HDMI Mirroring

One of Tegra 2’s most interesting features is support for multiple displays—HDMI 1.3 at 1080p mirroring is supported. The implementation on the 2X is how other Android phones with HDMI ports should have worked, you plug the HDMI cable in, and everything on the phone is instantly mirrored on the connected display. Android isn’t suddenly rendered at higher resolution, it’s just scaled up to whatever resolution of HDMI device you connect to, but that looks surprisingly good.

In portrait mode, there are black bars at the left and right, but rotate to landscape and the WVGA Android screen fills 1080P displays. WVGA (800x480) isn’t exactly 16:9, but it’s close, so there’s a little stretching in landscape but nothing noticeable.

The result is that you can use the 2X to play angry birds on a 55” TV without waiting for the console version, browse the web, give a PDF or PPT presentation, or do anything you’d do on the phone on a different screen. I put together a reasonably comprehensive video showing off HDMI mirroring.

There’s a tiny bit of input lag. In the video I shot showing off HDMI mirroring, it’s entirely possible some of that is just the result of my Onkyo TX-SR608 A/V receiver which seems to add a consistent 100ms of lag to almost everything, even in game mode. The supplied microHDMI cable is just long enough to stretch from the receiver to my couch, I could use a few more feet to be comfortable however.

You can also play videos over the HDMI connection, while doing so the 2X shows a "showing on second display" message:

HDMI mirroring works shockingly well, and sends all audio over HDMI. It’s a bit difficult to look at the TV and interact with the phone’s touchscreen, but not impossible. WebOS and others have drawn circles on the screen to show where fingers are. The tradeoff there is that it’s one more element to clutter display.

Video Playback

The big question is how well the X2 (or any Tegra 2 smartphone) could work as a mini-HTPC. NVIDIA advertises a big long list of codecs that Tegra 2 can decode:

LG’s own spec list (what's below is actually for the Korean version, but the video codec support is the same) is much closer to the truth for the X2 because of Android’s player framework and other limitations.

You can play back H.264 1080p30 content, but it has to be Baseline profile—no B frames, two reference frames. I used handbrake and messed around with a variety of other encode profiles and eventually settled on a bitrate of around 10 Mbps. That puts a 2 hour movie at around 8 GB total, which is too big to fit on a FAT32 microSD card. If you’re going to fit 2 hours of video on that SD card and stay under 4 GB, bitrate should be around 4 Mbps. Tegra 2 can decode H.264 1080P baseline at a maximum of 20 Mbps.

Interestingly enough, I tried the iPhone 4 preset in handbrake which is H.264 960x400 High profile and noticed some stuttering and dropped frames. Media playback on Tegra 2 as it stands definitely works best with H.264 baseline, it’s just a matter of having gobs of storage to park video on.

The 2X didn’t do very well in our media streamer test suite. Some of that is because the software lacks the ability to open mkvs and a huge number of our files. The two that did open and playback successfully were test 3, an 8 Mbps 1080p WMV9 video with 5.1 WMA audio, and file 19, a simple m4v container test. Unfortunately we’re still not at the point where you can dump just about anything you’d stick on an HTPC on your mobile device without a transcode in-between, it’s no pirate phone.

Software Preload and Constant Crashing Battery Life and Final Thoughts
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  • Exophase - Monday, February 7, 2011 - link

    Thanks Anand.

    I'm surprised to hear that shot was from IMG, given that it was an IMG employee who made the comment originally about Tegra's 16-bit banding being evident on it, from the screenshot. Whoops. I do wonder what could be causing this, then.

    Nonetheless, while that definitely makes my 16bit color claim invalid the depth buffer one should still hold. We might need to wait and see how much of a difference this actually makes, or rather how effective nVidia's 16-bit depth space is.

    I'm glad to hear that you're as concerned about benchmarks on Android as I am. It's especially frustrating when I see people using them to try to indicate Atom being substantially better clock for clock than Cortex-A9.
    Reply
  • Exophase - Monday, February 7, 2011 - link

    Managed to miss this:

    "The test ramps from around 3k vertices to 15k vertices per frame, and 190k to 250k triangles per frame"

    That line doesn't make any sense. How would you have hundreds of times more triangles than vertices? You must have meant something else.
    Reply
  • sid1712 - Monday, February 7, 2011 - link

    Great review as usual but i'm disappointed about the lack of details on the Sound Quality of the phone. A comparison of the sound quality (via headphone jack) alongside the iPhone 4 and the Galaxy S (with Voodoo kernel preferrably) would give a good idea about the SQ of the phone. Reply
  • ScentedKandle - Monday, February 7, 2011 - link

    Related to this, the audio codec lists "lossless" but doesn't mention what format. Can the audio chip natively decode FLAC? Reply
  • teldar - Monday, February 7, 2011 - link

    The order of buttons if the same as my droid x. Reply
  • Pjotr - Monday, February 7, 2011 - link

    Does it really record 1920x1088? Does this unorthodox resolution play well on TVs, if you put it on a USB stick, for example? Reply
  • Brian Klug - Monday, February 7, 2011 - link

    It plays back from the phone properly, and most of the playback software just does a crop. A ton of devices actually produce 1088 and don't make note of it, it should playback fine.

    -Brian
    Reply
  • unmesh - Monday, February 7, 2011 - link

    For active aka switching transistor power consumption, C*V^2*f (C is capacitance and f is frequency) is a better proxy than V^2/R.

    The conclusion that operating voltage has a huge effect remains the same.
    Reply
  • Kevin098 - Monday, February 7, 2011 - link

    Hey, can you make a video comparison between the iphone 4 retina display and Optimus 2x ? Reply
  • StormyParis - Monday, February 7, 2011 - link

    Pages and pages of (apparently not very acurate, too) perf data, and not even one line on sound quality, which is one of my key buying points for a phone.

    No info on whether I'll be able to stream PC-resolution videos off my server to my bed over wifi.

    Overall, not a very useful review. More like a dick size contest.
    Reply

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