon Image’s port processors to make their TV sets MHL-capable, she said they must “ensure [that] the firmware in the DTV includes support for MHL technology, and then add a voltage regulator to enable the DTV to provide power over the existing connector.” She noted, “Our estimate is that the addition of the voltage regulator is 5 – 10 cents additional cost.”

Do mobile apps processors support DisplayPort?

Building the case for MYDP, Analogix’ Bouwer said, “All leading apps processors in the world are either designing in, or in the process of integrating DisplayPort in to their display output interfaces.” However, when EE Times asked Qualcomm and NVidia about such a plan, they both declined to answer.

Bouwer also stressed DisplayPort support among mobile OS suppliers. Google, for example, have joined a DisplayPort consortium earlier this year. “Their plan is to support the smartPhone and tablet space with DisplayPort driver functionality as they were requested to do so by their apps processor partners.”

But is there support for DisplayPort among handset OEMs vendors? So far, the Samsung and HTC handsets are the only devices designed with MHL. “With the introduction of SlimPort chipsets from Analogix (based on DisplayPort Technology) earlier this year, we have seen OEMS take significant interest in the elegance of the SlimPort solution,” said Bouwer. “With DisplayPort deployment in the hardware by apps processor providers and software by the OS providers, it is natural for handset makers to adopt the DisplayPort solution on the mobile devices,” he concluded.


What about MIPI-DSI for mobile devices?

But things may not be that simple. IHS iSuppli’s Lawson, arguing the case for MHL, stressed, “The embedded display interface technology of MIPI-DSI (digital serial interface) for mobile devices is not expected to change.”  He added, “So support for MYDP would make two separate high-speed serial display interface technologies required to be integrated in future apps processor chips, and even then would still require an active dongle between the DisplayPort output of such a device and the HDMI receiver input.”

Indeed, Analogix’s first SlimPort products, sampling now, have a MIPI input and DisplayPort output, Bouwer responded. “MIPI-DSI will continue to be the internal display interface for small and medium sized mobile phones.” But he added, “The higher resolutions used in planned tablet designs (e.g. 1920x1200 or higher) require the higher bandwidth capability of DisplayPort. Application processor makers will add eDP [embedded DisplayPort] in order to compete for tablet designs. DisplayPort and MIPI will coexist for large and small screens respectively.”